2014 CONFERENCE ABSTRACTS

Vol I: January - July These papers are published with permission of the authors who have granted IPEM a non–exclusive right to publish, reproduce, distribute, display and store the abstract worldwide in all forms (including on the Institute’s website), formats and media now known or as developed in the future, including print, electronic and digital forms. Full copyright of the abstracts remains with the author. Copyright of this publication remains with IPEM. ISBN 978-1-903613-59-7 Institute of Physics & Engineering in Medicine Fairmount House 230 Tadcaster Road York YO24 1ES

CONTENTS

Radiation Protection in Nuclear Medicine ................................................. 3

Flattening Filter Free Photon Beams in Radiotherapy ............................ 18

Advanced Neuro MRI .............................................................................. 43

CT Optimisation ....................................................................................... 56

Workflow: it’s not just DICOM .................................................................. 67

Preparing Clinical Engineers for the Future: implementing a practical approach ................................................................................................. 78

2nd UK Patient Specific Modelling Meeting ............................................ 87

Annual IPEM Technologists Study Day - Technology on the Road to Recovery – and Beyond ........................................................................ 112

MPE Update .......................................................................................... 130

RPA Update .......................................................................................... 136

RWA Update ......................................................................................... 145

Physics in Doppler Ultrasound .............................................................. 153

Radiation Protection in Nuclear Medicine 19th February 2014, Austin Court, Birmingham Organised by the IPEM Radiation Protection and Nuclear Medicine Special Interest Groups

FINAL PROGRAMME

09:00 - 09:55 Coffee and registration

09:55 - 10:00 Introduction

10:00 - 10:30 Patient restrictions for Lu177 and Y90 therapies Invited Speaker: Claire Hooker, King's College Hospital NHS Foundation Trust, London

10:30 - 10:45 A simple method to provide personalised radiation protection advice to patients after Lu-177 Peptide receptor therapy Laura Perry, Imperial College Healthcare NHS Trust, London

10:45 - 11:00 Practical Radiation Protection for Radiosynovectomy with Yttrium-90 – the City Hospital Experience Joseph O’Brien, Sandwell & West Birmingham Hospitals NHS Trust

11:00 - 11:15 Some observations on the surface and external dose rates from Y90 syringes and their shielding Sue Hooper, Velindre Hospital, Cardiff

11:15 - 11:40 Coffee

Chair: Joseph O’Brien

11:40 - 12:10 Update on patient restrictions following I-131 therapy Invited Speaker: Bill Thomson, Sandwell & West Birmingham Hospitals NHS Trust

12:10 - 12:25 Patients Sent to Other Hospitals Following the Administration of Therapeutic Radioiodine – Practical Experiences from the Mersey Region or “I’ve got this in the bag!?” Matt Ward, Integrated Radiological Services Limited, Liverpool

12:25 - 12:40 Semi-Automated program for auditing IRMER requirements Daniel Gillett, Addenbrooke’s Hospital, Cambridge

12:40 - 12:55 A Quality Systems Approach to Radiation Protection in Nuclear Medicine Joanne Kerry, Lincoln County Hospital

12:55 - 13:10 Discussion Session

13:10 - 14:00 Lunch

Chair: Andy Bradley

14:00 - 14:30 CT doses in hybrid imaging Invited Speaker: Gareth Iball, Leeds Teaching Hospitals NHS Trust

14:30 - 14:45 Radiation protection considerations in SPECT-CT Anita Jefferies, Sandwell & West Birmingham Hospitals NHS Trust

14:45 - 15:00 New technologies supporting staff Radiation Protection in PET Daniel McCool, Royal Free London NHS Foundation Trust

15:00 - 15:15 Introduction of an automated PET dose dispensing system: initial findings on staff whole body dose Dave Ashworth, The Christie NHS Foundation Trust

15:15 - 15:40 Coffee

Chair: David Temperton

15:40 - 15:55 Eye Dose measurements in a wide range of nuclear medicine departments indicate that it is unlikely that staff will need to be classified Jennie Prince, The Christie NHS Foundation Trust

15:55 - 16:10 Experiences in Planning, Preparing & Operating a Radiation Monitoring Unit Anthony Hughes, The Christie NHS Foundation Trust

16:10 - 16:25 Transport of radioactive materials – the Newcastle experience Ian Driver, The Newcastle upon Tyne NHS Foundation Trust

16:25 - 16:45 Discussion Session

16.45 Close

A simple method to provide personalised radiation protection advice to patients after Lu-177 Peptide receptor therapy Miss Laura Perry, Radiological Sciences Unit, Imperial College Healthcare NHS Trust, Charing Cross Hospital, London W6 8RF Email: laura.perry2@nhs.net Perry L, Meades RT, Nijran KS, Al-Nahhas A PURPOSE: Lu177 Peptide receptor therapies are administered on an out-patient basis at our centre. Advice is given to patients at discharge to ensure radiation exposure to family, friends and members of the public is kept within legal limits and ALARP. A simple method to provide personalised radiation protection advice for patients is presented. METHOD: Retrospective analysis of doserate measurements from patients administered Lu-177 dotatate was undertaken to calculate an effective half-life of the therapeutic agent. At our centre four cycles of 7.4GBq Lu177-dotatate are administered over 12 months for each patient. The therapy is administered on an out-patient basis and post therapy imaging is performed either on the day of therapy or 3 days post-therapy. Doserate measurements are taken at 1m from the patient’s umbilicus immediately post administration, at discharge (typically 6 hours post administration) and 3 days post therapy where possible. Retrospective analysis identified 7 patients with doserate measurements that extended to 3 days post-therapy. For each patient an exponential fit was applied between the doserate measurements at discharge and 3 days post therapy. The average effective half-life for the doserate at 1m was calculated. Using behavioural models, adapted from O’Doherty (1993), the total effective wholebody dose from contact with the patient for other adults (including work colleagues), infants less than 2 years old, children between 2 and 5 years old and children between 5 and 11 years old was calculated. The doserate at 1m from the patient was modelled as exponential decay of the doserate at discharge with the calculated average effective half-life. It was assumed that inverse square law corrections could be made to calculate the doserate at other distances from the patient. For each behavioural group the number of days that contact should be avoided, to keep the dose within legal limits over 4 cycles of treatment, were derived. Restrictions for one-off exposures including maximum durations for travel using private and public transport were also calculated. These restrictions were calculated for discharge doserates between 0-50µSv/hr and summarised in a discrete look-up table which is used to provide personalised radiation protection advice to patients at discharge. RESULTS: The effective halflife for the average, normalised, doserate measurements at 1m was 35.9 (standard deviation 21.4) hours. This is shorter than values previously published by Fitschen (2011) and Wehrmann (2007) however these studies included larger numbers of patients with more, and later, doserate measurements. CONCLUSIONS: This work demonstrates a simple methodology that has the potential to provide patient specific radiation protection advice utilising limited patient data. Furthermore this method could easily be adapted for use with other radionuclide therapies. O’Doherty M.J., et al 1993 Radiation dose rates from adult patients receiving I-131 therapy for thyrotoxicosis Nucl Med Comms 14 160-168. Fitschen, J., et al 2011 External radiation exposure and effective half-life in Lu-177-Dota-Tate therapy Z. Med. Phys. 21 266-273 Wehrmann C., et al 2007 Results of Individual Patient Dosimetry in Peptide Receptor Radionuclide Therapy with

177Lu

DOTA-TATE and 177

Lu DOTA-NOC Cancer Biother Radio Vol 22 406-416

Practical Radiation Protection for Radiosynovectomy with Yttrium-90 – the City Hospital Experience Mr Joseph O'Brien, Sandwell & West Birmingham Hospitals NHS Trust, City Hospital, Dudley Road, Birmingham B18 7QH Email: joseph.o'brien@nhs.net Mr Joseph O’Brien, Mr Neil Smith, Dr D Situnayake, Dr WH Thomson, Mrs J Croasdale Radiosynovectomy is a long established therapy technique to treat the painful knee due to synovitis (painful inflammation of the synovial joint caused by over production of the synovial fluid). The technique involves the local administration of 185 MBq of Yttrium-90 colloid to the synovial cavity within the knee. This practice has inherent risks associated with radiation exposure and contamination from the beta radiation emitted by Yttrium-90. There is little information associated with minimising these risks published in the European Association of Nuclear Medicine Guidelines for Radiosynovectomy (1). The procedure is often carried out in clinic rather than the nuclear medicine department which can increase any potential risks. Our local procedure has incorporated several practical steps that are aimed at minimising these risks. In particular there is a potential for high finger doses from handling syringes and vials containing Yttrium-90. The surface dose on an unshielded syringe containing 185 MBq of Yttrium-90 can be as high as 8 Sv.h-1 The presentation will cover an overview of the procedure, explaining the methods we used to minimise personnel exposure and contamination. This will include:

Introduction to the team - prearranged tasks and responsibilities

Preparation and handling of the Yttrium-90 syringe

Radiation dosimetry for Yttrium-90 in vials and syringes

Appropriate shielding methods

Appropriate monitoring techniques

Administration of the Yttrium-90 – practical ways to minimise and check for contamination.

Dealing with Yttrium-90 waste References (1) Available online at <http://www.eanm.org/publications/guidelines/gl_radio_synovectomy_1.pdf?PHPSESSID=bpgf5piei53207ig2623jsdnd5> December 2013

Some observations on the surface and external dose rates from Y90 syringes and their shielding Miss Susan Hooper, Velindre NHS Trust, Velindre Road, Whitchurch, Cardiff CF14 2TL Email: Sue.Hooper2@wales.nhs.uk S Hooper and CA Crossley, Velindre Hospital, Cardiff WH Thomson, City Hospital, Birmingham Introduction Y90 is being used increasingly in GBq quantities for therapeutic purposes, e.g. Zevalin, DOTATATE and microspheres. Surface dose rates can be extremely high; there is a reported case of radiation dermatitis from the inadvertent handling of an unshielded vial of 16.7GBq Y90 for 10s. We have examined the surface and external (30cm) dose rates from different volume syringes containing Y90 using TLDs, dosemeters and spectral analysis, and also examined the effectiveness of different syringe shields. Method Surface dose rates for 1ml, 5ml and 10ml syringes were measured with TLDs over the active volume. The syringes were approximately half-full. Measurements were made with and without backscatter material representing finger tissue. Syringe shields (available for 1ml and 10ml syringes only) included Perspex (wall thickness 10.8mm, tapered to 2.7mm), standard tungsten shields, , and a commercial Zevalin shield (‘sandwich’ Perspex/lead ‘sandwich’, wall thickness 11.2mm Dose rates at 30cm were also measured (Smartion dosemeter). Results Surface dose rates (LiF-TLD-100) for unshielded syringes (held vertical) are shown Sv/h/GBq 1ml syringe 13.5 5ml syringe 7 10ml syringe 4.3 However there was bigger variation seen with 1ml syringe placed horizontal with 46Sv/h/GBq on top and 444Sv/h/GBq underneath. This variability resulted from rapid gravitational settling of Y90 citrate. Using syringe shields, results are shown mSv/h/GBq

Perspex shield Tungsten shield Zevalin shield

1ml 6.9 16.5 0.75

10ml 2.8 1.8 0.64

Backscatter (from finger tissue) was found to increase doses by approximately 18%.

Dose rates (Sv/h/GBq) at 30cm were also assessed using a Smartion dosemeter (beta shield in place). For reference, the value with the beta shield withdrawn and the syringe unshielded is also shown.

No Shield Perspex Tungsten Zevalin

1ml 47000 11 8 2.8

10ml 17100 11 3.7 3.2

Conclusions Y90 syringes should never be handled without shielding since very high surface dose rates can occur. When handling Y90 citrate invert the syringe prior to injection to achieve uniform mixing of the colloid suspension, and also note the higher dose rates on the underside of the syringe. Perspex shields often have a tapered edge on the underside where it may be held which would also significantly increase finger dose. The best syringe shield for both the 10ml and 1ml syringe was the Zevalin perspex/lead sandwich, but they are bulky and difficult to handle. Tungsten and Perspex shields are both acceptable however. Tungsten gives lower external doserates (contrary to popular opinion) and is easier to handle. However initial spectral analysis work has shown that a combination of 3mm Perspex and 1.6mm lead is as effective as the Zevalin shield, and would be much easier to handle. The critical tissue is the basal cell layer of the epidermis. The dose equivalent at a depth of 0.07mm, Hp(0.07) averaged over an area of 1cm2 is required to be assessed to satisfy Reg.11 of the IRR1999.This measurement requires care when handling Y90. ORAMED has recommended ring TLDs and a conversion factor. However with the difficulties of monitoring Y90 finger dosimetry and the wide variation in their recommended conversion factor it seems difficult to accept this monitoring method. Even with TLDs on the finger pulp, the beta response of the TLD should be known.

Patients Sent to Other Hospitals Following the Administration of Therapeutic Radioiodine – Practical Experiences from the Mersey Region or “I’ve got this in the bag!?” Mr Matthew Ward, Integrated Radiological Services Ltd, Tower Street, Brunswick Business Park, Liverpool L3 4BJ Email: mattward@irs-limited.com Matt Ward, Radiation Protection and Radioactive Waste Adviser, Integrated Radiological Services Limited, Liverpool. Melvyn Carroll, Consultant Physicist in Nuclear Medicine, Royal Liverpool and Broadgreen University Hospitals NHS Trust. Karen Harrison, Senior Radiographer and Radiation Protection Supervisor, Warrington and Halton Hospitals NHS Foundation Trust Outline: The aim of this work is to review and share with the community potential pitfalls of radioactive waste management in the context of recently administered radioiodine patients returning to non-administering hospitals, considering specifically the problems presented by unauthorised waste transfer across the hospital and off site. Therapeutic radioiodine services are frequently delivered in Liverpool on both inpatient and outpatient bases. The high volume of patients and activity involved in the former require that the specialist administering centre, Royal Liverpool University Hospitals NHS Trust, carries a suitable permit that includes I-131 as a registered radioactive material and accumulated waste product. There are strict radiation protection measures in place for this (frequently occurring) inpatient service. Where the latter outpatient service occurs, and the returning centre for the patient is another hospital, then the referring site and receiving hospital must carefully consider their own permitted (or exempted) situation with their RWA, RPA and MPE staff. In the Mersey region, this is a much less frequent occurrence. Suitable radiation risk assessments and, where necessary, controls, must be in place in order to restrict radiation doses, contamination and environmental waste hazards arising from the patient. What happens when things don’t proceed as planned? An account of an outpatient attendance is presented whereby a referral for an infirm incontinent patient was made from a local district general hospital to the specialist administering centre. The treatment was delivered in an outpatient fashion; the referring site requested that the patient return to their host premises in order to continue their care and thus became the receiving hospital for the active patient and associated radioactive waste generated. The episode is of note since an unauthorised transfer of waste occurred such that the waste was removed from the patient ward area and transferred off the DGH site through the established channels of the Trust’s clinical waste contractor, SRCL. The waste was radioactive and not classed as very low level (VLL) at the time of the transfer. The account aims to highlight difficulties encountered at the local hospital level prior to this waste transfer, subsequent information received from the waste contractor, communications with the administering site and details of the efforts to quantify the total activity and minimize the environmental hazard. Experiences, lessons learned and improvements made following the internal investigation and formal external involvement from the Environment Agency will be presented.

Semi-Automated program for auditing IRMER requirements Mr Daniel Gillett, Cambridge University Hospitals NHS Foundation Trust, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ Email: daniel.gillett@addenbrookes.nhs.uk Aims: Under IRMER 2000 there are requirements that patient doses are kept as low as responsibly practicable, that all exposures are documented, a clinical report is written for every exposure and local DRLs are established. Ensuring that these requirements are met can be a time consuming and labour intensive. Also, with many Nuclear Medicine departments adding CT to their service, this task becomes more complex and, arguably, more important because a CT scanner can give many times more dose than necessary if not audited regularly. The aim of this project was to create an automated system for auditing IRMER requirements. Method: Currently our Trust uses a Radiology Information System (RIS) to manage radiology patient appointments and clinical reports. This software has the functionality to record radiopharmaceutical administrations and CT doses. Data extracted from RIS can be imported into MS Excel. A visual basic program was created which performs a series of checks on the data. These include checking that:

i. every entry (excluding those that do not require exposures) has an exposure electronically documented;

ii. the exposure is within the acceptable range; iii. details including the isotope and chemical are correct.

Paediatric administrations are checked against a weight-adjusted activity for a child of that age. Reports that have not been written and/or verified are highlighted along with any other identified discrepancies. These are manually investigated and then a report is sent to every member of the department. Results: The program has been used for 6 months. There has been a reduction in the time it takes to audit the requirements specified in the introduction from several days by hand to a few minutes. The time taken to follow up on any potential faults has also been reduced because the program can look for solutions to common errors automatically which may otherwise be time consuming. The scope of the audit has been widened during the first six months from primarily checking administered activities to also checking reporting, CT doses and paediatric doses. This has enabled us to start the process of establishing local DRLs for CT. Several changes to practice have been implemented much earlier as a result of the increased frequency, such as ‘reporting’ of research studies and weight adjustment of PET scans. Also, the frequency of DRL limits being exceeded has been reduced by approximately 75% (4 to 1 per month) as a result of increased staff awareness. Conclusion: This semi automated audit program increases confidence that exposures are being performed safely and in accordance with national legislation and guidance. There has been a significant reduction in the time spent ensuring these requirements are met and, because the number of erroneous inputs has fallen, there has also been a reduction in the time wasted following up missing data and incorrect entries. However, by far the most useful outcome of introducing this auditing program has been the increased awareness of the staff to the requirements of the legislation and ultimately patient safety.

A Quality Systems Approach to Radiation Protection in Nuclear Medicine Mrs Joanne Kerry, Nuclear Medicine, United Lincolnshire Hospitals NHS Trust, Lincoln County Hospital, Greetwell Road, Lincoln LN2 5QY Email: Joanne.Kerry@ulh.nhs.uk J.Kerry, P.S.Cosgriff, Nuclear Medicine Department, Lincoln County Hospital Regulatory compliance is a major issue in nuclear medicine, and departments are subject to regular external inspection from several government agencies (e.g. EA, ONR, HSE). Demonstrating compliance depends heavily on written procedures, so accreditation to a recognised quality management standard (e.g. ISO9001:2008) is a good foundation from which to build. This obviously increases the number of external inspections, but ISO 9001 compliance visits tend to be helpful and supportive rather than threatening. This presentation will show how a document management system designed to support ISO9001 can be used to support procedure sign-off (e.g. Local Rules) and audit in radiation protection. Local audits recently undertaken include inter-site transport of radiopharmaceuticals (Road Transport Regulations), request form vetting (IRMER) and ARSAC DRLs. The benefits of an all-embracing annual RP audit (i.e. checklist) will also be discussed. Finally, the way in which NM radiation protection fits within the Trust’s Governance and Health and Safety structures will be explained, including escalation of ‘reportable incidents’. In summary, quality management system accreditation does not guarantee that all radiation protection regulations are adhered to, but the necessary ‘continuous improvement framework’ does provide a pro-active means of finding and fixing compliance issues within the system.

Radiation protection considerations in SPECT-CT Ms Anita Jefferies, Sandwell & West Birmingham Hospitals NHS Trust, City Hospital, Dudley Road, Birmingham B18 7QH Email: anita.jefferies@nhs.net The Department of Physics and Nuclear Medicine at Sandwell and West Birmingham Hospitals NHS Trust has had a GE Infinia-Hawkeye SPECT-CT system since 2007 and a GE Discovery NM-CT D670 since February 2013. The Hawkeye system provides basic CT-like images to allow attenuation correction and lesion localisation. The D670 on the other hand incorporates a “diagnostic” quality, full-specification 16-slice CT scanner. The new system has necessitated several changes in working practice, over and above those needed for the Hawkeye. This talk summarises some of these changes and the issues arising from this new technology, including:

Risk assessments

Room shielding and other design features

Staff training

Staff roles in justification and authorisation

Protocol optimisation

Image reporting

Dose audit The department is in the unusual situation of having “in-house” diagnostic radiology physicists who have had significant input to this evolving work. It is clear however that a team effort is essential, with contributions from nuclear medicine physicians, radiologists, nuclear medicine physicists and clinical technologists.

New technologies supporting staff Radiation Protection in PET Mr Daniel McCool, Royal Free Hampstead NHS Trust, Pond Street, London NW3 2QG Email: daniel.mccool@nhs.net Daniel McCool, Annah Skillen, Maria Burniston Aim The number of PET scans delivered annually in the UK is rising rapidly, but these scans give rise to significant doses to staff, with many more departments considering the necessity of classification. The aim of our work was to assess to what extent we could use a variety of technologies that have become available in recent years to a) make more accurate assessments of relevant staff doses and b) to minimise these doses. Methods 1. We assessed the impact of increased sensitivity and improved reconstruction techniques of

PET cameras and concluded that we could reduce average administered activity from a standard 370MBq to a weight based regime with a mean administered activity of 220MBq without significant loss of image quality. We monitored daily staff doses using electronic personal dosemeters before and after making the change to administered activity.

2. We used an Aegis dose monitor for real time logging of dose rate data in conjunction with monitoring staff tasks. Dose rate data were recorded both at the base of finger and at the fingertip.

3. We measured staff doses during various drawing up and administration procedures with and without the use of an automatic injector.

Results 1. Reducing administered patient activities led to approximately proportional reductions in staff

body doses (down to <2 microsievert per patient). 2. Real time logging of finger dose data demonstrated both a significant dose gradient between

finger base and tip and also which part of the administration procedure contributed to the greatest proportion of the dose. This informs effective dose reduction stratagems.

3. Staff doses were reduced significantly through the use of an automatic injector, with the major benefit being to finger doses.

Conclusions There have been significant technological advances in recent years in imaging, patient administration, and dose monitoring equipment. This allows the deployment of techniques which can deliver important benefits, including well informed risk assessment and actual reductions in staff dose.

Introduction of an automated PET dose dispensing system: initial findings on staff whole body dose Mr David Ashworth, The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX Email: david.ashworth@christie.nhs.uk Introduction Positron Emission Tomography (PET) technologists have been shown to receive higher doses than staff working in general Nuclear Medicine departments due to the higher specific gamma ray dose constant and greater penetrating ability of the annihilation photons of positron emitting isotopes. At the Christie, approximately 3000 18F-FDG PET-CT studies are performed per year. This workload is shared between 10 technologists who spend, on average, 2 days per week carrying out PET procedures. Whole body doses for technologists involved in PET procedures are regularly close to the local investigation level of 3 mSv/year. In August 2013, the department installed an automated PET dose dispensing and administration system (Trasis Unidose) in order to reduce the dose staff receive from PET administrations. As well as monitoring daily whole body doses before and after the introduction of the automated system, a number of individual patient administrations were analysed to determine the effect of the automated system on the dose received from each individual stage of the administration procedure. Methods EPD monitors (Canberra Dosicard) were worn by PET technologists to monitor daily whole body dose. Doses recorded with the EPDs included dose from all stages of the PET procedure including dose preparation, administration, patient escorting and positioning. Daily whole body doses for each technologist were compared before and after the introduction of the automated dispensing system. An ED3 Active Extremity Dosimeter (on loan from John Caunt Scientific), capable of logging dose rates at 1 second intervals, was used to monitor the relative doses received for the individual stages of the dose administration procedure. The only probe available for use during the loan period of the ED3 monitor was uncalibrated for whole body dose so it was only possible to record detected counts for each stage. As such it was not possible to directly compare these results with historical dose data collected for the manual administration method. Results Whole body doses recorded using EPDs reduced from 5.5 µSv/patient before the introduction of the automated system, to 3.7 µSv/patient after the introduction of the automated system, a reduction of 33%. Relative doses for the individual stages of the administration procedure, recorded using the ED3 dosimeter are given below:

Manual Automated

Prepare dose 0.45 µSv

(14%) 12 cnts (6%)

Administer to patient 1.81 µSv

(56%)

189 cnts

(90%)

Other (re-assay, disposal, transport

dose)

0.96 µSv

(30%) 9 cnts (4%)

Total dose per administration: 3.2 µSv unknown

Conclusion Whole body doses to PET technologists have reduced by 33% (from 5.5 µSv/patient to 3.7 µSv/patient) since the introduction of the automated dose dispensing system. Analysis of the individual stages of the administration procedure showed the automated system greatly reduced the proportion of dose received during dose preparation and re-assay and disposal of

consumables. As it was not possible to record calibrated dose rates, the absolute dose for each individual stage using the automated system is unknown, however based on the daily EPD figures, dose from the automated administration technique is significantly lower than the manual method. Eye Dose measurements in a wide range of nuclear medicine departments indicate that it is unlikely that staff will need to be classified. Mrs Jennie Prince, Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Wilmslow Road, Withington, Manchester M20 4BX Email: jennie.prince@christie.nhs.uk Aims: To measure eye dose to staff in nuclear medicine departments, in order to determine whether such staff will need to be classified when reduced dose limits for the lens of the eye are introduced. Methods: Eye badges (Mirion) were worn on the forehead throughout the working day to assess the dose to the lens of the eye (Hp(3)). A total of 81 staff were monitored:

61 from 10 departments carrying out primarily diagnostic procedures with Tc-99m

13 in an oncology hospital performing both diagnostic procedures including PET and a range of radionuclide therapies

7 in a regional radiopharmacy. In all departments, appropriate dispensing and syringe shields were used at all times. Eye doses were compared with doses obtained for the trunk (Hp(10), Mirion 'Genesis' ) for the same wear period. Projected annual eye doses were calculated. Results: 4 of the 81 eye badges registered a dose above the measurement threshold of 0.2mSv: 3 from staff in the oncology hospital (0.20, 0.22, 0.31mSv over 1 month) and one in a diagnostic department (0.21mSv over 2 months). Eye doses were similar to or less than body doses. The highest projected annual eye dose was 3.2mSv. Conclusion: The highest projected annual eye dose was found to be significantly below the expected classification level for eye dose of 15mSv. Therefore for the range of workloads studied, it is not expected that nuclear medicine staff will need to be classified on the basis of eye dose when new limits are introduced. Eye dose was found to be similar to or less than body dose. Therefore, there is no reason to monitor eye dose in future, unless there is a significant change in working practice or workload which could lead to an increase in eye dose disproportionate to the change in whole body dose.

Experiences in Planning, Preparing & Operating a Radiation Monitoring Unit: Exercise Challenge II Dr Anthony Hughes, Christie Medical Physics & Engineering, Nuclear Medicine Department, Royal Preston Hospital, Sharoe Green Lane, Preston PR2 9HT Email: tony.hughes@lthtr.nhs.uk Tony Hughes and Jennie Prince, Christie Medical Physics and Engineering Aims (1) To devise a local plan to provide a Radiation Monitoring Unit (RMU) for the provision of

public reassurance monitoring in the event of a radiation incident (2) To test the plan by holding a one-day live exercise Methods The Lancashire Reassurance Planning Group (LRPG) was formed in October 2011 to explore, develop and validate the latest Health Protection Agency (HPA) guidance with regard to the provision of public reassurance monitoring and to devise an RMU plan for Lancashire. The LRPG was a multi-agency body, comprised of members from the HPA, the NHS (including medical physics/radiation protection), the Police, local authorities & industry. The following topics were debated for inclusion in the RMU plan:

RMU activation

RMU management

Premises

Staff

Equipment

Record keeping

Waste management

Media/Communication Upon completion, the plan was then tested during Exercise Challenge II. This was a live exercise whose purpose was to prepare & operate an RMU capable of monitoring 200 individuals. Results Exercise Challenge II was held in October 2012. A local sports centre was selected as an appropriate venue for the exercise. The essential resources needed to operate the RMU were identified as well as the organisations that would be expected to supply them and the roles and responsibilities of different agencies with regard to radiation protection were allocated. On the day, the RMU was staffed by volunteers from the NHS (medical physics and radiology, Ambulance service), HPA, Police, Lancashire County Council and staff from the local nuclear industry. Local volunteers presented as potentially contaminated members of the public. Members of the planning committee observed the action in all areas of the RMU. The RMU was successfully set up and the aim of monitoring 200 volunteers was achieved. However a number of issues were raised by observers and participants. These included logistical problems and issues of radiation protection. This feedback has since been used to amend the plan. Conclusion The multi-agency exercise to establish and run an RMU, with input from NHS nuclear medicine physicists, was successful, although inevitably many issues were raised for future improvements. This talk will discuss the challenges and decision processes involved with developing an RMU plan and then go on to present the lessons learned during its enactment as part of a live exercise. In each case, the role of nuclear medicine physicists & radiation protection issues will be discussed.

Transport of radioactive materials inspection – the Newcastle experience Dr Ian Driver, Newcastle Hospitals NHS Foundation Trust, Freeman Hospital, Newcastle NE7 7DN Email: ian.driver@nuth.nhs.uk R Peace1, I Driver1 and S Willis2 1The Newcastle upon Tyne NHS Foundation Trust 2University of Newcastle Introduction The Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations 2009 are detailed, complex and impose significant responsibilities on organizations transporting radioactive materials. The Regulations apply not only to carriers of radioactive materials but also to those that only consign and receive packages. Inspections by the Office for Nuclear Regulation (ONR) are pro-active and at short notice. Therefore compliance with the Regulations in advance of inspection is essential to avoid embarrassment. The aim is to present the Newcastle experience of three recent, local inspections so that other organizations subject to the Regulations may learn from both our actions to implement and our successes. Transport within Newcastle The focus of the presentation will cover the Newcastle upon Tyne Hospitals NHS Trust. Type A and excepted packages are transported between the two hospitals of the Trust by means of an external courier. Typically these are Technetium-99m stocks during planned maintenance of one of the radiopharmacies Type A packages (up to 6GBq Technetium-99 HDP) are also consigned to Bearl Equine clinic from the Trust with the clinic providing their own transport. Type A and excepted packages are consigned and received by Newcastle University through a courier, including Fluorine-18 FDG The Trust and University do not employ the services of a Carriage of Dangerous Goods Advisor Experience from the inspections at the University and Bearl Equine clinic will also be drawn on. Inspection by ONR HM Inspector (Transport Programme) gave seven working days notice prior to a pro-active inspection of the Trust in November 2013. There were no previous inspections to set precedence. The inspector required sight of evidence in terms of:

Awareness of Road Regulations Company Quality / Management System Radiation Protection Requirements DGSA Activities Emergency Arrangements Driver/Operator Requirements Training Consignment Documentation Package and Material Integrity Shipping Approval Certificates Supplier Services Marking and Labeling of Packages Security Provisions

All evidence was thoroughly reviewed over three hours and provided by senior physics and technology staff. A Clinical Governance Manager attended for introductions and ‘wash up’ session.

Outcome Within the Trust, there were no major issues and eight minor issues. Of note, the inspector required that: 1) Emergency arrangements must be conveyed to the courier in advance in order that they can

prepare the driver for dealing with our goods 2) A Type A package must not be used unless a current certificate of assessment has been

issued 3) A regular assessment of the couriers compliance with the Regulations is required. An email

stating compliance is not sufficient Conclusions Robust procedures, training and understanding in advance of notification of inspection are essential for compliance with the Regulations

Flattening Filter Free Photon Beams in Radiotherapy 6th March 2014, British Dental Association, London

Organised by the IPEM Radiotherapy Special Interest Group

FINAL PROGRAMME

09:00 - 09:50 Coffee and registration

09:50 - 10:00 Introduction Jason Cashmore

Chair: Andrew Morgan

10:00 - 10:15 Beam characteristics and QA aspects of Flattening Filter Free beams

David Paynter, St. James’s Institute of Oncology, Leeds

10:15 - 10:30 Absolute dose calibration for operation of the FFF mode of a TrueBeam STx linac

John Frame, Beatson Cancer Centre, Glasgow

10:30 - 10:45 Symmetry and Flatness Tolerances for Flattening Filter Free Beams

Geoff Budgell, The Christie NHS Foundation Trust

10:45 - 11:00 Traceable dosimetry in FFF beams

Invited speaker: Simon Duane, National Physical Laboratory

11:00 - 11:15 Investigation into recombination losses in six thimble ionisation chambers at high dose rates

Mohamed Metwaly, Beatson Cancer Centre, Glasgow

11:15 - 11:30 Detector comparison for small field output factor measurements in flattening filter free photon beams Wolfgang Lechner, Medical University Vienna

11:30 - 12:00 Coffee & Exhibition

Chair: Jason Cashmore

12:00 - 12:15 Commissioning 6MV FFF on the Elekta Versa HD and Pinnacle

Geoff Budgell, The Christie NHS Foundation Trust

12:15 - 12:45 Clinical experience in one year of FFF treatment delivery

Invited speaker: Jens Fleckenstein, University Medical Centre, Mannheim, Germany

12:45 - 13:00 Evaluation of the utility of FFF beams in radiotherapy: comparing plan parameters and out-of-field doses when using flattened and FFF VMAT Alikhan Esmail, Ipswich Hospital NHS Trust

13:00 - 13:15 Comparison of second malignancy risks following prostate radiotherapy using modern radiotherapy techniques including FFF and SABR Louise Murray, St. James’s Institute of Oncology, Leeds

13:15 - 13:30 A comparison of FFF versus flattened modes with HD and standard MLCs to deliver SRS utilising VMAT Suzanne Smith, Beatson Cancer Centre, Glasgow

13:30 - 14:30 Lunch & Exhibition

Chair: Geoff Budgell

14:30 - 14:45 Investigating the advantages of RapidArc IMRT prostate treatment using 6MV flattening filter free beams Hannah Eyles, Mount Vernon Cancer Centre

14:45 - 15:15 Clinical use of FFF: dosimetric effect on plans for different treatment sites

Invited speaker: Wilko Verbakel, VU University Medical Centre, Amsterdam

15:15 - 15:30 Radical Prostate VMAT (FFF)

Christopher Thompson, St. James’s Institute of Oncology, Leeds

15:30 - 16:00 Coffee & Exhibition

Chair: Gordon Galloway

16:00 - 16:15 FFF for Lung VMAT SABR with Elekta VersaHD David Paynter, St. James’s Institute of Oncology, Leeds

16:15 - 16:30 The influence of FFF beams on the interplay effect for SABR treatments Josep Puxeu Vaqué, Edinburgh Cancer Centre

16:30 - 16:45 Lung SABR Treatment Planning with 10X FFF photons utilising TrueBeam

Suzanne Smith, Beatson Cancer Centre, Glasgow

16.45 - 17.00 Intra-fraction dosimetric interplay analysis of flattened and unflattened photons for stereotactic lung Radiotherapy using VMAT Chris Stacey, University College London

POSTER Flattening filter free photon beams in radiotherapy: plan comparison of FFF versus flattened modes for prostate SABR Suzanne Smith, Beatson Cancer Centre, Glasgow

Beam characteristics and QA aspects of Flattening Filter Free beams Mr David Paynter, Medical Physics and Engineering, The Leeds Teaching Hospitals NHS Trust, Level 1 Bexley Wing, Beckett Street, Leeds LS9 7TF Email: david.paynter@leedsth.nhs.uk David Paynter1, Steve Weston1, Vivian Cosgrove1, David Thwaites2

1 Department of Medical Physics, St. James’s Institute of Oncology, Leeds, UK 2 Institute of Medical Physics, School of Physics, University of Sydney, Australia Purpose/Objective Flattening Filter Free (FFF) beams are available on a number of modern linear accelerator machines with differing methods of implementation. The FFF beams are either delivered by removing the filter from the standard flattened beam with the same nominal accelerating potential or have their filter removed and replaced by a flat filter and their energy tuned so that they ‘match’ the associated flattened beam. This investigation highlights the difference between the two implementations are also the associated machine QA required to maintain a clinically acceptable beam. Materials/Methods Four FFF beams were implemented on an Elekta Synergy Linac with Agility head. A 6MV ‘unmatched’ FFF beam, 6MV ‘matched’ FFF beam, 10MV ‘unmatched’ FFF beam and 10MV ‘matched’ FFF beam. The matched beams were produced by adjusting the beam energies so that the PDD at 10cm depth in water matched that of a flattened beam with the same nominal energy. Measurements were performed using a PTW MP3-M water tank, PTW semiflex chamber and PTW 60008 photon diode at 100SSD with field sizes between 3cm x 3cm and 40cm x 40cm for all photon energies. Beam steering and energy parameters were altered so as to take the matched 6MV FFF beam out of tolerance and the sensitivity of the profile and PDD parameters determined to establish quality assurance limits. Results The profiles of the ‘matched’ FFF beams were less homogeneous than those of the unmatched beams and therefore exhibited a more peaked profile. The PDDs of the matched FFF beams were closer to the associated flattened beams with depths of maximum dose deeper than the unmatched beams. Penumbra was equal for both modes within experimental errors. The homogeneity of the FFF profiles was more sensitive than the PDD to changes in beam energy. The symmetry of FFF beams is more stable than flattened beams with the profile’s central axis shifting in the transverse direction rather than a symmetry change. Conclusion Both implementations of FFF beams show an increased dose-rate relative to the flattened beam. 'Matched' beams have a higher energy and are less homogeneous than 'unmatched' beams. Current QA measures may not be sufficient for FFF beams it is suggested that weekly profile measurements are performed comparing the central axis position to that of a flattened beam in addition to a symmetry measurement, the homogeneity of the beam should be measured to assess beam energy in addition to output checks.

Absolute Dose Calibration for Operation of the Flattening-Filter Free Mode of a Truebeam Linac Mr John Frame, Beatson West of Scotland Cancer Centre, 1053 Great Western Road, Glasgow G12 0YN Email: John.Frame@ggc.scot.nhs.uk John Frame, Kirstie Brown, Martin Ford Radiotherapy Physics, Department of Clinical Physics & Bioengineering, NHS Greater Glasgow & Clyde Purpose Radiotherapy Physics in Glasgow has, in the last 2 years, installed and commissioned four Varian Truebeam Linacs all of which are capable of operating in flattening-filter free (FFF) mode. FFF allows much higher dose rates than usual to be achieved, which is desirable when performing stereotactic radiosurgery due to the reduction in treatment delivery time. Removing the flattening filter is problematic in terms of dosimetric calibration, however, due to the change in energy spectrum of the beam. As a result, calibration factors as currently supplied by the NPL may not be valid for the transfer of absolute dose calibration from the primary standard in the UK. The purpose of this work was to establish a traceable calibration to the NPL primary standard for a 10MV FFF photon beam as produced by a Truebeam Linac. Methods Initial dose calibration of the 10MV FFF beam was performed according to the current UK photon Code of Practice. Output measurements were made using Alanine dosimeters, supplied by the NPL, and with a calibrated 0.6cc Farmer chamber for comparison. Additionally, Gafchromic EBT2 film was employed as an independent measurement of dose accuracy. Results Dose measured using Alanine was approximately 2% lower than that measured with an ionisation chamber, with Gafchromic film measurements in good agreement with the dose measured by Alanine. Conclusions Using the current UK Code of Practice to calibrate 10MV FFF output on a Truebeam appears to lead to an overestimate of delivered dose. Using the NPL Alanine dosimetry service allows the production of an additional correction factor to be included in FFF absolute dose calibrations to account for this change.

Symmetry and Flatness Tolerances for Flattening Filter Free (FFF) Beams Mr Geoff Budgell, Christie Medical Physics & Engineering, The Christie NHS Foundation Trust, Wilmslow Road, Withington, Manchester M20 4BX Email: geoff.budgell@christie.nhs.uk McGrath NA, Bendall LS, Budgell GJ The Christie NHS Foundation Trust, Manchester, M20 4BX Aims Flattening filter free (FFF) radiotherapy is becoming more common as there is often no longer the need for a conventional “flat” beam profile in modern radiotherapy techniques. Tolerances for quality control (QC) tests are generally set based on recommendations, what is clinically acceptable and also what can be reasonably achieved. For standard flattened beams, tolerances currently employed at The Christie are 2% and 1.5% for symmetry and flatness respectively. No formal recommendations currently exist for FFF beams, therefore the aim of this investigation was to explore the traditional definitions of symmetry and flatness and determine suitable tolerances for non flattened beam profiles. Methods Symmetry was measured on an Elekta Versa HD linac equipped with 6MV FFF using an IC ProfilerTM device (Sun Nuclear). Reference profiles were acquired, and then the steering was adjusted in order to induce an asymmetry in the beam. The symmetry values calculated by the IC ProfilerTM software were then used to determine what degree of asymmetry is clinically acceptable in order to set appropriate tolerances. In addition to this the symmetry values were compared to the error signals measured by the linac ionisation chamber to ensure that this was appropriately calibrated. The IC ProfilerTM was also used to measure flatness, both for a reference profile and after adjusting the energy of the beam by varying degrees. The PTW Octavius 729 array was also used in order to carry out a gamma analysis on the resultant beam profiles and the routine method of checking the energy by using a ratio of the readings at different depths in a hardboard block was calculated. The results from these methods were collated and compared in order to determine acceptable variations and hence tolerances. Results Adjustment of the symmetry results in a shift in the profile as opposed to the traditional tilt. This still results in an asymmetric beam profile relative to the central axis. The shift relative to the reference profile was calculated and is shown in Table 1 along with the linac error signal and the symmetry calculated for the GT direction. Based on the results the traditional method of measuring symmetry and a tolerance of 2% seems appropriate for FFF beams.

Linac 2R error ICProfilerTM symmetry Shift (mm)

+5% 105.2 0.6

+3% 103.0 0.3

0% 100.4 -

-3% 103.3 -0.3

-5% 105.4 -0.6

Table 1: Results of the investigation into effect of steering the 6MV FFF beam. Changes in flatness varied linearly against beam energy measured using the ratio method, with a 2% flatness change approximately equal to a 1% change in energy ratio. Changes in beam profile using a 2%/2mm global gamma evaluation start to become significant around this level. Conclusion Existing tolerances for symmetry and flatness appear to be suitable for safe clinical implementation of FFF. The suitability of these tolerances will be reassessed in the future as further experience is gained.

Traceable Dosimetry in FFF Beams Dr Simon Duane, National Physical Laboratory, Hampton Road, Teddington TW11 0LW Email: simon.duane@npl.co.uk Until we have a dosimetry code of practice designed to accommodate flattening filter free beams, there are three features of these beams that may introduce additional uncertainty in the measurement of absorbed dose to water. • Increased dose gradients, compared to standard reference conditions, mean that volume averaging

effects may work differently. • The absence of a flattening filter changes the photon energy spectrum and must have some effect on

the effective mass stopping power ratio, which determines the beam quality-dependence of secondary and tertiary standard sensitivity.

• The much higher dose rate in FFF beams increases the significance of non-linearities such as ion recombination.

The commissioning of our primary standard calorimeter in FFF beams is still a work in progress: in the meantime, evidence from its use in non-clinical beams, and from measurements using alanine/EPR dosimetry is summarised and tentative conclusions drawn for the likely magnitude of these effects.

Investigation into recombination losses in six thimble ionisation chambers at high dose rates Dr Mohamed Metwaly, The Beatson West of Scotland Cancer Centre, 1053 Great Western Road, Glasgow G120YN Email: mohamed.metwaly@ggc.scot.nhs.uk Kurian Oommen, Kirstie Brown, Mohamed Metwaly, John Frame Radiotherapy Physics, Department of Clinical Physics & Bioengineering, NHS Greater Glasgow & Clyde Aim Some concern has been raised with regards to the collection efficiency of the chambers in flattening filter free (FFF) mode on a Varian TrueBeam at a DPP that is two to four times that in the Varian Clinacs currently in service. The aim of this study is to experimentally determine k ion as a function of dose per pulse for six different thimble ionisation chambers used routinely in clinical practice in Glasgow. This study also aims to answer the question of whether kion would change significantly at the higher dose rates, and if so, which chamber is most suitable for carrying out commissioning of the new linacs. Method Measurements were carried out in a 6MV photon beam generated by Varian Clinac 21iX. The measurements were taken with the chambers positioned centrally at 5cm depth in a 10x10cm field. The NPL cross calibration phantom was used for chambers 1-3 and a small water tank was used for chambers 4-6. For all measurements there was at least 10cm of phantom material behind the chamber to provide backscatter. The DPP was altered by varying the SSD and the corresponding dose rates were computed from the standard dose rate of 0.0278cGy per pulse measured previously at a depth of 5cm in water.

ID Type Electrometer Vnormal Volume

1 NE 2571 NE 2620 -360V 0.69cm3

2 NE 2581 NE 2620 -360V 0.56cm3

3 NPL 2611 ScanditronixWellhofer +200V 0.33cm3

4 IBA CC04 PTW Unidose +300V 0.04cm3

5 IBA CC13 PTW Unidose +300V 0.13cm3

6 PTW31014 PTW Unidose -250V 0.01cm3

Table 1: Ionisation chambers tested The results were verified by comparing the computed kion values with the theoretical formula for general recombination given in ICRU-34 [4], as well as measurements made in the Varian TrueBeam, which was recently installed. Results Table 2 summarises the recombination correction factors at the TrueBeam DPPs for all investigated thimble chambers, computed from the linear fit to the DPP vs. kion data.

Type 6X (0.028cGy)

10X (0.029cGy)

6XFFF (0.063cGy)

10XFFF (0.112cGy)

2611 1.006(0.001) 1.006(0.001) 1.012(0.001) 1.021(0.002)

CC13 1.004(0.001) 1.005(0.001) 1.009(0.001) 1.015(0.002)

2571 1.004(0.001) 1.004(0.001) 1.008(0.001) 1.013(0.002)

2581 1.003(0.001) 1.003(0.001) 1.005(0.001) 1.007(0.002)

CC04 1.002(0.001) 1.002(0.001) 1.004(0.001) 1.006(0.002)

31014 1.000(0.001) 1.000(0.001) 1.000(0.001) 1.000(0.001)

Table 2: kion values with 95% prediction intervals The NPL 2611 chamber has the smallest collection efficiency (kion=1.021±0.002) at the highest DPP as well as the steepest change going from 6X to 10FFF DPP (1.5% drop in efficiency). From the three large volume chambers the NE2581 has the highest collection efficiency as well as the smallest change in efficiency going from 6X to 10FFF. Similarly among the small volume chambers the PTW31014 has the highest collection efficiency (kion=1.000±0.001 at all DPPs). Conclusions The CC04 chamber was chosen for commissioning measurements based on its high charge collection efficiency (Table 2), higher geometric resolution (due to small size), good sensitivity and small stem effect.

Detector comparison for small field output factor measurements in flattening filter free photon beams Mr Wolfgang Lechner, Department of Radiation Onology, Medical University of Vienna, Division of Medical Radiation Physics, Waehringer Guertel 18-20, Vienna 1090, Austria Email: wolfgang.lechner@akhwien.at 1,2Wolfgang Lechner, 3Hugo Palmans, 1,2Lukas Sölkner, 3Paulina Grochowska, 1,2Dietmar Georg 1Department of Radiation Oncology, Medical University Vienna, Austria 2Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University Vienna, Austria 3National Physical Laboratory, Teddington, Middx TW11 0LW, United Kingdom 4International Atomic Energy Agency, A-1400 Vienna, Austria Purpose The applicability of various detectors for small field dosimetry and whether there are differences in the detector response when irradiated with FF- and FFF-beams was investigated. Materials and Methods Output factors of 6MV and 10MV FF- and FFF-beams were measured with 14 different online detectors using field sizes between 10x10cm² and 0.6x0.6cm² at a depth of 5cm of water in isocentric conditions. A summary of all investigated detectors can be found in Table 1. Alanine pellets with a diameter of 5mm and 2.5mm were used as reference dosimeters for field sizes down to 1.2x1.2cm² and 0.6x0.6cm², respectively. The ratio of the relative output measured with the online detectors to the relative output measured with alanine was evaluated (referred to as dose response ratio). Results After correcting all detector readings for volume averaging effects the unshielded diodes (EFD and SFD), the microDiamond and the microLion overestimated the relative output factor by about 3% compared to alanine at the smallest field size. The dose response ratios of two different shielded diodes (PFD and DiodeP) measured with 10MV FF-beams deviated substantially by 2% and 3% compared to FFF-beams at a field size of 0.6x0.6cm². This difference was less pronounced for 6MV FF- and FFF-beams. For all other detectors the dose response ratios of FF- and FFF-beams showed no significant difference. In contrast to the solid state detectors, the air filled ionization chambers CC01, Pinpoint14, Pinpoint16 and CC04 underestimated the relative output factors compared to alanine with values in the order of 1%, 5%, 8% and 9%, respectively. This behavior was even more pronounced for larger chambers such as the IC10, CC13, Semiflex and NPL2611. Figure 1 depicts the dose response ratios of all detectors measured with the 6MV FFF beam. Conclusion The dose response ratios of the majority of the detectors agreed within the measurement uncertainty when irradiated with FF- and FFF-beams. Correction factors for shielded diodes determined for FF- beams might not be applicable for FFF-beams, especially for higher energies. Of all investigated detectors, the microDiamond and the unshielded diodes would require only small corrections which make them suitable candidates for small field dosimetry in FF- and FFF-beams. Table 3: Summary of the investigated detectors

Category Label Vendor

Micro

microDiamond 60019

PTW

SFD IBA

DiodeP 60008 PTW

EFD IBA

PFD IBA

microLion 31018

PTW

Mini

CC01 IBA

PinPoint14 310014

PTW

PinPoint16 310016

PTW

CC04 IBA

Standard

Semiflex 31010 PTW

IC10 Wellhöfer

CC13 IBA

NPL2611 NPL

Fig 1: Dose response ratios of all detectors measured with the 6MV FFF beam

Bar Test (90cm SSD, 10cm Deep, 6MV FFF)

0

10

20

30

40

50

60

70

80

-10 -5 0 5 10Distance off-axis (cm)

Ab

solu

te d

ose

(cG

y)

Pinnacle

Film

Chamber

Commissioning 6MV FFF on the Elekta Versa HDTM and Pinnacle Mr Geoff Budgell, Christie Medical Physics & Engineering, The Christie NHS Foundation Trust, Wilmslow Road, Withington, Manchester M20 4BX Email: geoff.budgell@christie.nhs.uk L. Bendall, I. Patel, N. McGrath, C. Rowbottom. The Christie NHS Foundation Trust Aim To commission 6MV FFF on the first Elekta Versa HD™ Linac at The Christie and to create a beam model in version 9.6 of Pinnacle treatment planning system. Method The new linac was setup to match the Elekta “golden” data set, and data required for commissioning was collected across a range of field sizes (2x2 – 40x40cm2). This included open field profiles, percentage depth dose curves, output factors and tissue standard ratios (TSRs). Equipment used during commissioning included a PTW MP3-M water tank, a PTW semiflex (0.125cm3) ionisation chamber and a 3D pin-point (0.016cm3) chamber (chamber used depended on field size). The FFF beam was modelled within Pinnacle version 9.6 using a conventional 6MV flattening-filter beam model created at the Christie as a starting point. The model was fine-tuned to improve agreement between model and measurements. Due to the removal of the flattening filter, as expected the spectrum of the beam required adjusting. Other parameters changed within the model included electron contamination parameters. Model validation tests carried out included:

MLC test fields (picket fence, closed leaf sweep, stairstep, bar test) delivered to film and point doses measured in a water phantom

TSR calculation against measured

Clinical plan verifications. Results The results of the model validation measurements showed good agreement between calculated and delivered doses. Figure 1 shows an example of a comparison between a profile acquired using film with 6MV FFF and that computed by Pinnacle for the bar test. The profiles are shown in absolute dose (cGy). This particular field confirms that the tongue & groove parameter (although the Agility MLC bank in the Versa HD™ does not have an actual T&G), the MLC transmission (trough) and the additional interleaf leakage transmission (trough) are set appropriately to provide an accurate model of the machine.

Figure 1 Bar test results for 6MV at 10cm deep showing film measurements and Pinnacle calculations.

The maximum difference between calculated (Pinnacle) and measured TSRs over a range of field sizes (4-30cm2) and depths (1.6-20cm) was found to be <1%. Conclusion 6MV FFF has been commissioned on an Elekta Versa HD™ and a beam model has created and validated in Pinnacle version 9.6. Future Work Planning studies are currently underway to produce a class solution for Lung SABR VMAT, progress with this will be reported at the meeting.

Evaluation of the utility of FFF (flattening filter free) beams in radiotherapy: comparing plan parameters and out-of-field doses when using flattened and FFF volumetric arc therapy (VMAT) fields Mr Alikhan Esmail, Ipswich Hospital NHS Trust, Ipswich Hospital, Heath Road, Ipswich IP4 5PD Email: ali.esmail@ipswichhospital.nhs.uk ESMAIL Alikhan, ALDER Louisa Radiotherapy Physics Department, Ipswich Hospital NHS Trust. Purpose: 6X FFF mode has recently been commissioned on our TrueBeam (Varian Medical Systems). FFF beams have the potential to reduce treatment times compared with flattened beams due to the higher dose rates that can be delivered. The aims of this study were to investigate the differences between flattened and FFF VMAT plans when using standard fractionation techniques and high dose fractionation SABR lung regimens. The parameters that were evaluated were plan distribution, DVH statistics, MU, maximum dose rate (DR) employed, delivery time and assessment of out-of-field doses. Out of field doses are governed by leakage radiation (governed by plan MU’s) and scattered radiation. FFF beams have no flattening filter in place so the latter contribution will be reduced. Therefore another potential benefit of FFF beams could be the reduction in risk of radiotherapy induced secondary malignancies. Methods: Six VMAT patients previously treated were selected. The dose fractionation and trial arm delivered are outlined in Table 1. Treatment planning was performed using Eclipse and dose calculation was carried out using the AAA algorithm (version 10.0.28). The final PTV and OAR optimiser objectives used in the clinical plan were re-run from the start of the optimisation process using 6X (max DR 600MU/min) and 6X FFF (max DR 1400MU/min). All plans were then delivered onto a solid water phantom. EBT2 Gafchromic film (supplied by International Specialty Products) was placed at a depth of 5 cm to assess the out of field doses. The film was calibrated using the calibration steps outlined by the supplier. Table 2 outlines the doses measured at 1cm and 5 cm away from the furthest field edge in the inplane axis. Results:

Conclusion:

With regards to dose distribution, PTV coverage and OAR sparing, there were no marked differences between the flattened and FFF VMAT plans. In relation to standard fractionated radiotherapy, FFF beams do not offer any significant advantages in delivery time because there was no significant change in max doserate used. However for high dose fractionated treatments, such as SABR, there is a clear advantage in terms of delivery time due to the higher doserate being utilised. From the results, a 56.8% decrease in time was observed. Plan MUs for FFF standard fractionated plans were on average 14.2% higher and for high dose plans 0.6% higher when compared with 6X plans. The increase in plan MUs for the FFF plans has not led to an increase in out-of-field doses. Out-of-field doses for both FFF and 6X plans were generally of the same order. A reason for this is that the increased leakage radiation which is governed by the MUs is offset by the reduction in scattered radiation due to no flattening filter being present.

Comparison of second malignancy risks following prostate radiotherapy using modern radiotherapy techniques including Flattening Filter Free and Stereotactic Ablative Radiotherapy Dr Louise Murray, St James's University Hospital, University of Leeds, Leeds LS9 7TF Email: L.J.Murray@leeds.ac.uk Louise J Murray*§, Christopher M Thompson†, John Lilley†, Vivian Cosgrove†, Jonathan Sykes†, Kevin Franks*, David Sebag-Montefiore*§, Ann M Henry*. Departments of *Clinical Oncology and †Medical Physics, Institute of Oncology, Leeds Cancer Centre, St James’s University Hospital, Beckett St, Leeds LS9 7TF, UK. §University of Leeds, Leeds LS2 9JT, UK. Aims: Radiotherapy-induced second primary cancer (RISPC) is one of the most serious side-effects of successful cancer treatment. This study assesses the risks of RISPC following prostate radiotherapy using modern techniques. The risks associated with intensity modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), flattening filter free (FFF) mode and stereotactic ablative radiotherapy (SABR) are evaluated. Methods: Prostate radiotherapy plans were created using 5-field IMRT (78Gy in 39 fractions), VMAT non-FFF mode (78Gy in 39 fractions), VMAT with FFF mode (78Gy in 39 fractions), SABR non-FFF mode (42.7Gy in 7 fractions) and SABR with FFF mode (42.7Gy in 7 fractions). Differential DVHs from three patient datasets, each planned with all 5 techniques, were used to calculate average organ equivalent doses (OED) and excess absolute risks (EAR) for second rectal and bladder cancers using Schneider’s mechanistic model (which incorporates the effects of fractionation, repair and repopulation, as described in Schneider et al, Theor Biol Med Model 2011,8:27). Out-of-field chamber measurements were performed in an anthropomorphic phantom for each technique and were used to calculate OED and EARs for organs distant from the treatment field using the linear-no-threshold model (which is appropriate for low dose out-of-field regions). OED is proportional to RISPC risk and ratios of OED give the risk ratio for RISPC for one technique compared to another. EARs were calculated based on patients being irradiated aged 60 years and living till 80 years. Results: Figure 1 shows RISPC risk ratios for each technique relative to 5-field IMRT. SABR techniques resulted in lower second cancer risks in all sites relative to 5-field IMRT. For all techniques, EARs were consistently low (Figure 2): EARs for rectal and bladder RISPC were 1.44-2.57 and 1.70-2.42 per 10000 person-years respectively; EARs for all other organs were lower. Absolute differences in EAR between techniques were also small (all differences ≤1.13 per 10000 person-years). Techniques using FFF resulted in lower RISPC risks in tissues beyond the DVH volume compared to equivalent techniques without FFF. For example, FFF reduced the risk of RISPC by up to 20% in the region of the stomach and up to 56% in the region of the oral cavity, when comparing the same techniques with and without FFF. Conclusions: Calculated absolute risks of second rectal and bladder cancers were low using all modern radiotherapy techniques. SABR techniques conferred lower RISPC risks at all sites relative to 5-field IMRT and FFF techniques conferred lower RISPC risks in organs at greater distances from the treatment field. This is because: i) SABR delivers lower physical doses compared to conventional dose-fractionation schedules (and in low dose regions the dose-risk relationship is linear), and ii) FFF results in reduced leakage from the machine head. Figure 1.

Figure 2.

A comparison of FFF versus flattened modes with HD and standard MLCs to deliver SRS utilising VMAT Mrs Suzanne Smith, NHS Greater Glasgow and Clyde, Gartnavel General Hospital, 1053 Great Western Road, Glasgow G12 0YN Email: suzanne.smith2@ggc.scot.nhs.uk Smith S, Currie GD, Kearns D Radiotherapy Physics, Department of Clinical Physics & Bioengineering NHS Greater Glasgow & Clyde Aim: To compare plan quality in terms of dosimetric homogeneity, target conformity, organ-at- risk (OAR) sparing, monitor unit (MU) usage, and beam-on time for eleven stereotactic radiosurgery patients using RapidArc™ volumetric- modulated arc therapy (VMAT) with both standard and flattening filter free modes. Plans where calculated with both a standard 120 leaves MLC and a HD120 MLC. Methods: Eleven patients with one or more brain metastases underwent computed tomography simulation. Treatment planning was performed using Varian Eclipse ™ v10.0.39 to generate four 2-arc RapidArc plans. Each patient was planned with FFF and flattened mode with both a standard and HD120 MLC. All plans were calculated to deliver the same mean dose to the PTV. Plans were created with dose control tuning structures surrounding targets to maximize conformity and dose gradient. Dosimetric parameters used for target analysis were RTOG conformity index (CIRTOG), homogeneity index (HIRTOG), inverse Paddick Conformity Index (PCI) and D5–D95. OAR sparing was analyzed in terms of Dmax and D10cc for Brain. Treatment delivery was evaluated based on measured beam-on times delivered on a Varian Truebeam, Varian Truebeam STx and Varian Clinac iX linear accelerators. Results: Dosimetric conformity, homogeneity, and OAR sparing were comparable when using the HDMLC irrespective of mode for all patients. The Paddick Conformity Index was inferior for the standard MLC plans than the HDMLC with the mean decreasing from 4.3 (±1.2) to 3.8 (± 0.7). The PTV homogeneity index was also inferior for the standard MLC than the HDMLC plans, decreasing from 3.3 (± 0.8) to 2.4 (± 0.7). Mean beam-on times for FFF mode and flattened mode were 3 (±0.7) and 12 (±2.4) minutes, respectively. Mean MUs were 6,760 and 7,015 respectively. Conclusions: Dosimetric conformity, homogeneity, and OAR sparing were similar when planned with a HDMLC. There was some reduction in conformality when planned with a standard MLC. Conformality was independent of treatment mode. The use of FFF resulted in substantially less beam-on time and fewer MUs than standard mode. The rapid delivery of SRS with an HDMLC and FFF improved workflow on the linac and limited the potential for intrafraction organ and patient motion, which can cause dosimetric errors. To date, over seventy patients have been treated using FFF mode for Stereotactic Brain Radiosurgery in Glasgow. The reduction in treatment time and the improvement in conformality have resulted in a two fold increase in referral requests.

Investigating the advantages of RapidArc® IMRT prostate treatment using 6MV flattening filter free beams Miss Hannah Eyles, Mount Vernon Cancer Centre, Rickmansworth Road, Northwood, HA6 2RN Email: hannah.eyles@nhs.net Hannah Eyles, James Burnley, Rachel Wills, Karen Venables Radiotherapy Physics, Mount Vernon Cancer Centre Aim The aim of this work was to investigate the potential benefits of implementing Flattening Filter Free (FFF) radiotherapy on the Varian TrueBeamTM linear accelerator at the Mount Vernon Cancer Centre (MVCC). This work concentrates on the potential advantages of 6MV FFF beams over conventional flattened beams , investigating total number of monitor units, treatment time, dose distribution and out of field dose through a planning study of RapidArc® prostate patients. Methods The planning study was performed using the 6MV FFF beam model in EclipseTM Version 11 and using the Analytical Anisotropic Algorithm (AAA). Ten RapidArc prostate patients were chosen and the optimisation criteria from the original clinical plans were used to re-optimise both the flattened and the FFF beam plans. The dose distributions were compared using plan objectives (planning target volume (PTV) coverage and the organ at risk (OAR) doses) The number of monitor units, the dose rate and the treatment time were all recorded and the dose outside of the treatment field was measured using an ionisation chamber. Results Preliminary results indicate that the dose distribution does not change significantly when using the 6MV FFF beam model, and based on the dose statistics such as PTV coverage and doses to OARs the FFF plan would be clinically acceptable. Adequate coverage of the target volume was achieved, and only minor differences in the doses to the bladder and rectum were observed. The FFF plan required more monitor units than the flattened plan, and despite being optimized at 1400 MU/minute, the mean dose rate achieved in the FFF plan was only just over 600MU/minute. This suggests that the chosen optimisation criteria and single arc technique did not allow the dose rate advantages of the FFF beam to be fully utilised. The out of field dose was found to be similar for both the flattened and the FFF plans likely due to the increased number of monitor units required for the FFF plan. Conclusion It is hoped future work including the pre-treatment verification of clinical FFF plans should reveal further advantages but these initial findings suggest that applying the 6MV FFF beam to current planning and treatment techniques for prostate IMRT does not allow the full advantages of FFF radiotherapy to be utilised.

Clinical use of FFF: dosimetric effect on plans for different treatment sites Dr Wilko Verbakel, Department of Radiation Oncology, VU University Medical Center Amsterdam, PO Box 7057, Amsterdam, The Netherlands Email: w.verbakel@vumc.nl Flattening Filter Free (FFF) beams allow for an up to 4 times higher dose rate to be applied during radiotherapy treatments. The question is where this is useful and what are the potential advantages and disadvantages of using such intense radiation beams. Since the beam profile is not homogeneous anymore, it is expected to be most useful for small targets treated to high dose per fraction. This are typically the stereotactic body radiotherapy treatments (SBRT). We evaluated the use of FFF beams for lung and spine SBRT in terms of plan quality and dlivery time. For the first group of patients treated with FFF for lung SBRT, we retrospectively evaluated the intrafraction motion, delivery and treatment times. The much sorter delivery times pose also an increased dosimetric risk after intrafraction motion, which is evaluated for spine SBRT treatments. Radiobiological experiments have shown no difference in cell kill between irradiation with FFF and flattened beams. Finally, plan quality was evaluated for normal fractionated radiotherapy to prostate and head and neck. Results showed that FFF beams are useful for prostate and small head and neck tumors (larynx) whereas FFF plans are of inferior quality when optimized for larger head and neck tumors like oropharynx and nasopharynx.

FFF VMAT for Prostates with Elekta VersaHD Mr Christopher Thompson, The Leeds Teaching Hospitals NHS Trust, Level 1 Bexley Wing, Beckett Street, Leeds LS9 7TF Email: christopher.thompson@leedsth.nhs.uk CM Thompson1, G Ward, J Dunning2, J Lilley1 1 Department of Medical Physics, St. James’s Institute of Oncology, Leeds, UK 2 Department of Medical Physics Royal Marsden Hospital, London, UK Purpose / Objective Using Flattening Filter Free (FFF) to deliver prostate VMAT should increase treatment delivery efficiency, while maintaining critical structure sparing. The feasibility of planning VMAT prostate treatments using Elekta’s 160 5mm leaf Agility MLC on a VersaHD linac was investigated. Treatment plans were compared with our previous flattened VMAT technique and IMRT plans for an 80-leaf MLC with a 4 mm leaf width Beam Modulator linac. Material / Methods Monaco Treatment Planning System (Elekta) was used for VMAT planning, working to dose criteria: 76Gy in thirty seven fractions prescribed to the GTV excluding seminal vesicles, 68.8 Gy prescribed to a lower dose PTV defined as the GTV plus seminal vesicles with a 0.8 cm posterior margin and 1 cm margin in all other directions. Comparison was made on 5 patients between IMRT plans, VMAT plans for a flattened beam and VMAT plans for a FFF beam. A diode array phantom (Delta4-Scandidos) was used for dosimetric validation, together with a small ionisation chamber placed in a phantom at the centre of the high-dose region for all plans produced. Results Target coverage, segment number and OAR sparing for all plans was comparable, with no significant differences noted between the VMAT and IMRT plans. The different treatment times were 528 s, 80 s and 53 s for the IMRT, VMAT and FFF VMAT respectively. The ratio of the volume of the 95% isodose to the volume of the PTV was 1.44, 1.38, 1.35 for PTV1 and 1.21, 1.18 and 1.13 for PTV2 for the IMRT, VMAT and FFF VMAT plans respectively. Ion chamber measurements agreed with planned dose calculations to within 2%. Gamma analyses of the planned dose distributions with measurements showed ≥95% of points above the 5% isodose level agreed within 3%/3mm. Conclusion VMAT planning methods have been developed for an Agility MLC, to meet radical prostate planning aims using a single 220o arc. Plans have been successfully delivered, demonstrating good agreement with measurements. VMAT provided some advantages for treatment times and dose conformality, which were further enhanced by the addition of the FFF beam energy. This technique was implemented in July 2013 and the decrease in treatment time has meant we have reduced the length of patient’s appointment times and have treated up to 61 prostate patients on one linac in a 10 hour day.

FFF for Lung VMAT SABR with Elekta VersaHD Mr David Paynter, Medical Physics and Engineering, The Leeds Teaching Hospitals NHS Trust, Level 1 Bexley Wing, Beckett Street, Leeds LS9 7TF Email: david.paynter@leedsth.nhs.uk D Paynter1, A Perkinson, SJ Derbyshire1, J Lilley1,VP Cosgrove1 1 Department of Medical Physics, St. James’s Institute of Oncology, Leeds, UK Purpose / Objective This study describes the clinical implementation of Flattening-Filter Free (FFF) for VMAT lung SABR with prescribed doses of 54Gy in 3, 55Gy in 5 and 60Gy in 8. We compare the FFF delivery with both our conformal generally 7 unflattened beam technique in use since May 2009 and VMAT without FFF. Material / Methods The 6MV FFF beam energy was tuned so that dose was matched to the flattened 6MV beam energy at a depth of 10cm in water. All planning was performed with Monaco v3.3*1 for delivery on a VersaHD*1 linac utilising the 160 5mm leaf AgilityTM head. Initially 5 patients were planned with a dose of 55Gy in 5 fractions. An isocentre positioned at the patient mid-line was used for all plans. Plans were compared in terms of measured delivery time, gamma index and PTV point dose. Treatment deliveries were verified using the Delta4*2 phantom and chamber measurements in a CIRS*3 lung phantom. After clinical implementation with 55Gy in 5 plans for both 54Gy in 3 and 60 in 8 were also investigated. These plans were specifically chosen as they had proved challenging to plan with our conformal technique. Some of these plans had required at least one beam to be non-coplanar. For these cases multiple non coplanar arcs were investigated Results All plans produced with the 3 different techniques were comparable in terms of plan quality and were produced in a similar time-frame. Dose deliveries for all plans were acceptable and within the clinical tolerances of this institution: ≥95% of points passed a gamma analysis of 3%/3mm and PTV point dose within 2% of calculations. The treatment delivery times for the VMAT FFF (55Gy in 5) plans were less than 2 minutes compared with 4 mins for the VMAT non FFF and about 8 mins for the conformal technique. Acceptable plans were produced for VMAT FFF using a 200 deg arc even for patients that had proved difficult to plan with our conformal technique Conclusion We have shown based on our experience of treating >570 lung patients with SABR that VMAT FFF can be used to treat even the most challenging cases. VMAT FFF has the advantage of decreased delivery times which as well as being popular with patients should mean that intra fraction errors are reduced *1: Elekta AB, Sweden. *2: ScandiDos AB, Sweden. *3: Computerized Imaging Reference Systems Inc, USA.

The influence of FFF beams on the interplay effect for SABR treatments Mr Josep Puxeu Vaque, NHS Lothian, Edinburgh Cancer Centre, Crewe Road South, Edinburgh EH4 2XU Email: jpuxeu@gmail.com Josep Puxeu Vaqué, Bill Nailon, Paul Drewell and Andiappa Pillai Sankar Department of Oncology Physics, Edinburgh Cancer Centre, Edinburgh, EH4 2XU. Intrafraction organ motion, characterised by breaths per minute (BPM) and amplitude motion, significantly affects the dose distribution. In addition the treatment irradiation time can lead to differences, particularly on flattening filter free (FFF) beams, where the slope and the maximum dose rate are significantly different from conventional flattened beams (FF). It is important to take account of these effects in stereotactic ablative radiotherapy (SABR) where a high dose per fraction can be delivered on the Varian TrueBeam linear accelerator (linac), which is capable of 2400 monitor units (MU)/min. At the Edinburgh Cancer Centre SABR is delivered using four partial low modulated arcs on conventional linacs (max dose rate 600 MU/min) with irradiation time less than six minutes for 18Gy/# plans. With the Truebeam linac this could be reduced to approximately three minutes for the original configuration or less than two minutes when 10MV FFF with two partial arcs is used. The aim of this study was to investigate the interplay effect on low modulated FFF SABR plans and the number of cycles necessary to reduce the interplay effect on the final dose distribution. Methods Eight treatment plans previously created with 6MV FF beams were adapted for FFF beams. The effects of Intrafraction motion were investigated using a Quasar programmable phantom. Static beams with different BPM and amplitude were also studied. To remove the influence of setup and reading of the radiochromic film, dose distributions simulating the same motion parameters were produced. The penumbra for FF and FFF beams in static and dynamic configurations were compared and the differences on the high dose region for the four energies on a 5 cm x 5 cm field were also compared. Results During verification of the eight adapted plans, large differences between predicted and measured (gamma(3%,3mm)>1 in more than 5% of points) were observed for three plans. These large differences cannot be explained by the penumbra size and flatness (Table 1). Verification of the original modulated plans with FFF demonstrated that differences in verification were related to the alteration of the conventional plan for FFF.

Parallel Perpendicular

Penumbra (cm)

Flatness (%)

Symmetry (%)

FWHM (cm)

Penumbra (cm)

Flatness (%)

Symmetry (%)

FWHM (cm)

6X

Static 0.45 1.86 -0.21 5.03 0.45 1.76 0.15 5.03 Dynamic 0.90 7.54 -0.18 5.07 0.45 1.76 0.15 5.03

6X FFF

Static 0.47 2.85 -0.26 4.99 0.47 2.60 -0.29 4.99 Dynamic 0.86 7.26 1.50 4.98 0.48 2.58 -0.29 4.99

10X FFF

Static 0.47 4.45 -0.16 4.99 0.47 4.30 -0.43 4.99 Dynamic 0.94 0.86 -0.12 4.99 0.47 4.26 -0.43 4.99

Table 1. Variation of different parameters when motion was simulated with an amplitude of 1.2 cm peak to peak on a initial field of 5 cm x 5 cm in the parallel and perpendicular direction of the motion.

Conclusions MU/Gy and average leaf pair opening (ALPO) are indicators of modulation of the plan but they do not completely predict the effect of intrafraction motion on the final dose distribution. The differences on the shape for FF and FFF on SABR field sizes (5cm x 5cm) do not explain the differences on the motion verification of certain plans. The motion effect can be simulated and reduce verification time.

Transition in the provision of a RapidArc Lung SABR Service: Treatment Planning with 10X FFF photons utilising TrueBeam Mrs Suzanne Smith, NHS Greater Glasgow and Clyde, Gartnavel General Hospital, 1053 Great Western Road, Glasgow G12 0YN Email: suzanne.smith2@ggc.scot.nhs.uk A. Aitken, S Smith, M Ford , M Glegg, G Currie Radiotherapy Physics, Department of Clinical Physics & Bioengineering NHS Greater Glasgow & Clyde. Aims: Building on an already established RapidArc clinical practice for Lung SABR, it was recognised that the increased functionality offered by more advanced treatment delivery hardware and associated peripherals, would facilitate further development of the existing level of service provision. To this end, our Centre sought not only to further expand the availability of inverse planned dynamic treatments but also to evolve the treatment planning and delivery process for Lung SABR to include the adoption of additional local constraints and improve compliance within the limits of the existing Clinical Protocol. Methods: All SABR patients were immobilised in an arms down position using a beam direction shell and scanned using 4DCT. Plans were then calculated on the Average Intensity Projection using two full arcs of rotation. Avoidance sectors were also incorporated in some cases when required. During the treatment planning process, the optimisation parameters were extended to include additional constraints for contra-lateral lung (V5 < 1%) and for selective sparing of the chest wall where appropriate. Results: Analysis of the PTV dose statistics demonstrated conformance with the ROSEL Protocol requirements for all 10X FFF (55Gy in 5 fractions and 54Gy in 3 fractions) Lung SABR treatments to date, with noted reductions in dose at the 2 Gy level of up to a factor 4 for contra-lateral lung and a factor of 2 for whole Lung-GTV when compared with 6X Flattened treatment plans. In 9% of the cases analysed to date, the PTV has been situated within 1.5 cm of the ipsilateral brachial plexus. Despite the close proximity to the PTV, the use of planning risk volumes within the optimiser have enabled dose constraint conformance for this organ at risk to be achieved in all cases. The risk adapted central lesion dose and fractionation schedule (50Gy in 5 fractions) has been used in 7% of cases to date with no minor deviations required to conform to the requirements of the adopted RTOG 0813 Protocol. Conclusions: At the time of writing, 55 Lung SABR patients in total have been planned and treated using 10X FFF, utilising 3 different dose and fractionation schedules (55Gy in 5 fractions, 54Gy in 3 fractions and 50Gy in 5 fractions). The latter of the three regimens has been used in the treatment of central lesions as defined by the ROSEL Protocol. The use of FFF in conjunction with the Truebeam HDMLC and 2400 MU/min dose rate has enabled the treatment of lesions which are in close proximity to specified organs at risk with total beam on times of between 1.2 and 3 minutes.

Intra-fraction dosimetric interplay analysis of flattened and unflattened photons for stereotactic lung Radiotherapy using VMAT Mr Christopher Stacey, University College London Hospitals NHS Foundation Trust, Radiotherapy Physics, 250 Euston Road, London NW1 2PG Email: chris.stacey@uclh.nhs.uk C. Stacey, R. Bodey & D. D’Souza Radiotherapy Physics Group, University College London Hospitals Introduction UCLH delivers stereotactic ablative lung treatments under free-breathing, using Varian RapidArc VMAT. Interplay effects between the dynamic radiation delivery and the tumour motion are of particular interest and dosimetric investigations have been published in the literature1. Implementation of the Varian TrueBeam STx flattening filter free (FFF) modality has potential benefits, particularly a 60% reduction in treatment time, but the effect this faster treatment has on the dosimetric interplay is uncertain. Materials and methods The Hexamotion platform (Scandidos) allows complex motion patterns to be applied to the Delta4PT diode phantom. This requires the input of motion files. Files have been generated for a succession of situations, from periodic longitudinal motion to patient-specific organ motion evaluated from 4DCT data. VMAT plans are to be delivered on the TrueBeam STx using both flattened and FFF 6MV X-rays. The interplay of the assigned phantom motion will be investigated with reference to the static case for each energy mode. The impact of dosimetric interplay will be compared between the flattened and FFF plans. References 1. Ong CL et al. Dosimetric impact of interplay effect on RapidArc lung stereotactic treatment delivery. Int. J. Radiation Oncology Biol. Phys., Vol. 79, No. 1, pp. 305–311, 2011

POSTER: Plan comparison of FFF versus flattened modes for prostate SABR Mrs Suzanne Smith, NHS Greater Glasgow and Clyde, Gartnavel General Hospital, 1053 Great Western Road, Glasgow G12 0YN Email: suzanne.smith2@ggc.scot.nhs.uk Thomson S, Smith S, Ferguson R, Aitken A Radiotherapy Physics, Department of Clinical Physics & Bioengineering NHS Greater Glasgow & Clyde Aim: Stereotactic ablative body radiotherapy (SABR) delivers ultra-hypofractionated treatments, and in the treatment of prostate cancer, offers the potential for dose escalation whilst harnessing the radiobiological advantages of increased tumour control and reduced toxicity. In Glasgow, a new phase one clinical trial aiming to assess acute gastro-intestinal (GI) and genito-urinary (GU) toxicity in patients treated using Varian TrueBeam™ linear accelerators with flattening filter free (FFF) RapidArc™ for prostate SABR started in December 2013. This work describes the preparation of the treatment planning methods for the implementation of this new technique. Method: A planning study comparing 6MV flattened photon beams with 10MV unflattened photons beams for prostate SABR treatments was performed. Ten patients were randomly selected from the pool of patients who had previously received RapidArcTM treatment for low risk prostate cancer. Two RapidArc plans were created for each patient: one delivering treatment arcs with flattened photon beams at 6MV and one with unflattened beams at 10MV. Comparison was made between these plan by analysis of the number of monitor units (MUs), beam on time, conformity number, homogeneity index and gradient index. The significance of the differences was evaluated using a two-tailed paired t-test. A further planning study was then undertaken to assess if there was any significance in planning using either a standard 120 multileaf collimator (MLC) or high definition 120 MLC. Results/Conclusion: Significant differences at the 95% confidence interval were found in the following parameters in the 10MV FFF plans when compared with the 6MV plans: a mean reduction in MU, shorter beam on times, a reduction in mean body dose and a reduction in skin dose. There was no significant difference in PTV conformity number and the homogeneity index. These result show an improvement in treatment time and some dosimetric advantages when 10MV FFF is adopted. Dosimetric conformity, homogeneity and gradient indices were not found to be significantly different when planned with a HDMLC and therefore offered no advantage over the standard MLC. This has allowed patients to be treated on any of the Department’s four TrueBeam accelerators.

Advanced Neuro MRI 18th March 2014, Austin Court, Birmingham

Organised by the IPEM Magnetic Resonance Special Interest Group

FINAL PROGRAMME

09:00 – 09:50 Coffee and registration

09:50 – 10:00 Introduction

Chair: Stephanie Withey, Birmingham

10:00 – 10:35 MRI: A Rich Canvas for Studying Brain Physiology and Disease Invited speaker: Prof Peter Jezzard, University of Oxford

10:35 – 10:50 Evaluation of diffusion acquisition and tractography methods for neurosurgical planning Dr Jonathan Ashmore, Kings College Hospital NHS Foundation Trust

10:50 – 11:05 A study of cerebral blood flow and oedema in hypoxia Dr Victoria Bull, University Hospitals Coventry and Warwickshire NHS Trust

11:05 – 11:30 Coffee & Exhibition

Chair: Cormac McGrath, Belfast

11:30 – 12:05 Magnetic Resonance Spectroscopy: methods and applications in adult and childhood brain tumour imaging Invited speaker: Dr Nigel Davies, University Hospitals Birmingham NHS Foundation Trust

12:05 – 12:20 The use of SWI MRI in newborns with hypoxic ischaemic encephalopathy to predict clinical outcome Dr Angela Darekar, University Hospital Southampton NHS Foundation Trust

12:20 – 12:35 Clinical evaluation of language lateralization using fMRI in epilepsy surgery candidates Dr Jonathan Ashmore, Kings College Hospital NHS Foundation Trust

12:35 – 13:35 Lunch & Exhibition

Chair: Sian Curtis, Bristol

13:35 – 14:10 Advanced neuro MRI in the clinic - present and future perspectives Invited speaker: Prof Dorothee Auer, University of Nottingham

14:10 – 14:25 Arterial Spin Labelling at Birmingham Children’s Hospital Jan Novak, University Hospitals Birmingham NHS Foundation Trust

14:25 – 14:40 Hippocampal subfield volumetry as a marker of early Alzheimer's disease Bryony Wood, University of Bristol

14:40 – 14:55 Towards discrimination of differential ageing processes by quantitative MRI relaxometry Risto Kauppinen, University of Bristol

14:55 – 15:20 Coffee & Exhibition

Chair: Dorothee Auer, Nottingham

15:20 – 15:35 Multi-modality, multi-parametric imaging for pre-surgical evaluation of epilepsy seizure focus: a one stop shop Dr Anna Barnes, UCL Hospitals NHS Foundation Trust

15:35 – 15:50 Deblurring in clinical applications of 3D Arterial Spin Labelling Enrico De Vita, National Hospital for Neurology & Neurosurgery, London

15:50 – 16:05 Mismatch of diffusion and T1/T2 MRI during acute ischaemic stroke in rats Bryony McGarry and Harriet Rogers, University of Bristol

16:05 – 16:15 Questions/discussion

16:15 Close

Evaluation of diffusion acquisition and tractography methods for neurosurgical planning Jonathan Ashmore1 Flavio Dell'Acqua2 Ruth O'Gorman 3 Gareth Barker2 Jozef Jarosz1

1Neuroradiology, Kings College Hospital, London 2Department of Neuroimaging, Kings College London, London 3University Children's Hospital, Zurich email: jonathan.ashmore@nhs.net

Background. Regulatory approved neurosurgical planning systems which include tractography are becoming increasingly used in the clinical setting. There are however well publicised limitations to the tractography process having serious implications to surgical outcome [1]. The goal of the work presented here was to investigate various refinements to the diffusion acquisition and postprocessing methods for the reproduction of the cortico-spinal tract, a pathway of significant interest to neurosurgeons. We evaluated a commercial neurosurgical planning system against freely available research software and the tracts reproduced were compared to cytoarchitectonic maps of the corticospinal tract which act as a gold standard for its true anatomical location [2].

Methods. Diffusion weighted images were obtained for 7 volunteers at 1.5T: TR=17s, TE=101ms, FOV=32cm, slices=52, 32 diffusion directions, b-value=1500s/cm2, 4xb0 images, isotropic voxels (2.5mm3). This “base” acquisition was repeated with the following modifications applied separately: (a) 64 diffusion directions, 7xB0 images; (b) peripheral gating to the cardiac cycle (c) non-isotropic voxels (1.25x1.25x2.5mm3 - this being the default scanner resolution). Tracts were obtained using the StealthViz neurosurgical planning software with a seed region positioned in the posterior limb of the internal capsule. The 32 (“base”) and 64 direction datasets were subsequently re-processed with mrtrix (http://www.brain.org.au/software/) to produce tracts using the diffusion tensor and the constrained spherical deconvolution (CSD) algorithms for both streamline and probabilistic tractography. Each subject’s tractography images were warped into the standard space of the cytoarchitectonic corticospinal tracts. Tract images were summed across all subjects to create frequency maps in standard space. The fraction of voxels which overlapped, and were outside the region of the cytoarchitectonic corticospinal tract were defined as the overalap and spurious fractions respectively. An accuracy score was defined as [# true positives + true negatives]/[# true positives + true negatives + false positives + false negatives]

Results. Quantitative results, and tract frequency maps are shown in figures 1 and 2 respectively

Conclusion. All methods investigated were limited in depicting the corticospinal tract compared to the cytoarchitectonic maps, in particular the lateral projections were not well represented. We found that tracts generated from non-isotropic voxels had poorer overlap with the cytoarchitectonic maps, a result reported by others [4]. Applying cardiac gating had little effect on the accuracy of tractography (although the effect may be greater for tracts closer to pulsatile blood vessels or CSF). CSD based streamline tractography provided the largest overlap fraction with a corresponding high number of spurious pathways, a result in agreement with published studies [5]. We found that CSD based probabilistic tractography provided the best compromise between overlap and spurious fractions leading to the highest accuracy. This tractography technique is not available in any regulatory approved neurosurgical packages and hence the results from this study may provide justification for the clinical use of non-CE marked software within the EU.

Key references. [1] Kinoshita M. et.al. NeuroImage 25:424 (2005) [2] Burgel U. et.al. NeuroImage 29:1092 (2006) [3] Burgel U. et.al. Cent. Eur. Neurosurg 70:27 (2009) [4] Neher P.F. ISMRM 3166 (2013) [5] Farquharson S. et.al. J Neurosurg 18:1367 (2013)

Figure 2. Tract frequency

maps comparing (a) isotropic

voxels (red) vs non-isotropic

voxel (blue). (b) mrtrix DTI

streamline tractography (red),

mrtrix CSD streamline

tractography (blue) and mrtrix

CSD probabilistic tractography

(yellow). Cytoarchitectonic

maps of the corticospinal tract

are shown in white

Figure 1.

Overlap

fraction,

spurious

fraction

and

accuracy

for the

various

acquisition

and

tractograph

y methods

A study of cerebral blood flow and oedema in hypoxia Victoria Bull1, Sarah Wayte1, Ravjit Singh Sagoo2, Eddie Ng’andwe2, Alex Wright3,4, Jamie Goodhart5, Mark Wilson6, Charles Handford7, Chris Koller1 Charles Hutchinson2,5 and Christopher Imray4,5,8

E-mail: victoria.bull@uhcw.nhs.uk 1Department of Radiology Physics, University Hospitals Coventry and Warwickshire NHS Trust, 2Department of Radiology, University Hospitals Coventry and Warwickshire NHS Trust, 3University of Birmingham, 4Birmingham Medical Research Expeditionary Society, 5Warwick Medical School, University of Warwick, Coventry, 6St Mary’s Hospital, Imperial College, London, 7University Hospitals Birmingham NHS Foundation Trust, 8Department of Surgery, University Hospitals Coventry and Warwickshire NHS Trust, Aims: During rapid ascent to high altitude there is a reduction in inspired oxygen levels (FiO2)

1,2. This may cause acute mountain sickness (AMS), and occasionally potentially fatal high-altitude cerebral oedema (HACE)1,3. It is believed that one of the processes by which cerebral oxygenation is maintained under hypoxic conditions is an increase in cerebral blood flow. The aim of this study was to quantify changes in arterial and venous cerebral blood velocity and vessel calibre, and to look for signs of cerebral oedema. Methods: Twelve subjects were scanned using a clinical 3T HDxt scanner (GE, Milwaukee, USA), at baseline (FiO2=21%) and at 2, 4, 6, 11 and 22 hours of continuous normobaric hypoxia (FiO2=12%) approximately equivalent to an altitude of 4,400m. T1-weighted images were acquired using a 3D Fast-Spoiled Gradient-Echo (FSPGR) sequence to provide structural information. Phase contrast angiography (PCA) of the right middle cerebral artery (MCA) was performed, allowing calculation of the diameter and flow velocity at each time point, approximately 1 cm proximal to the M1 bifurcation. Susceptibility-weighted images were acquired in 10 subjects to assess the cerebral venous anatomy. These images were registered to a standard brain space using SPM8 and post-processed using Matlab, in order to quantify the number of image voxels below a chosen threshold intensity at each time point, to look for changes in the venous space. In all subjects diffusion-weighted imaging (DWI) was conducted to allow calculation of the apparent diffusion coefficient (ADC). ADC values within the genu and splenium of the corpus callosum were calculated at each time point to look for signs of oedema. Each of the quantitative parameters were compared over time using paired t-tests. Results: The flow velocity within the MCA increased significantly at 2 hrs compared to baseline (p<0.05) then gradually reduced back to the baseline level. There was no significant increase in the diameter of the MCA from baseline to 6 hrs. For all subjects imaged, the median increase in the number of voxels in susceptibility-weighted images within the set intensity window was greater at all time points compared to baseline (representing an increase in venous calibre) (Fig. 1). The increase was statistically significant at 2, 4, 6 and 11 hrs. There was a significant increase (p<0.05) in the ADC within the splenium of the corpus callosum at 11 and 22 hrs, and in the genu of the corpus callosum at 22 hrs (Fig.2). Conclusions: This is the first study to measure changes in arterial and venous flow and brain oedema simultaneously on exposure to a 12% hypoxic stimulus. The results indicate that hypoxia induces an increase in CBF with concurrent venous distension implying a ‘restricted efferent flow’2,4,5 causing an increase in intra-cranial pressure together with an increase in cerebral arterial flow. Vasogenic oedema was also demonstrated within the corpus callosum, which has been noted previously3. Further analysis is taking place to establish the relative changes of venous engorgement and cerebral oedema that may underlie changes in intracranial pressure.

Fig. 1 Number of voxels falling below a set threshold intensity in susceptibility-weighted

images as a function of time.

Fig. 2 Mean ADC within an ROI in the splenium or genu of the corpus callosum

1Imray C, Booth A, Wright A and Bradwell A., Acute altitude illnesses. BMJ. 2011 15:343:d4943. 2Wilson MH, Newman S and Imray CH., The cerebral effects of ascent to high altitudes. Lancet Neurol. 2009 8(2):175-91. 3Hackett, P, Yarnell P, Hill, R, Reynard K. et al., High-altitude cerebral edema evaluated with magnetic resonance imaging. JAMA. 1998; 280(22):1920-5. 4Wilson MH, Davagnanam I, Holland G, Datani RS. et al., The cerebral venous system and anatomical predisposition to high altitude headache. Annals of Neurology 2013; 73(3):381-9. 5Wilson MH, Imray CH, Hargens AR. The headache of high altitude and microgravity-similarities with clinical syndromes of cerebral venous hypertension. High Alt Med Biol. 2011; 12(4):379-86.

The use of susceptibility weighted magnetic resonance imaging (SWI) in newborns with hypoxic ischaemic encephalopathy (HIE) to predict clinical outcome Darekar AA1, Thyagarajan B2, Joy HM3, Gawne-Cain M3, Baral V4, Kirkham F5,6, Vollmer B5,6 1Department of Medical Physics and Bioengineering, University Hospital Southampton NHS Foundation Trust 2Neonatal Unit, Princess Anne Hospital, University Hospital Southampton NHS Foundation Trust 3Department of Radiology, University Hospital Southampton NHS Foundation Trust 4Department of Neonatal and Developmental Medicine, The Academia, Singapore 5Paediatric Neurology, Child Health, University Hospital Southampton NHS Foundation Trust 6Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton email: angela.darekar@uhs.nhs.uk

Background Susceptibility weighted imaging[1] (SWI) is an advanced neuro MR imaging technique which accentuates image contrast due to the magnetic susceptibility of substances such as venous blood, blood products and iron[2]. It is increasingly being used in paediatric neuroimaging[3]. The intention of this pilot study is to explore the use of SWI in newborns with hypoxic ischaemic encephalopathy (HIE). As SWI is sensitive to blood products and venous oxygenation, it may be a useful adjunct to conventional MRI for detecting infarcts[3] and/or assessing oxygenation/metabolism changes in the brain[4] or the extent of venous occlusion[5] in HIE. We explored associations between SWI findings[6] and short-term neurological outcome to determine whether this technique is a valuable addition to standard MRI techniques[7] in predicting outcome. Methods Thirty newborns with HIE (13 male, 17 female, mean gestational age 39.8 (SD 1.6) weeks) were scanned at a mean age of 40.8 (SD 1.7) weeks on a 1.5T Siemens Symphony MRI scanner. The MRI protocol included proton density (PD), T1-weighted, T2-weighted, turbo inversion recovery (IR) and diffusion weighted imaging plus SWI imaging (TR/TE/flip angle = 50 ms/40 ms/12°). In 22/30 newborns good quality imaging data were available. Two paediatric neuroradiologists, blinded to the subject’s neurological status, reviewed the images and scored: (A) abnormal signs on the T1, T2, PD and IR images using the “Barkovich” scoring system[7] which examines the basal ganglia (BG) and watershed (WS) regions, and (B) “prominence of veins” signs (an indication of the level of venous oxygenation or occlusion) on the SWI images[6]. Scores were correlated to neurological outcome at age 12 months (Chi-Square test for the “SWI score”, Spearman’s correlation for the combined BG/WS score). Results The combined BG/WS score was significantly correlated with outcome (Spearman’s rho=0.51, p=0.01). Initial results show that there is evidence (p=0.049) for an association between SWI findings and neurological outcome at 12 months. Sensitivity of the SWI score was 42.8%, specificity 91%; sensitivity of the BG/WS score was 100%, specificity 21%. Discussion A low (abnormal) SWI score was associated with poor outcome; however the effects of variations in blood oxygenation and blood flow on SWI signal intensity, which might be present in newborns with HIE, should be investigated in more detail. In addition, development of a more specific scoring system and quantitative analysis methods to assess the SWI data may yield more detailed information to relate to clinical outcome measures. Conclusions This study has provided valuable pilot SWI data in a homogeneous cohort of newborns. SWI is a useful adjunct to standard imaging in HIE and could help predict outcome. Further work is required to fully assess the value of SWI. References [1]Haacke et al (2004) MRM 52:612–618, [2]Mittal et al (2009) AJNR 30:232-252, [3]Tong et al (2008) AJNR 29:9-17, [4]Kesavadas et al Neuroradiology (2010) 52:1047–1054, [5]Meoded et al (2012) Clinical Radiology 67:793-801, [6]Kitamura et al (2011) Pediatric Neurology 45:220-224, [7]Barkovich AJ et al (1998) AJNR 19:143-149.

Clinical Evaluation of Language Lateralization using fMRI in Epilepsy Surgery Candidates Jonathan Ashmore1 Karlene Fraser2 Ruth O'Gorman 3 Gareth Barker2 Jozef Jarosz1

1Neuroradiology, Kings College Hospital, London 2Department of Neuroimaging, Kings College London, London 3University Children's Hospital, Zurich email: jonathan.ashmore@nhs.net

Background. Language fMRI is often used for the assessment of epilepsy surgery candidates to determine the language dominant hemisphere. One confound to the interpretation of these studies is that the apparent (bi-)laterality of language regions can depend on the user defined activation threshold. Previous studies have addressed this problem through representing language lateralisation graphically on

a curve of lateralisation index (LI=(left-right)/(left+right)) vs statistical activation threshold2 or number of activated voxels3. A Bootstrap analysis can also be used to calculate LI producing results which are robust to data outliers4. In this study we evaluate these methods for volunteers and selected patients where “ground truth” language lateralisation is known through intraoperative electrocortical mapping or the presence of postoperative language deficit.

Methods. Functional MRI studies were performed on 2 volunteers and 9 patients at 1.5T. Language fMRI was assessed with a verb generation paradigm5 Images were acquired using gradient echo EPI: TR=3000ms, TE=40ms, voxel=3.75x3.75x3mm. fMRI processing was performed using SPM and incorporated motion correction, smoothing, normalisation and statistical testing. Unthresholded activation maps were masked to include only Broca’s and Wernicke’s areas using the Harvard-Oxford cortical structural atlas. Masked activation maps were processed to produce curves of LI vs statistical activation threshold and LI vs number of activated voxels. Bootstrap analysis was undertaken using the SPM LI toolbox3. The test-retest reproducibility of the LI curves was assessed from repeat fmri measurements on two volunteers who were subsequently classified as bilateral (Volunteer 1) and left lateralised (Volunteer 2). Patients were classified as left lateralised through presence of a postoperative language deficit (patient 1) or electrocortical mapping (patient 2).

Results. Figure 1 indicates that the LI curves for the two volunteers appear to have the highest intrasubject reproducibility when calculated using Bootstrap methods and displayed as a function of activated voxel number (fig1-right). This combination also best distinguishes between the two volunteers, who appear to have different language lateralisation. The LI curve for patient 1 (with known left lateralisation) appears to overlap with the repeated studies for the bilateral volunteer.

Figure 2. Lateralisation curves of LI vs statistical activation threshold with standard LI calculation (left); LI vs statistical activation threshold with LI calculated using bootstrap analysis (middle) LI vs number of activated voxels with LI calculated using bootstrap analysis (right).

Conclusion. The results suggest that the Bootstrap calculated lateralisation index plotted against activated voxel number is the most reproducible method. However the variability of the bilateral volunteer and their apparent overlap with the results of patient 1 (with known left lateralisation) highlights the uncertainty in the technique and how caution should be taken when drawing conclusions on language lateralisation from fMRI studies. The data presented in this study could help guide the risk assessment for future epilepsy candidates.

Key references. 1. Binder J.R Epilepsy Behav 20:214 (2011) 2. Ruff I.M. et.al. AJNR 29:528 (2008) 3. Abbott. D.F. et.al. NeuroImage 50:1445 (2010). 4. Wilke M. et.al. NeuroImage 33:522 (2006). 5. Leslie KR et al NeuroImage 21:601 (2004).

Multi-delay Pseudocontinuous Arterial Spin Labelling Protocol Development for the Assessment of Paediatric Brain Tumours

Jan Novak1,2,3, Stephanie Withey1,2,3, Lesley MacPherson3, Andrew C Peet1,2,3

Email: j.novak@bham.ac.uk 1. School of Cancer Sciences, University of Birmingham, Birmingham, UK. 2. Department of Imaging and Medical Physics, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK . 3. Birmingham Children’s Hospital NHS Foundation Trust, Birmingham, UK. Background Although rare, one third of childhood brain tumour patients die as a result of their disease. Therefore, novel methods to aid tumour detection, diagnosis and assessment of treatment efficacy would be greatly beneficial. Early response to treatment has been established as the most important indicator of long term survival in most cases (Leukaemia is the best example) and is used to stratify treatment. An important factor in tumour growth and response to treatment appears to be blood flow which can be measured via a number of different Magnetic Resonance Imaging (MRI) methods including the non-invasive Arterial Spin Labelling (ASL) technique. We propose the use of ASL for the assessment of paediatric brain tumours. Aims The aim of the project was to develop an ASL protocol at Birmingham Children’s Hospital which can reproducibly measure blood flow in a clinically acceptable timescale. Physiological parameters measured such as cerebral blood flow (CBF) will then be investigated as potential biomarkers. Methods All MRI was performed using a Philips 3T TX Achieva Scanner using a 32 channel head coil. ASL images were obtained using a pseudocontinuous labelling scheme and a multi-phase Look-Locker readout. This sequence allowed the acquisition of ASL data at six different post labelling delays: 800, 1000, 1200, 1400, 1600 and 1800 ms. The ASL scan took only 4.5 minutes. T2-weighted images were acquired for delineation of the tumours and proton density maps were acquired and used in the production of CBF maps. Total data acquisition was six minutes. Three volunteers were scanned in consecutive weeks to assess reproducibility. Data was analysed using in-house software developed using the Python programming language.

Results and Discussion Figure 1: The top left image shows an example T2-weighted image from a paediatric brain tumour patient with a CBF (in 100ml 100g-1 min-1) map generated from the ASL data. The table shows the average CBF values for both the tumours and grey matter of a series of paediatric brain tumour patients. The starred patients have had repeated scans three months apart with good reproducibility. The volunteer study showed that our

protocol produced reproducible CBF values within subjects across multiple scans over the course of one week (maximum error of 5.1%). All results obtained agreed well with reported literature values1. For the tumours, variable CBF values were observed for different PLDs highlighting the importance of using a multi-PLD acquisition. We found that the brain tumours were all hypoperfused when compared to grey matter which could be expected for low grade tumours2. Interestingly, we found that the high grade Medulloblastoma was also hypoperfused. Conclusion We have tested a multi-delay pseudocontinuous ASL protocol in a small cohort of paediatric brain tumour patients. The results were produced on a clinically-acceptable timescale, were reproducible for both volunteers and patients and calculated CBF values were within reported literature values. References 1. Calamante F, Thomas DL, Pell GS, Wiersma J, Turner R. Measuring cerebral blood flow using

magnetic resonance imaging techniques. J Cerebr Blood F Met. Jul 1999;19(7):701-735. 2. Yeom KW, Mitchell LA, Lober RM, et al. Arterial Spin-Labeled Perfusion of Pediatric Brain Tumors.

AJNR Am J Neuroradiol. Aug 1 2013.

Hippocampal Subfield volumetry as a marker of early Alzheimer's Disease Bryony J. Wood1

, Michael J. Knight1, Elizabeth Coulthard

2, Risto Kauppinen

1

1 SOEP, University of Bristol, 12a Priory Road, Bristol BS8 1TU.

2 BRACE, Frenchay Hospital, Frenchay park road, Bristol BS16 1LE.

email: bw9068@bristol.ac.uk

A

Aims Pathological progression in Alzheimer's disease (AD) begins years prior to the display of symptoms meaning that early detection is essential for treatment development. Hippocampal atrophy is a well-established feature of AD. However, it is not a uniform structure but composed of multiple subfields which are differentially vulnerable to the effects of the disease (1). Therefore, measures of hippocampal subfield volumetry could be more sensitive measures of early disease progression than global hippocampal volumetry. The aims of this project are to use MRI techniques to assess volumetric changes within subfields at the earliest stages of the disease to identify regions of vulnerability. These, in conjunction with cognitive tests are hoped to be useful in detecting AD pre-symptomatically. Methods High quality T2-weighted images were acquired on a 3T Skyra Siemens scanner using Carr-Purcell-Meiboom-Gill-like pulse sequences with an acquisition time of 10mins. A protocol for labelling subfields was written based on differences in image contrast and markers specified in neuroanatomical atlases (2). Volumetric analysis was subsequently performed on each subfield using the MRI analysis software FSL. The cohort comprised of 5 subjects, both male and female, including 2 healthy young participants, 20-25 years, 2 healthy elderly participants, 65- 90years and 1 participant with a recent diagnosis of mild cognitive impairment (MCI). Results In a cohort of 5 subjects (with a target of 80), subfield atrophy, expressed as a percentage of total hippocampal volume, was found to be particularly pronounced in the stratum lacunosum/ stratum moleculare and stratum radiatum (SL/SM/SR), considered as one subfield, and the dentate gyrus in MCI, beyond that expected in normal ageing. In comparison volumes of the CA1, CA2 and CA3 subfields remain relatively preserved.

Hippocampal Subfield Healthy elderly

participants (average) MCI Participant

Healthy Young Participants

(average)

CA1 32 34 32

CA2 3 5 3

CA3 7.7 12 8.47

Dentate Gyrus 23.78 16.43 23

Subiculum 11.21 12.5 11.5

SR/SL/SM 21.7 16 22.3

Table 1.Subfield volume expressed as a percentage of total hippocampal volume Figure 1. T2-weighted image displaying hippocampal subfield labels in the left hippocampal body for healthy elderly participant. Yellow= CA1, Orange= CA2, Red= CA3, Green= SL/SM/SR, Pink= Dentate Gyrus, Blue= Subiculum.

Conclusions The segmentation protocol is a useful technique, allowing volumetric analysis of different hippocampal subfields. The pronounced atrophy of the subfields named above is a promising means to report early stages of AD. We aim to correlate findings with cognitive test performance which, when combined, could be a sensitive marker of disease development. References 1. La Joie, R et al. (2013) Hippocampal subfield volumetry in MCI, AD and semantic dementia. NeuroImage Clinical, 3:155-162. 2. Duvernoy, HM. (2005) The Human Hippocampus: Functional Anatomy, Vascularisation and Serial sections with MRI. SpringerVerlag.

Towards discrimination of differential ageing processes by quantitative MRI relaxometry Michael J. Knight1, Bryony J. Wood1, Elizabeth Coulthard2, Risto A. Kauppinen1 1SOEP, 12a Priory Road, BS8 1TU 2BRACE, Frenchay Hospital, Bristol BS16 1LE email: psrak@bristol.ac.uk, mk13005@bristol.ac.uk

Aims Dementia has emerged as a leading global health concern, with Alzheimer’s disease (AD) the most prevalent type. Early, even pre-symptomatic, detection of such disorders is required for development and administration of appropriate therapy and support. The aims of the current project are to gain greater insight into the processes involved in normal ageing of the brain, and those in mild cognitive impairment (MCI) and early AD, with concomitant development of MRI protocols for distinguishing such pathways. The focus will be the hippocampus, due to its central roles in the above processes. It is not well understood which, if any, of the hippocampal subfields are principally affected by each ageing/dementia pathway (1). Methods A combination of quantitative MRI and cognitive tests are in use in this project. A principle hypothesis is that healthy aging and AD will lead to differential changes in T2 behaviour, particularly in the hippocampus. We are therefore using T2 quantitation by Carr-Purcell-Meiboom-Gill-like (CPMG) (2) pulse sequences, which simultaneously provide high quality T2-weighted images suitable for characterising individual subfields of the hippocampus. The sequences have been modified in-house and implemented on a Siemens Magnetom Skyra 3 T. The cohort comprises young healthy subjects, healthy elderly subjects, elderly subjects with a recent MCI diagnosis and elderly subjects with early AD. Results T2 quantitation by CPMG is fast, robust and accurate when implemented as a 2D multislice sequence with 12-14 spin echoes (echo spacing 12.5 ms) acquired per slice. With an acquired resolution of (0.6x0.6x1.84) mm3 in the coronal plane the acquisition time is 10 minutes. Typical images are given below. In a cohort of 5 subjects (with a target of 80) lengthened T2 is seen in a highly atrophied brain in a subject with MCI (B and D), whereas reduced T2 is seen in an elderly subject with no apparent atrophy and no MCI or dementia (A and C) relative to young controls. Typically, around 10000 voxels are sampled per hippocampus.

Fig 1: T2 mapping results in an elderly control (A,D) subject, an elderly MCI (B,E) subject and a young control (C,F). A-C: T2 maps overlaid with T2-weighted images through the hippocampal head, coloured by T2. Cool colours indicate short T2, warm colours long T2. D-F: Histograms of the hippocampal T2 show significantly different distributions in the 3 subjects.

Conclusions The current approach extends and

complements high-resolution volumetrics and it appears that T2 quantitation is a promising means to differentiate aging from MCI and potentially incipient dementia. The patients with MCI will be reassessed at 1 year to examine progression of MCI and clinical abnormalities. References 1: Frisoni et al, Nat Rev Neurol 2010, 6(2), 67-77 2: Haacke et al, Magnetic resonance imaging; physical principles and sequence design, Ch 21

Multi-modality, multi-parametric imaging for pre-surgical evaluation of epilepsy seizure focus: a one stop shop

Anna Barnes1, Illaria Galazzo2, Celia O’meara1, John Dickson1, Francesco Fraoli1 Email: anna.barnes1@nhs.net 1. Institute of Nuclear Medicine, University College London Hospitals Trust, UK. 2. Department of Neurological, Neuropsychological, Morphological and Movement Sciences, University of Verona, Italy Introduction. Brain scanning methods were first applied in patients with epilepsy more than 30 years ago. The main role of imaging tests is to noninvasively obtain localization of the presumed source of seizures and to optimally select surgical candidates, that is, those most likely to have a seizure-free outcome. Nonetheless, the decision algorithm for epilepsy surgery is generally based on empirical and center-specific logistics. A very substantial literature now exists in this field, covering the full range of neuroimaging methods with SPECT, PET and MRI in epilepsy. Consensus is that emission tomography scans are essential for temporal lobe epilepsy patients but destined for surgery but negative for structural abnormalities. However, recent advances in neuroMRI now provide a range of sequences that assess brain function as well as structure. We present data that show promising evidence that new advanced neuroMRI methods can provide corroborative data to those made by PET imaging using a simultaneously acquired PET and functional MRI data set.

Methods. 5 epilepsy patients referred for PETCT at the INM, UCLH, were also imaged on PETMR (mMR Biograph, Siemens, Germany). Each patient had the following data collected. PET static scan for 15 mins for the purposes of mapping CMRglu. Simultaneous MRI data was collected: arterial spin labelling ASL (50 control-tag pairs), High res T1 volume MPRAGE, Diffusion tractography DTI (b-vals:0,1000, 30 directions, 2 aves). In addition single voxel spectroscopy and chemical shift imaging (TE=144ms) were collected in the region of the temporal lobes immediately following the cessation of the PET acquisition. Attenuation corrected PET data were iteratively reconconstructed using a segmented UTE sequence, which captures the MR signal from bone, as an analogous electron density map. The ASL, DTI and spectroscopy data, were all processed using the Siemens applications (VB18p) to produce relative CBF maps, fractional anisotropy maps and spectra respectively. In addition the CBF and FA maps were transferred into standard anatomical space. Grey and white matter maps were calculated using SPM8 (DARTEL processing) matlab vR13 based software application. Results Initial visual evaluation of the data shows a good correspondence between ASL relCBF maps and CMRGlu in terms of overlapping hypo flow and metabolism. The Spectral maps showed asymmetrical features such that the effected hemisphere showed a decrease in the NAA/Cr ratio. Correspondence between grey matter maps and FA maps with the relCBF and CMRGlu is yet to be assessed.

An example from one single subject of 18F-FDG, ASL and single voxel spectroscopy data showing good correspondence between each type of data.

Discussion The assessment of epilepsy for the purposes of pre-surgical planning is already a multi-modal, multi-parametric exercise but done on separate scanners and assessed by different people. The introduction of the first true hybrid PETMR scanner into clinical practice has given us the opportunity to do a head-to-head validation of ‘functional’ MRI with 18F-FDG PET images acquired simultaneously. There is clearly a lot more work to be done not least to understand when the MR data doesn’t not corroborate the PET data. Future plans will incorporate simultaneous EEG and the mathematics of multi-variate pattern recognition algorithms will need to be developed to encompass the huge amount of data currently being generated by these type of investigations.

Deblurring in clinical applications of 3D Arterial Spin Labelling 1,2De Vita E, 3Boscolo Galazzo I, 2Oliver R, 2Thomas D, 2Golay X, 1,2Yousry T, 1,2Thornton J, 1,2Jäger HR, 4Chappell M Email: e.devita@ucl.ac.uk 1. Lysholm Department of Neuroradiology. National Hospital for Neurology and Neurosurgery, London, UK. 2. Academic Neuroradiological Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, London, UK. 3. Department of Neurological and Movement Sciences, Universityof Verona, Verona, Italy. 4. Institute of Biomedical Engineering, University of Oxford, Oxford,UK. Background. Arterial Spin Labelling (ASL) MRI allows non-invasive cerebral blood flow (CBF) measurements. Clinical application of ASL is rapidly increasing. Beside labelling method (pulsed ASL, pASL, pseudo-continuous ASL) the readout module must be chosen: 3DGRASE offers improved signal to noise ratio (SNR) and reduced in-plane distortions with respect to 2DEPI [1,2], but single-shot implementations suffer from severe partition-direction blurring. Multi-segment acquisitions reduce blurring by decreasing echo-train duration and related signal decay. However using higher number of segments decreases the number of averages achievable in a fixed examination time. In clinical settings multi-inversion time (multi-TI) ASL acquisitions are also attractive as they allow bolus arrival time evaluation, though, again, at the expense of averaging. We here apply a recently developed deblurring technique [3,4] to clinical multi-TI pASL data. Methods. MRI scanner: 3T Siemens Skyra. 3DGRASE patients acquisitions: 4-segment, 1 average (avg), total acquisition time (AcqT) 4’47", TE/TR=21.1/3500ms, in-plane resolution 3.75mm2, 20 5.25mm slices, 10 TIs: 0.35-2.6s (interval 0.25s). Volunteer acquisitions: different combinations of number of segments/avg: 2-segment (2 avg; AcqT 4’47”); 4-segment (1 avg; AcqT 4’47”); 8-segment (1 avg; AcqT 9’27”). Volunteers (n=4) gave informed consent; data from patients (n=12, one patient twice) were analysed within a wider audit aimed at evaluating the impact of ASL perfusion imaging on clinical management. Analysis: The width of the point spread function (PSF) describing blurring in the head-feet (z) direction (and assumed to be Lorentzian) was estimated as in [3,4] from the residuals after fitting the multi-TI perfusion data with the general kinetic model [5] using FSL BASIL. The data were then deblurred using a Lucy-Richardson iterative deconvolution procedure [6] and finally fitted again with FSL BASIL to extract CBF and BAT maps. Results. The width of the estimated Lorentzian PSF decreased with number of segments in all volunteers (mean values 1.08±0.04, 1.04±0.04, 0.96±0.03 for 2, 4, 8-segment respectively). Mean width for patients was 1.07±0.13 (median 1.06, range 0.84-1.33, %SD=12%). In one patient scanned twice 4 months apart, the later PSF width was within 3.5% the initial width. The green Figure shows CBF for a volunteer. The orange Figure shows data from a patient scanned for surveillance of a low-grade glioma displaying areas of contrast enhancement concordant with increased CBF in the ASL images (cross) indicating progression to high-grade glioma. Discussion and Conclusions. As expected greater z-blurring is associated with fewer segments acquisitions. The 8-segment acquisitions show little signs of blurring but double the acquisition time. After deblurring even the 2-segment acquisitions appear acceptable. The estimated PSF width varies between patients, probably due to intra-individual variation in parenchymal T1 and T2 relaxation times. The application of the deblurring algorithm to clinical 4-segment data improves their appearance and facilitates matching with higher spatial-resolution routine clinical images. Our study supports the use of the deblurring algorithm even for high-number-of-segment acquisitions. Future assessment of the SNR in the 2-segment/2-average vs the 4-segment/1-average datasets post deblurring will be carried out to establish which protocol can provide the most accurate perfusion information. References. 1) Gunther, MRM 2005, 54:491. 2) Fernandez-Seara M, MRM 2008, 59:1467. 3) Chappell MA, MRM 2010,63:1357. 4) Boscolo Galazzo I, ESMRMB 2013, 332. 5) Buxton R 1998 40:383. 6) Lucy LB, Astron J 1974, 79:745. Acknowledgments: COST Action BM1103: ASL Initiative in Dementia (AID).

2DEPI 2-segment 4-segment 8-segment MPRAGE debl-2 debl-4 debl-8

MPRAGE T1

postGd

Original Deblurred

CBF CBF

4-segment 4-segment

Mismatch of Diffusion and T1ρ/T2 MRI During Acute Ischaemic Stroke in Rats Bryony L. McGarry1* and Harriet J. Rogers1*, Michael J. Knight1, Kimmo T. Jokivarsi2, Olli H. J. Gröhn2, Risto A. Kauppinen1

1Bristol Clinical Research and Imaging Centre, University of Bristol, UK, 2 Department of Neurobiology, A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland, *Authors contributed equally

Aim: Multiparametric MRI has been proposed as an imaging tool for patient management in acute ischaemic stroke 1,2. It is well established that hyper-intense regions on Diffusion Weighted Images (DWI) and hypo-intense regions of Apparent Diffusion Coefficient images (ADC) represent acute ischaemia 3,4. Incorporating absolute relaxation time data from parenchymal T1, T2 and T1ρ a much fuller picture of brain tissue viability is obtained1-4. For instance, it has been proposed that T1ρ and T2 increase linearly with time during ischaemia1,5. This study aimed to determine whether significant increases in T1ρ and T2 occur in the same pixels as hypo-intense pixels on absolute ADC images. Methods: Wistar rats (n=7) underwent permanent Middle Cerebral Artery Occlusion (MCAO) to induce focal stroke1. Rats were scanned at several time points using a Varian horizontal 4.7T MRI scanner with surface coil in T/R mode for absolute ADC images, T1ρ and T2 maps as described previously1. Non-ischaemic hemisphere was used as a reference for MRI parameters. Images displaying the absolute percentage difference in T1ρ and T2 between analogous tissues in each hemisphere were computed on a pixel-by-pixel basis. Pixel-wise one sample t-tests were performed on absolute percentage difference images resulting in maps displaying the confidence interval for each pixel. Visually guided ROIs were manually drawn around hypo-intense regions on ADC images and loaded onto corresponding confidence interval maps. To depict which pixels within the ROI differed significantly from the non-ischaemic hemisphere, different confidence intervals were colour-coded. The number of pixels within each confidence interval were recorded for each rat at each time point. Results: Figure 1A., shows typical ADC images during ischaemia. ADC defined ROIs with significantly different relaxation times to analogous non-ischaemic brain are shown for T2 (Figure 1Bi.) and T1ρ (Figure 1C.); confidence interval colour codes are shown. Both T2 and T1ρ maps showed heterogeneity within ischaemic tissue defined by the ADC ROI. These patterns were typical for all rats. Non-significant differences were found within the ROI of both T1ρ and T2 maps (Figure 1Bi. and 1C.). Additionally both negative and positive differences were seen in T2 (Figure 1 Bii.) but not T1ρ. The number of significantly different T2 and T1ρ pixels increased linearly with time (Figure 2.) consistent with the previous study1. Pearson’s correlations showed these relationships were significant for T2 (r = .80, p = <.001) and T1ρ (r = .91, p = <.001) which increased at a faster rate. Discussion: Ischaemic brain parenchyma, as revealed by hypo-intense ADC, contain tissue with heterogeneous T2 and T1ρ relaxation times. Both relaxation times change in a time-dependent manner potentially allowing stroke onset time to be determined1. Interestingly, T2 maps show regions with a negative difference to non-ischaemic brain. These regions may have ongoing oxidative metabolism and thus are still viable6. As some areas within ADC ROIs show no significant change, results suggest ADC defined ischaemia over-estimates irreversibly damaged tissue. Multiparameteric MRI may be useful for identifying salvageable tissue and estimating stroke onset, both factors being of paramount impact in clinical patient management.

References: [1].Jokivarsi, K. T. et al., Stroke 41 (2010). [2].Neumann-Haefelin, T. et al., Stroke 30 (1999). [3].Olivot, J.-M.

et al., Stroke 40 (2009). [4].Schaefer, P. W. et al., AJNR Am J Neuroradiol 24(2003). [5].Siemonsen, S. et al., Stroke 40

(2009). [6].Gröhn et al. JCBFM 20 (2000).

CT Optimisation 8th April 2014, Park Inn Hotel, York Organised by the IPEM Diagnostic Radiology Special Interest Group

FINAL PROGRAMME

09:00 – 09:55 Coffee and registration

09:55 – 10:00 Introduction

Chair: Gareth Iball

10:00 – 10:30 What a Radiologist wants from CT images Dr Damian Tolan, Leeds Teaching Hospitals NHS Trust (Invited Speaker)

10:30 – 11:00 Measurement and optimisation of image quality in CT Koos Geleijns, Leiden University Medical Centre, The Netherlands (Invited Speaker)

11:00 – 11:30 Coffee

Chair: Gareth Iball

11:30 – 11:45 Reflections and Perspectives on Optimisation and how to achieve it Hugh Wilkins, Royal Devon and Exeter NHS Trust

11:45 – 12:00 CT dose monitoring and optimisation in paediatric CT using Radiation Dose Tracking Software (RDTS) Dr Kevin Murphy, Cork University Hospital, Ireland

12:00 – 12:15 Chipping away at CT doses; the long road to optimisation Mandy Moreton, Colchester Hospital University NHS Foundation Trust

12:15 – 12:30 Questions

12:30 – 13:30 Lunch

Chair: Paul Charnock

13:30 – 13:45 The Importance of Patient Centring in Hybrid Imaging Maria Burniston, Royal Free London NHS Foundation Trust

13:45 – 14:00 Use of dose tracking software for assessment of patient positioning in CT Dr Kevin Murphy, Cork University Hospital, Ireland

14:00 – 14:15 4D CT protocol optimisation on the Philips Big Bore; practical experience and pitfalls Dr Tim Wood, Hull and East Yorkshire Hospitals NHS Trust

14:15 – 14:30 Cardiac CT optimisation on a Siemens Definition Flash Dr Elly Castellano, The Royal Marsden NHS Foundation Trust

14:30 – 14:50 Questions

14:50 – 15:15 Coffee

Chair: Tim Wood

15:15 – 15:30 Cone Beam CT Protocol Optimisation for Prostate Imaging with the Varian Radiotherapy OBI imaging system Dr Craig Moore, Hull and East Yorkshire Hospitals NHS Trust

15:30 – 15:45 Comparison between diagnostic reference levels by anatomy and clinical indication Paul Charnock, Integrated Radiological Services (IRS) Ltd, Liverpool

15:45 – 16:00 A tale of two CTs (plus one) Gareth Iball, Leeds Teaching Hospitals NHS Trust

16:00 – 16:30 Questions/discussion

16:30 Close

Reflections and Perspectives on Optimisation and how to achieve it Hugh Wilkins, Royal Devon & Exeter NHS Foundation Trust Email: hw@nhs.net

CT optimisation has become a ‘hot topic’ in recent years. Reasons for this include the substantial increase in numbers of CT scans shown in serial surveys, notably from PHE and its predecessor bodies in the UK1..4, and the consequent substantial increase in population doses from CT examinations1,2. Worldwide, just under 43% of the radiation dose to the world’s population from medical exposures arises from CT scanning5. This has prompted predictions of consequential radiation-induced cancer, e.g. from Brenner et al6, with recent epidemiological studies7,8 demonstrating CT-cancer associations, though these are areas of scientific controversy. Radiation risk from CT has become an issue of public interest following several incidents in the USA resulting in deterministic effects, prompting new legislation. This has been against a background of significant developments in CT technology9 and significant informatics developments opening the door to ‘big data’ data-mining techniques, which are likely to play a large role in future CT Optimisation10.

1. Hart D, Hillier MC & Shrimpton PC. Doses to Patients from Radiographic and Fluoroscopic X-ray Imaging Procedures in the UK - 2010 Review. Chilton: Health Protection Agency, 2012. HPA-CRCE-034

2. Hart D, Wall BF, Hillier MC and Shrimpton PC. Frequency and collective dose for medical and dental X-ray examinations in the UK, 2008. Chilton, Didcot: Health Protection Agency, CRCE 2010. HPA-CRCE-012

3. Shrimpton PC, Hart D, Hillier MC, Wall BF & Faulkener K. Survey of CT Practice in the UK. Chilton 1991 NRPB-R248,R249

4. Shrimpton PC, Hillier MC, Lewis MA & Dunn M. Doses from Computed Tomography (CT)

Examinations in the UK - 2003 Review. Chilton 2005 NRPB-W67

5. United Nations Scientific Committee on the Effects of Atomic Radiation. UNSCEAR 2008 Report: Volume 1: Sources. Report to the General Assembly: Annex A - Medical radiation exposures. New York: United Nations, 2010

6. Brenner DJ Elliston CD Hall EJ & Berdon WE. Estimated Risks of Radiation-Induced Fatal Cancer

from Pediatric CT. AJR 2001;176:289–296

7. Pearce MS, Salotti JA, McHugh K, Lee C, Kim KP et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet online. 2012;June 7

8. Mathews JD, Forsythe AV, Brady Z, Butler MW, Goergen SK, Byrnes GB et al. Cancer risk in

680,000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians. BMJ. 2013;346:BMJ 2013;346:f360

9. Kalendar WA. Doses in x-ray computed tomography. Phys. Med. Biol. 2014;59(3):R129-R50

10. Wilkins H & Knapp KM. Potential applications of dose-tracking and active dosimetry systems to encourage X-ray image optimisation and minimise staff dose. Proceedings of IAEA/WHO International Conference on Radiation Protection in Medicine: Setting the Scene for the Next Decade; 2012 3-7 December 2012 Bonn (in press).

CT dose monitoring and optimisation in paediatric CT using Radiation Dose Tracking Software (RDTS) Kevin Murphy 1Twomey M, 1Murphy KP, 1Moloney F, 2Sheehy M, 1O’Connor OJ, 1Maher MM. 1Department of Radiology, Cork University Hospital, Cork, Ireland. 2Department of Medical Physics, Cork University Hospital, Cork, Ireland. email: kevinpmurphy@ucc.ie

Background: The use of CT in the paediatric population has increased exponentially, particularly with the advent of MDCT. Dose monitoring and optimisation is of key importance in this cohort. The purpose of this study was to document the dose range in DLP and SSDE in a cohort of paediatric patients utilising RDTS (DoseWatch, GE Healthcare). Factors evaluated include patient age, choice of acquisition parameters, time of study and diagnostic yield.

Methods: 160 paediatric CT brain, skull, thorax and abdominopelvic performed over a 4 month period (Sept 2013-Jan 2014) on two MDCT scanners were evaluated. Individual dose reports including CTDivol, DLP and SSDE were recorded by DoseWatch for all patients. The range and mean dose values, mA, kV, isocentre analysis tool values and scan length were analysed to better identify parameters that could be optimised. Positive diagnostic yield and variation in dose over the study period was investigated. The local dose range was compared to international diagnostic reference levels.

Results: The DLP and SSDE range across all age categories were 240-1580 mGy.cm (DLP) and 1.9-18mGy (SSDE) for brain examinations; 9-374mGy.cm (DLP) and 0.3-5mGy (SSDE) for skull; 13-150 mGy.cm (DLP) and 0.9-2.8 mGy (SSDE) for thorax and 30-400 mGy.cm (DLP) and 1.8-10.9 mGy (SSDE) for abdominopelvic CT. 92% of CT examinations had recorded exposures within diagnostic reference level ranges. Substantial differences were noted in the selection of specific protocols for the same clinical indication. 58% of CT brains were performed outside of working hours with a low positive diagnostic yield of only 25%.

Discussion: RDTS offers significant advantage in streamlining dose data analysis with the automatic generation of individual SSDE. The assessment method used, proved useful for identifying dose outliers and potential explanations for same. The hospital mean DLP values are similar to international DRLs for CT brain studies and considerably lower than international DRLs for thorax and abdominoplevic studies.

Conclusion. Optimisation of CT protocols is paramount particularly for children who are more radiosensitive than adults. RTDS facilitates assessment of dose associated with individual CT protocols and comparison with DRLs and enables identification of those protocols where risk for over-exposure occurs.

Key references:

1. Arch ME, Frush DP. Paediatric body CT: a 5 year follow-up survey of scanning parameters used by paediatric radiologists. AJR 2008:191(2): 611-617.

2. Brady SL, Kaufman RA. Investigation of American Association of Physicists in Medicine Report 204 size-specific dose estimates for pediatric CT implementation. Radiology 2012;265(3):832–840.

3. Pages J, Buls N, Osteaux M. CT doses in children: a multicentre study. Br J Radiol 2003;76:803–11

4. Larson DB, Johnson LW, Schnell BM et al: Rising use of CT in child visits to the ED in the US, 1995-2008. Radiology 2011;259(3):973-801.

5. Shrimpton PC, Hillier MC, Lewis MA, Dunn M. Doses from computed tomography (CT) examinations in the UK: 2003 review. Report NRPB-W67. Chilton, UK: National Radiological Protection Board; 2005.

Chipping away at CT doses; the long road to optimisation Mandy Moreton 1Moreton A, 2Pellow C, 1Porter A, 1Koutalonis M

1Radiation Protection, Medical Physics Department, Colchester Hospital University NHS Foundation Trust, Essex, UK. 2Radiology Department, Colchester Hospital University NHS Foundation Trust, Essex, UK. email: mandy.moreton@colchesterhospital.nhs.uk

Background.

Patient dose data was collected from a Toshiba Aquilion 64 slice CT scanner to determine compliance with current national DRLs and for submission to the national CT dose survey in 2011. Initial datasets collected for High Resolution Chest CTs and Chest CT scans showed that scan protocols were not optimised. This led to a series of changes in protocols on both the 16 and 64 slice Toshiba Aquilion scanners to reduce patient doses for many examinations.

Methods.

Data was collected by Radiographers for Head, Chest, Abdo/Pelvis and Chest/Abdo/Pelvis scans as well as other examinations on both the 16 slice and 64 slice scanners. This data was analysed by Radiation Protection who worked closely with the Radiographers, Radiologists and Toshiba to amend protocols and assess the effect of the changes made on both patient dose and image quality.

In order to achieve acceptable dose reduction and maintain adequate image quality, the noise settings, reconstruction algorithms and scan lengths have had to be changed on various protocols.

Results and Discussion.

As a result of the work, median DLPs are now within national DRLs for standard examinations. Baselines for other examinations, for which national DRLs are expected, have also been set. For one examination in particular, the average DLP has been reduced by more than 25% and other examinations saw average DLP reductions of the order of 20%. For fixed mA HRCT scans, standard patient and large patient protocols have been set up to optimise patient dose. Thin patient protocols, with lower noise settings (on auto mA scans), have also been set up to improve image quality at the expense of increased patient dose.

The importance of clear communication and training was highlighted throughout the process, as well as the need to understand in depth the effect of protocol parameters and equipment settings on patient dose and image quality.

Conclusion.

Significant dose reduction can be achieved; however this must be done in a controlled manner with input from all staff groups. Communication and trust are key elements in the process and the impact of protocol changes on image quality must be considered at all times.

Key references.

Doses from Computed Tomography (CT) Examinations in the UK – 2003 review NRPB W67

The Importance of Patient Centring in Hybrid Imaging Maria Burniston Almeida A, McMeekin H, Burniston M Nuclear Medicine, Royal Free London NHS Foundation Trust email: mariaburniston@nhs.net

Background: Patient centring is important for dose and image quality, but many technologists working in nuclear medicine have limited training in CT techniques. We aimed to audit the variability in patients centring in both phantom and clinical studies and evaluate the impact on dose. Methods: An anthropomorphic phantom was used to assess differences in dose at different bed heights in SPECT CT and PET CT and to assess variability of set up between 9 trained technologists. The scans of patients who attended for PET CT scans on multiple occasions were analysed to check for differences in bed height. Results: Results from the anthropomorphic phantom showed that dose differences of up to 28% from the ideal centring position resulted from changes to bed height of 5 cm. Results from both the anthropomorphic phantom audit and from the repeat patient scans showed that differences of this magnitude are common (mean difference 3.7cm). Discussion: Isocentre positioning, even with small differences in bed height, has a large impact on mA modulation and the bow-tie filter, which are essential to image quality and dose optimisation. Conclusion: There is significant variability in patient centring. Training and education in this area are vital.

Use of dose tracking software for assessment of patient positioning in CT Kevin Murphy 1,2Murphy KP, 1Nicholson P, 1Twomey M, 1O’Connor OJ, Sheehy M, 1Moore N, 1,2Maher MM. 1Department of Radiology, Cork University Hospital, Cork, Ireland. 2Department of Radiology, University College Cork, Cork, Ireland. email: kevinpmurphy@ucc.ie

Background. Due to bow-tie filter employment at CT, correct patient centring is of key importance in reducing patient dose and image noise (1–3). Accurate patient positioning is also important for optimal performance of automated tube current modulation which in turn reduces radiation dose (4). Incorrect centring has been shown to increase dose by up to 140% (2). We utilised newly available dose tracking technology to assess variance in patient positioning in CTs of the abdomen and pelvis and factors associated with sub-optimal patient centring.

Methods. Patient centring during abdominal CT was retrospectively analysed in 121 studies using an automated dose tracking programme (DoseWatch, GE Healthcare). Scan type, scan time, patient anatomical position and distance from the epicentre in both the X and Y planes were recorded.

Results. The mean distance from the epicentre was significantly greater in the Y plane (delta Y) 17.47±11.7 mm (range 0-52.91 mm) than the X plane (delta X) 10.22±8.8 mm (p < 0.001) (range 0-60.55 mm) for all studies. Prone studies showed greater mean delta Y isocentre deviations (20.71±18.28 mm) than supine studies (15.81±14.18 mm) though this difference did not reach significance. There was no significant difference between studies performed during daytime hours and ‘out of hours’.

Discussion. CT dose reduction is an important challenge for healthcare institutions. Efficient patient centring is an important CT dose reduction strategy to complement other dose reduction strategies. Our results show that miscentring is more likely to occur in the Y plane and during prone scanning. A mean deviation in the Y plane of 17.47 mm may result in a mean dose increase of almost 13.5% per patient using data published by Habibzadeh et al (3). It is also worth noting that some patients had deviations of up to 6 cm which is reported to lead to a dose increase of 51.1% (3). Given the dose increases associated with isocentre divergence, a more robust process to ensure patient centring would be welcome, with an automated procedure being optimal.

Conclusion.

In this study, suboptimal patient centring is associated with Y plane positioning and prone scanning. Based on previous studies, suboptimal-positioning of this nature may be associated with significant dose increases.

Key references.

1. Kaasalainen T, Palmu K, Lampinen A, Kortesniemi M. Effect of vertical positioning on organ dose, image noise and contrast in pediatric chest CT--phantom study. Pediatr Radiol. 2013 Jun;43(6):673–84.

2. Toth T, Ge Z, Daly MP. The influence of patient centering on CT dose and image noise. Med Phys. 2007 Jul;34(7):3093–101.

3. Habibzadeh MA, Ay MR, Asl ARK, Ghadiri H, Zaidi H. Impact of miscentering on patient dose and image noise in x-ray CT imaging: phantom and clinical studies. Phys Med. 2012 Jul;28(3):191–9.

4. Gudjonsdottir J, Svensson JR, Campling S, Brennan PC, Jonsdottir B. Efficient use of automatic exposure control systems in computed tomography requires correct patient positioning. Acta Radiol. 2009 Nov;50(9):1035–41.

4D CT protocol optimisation on the Philips Big Bore 16 slice CT scanner; practical experience and pitfalls Tim Wood Wood T J, Moore C S Radiation Physics Department, Hull and East Yorkshire Hospitals NHS Trust, Castle Hill Hospital, Cottingham, HU16 5JQ. email: tim.wood@hey.nhs.uk

4D CT is now becoming common place in many radiotherapy centres for assessing the motion of both the tumour and organs-at-risk, and hence ensuring the best possible treatment delivery for particularly mobile organs, such as the lung and oesophagus. In the Hull and East Yorkshire Hospitals NHS Trust, we have recently commissioned our Philips Big Bore CT scanners for the acquisition of 4D data sets via retrospective gating with the Varian RPM system. As part of this process, it became very apparent that protocol optimisation was essential for these types of examination due to the relatively high dose (compared with a standard fast-3D helical scan), and the additional complexity of the ‘phased’ reconstructions and resulting image quality.

Initial work with our automatic exposure control (AEC) phantom highlighted that the manufacturers recommended protocol had clear limitations owing to the single mAs value that is used (the AEC was not activated for these protocols), and the limited range of breathing rates that could be imaged (10 to 20 breaths per minute). Of particular concern were the variations in noise between the different size ‘patients’, and the sharp increase in noise for individuals with slow breathing rates. The results of this study will be presented, highlighting the limitations of this type of 4D CT acquisition, with some suggestions for optimisation strategies that should reduce the impact of these image quality concerns.

Cardiac CT optimisation on a Siemens Definition Flash Elly Castellano, Physics Department, Royal Marsden Hospital, Fulham Road, London SW3 6JJ Email: Elly.Castellano@rmh.nhs.uk

Coronary CT angiography poses additional challenges for optimisation over general CT because of the temporal aspect of these exams. A multidisciplinary approach is therefore essential because the decision about which cardiac phases to image and how to image them is a clinical one. At the Royal Brompton Hospital a multidisciplinary group has been working to optimise coronary CT angiography protocols on the Siemens Definition Flash scanner. This scanner offers step-and-shoot protocols with prospective ECG-triggering, low-pitch helical protocols with retrospective ECG-gating and high-pitch helical protocols with prospective ECG-gating (Flash mode). The scanner features tube current modulation according to patient size and the ECG, and algorithms to predict the timing of future cardiac cycles. This presentation describes how the group has approached optimising coronary CT angiography. The first step was to carry out a dose audit to benchmark dose levels and clinical practice. The second step was to invite the manufacturer to review the existing protocols and the selection of scan technique according to heart rate and heart rate variability. Thirdly, the medical staff reviewed the use of beta blockade. The group then made extensive use of radiation and clinical audits in order to confirm the efficacy of the new protocols. For example, a clinical audit was carried out to evaluate the prevalence and clinical impact of the “Flash artefact” in Flash scans, and a detailed radiation audit was carried out to understand the broad range of doses encountered with prospectively triggered exams. As a consequence of these audits, confidence in the Flash technique has grown, and the prospectively ECG-triggered protocol has been further refined. The outcome of the optimisation exercise has been a clear, efficient imaging pathway and reduced collective dose to this patient cohort.

Cone beam CT protocol optimisation for the Varian OBI system, and the impact on patient dose

Craig Moore Wood T J, Moore C S Radiation Physics Department, Hull and East Yorkshire Hospitals NHS Trust, Castle Hill Hospital, Cottingham, HU16 5JQ. email: craig.moore@hey.nhs.uk

The use of cone-beam CT (CBCT) in the radiotherapy treatment room is becoming increasingly common with the implementation of image-guided and adaptive radiotherapy. Whilst the benefits of CBCT are now well established, it must always be remembered that the use of ionising radiation for these purposes will present additional risks to that associated with the radiotherapy treatment, and these may often be more significant than people realise. Hence, it is important to ensure that our protocols are optimised to ensure that all doses of ionising radiation ‘are kept As Low As Reasonably Practicable (ALARP), consistent with the intended purpose’. However, without a clear understanding the level of radiation exposure to which these systems subject the patient, it is difficult to optimise imaging protocols as the impact of any changes on patient dose and image quality may not be clearly understood. It is for this reason that we have developed and validated a technique that utilises commercial software (PCXMC 2.0) to estimate the individual organ doses for typical CBCT examinations. This has demonstrated that over a 37 fraction treatment, organs such as the bladder, rectum and gonads may receive doses well in excess of 1 Gy when a daily imaging regime is implemented. The range of optimisation issues that have been encountered with the Varian OBI system will then be discussed, and in particular our attempts to develop patient size specific imaging protocols; currently each anatomical site has fixed exposure factors for every patient, no matter how large or small they are. The consequences of these limited protocols are that image quality may not be sufficient for the largest patients, whilst particularly slim patients will receive a dose that is much higher than is actually required. The effect of this has been modelled with PCXMC, and the resulting doses compared with alternative imaging protocols that take into consideration patient size. Other practical considerations for the optimisation of CBCT examinations have also been investigated, and some practical tips will be presented.

Comparison between diagnostic reference levels by anatomy and clinical indication in CT

Paul Charnock, Integrated Radiological Services Limited, Unit 188 Century Building, 102 Tower Street, Brunswick Business Park, Liverpool, L3 4BJ Charnock P, Dunn F, Murphy J, Tickle C Email: PaulCharnock@irs-limited.com

It has been shown that methodologies exist to obtain mass data exports from local hospital radiology information systems or via the DICOM header. This allows local DRLs to be established for more examination types, however these methodologies obtain examination names that are usually given with reference to the body part being examined. During a recent routine dose audit at a major Trust hospital, it was noted that some examinations appeared to consist of a bi- or multi- modal distribution of doses, indicating that the examination name was being used for two or more types of examination. This study looks at two of these examinations and compares the results of a dose audit based on the examination name or body part versus the results of an audit against an examination based on clinical indication. The two examinations chosen are: • Routine Chest vs Follow up Chest • CT Head separated into stroke detection and trauma Data extracted from RIS is used to establish a local DRL based on body part. This method follows the process recommended in IPEM 88 by comparison with national data as a first step and then with previous audits from the same Trust. In addition the DICOM header data for a selection of examinations has been obtained which will show specifically the clinical indication for these examinations. The DICOM data and the RIS data will then be compared and recommendations made towards the use of RIS codes for clinical indication rather than body part. Initial results have shown that a lower DRL would be applicable for stroke detection whereas a higher DRL would be obtained for Trauma.

A tale of two CTs (plus one) Gareth Iball, Leeds Teaching Hospitals NHS Trust, Leeds General Infirmary, Leeds, LS1 3EX Email: GRI@medphysics.leeds.ac.uk

Three Siemens Sensation Open scanners were installed in a new oncology centre in late 2007. These included two 24 slice systems (Sim 2 and Sim 4) and a 40 slice system (Sim 1). All were tested by Medical Physics and were considered to perform identically. A patient dose survey in 2008 showed some significant variations in both CTDIvol and DLP between the three scanners. For scan protocols that used CARE Dose 4D average doses were always lowest on Sim 4 and generally highest on Sim 1, despite the scanners using identical scan protocols. Dose differences were most marked for neck scans where average doses on Sim 1 were double those on Sim 4. Both case mix and scan length were broadly consistent on the three systems. The dose differences were traced to the setup of the CARE Dose 4D tube current modulation system. Sims 1, 2 and 4 were set to weak/strong, weak/average and average/average adaptation respectively. Oncologists considered that image quality was satisfactory on all three scanners and as such the average/average setting was adopted for all systems. (Optimisation step one.) A subsequent dose survey, following the UK 3rd CT Dose Survey methodology, showed that significant variations in dose remained. Sim 4 yielded the highest doses for some scan protocols but the lowest doses for others. These dose differences were investigated and were found to be a result of the incorrect application of scan protocols. The functionality of CARE Dose 4D depends not just on the adaptation strength, but also on the reference attenuation, which is specified for each separate body part (and cannot be adjusted by the user). Some scan protocols on each of the scanners had been built from an incorrect base protocol and as such the reference attenuation was not appropriate for the body part that was being scanned. All scan protocols were rebuilt, starting from Siemens default protocols and were tested on a Rando phantom prior to clinical use. (Optimisation step two.) Siemens CARE Analytics was subsequently used to analyse doses pre and post protocol change through harvesting Radiation Dose Structured Reports from the Radiotherapy DICOM store. Doses for pelvis and neck protocols are now consistent across all three systems. However, for thorax based protocols (thorax and breast) average doses remain approximately 20% higher on Sim 4 than on Sim 2. It is unclear why these dose differences remain and what can be done to change this. (Further optimisation may be required.)

Workflow: it’s not just DICOM 28th April 2014, The Wesley, London Organised by the IPEM Informatics & Computing Special Interest Group FINAL PROGRAMME

09:00 – 09:55 Coffee and registration

09:55 – 10:00 Introduction

Chair: Patrick Downes

10:00 – 10:30 IHE-UK: An introduction to IHE Invited Speaker: Niall Monaghan, Steering Committee member and past Chair of IHE-UK / Radiation Consultancy Services Ltd

10:30 – 10:50 A business analytics software tool for monitoring and predicting radiology throughput performance Stephen Jones, Trinity College Dublin

10:50 – 11:20 Coffee

Chair: Padraig Looney

11:20 – 11:40 Collation and presentation of multi-source clinical data to inform and support the radiation oncology service Bob Wheller, Leeds Teaching Hospitals NHS Trust

11:40 – 12:00 Development of a pre-treatment worklist, to fit in with current clinical practice Martin Green, The Clatterbridge Cancer Centre

12:00 – 12:20 Software for the multidisciplinary management of breast cancer; a private sector perspective Tim Cross, HCA International

12:20 – 12:30 Questions/discussion

12:30 – 13:30 Lunch

Chair: Patrick Downes

13:30 – 13:50 Electronic check-in and process workflow for outpatient clinics David Jones, Sheffield Teaching Hospitals

13:50 – 14:10 On the Design of an Electronic Radiotherapy Referral System David Spendley, Brighton and Sussex University Hospitals NHS Trust

14:10 – 14:30 Questions/discussion

14:30 – 14:55 Coffee

Chair: Padraig Looney

14:55 – 15:15 Combining different hospital system datasets to examine the influence of MRI inpatient turnaround times on outcome and hospital length of stay Seán Cournane, St. James’s Hospital, Dublin

15:15 – 15:35 CT patient data workflow Patrick Downes, Velindre Cancer Centre, Cardiff

15:35 – 16:00 Questions/discussion

16:00 Close

IHE-UK: An introduction to IHE Niall Monaghan, Senior Physicist, Radiation Consultancy Services Ltd and IHE-UK Steering Committee Member Email: niallmonaghan@me.com IHE is an initiative by healthcare professionals and industry to improve the way computer systems in healthcare share information. This talk is a brief introduction to IHE and the IHE process. I will be highlighting a couple of the more common integration profiles that may be of interest to the audience.

A BUSINESS ANALYTICS SOFTWARE TOOL FOR MONITORING AND PREDICTING RADIOLOGY THROUGHPUT PERFORMANCE 1Jones S, 2Cournane S, 2Sheehy N, 1Hederman L. 1Centre for Health Informatics, Trinity College Dublin. 2Diagnostic Imaging Department, St. James Hospital, Dublin. email: joness4@tcd.ie

Background: A primary cause for the build-up of patient wait times in radiology departments is a mismatch between capacity and demand. Lack of understanding of this mismatch as well as inefficient management of radiology resources contributes to inadequate capacity planning [5]. Business Intelligence (BI) software systems combine data gathering, storage and knowledge management with analytical software tools that analyse and present complex data to planners and decision makers [3]. Business Analytics (BA) also encompasses statistical analysis, predictive modelling and forecasting systems and is used as an umbrella term for decision support and Business Intelligence systems [1]. BA functionality is being utilised as a driver for decision support based on past performance [2,4]; however, there is little evidence of the utilisation of future predictive analysis to drive decision making in radiology departments. The objective of the study was to implement a software tool combining data from the Electronic Patient Record (EPR), Radiology Information System (RIS) and Picture Archiving and Communications System (PACS) in order to display existing radiology Key Performance Indicators (KPIs) and provide functionality that allows the forecasting and modelling of future demand and capacity data through predictive scenarios.

Methods: MRI, US and CT time (times of orders raised, cancelled, completed and finalised) and patient data (Modality, encounter type, speciality) from January 2010 to February 2014 was extracted from the EPR, RIS and PACS and imported into Qlikview, a commercially available BA software package. Radiology KPIs including patient waiting lists, backlog and 90th, 75th and 50th percentile turnaround times were calculated and visualised via a specially designed dashboard. Bespoke functionality allowed the entry of various radiology predictive scenarios. Predictive demand and capacity data was then generated based on the inputted scenario data and visualised utilising the Qlikview software tool.

Results: Historic and current KPI data provides the information necessary to analyse radiology patterns and trends. Predictive analysis via user-defined scenarios can be used to visualise future demand and capacity data as well as calculating optimum mix of inpatient versus outpatient capacity allocation.

Conclusion: BA software tools combined with bespoke software applications can provide visibility of radiology data across all time horizons. Historic data provides retrospective analysis which can be used to inform and create predictive scenarios. These scenarios can then be utilised to generate and visualise future predictive demand and capacity data enabling proactive decision support to deliver improved operational efficiencies within radiology departments.

Key references: [1] Cosic et al. Proceedings of the 23rd Australasian Conf. on Information Systems 2012. 1–11. [2] Nagy et al. Radiographics. 29, 7 (2009), 1897–1906. [3] Negash Communications of the Association for Information Systems. 13, 1 (2004), 177–195. [4] Prevedello et al. Journal of Digital Imaging. 23, 2 (2010), 133–141. [5] Silvester et al. Clinician in Management. 12, 3 (2004), 105–111.

COLLATION AND PRESENTATION OF MULTI-SOURCE CLINICAL DATA TO INFORM AND SUPPORT THE RADIATION ONCOLOGY SERVICE

Bob Wheller

Leeds Cancer Centre

Department of Medical Physics & Engineering, Leeds Teaching Hospitals NHS Trust

email: bob.wheller@leedsth.nhs.uk

Background.

The clinical radiotherapy workflow is complex and involves the interoperation of highly complex medical technology. Most radiation oncology management systems have emerged from record and verify systems and as such provide limited visibility of workflow and the patient pathway.

Methods.

A pilot project has been established at Leeds Cancer Centre to investigate the feasibility and value that clinical staff might get from an oncology data warehouse and reporting server. The system integrates and presents data from many oncology sources and works independently of operational clinical systems. Data is captured from both nightly data extraction and from interception of real time electronic messaging such as DICOM and HL7. Data validation and a limited amount of data transformation have also been implemented. Presentation is achieved through a variety of tools ranging from simple Crystal Reports on denormalised data to web based reporting services.

Results.

This is a work in progress presentation illustrating initial findings and highlighting some of the practical applications that the system has been used for. Initial success in acquiring a high quality data set has encouraged better resourcing of the project and future plans that might inform likely clinical demand and contribute to strategic decision making.

DEVELOPMENT OF A PRE-TREATMENT WORKLIST, TO FIT IN WITH CURRENT CLINICAL PRACTICE Green MJ, Mayles H The Clatterbridge Cancer Centre, UK. email: Martin.Green@clatterbridgecc.nhs.uk

Introduction. Prior to this work Clatterbridge Cancer Centre (CCC) workflow was managed by patient packets being placed in the correct baskets and slots, a collection of spreadsheets, e-mails and conversations, backed up by the first treatment date stored in an EPR. Patient workflow typically worked well enough within each area, but it was hard to get an overview of what was going on or predict problems in advance.

From work, first initiated at a NHS hack day and further developed at CCC, a cross department web based system has been developed and has been in widespread routine use for the last year. This has allowed a common thread to be established though a busy multi-vendor centre.

Features. For each patient episode a number of worksets are selected, which allow the tasks that each patient requires to be automatically determined, along with the order they can be performed in.

The interaction required to complete and document a task has been minimised by presenting all the pertinent questions in a single form, including:

select additional worksets,

allocate deadlines and users to future tasks,

specify details regarding the episode and

specify details regarding the specific task, eg which TPS was used.

Patient centric, staff centric and task centric views allow the users to get the information they need, answering questions such as:

I am about to go on holiday, can I do any of my tasks early?

What patient QA needs doing this week?

Are there any patients currently being treated, where further checks are required?

Rules can be added when completing a particular type of task, to add in an additional worksets, for specific treatment techniques, for particular trials, for a sample of the patients and much more, e.g. Delta4 QA is selected for 1 in 5 RapidArc lung patients who are being treated on our Novalis Linac.

Where staff do tasks on an ad hoc basis, and thus do not regularly check the worklist, E-mail messages are sent detailing what needs to be done, e.g. to upload an external MRI to PACS.

Analysis can be performed using built-in graphs of how the time between two events has varied by month for specific types of patient episodes. More generally Microsoft Excel’s import data from web tool can be used to create almost arbitrary dynamic reports.

Future development. This project has been developed as an interim measure, and thus there are areas where it could be improved:

Whilst the system gets its patient demographics from a trust integration engine, this should be limited to relevant patients. It would be better if patient episodes could be automatically picked up from our EPR.

Integration with TPS and R&V systems to independently verify that the plan does not significantly change during the checking and treatment processes.

Create an audit trail.

Integration with a forthcoming data warehouse and other SQL based reporting.

Availability. This software has been developed under an open source license, and is designed to be configurable for specific workflows.

Software for the multidisciplinary management of Breast Cancer; a private sector perspective

Cross T1, Blom S1, Uong T1, Thompson C1, Ferrario C1, Dixon S1, Buckley N2

1Clinical Services Department, HCA International, 242 Marylebone Road, London 2CEO for Cancer, HCA International, 242 Marylebone Road, London email: timothy.cross@hcahealthcare.co.uk

Background

The Multidisciplinary Team (MDT) process, long recognized as the gold standard in breast cancer management1, presents a particular challenge to the private sector. Whilst many patients remain within one organization for their entire pathway, it is not uncommon for patients to present post-operatively for adjuvant therapy or to receive treatment in another location following a diagnostic work up. It is essential that, irrespective of the healthcare provider, robust data is available to allow informed decision making by the MDT. In-house software has been developed to assist in this process, from managing patient workflow and aggregating clinical data to documenting MDT recommendations in real-time; a key characteristic of an effective MDT 2.

Method / Results

The current iteration of the software makes use of a Microsoft Access front end with a SQL Server back end. Access was chosen for front end development due to its wide install base in HCA International, its ease of connection to SQL server and as a result of pre-existing Access knowledge within the department.

The SQL server takes demographic data directly from HCA’s PAS, MEDITECH. The MDT coordinators then add relevant clinical information before and during the MDT meeting. The software’s live meeting function displays the patient’s clinical summary and the MDT recommendations are captured and validated in real-time. An outcome document is then produced containing the patient’s clinical summary, a record of the meeting’s attendees, and the MDT‘s recommendations. This is signed by the chair of the MDT, and scanned back into MEDITECH (figure 1). Barcodes, embedded automatically in the outcome document, ensure the document is correctly identified.

Figure 1 – example MDT patient workflow

In addition, the software captures data for HCA’s Cancer Registry database; analysis of which plays a major role in the quality assurance of the care provided.

Conclusion

HCA’s MDT software has been live since December 2013, following lengthy internal testing, and has managed ~1000 patients. Feedback from MDT coordinators and clinical nurse specialists has been positive.

A web-based replacement for the Access UI is currently being investigated. This will offer several improvements; chief amongst these being increased portability and responsiveness for the wide variety of devices and displays used in MDT working. This redevelopment will be used as an opportunity to develop further versions for other tumour types and non-cancerous diseases.

References

[1] Rajan S, et al. Multidisciplinary decisions in breast cancer: does the patient receive what the team has recommended? Br J Cancer. 2013 Jun 25;108(12):2442-7

[2] National Cancer Action Team. The Characteristics of an Effective Multidisciplinary Team (MDT) 2010

ELECTRONIC CHECK-IN AND PROCESS WORKFLOW FOR OUTPATIENT CLINICS 1Jones D M, 2Harrison S, 3Stone JA 1Medical Imaging and Medical Physics, Sheffield Teaching Hospitals, UK. 2Service Improvement, Sheffield Teaching Hospitals, UK. 3Strategy & Transformation Department, Sheffield Children's NHS Foundation Trust, UK. email: David.Jones2@sth.nhs.uk

Background

Hospital outpatient clinics differ from GP clinics in that the patient is much more likely to see several healthcare professionals in sequence, with possible optional and alternative pathways. We have combined electronic check-in kiosks with a workflow system to manage the subsequent clinic process [2].

Methods

One server hosts a web-based check-in system for touch-screen kiosks. A second server hosts the workflow engine used by client applications installed on clinic PCs. Microsoft’s Windows Workflow Foundation is used with custom additions for handling human user interactions [3]. A daily process initialises these systems using an appointment list extracted from the PAS. The system acquires and archives tracking data of timings for all operations performed. For each outpatient clinic, a customised state-machine workflow is defined in consultation with the clinic staff.

The impact of system introduction on staffing and visit duration was analysed for a Rheumatology outpatient clinic. The tracking data for an established Urology outpatient system was used to investigate changes in visit duration following changes made as part of a clinical microsystems analysis [1] of the Flexible Cystoscopy clinic. In a first phase, consultants moved to working from a common list and clinic timings were altered. In a second phase, the case mix was considered and variable length appointment slots introduced for different classes of patient.

Results

The introduction of the Rheumatology workflow system freed-up 1WTE support worker and 0.5WTE clinic operations nurse for other duties. For follow-up appointments, the mean visit duration decreased from 61min (n=515) to 46min (n=445). For new appointments, it decreased from 81min (n=124) to 64 min (n=101). Before Flexible Cystoscopy service reconfiguration, the mean visit duration was 70min (SD 30min, n=1855). After phase 1, this increased to 75min (SD 30min, n=950) and after phase 2, this decreased to 62min (SD 28min, n=1176).

Discussion

As well as quantifiable benefits such as decreased visit duration, anecdotal reports suggest that the system has led to a reduction in pedestrian traffic and a calmer and more organised clinic environment. The system assists with identifying possible optimisations to appointment booking patterns or the clinic process itself. For example, appointment slot durations may be increased if appointments towards the end of the clinic consistently run late.

Conclusion

The system reduces staff costs, decreases visit times and can be used to facilitate service improvement.

Key references [1] Quality by design: a clinical microsystems approach. Nelson E C, Batalden P B, Godfrey M M (eds.) John Wiley & Sons 2011 [2] Workflows: Principles, Tools and Clinical Applications, book chapter in Computational Biomedicine, Coveney P, Díaz-Zuccarini V, Hunter P, Viceconti M (eds.) OUP (in press) [3] WS-BPEL Extension for People – BPEL4People. A Joint White Paper by IBM and SAP. July 2005 http://scn.sap.com/docs/DOC-1294

On the Development of an Electronic Patient Referral System for Radiotherapy 1Spendley D G, 2Nikapota A 1Medical Physics, Brighton and Sussex University Hospitals NHS Trust, UK. 2Sussex Cancer Centre, Brighton and Sussex University Hospitals NHS Trust, UK. email: david.spendley@bsuh.nhs.uk

Background.

Our paper-based radiotherapy referral system introduced delays in receiving referrals from outlying centres, had incomplete and sometimes inaccurate data and the risk that referrals would be lost. The referral form could only be with one staff user at a time reducing the booking process to a linear activity introducing further delays. We wanted to replace the form by implementing a system that contributed to the safe, effective and expedient treatment of patients by providing complete and controlled referral data quickly to the point of use. We were aware of only one other such system but this was based on a proprietary oncology management system (1)

Methods.

A multidisciplinary team of medical physicists and oncology staff together with developers from the Sussex Health Informatics Service developed an electronic radiotherapy referral system. The referral process was analysed by the project team and a works-like design was produced and refined iteratively. A System Requirements Specification was written and from it a web-based system was produced that went through several further iterations before being fully validated by staff user groups.

Results.

The system was introduced on a single day with all paper referrals ceasing on that day. Over 6000 referrals have been made successfully in 24 months with 100% system availability. Patients can be referred from anywhere in the Sussex cancer network and be viewed by all staff groups immediately. There has been a large reduction in incomplete or inaccurate data because of embedded data validation including the provision of hard-coded coded Diagnosis descriptions, ICD10 international diagnosis codes and appropriate prescriptions.

Discussion.

In producing a works-like prototype users had an early opportunity to interact with the system and to give direct feedback. This involvement engendered a strong sense of ownership that contributed to the universal uptake of the system. Close involvement with the development encouraged the analysis of the referral process resulting in improvements to work flow that were then captured in the design.

There has been a reduction in the risk of misidentification of patients through links to PAS systems.

Complete and accurate data ensure that patient treatments start as soon as possible. There is better access to information through the web-based system. Transactions have been simplified by reducing geographical and time constraints and increasing convenience.

There has been a benefit in no printing or photocopying of forms or disposal as confidential waste and there has been a reduction in the instances of rework due to incomplete data or lost forms

Conclusion.

Collaboration between Software development professionals, physicists and oncology staff and the use of early prototyping and iterative development resulted in an electronic radiotherapy referral system that has contributed to greater patient safety and higher quality of care.

Key references.

1. eBooking – An Electronic Patient Referral System in Radiotherapy http://connect.qualityincare.org/oncology/cancer_team_of_the_year

COMBINING DIFFERENT HOSPITAL SYSTEM DATASETS TO EXAMINE THE INFLUENCE OF MRI INPATIENT TURNAROUND TIMES ON OUTCOME AND HOSPITAL LENGTH OF STAY. 1Cournane S, 2Creagh D, 1,2O’ Hare N, 3Sheehy N, 4Silke B 1Medical Physics and Bioengineering Department, 2Information Management Systems, 3Diagnostic Imaging Department, 4Division of Internal Medicine, St. James’s Hospital, Dublin 8. email: scournane@stjames.ie

Background: MR imaging is increasingly performed on emergency medical admissions (Upponi & Shaw,2010, Lee & Foster,2009); however, the increased use of advanced radiology imaging has not necessarily been reflected by a correlative improvement in inpatient outcome (Gilbert et al.,2012; Korley et al.,2010). The question remains as to whether an increase in scanning demand associates with an increased benefit, or rather whether it leads to an increased length of stay (LOS) and healthcare burden (Rosen et al.,2011). Accordingly, the purpose of this study was to examine 1) the predictive role of the association of MRI scan on in-hospital mortality in the setting of acutely ill medical patients, to infer scan justification, and 2) assess whether MR imaging is promptly provided for inpatients or whether it leads to a prolonged LOS and increased cost to the hospital. Methods: All patients admitted as medical emergencies between January 2010 and December 2012 were studied (18534 episodes); Hospital In-patient enquiry (HIPE), Patient Administration System (PAS) and Electronic Patient Record (EPR) data was combined to examine the relationship between an MR imaging request, the underlying diagnosis on any in-hospital death and the LOS. For mortality analyses, we used multi-variate logistic (generalized estimating equations regression, adjusted for readmissions. Odds Ratio (OR) estimates were calculated as appropriate. Results: MR imaging was requested in 8.6% of episodes. The in-hospital mortality was significantly higher where MRI was performed (7.8% vs. 4.6%: p<0.001). The unadjusted OR for an in-hospital death during that episode was 1.74 (95% CI:1.26,2.37;p<0.001) compared with episodes without MR. The hospital stay for those MR episodes was longer (median 9.1 days; IQR 4.0, 26.8) than for non-MR episodes (median 5.8 days; IQR 2.2,12.2;p<0.001). Each unit increase in MR waiting time (cut-offs set at 0,1,3,7 and 14 days) gave an estimated increase of 1.12 days increase in hospital LOS, adjusted for illness severity and co-morbidity. Conclusion: MR imaging identifies in a subgroup of emergency patients at higher risk of an in-hospital death and, thus, it was inferred that these scans were justified. These patients have a longer LOS, which associates with increased costs, attributable to a delay in MR scanning and not merely due to their illness severity or co-morbidities. This has implications for health funding as it implies that under-resourcing the radiology department is actually increasing costs in acute medical admissions. The analysis of combined datasets, from a number of systems, can thus offer a powerful tool for identifying inefficiency and informing change.

Key references. Gilbert et al. EMJ 2012; 29(7): 576-81. Korley et al JAMA 2010; 304(13): 1465-71. Lee & Foster. JACR 2009; 6(11): 780-5. Rosen et al. JACR 2011; 8(6): 428-35 e3. Upponi and Shaw. JACR 2010;7(8): 565-72.

CT patient data workflow Patrick Downes Velindre Cancer Centre, Medical Physics, Cardiff, Wales Email: patrick.downes@wales.nhs.uk Background: In Velindre Cancer Centre (VCC) we have two Siemens CT scanners. Patient appointments for CT are booked in our Patient Appointment Scheduling (PAS) system. Patient demographic data is transferred via printing a set of barcodes and scanning them individually at the CT scanner. This work looks at making this transfer electronic. The aim of this work is to avoid transcription errors and typos. Method: The latest version of Siemens CT software, Syngo CT, on site is version 2007. The PAS system used in VCC is CANISC1 which was developed in-house and is now used Wales-wide. This system supports sending of HL72 messages but has to be done on a case-by-case basis. Syngo CT only supports DICOM3 Modality Worklists (DMWL) and does not support HL7. This work looks at options of combining HL7 and DICOM for appointments. It investigated setting up a HL7 server to convert a patient appointment message (ORM^O01) to an appointment in a DMWL that can be queried by the CT scanner. It also investigated using a single DICOM server that supported both HL7 and DMWL. Results: It was found that both approaches were suitable with using a single DICOM server being the simplest option. It also could take advantage of existing infrastructure.

1 CANISC - http://www.wales.nhs.uk/nwis/page/52601

2 HL7 - https://www.hl7.org/

3 DICOM - http://dicom.nema.org/

Preparing Clinical Engineers for the Future: implementing a practical approach 21st May 2014, Austin Court, Birmingham Organised by the IPEM Clinical Engineering Special Interest Group FINAL PROGRAMME

09:00 – 09:55 Coffee and registration

09:55 – 10:00 Introduction

Chair: Paul Blackett, Lancashire Teaching Hospitals NHS Foundation Trust

10:00 – 10:45 Keynote address: Preparing Clinical Engineers for the Future Professor Sue Hill OBE, Chief Scientific Officer, NHS England

10:45 – 11:00 Questions

11:00 – 11:25 Coffee

11:25 – 11:55 The National School of Healthcare Science - now and in the future Dr Chris Gibson, Head of the National School of Healthcare Science and Professional Lead for Physical and Clinical Engineering

11:55 – 12:25 The Academy for Healthcare Science Prof Tony Fisher, Non-executive Director, Academy for Healthcare Science

12:25 – 13:10 Lunch

Chair: Andrew Davie, NHS Lothian

13:10 – 13:30 Training for CF 2-4 and apprenticeships from a national perspective Christine Sakhardande, Consultant to Chief Scientific Officer MSC Team, UK Department of Health

13:30 – 13:50 Apprenticeships in Medical Engineering Jo Young, King’s College Hospital NHS Foundation Trust

13:50 – 14:10 Practical Based Training Nigel Gowland, Avensys UK Ltd

14:10 – 14:30 How do you setup a Training Consortium? Experiences from the North Dr Emma Bowers, Newcastle upon Tyne Hospital NHS Foundation Trust

14:30 – 14:55 Coffee

14:55 – 15:15 Registration of Clinical Technologists Andy Mosson, Oxford University Hospitals NHS Trust and VRCT Registrar

15:15 – 15:35 Developing Consultant Clinical Biomedical Engineers, (CBE) via Higher Specialist Scientist Training Dr Richard Scott, Sherwood Forest Hospitals NHS Foundation Trust

15:35 – 15:55 Comparing Training Provision for 1st Year STP Clinical Engineering Trainees at Two Centres Dr Emma Bowers, Newcastle upon Tyne Hospital NHS Foundation Trust

15:55 – 16.15 Questions

16:15 Close

Training for CF 2-4 & Apprenticeships from a national perspective Christine Sakhardande, Science Apprenticeships Trailblazer Programme Manager, Cogent SSC Ltd email: christine.sakhardande@cogent-ssc.com

Through Modernising Scientific Careers the Healthcare Science workforce is being modernised, with review, revision and enhancement of the role of the healthcare science workforce at all levels and their contribution to the clinical care of patients. This includes a commitment to develop and accredit the support workforce of Assistants and Associates and ensure quality in early years of career development. The Apprenticeship Standards for Assistants and Associates are based on requirements of real work roles in the service and provide a leading-edge approach to employer-led, modular frameworks of development. The Apprenticeship programme structure for Assistant and Associate development and accreditation specifies knowledge, competence and skills through a flexible, modular structure. This enables individuals’ development to meet the real and changing needs of the service across a wide range of occupational contexts and roles within healthcare science.

The four levels of Apprenticeship will build on existing training arrangements and include; The Core Modules provide both introductory Awards for Assistants and for Associates and form the mandatory component of related Apprenticeships. Each level includes five modules for development and assessment which represent the basis of working within a healthcare science context. The knowledge component, based on optional themed modules, is knowledge/skill-based development at appropriate academic level which may be delivered by a variety of methods with assessment to required guidelines. Selection of knowledge-based options will be determined by role/job requirements. Apprentices will achieve the relevant knowledge qualification. The competence component will contain optional units from across thirteen functional categories and will be assessed in a work-based context, confirming application of relevant knowledge and understanding to real work activities. Apprentices will achieve the relevant work based competence award. The Personal Cognitive and Professional Skills framework underpins the Apprenticeship at each level and is integral to both Knowledge and Competence Components. Assessment of this framework will be integral to all Apprenticeship Standards and will confirm consistent performance of Professional standards and values.

Apprenticeships in Medical Engineering 1Young J, 2Green MFG 1Medical Engineering & Physics, King’s College Hospital NHS Foundation Trust, UK. 2The Medical Room Ltd, UK. email: jyoung2@nhs.net

Background: In 2005 a report commissioned by the South East London Workforce Development Commission identified a shortage of suitable candidates for Practitioner roles in some areas of Healthcare Science, and an aging workforce. In 2012, a report commissioned by NHS London (Scoping potential roles and associated training models for Assistant Healthcare Science Staff in a large Acute Trust), recognised that this situation still remained and indeed, the existing workforce was even closer to retirement. The Modernising Scientific Careers programme has, to date, sporadically addressed this problem, leading to gaps in the workforce and those exiting Practitioner Programmes not delivering staff that are fit for purpose. To address the shortage of Practitioners to maintain services it is essential to develop training routes for Assistants, Associates and Practitioners, to introduce young people into a career in Healthcare, specifically Healthcare Science, whilst ensuring routes for career progression, however it has been traditionally very difficult to get education providers to deliver the courses we would like in convenient locations.

Methods.

Following an investment from NHS London the Department of Medical Engineering & Physics at King’s College Hospital have developed a pilot apprentice scheme spanning several ‘equipment focussed’ areas within the Trust. The Assistant Clinical Technologist Apprentice Scheme (ACTAS) recruit 6 local young people and placed them onto the Trust’s existing Customer Service Apprenticeship Framework, allowing the Trust to draw Apprenticeship funding for this through an existing agreement with a local Further Education Provider. Once on the apprenticeship they were rotated through 4 ‘equipment focussed’ areas: Medical Engineering, Renal Technology, Theatres and A&E. In each area they were trained to a set of competencies developed according to the employers need. Competencies were signed off by Qualified Senior Practitioners. They also attend a weekly seminar program of underpinning knowledge.

Along side this development The Medical Room Ltd have developed a modular Medical Device Training Course, with the aim to being an accredited Level 3 training programme. This programme fits the requirements of the VRCT scope of practice for Medical Engineering. The programme has been delivered in partnership with King’s and 2 other Trusts across the country, enabling the students to learn in a ‘real work’ environment and has provided the underpinning knowledge required for the apprentices.

The complete programme will culminate in the RegSciTech award. As registration requirements for Assistants and Associates are still unclear, the RegSciTech award should allow equivalence to any Approved Register that may arise.

Results.

The pilot ACTAS programme has proven to be a real success. Several of the apprentices have been employed to substantive posts within the Trust when the programme is only 2/3rd complete.

They have made significant contribution to the workload:

In Medical Engineering, during 2 episodes where 100+ new devices entered the Trust due to expansions, repair turnaround figures were maintained, where in the past they would have fallen and there was no requirement for additional agency staff, as there has been in the past.

In Theatres, down time has been minimised, as they are able to fault find and prepare devices prior to the qualified Medical Engineer arriving.

Qualified practitioners in all areas have reported increased time for development of services.

The programme was awarded the Health Education South London (HESL) Widening Participation Award 2013 and has been short listed for an Advancing Healthcare Award 2014 – Inspiring the Workforce of the Future.

HESL has committed further funding to embed the current program and develop the next level on the career path. Local Councils are also keen to invest in the employment of local young people, given the high youth unemployment in the King’s locality.

This is an on-going project and there are still many things to be done to expand and improve on the scheme:

Accreditation of Medical Device Training Programme

Expand placement options, Critical Care, Maternity, Hospital@Night, iMobile, Respiratory Medicine

Map to MSC Apprenticeship Frameworks when they are released,

Engage with local schools and college to become feeder routes for suitable candidates,

Develop career progression routes to Practitioner level,

Hub & Spoke Training Model

Government reforms to the way Apprenticeships are delivered and funded should make apprenticeships more suited to Medical Engineering. There is a drive towards Employer led programmes with funding going directly to the employers rather than the education providers. The frameworks will be more ‘Outcome’ driven, rather than built around specific qualifications. This does, however, require engagement from the Healthcare Science Community in the development of the frameworks. Apprenticeship programmes can work for Medical Engineering, however, there is a need to work together on more generic programmes at the basic level to ensure viable numbers for training programmes and to allow for education to be local.

Practical Based Training Nigel Gowland, Training Manager, Avensys UK Ltd, Hoo Farm Industrial Estate, Kidderminster, UK email: nigel@avensysmedical.co.uk

Background The Gatsby report on “Technician and Intermediate Roles in the Healthcare Sector” Published in 2013 identified that action was needed to address the shortfalls in the many areas of the Technicians roles including appropriate training. It is widely appreciated that good quality grass roots practical based training is becoming harder to attain in the Clinical Engineering Field particularly at levels 3-5. Published in 2010, The Modernising Scientific Careers (MSC) – The UK Way Forward, which set out the four UK countries’ policy and proposals to reform Healthcare science training and careers for 21st century patient care, new curricula have been developed to inform academic programmes and work based

training for different stages of the healthcare science career pathway. This is still ongoing and the

framework is very complex and confusing; we, Avensys UK Ltd have identified the shortfall in Clinical Engineering training and are now delivering such training, which will aid the Clinical Engineer and develop their training needs. Methods Avensys working with various EBME departments throughout the UK, in particular Mr. Andrew Cooper from Pool Hospital NHS, researched what training was required for the clinical engineer; it was evident that practical based training in the core fields such as: electrical safety, patient monitoring, infusion, defibrillation etc. was much needed at level 3. The qualification would also have to be nationally recognised and listed on the Qualification Credit Framework to ensure that the courses were in line with the Modernising of Scientific Careers learning outcomes. A blended style of learning would be required for this and our expertise in training produced a package that consisted of theoretical classroom based lectures twinned with hands on practical work carried out on specific medical devices. So the engineer could be assessed faults are simulated on the equipment and complex diagnosis is carried out; this gives the student the in depth competency and skill set that is required for the modern day engineer. Mr Andrew Cooper has visited our training courses whilst his employees have been studying on the “Level3 Certificate in Medical Equipment Technologies” and he has expressed how well the information is taught on all levels of the training package. It was also recognised that a pathway linking level 3 qualifications to degree level was also required. Historically the foundation degree was in existence, but as Kingston University made this course redundant, there was no such qualification. Now the Higher National Diploma in Medical Equipment Technologies which is a distance learning program delivered by Coventry University has been designed and has been launched this year. This bridges the void in level 3-5 qualifications that our fraternity has been lacking over the years.

Conclusion Preparing Clinical Engineers for the Future is the goal of IPEM and many training providers such as Avensys. We are dedicated to delivering first class practical based training, which will ensure the future Clinical Engineer will be well equipment with the knowledge and skill set to tackle any complex engineering tasks.

How do you setup a Training Consortium? Experiences from the North 15 Bowers EJ, 2Chambers I, 3Knight A, 4Methven J, 5Marshall D , 6Mackie A, 1 Regional Medical Physics Department, Freeman Hospital, Newcastle upon Tyne, UK. 2 Medical Physics Department, James Cook University Hospital, Middlesbrough, UK. 3 Medical Physics Department, Royal Sunderland Hospital, Sunderland, UK. 4 Medical Physics Department, Cumberland Infirmary, Carlisle, UK. 5 Workforce Planning Department, HENE Newcastle upon Tyne, UK. 6 Regional Medical Physics Department, University Hospital of North Durham, Durham, UK. email: e.bowers@nhs.net

Background. When all Medical Physics and Clinical Engineering services in the North were managed by one department, regional workforce planning and regional training were straightforward to implement. The Northern Training Centre prided itself upon the quality of training that it was able to offer, and this was largely due to the sharing of best practice across the region and exposing trainees at all levels to different hospital environments. However in 2010 local Trusts started to manage some of their own Medical Physics and Clinical Engineering services; by 2013 there were 4 NHS Trusts providing separate services. At the same time Modernising Scientific Careers (MSC) [1] was being implemented and it quickly became apparent that MSC could only be successful if a regional approach was taken. The North was in the interesting position whereby the need for regional training was becoming greater but the ability to implement it was becoming more complicated. In order to simplify some of the workforce planning and training aspects of MSC the Northern Training Consortium was created.

Methods. All training consortia listed on the IPEM website were approached to determine how they operated. Discussions were held regionally to determine whether a Service Level Agreement should be drawn up or if a Statement of Agreement would suffice.

Results. Other Training Consortia across the country appear to run on ‘gentlemen’s agreements’ which may have been formalised slightly by paperwork arising from the IPEM training accreditation process. The Northern Training Consortium (NTC) is underpinned by a Statement of Agreement (SoA) which has been signed at board level by all Trusts involved: Newcastle upon Tyne Hospital NHS Foundation Trust (NuTH); South Tees Hospitals NHS Foundation Trust; City Hospitals Sunderland NHS Foundation Trust; Northumbria Healthcare NHS Foundation Trust and North Cumbria University Hospitals NHS Trust. The SoA covers Clinical Engineering training at Assistant/Associate level (ATP), Practitioner level (PTP), Scientist level (STP) and Higher Scientist level (HSST).

Discussion. The SoA defines roles and responsibilities for both individuals and Trusts. The number of Clinical Engineering PTP placements and STP training positions that the region is prepared to offer is determined by regional workforce requirements. The training burden is apportioned depending on the number of staff working at Practitioner or Scientist level within each Trust. Any In-Service PTP or STP trainees are able to move between Trusts if their home Trust is unable to provide any of the training at that level. All Direct-Entry STP trainees are employed by NuTH but are able to work across the region. ATP and HSST trainees are expected to be appointed and managed by individual Trusts depending on their local need, however mentors and best practice will be shared across the region. Other areas covered by the agreement are:

(1) Confidentiality ensuring that commercial sensitivities are respected;

(2) Intellectual Property (IP), stating IP ownership resides with the Trust(s) providing the project, not necessarily the trainee’s employing Trust; and

(3) The expectation that representatives from each Trust will attend the annual Northern Training Consortium meeting so any modifications to the SoA can be agreed.

Conclusion. The Northern Training Consortium is still in its infancy but so far Trusts, Trainees and Training Supervisors are happy with how it is working.

[1] UK Health Departments. Modernising Scientific Careers: The UK Way Forward. 26th February

2010 https://www.gov.uk/government/publications/modernising-scientific-careers-the-uk-way-forward (accessed 5th March 2014)

Developing Consultant Clinical Biomedical Engineers, (CBE) via Higher Specialist Scientist Training. Scott, R.S. Consultant Clinical Scientist, Medical Equipment Management Dept, Sherwood Forest Hospitals NHS Foundation Trust, UK & Editor CBE Curriculum Development Group, Royal College of Surgeons email: richard.scott@sfh-tr.nhs.uk

Background.

The vision for Higher Specialist Scientist Training, (HSST), to develop the Consultant Clinical Scientist workforce, is part of the UK Modernising Scientific Careers programme and has the support of the Academy of Medical Royal Colleges, (1). The Consultant Clinical Biomedical Engineering HSST curriculum has been developed to train the consultant workforce practicing in clinical engineering.

The curriculum envisions developing the leaders of the future, with a strong focus on driving innovative practice, ensuring the safe and effective use of healthcare technologies for patient benefit.

Methods.

The curriculum was developed under the auspices of a working group within the Royal College of Surgeons, with input from the Royal College of Physicians, members of the Institute of Physics and Engineering in Medicine and patient representatives. The presentation will describe the working group’s approach and findings, which informed the syllabus design and vision for the future role.

The specialist syllabus and wider curriculum elements will be presented

Results.

The key elements of the Clinical Biomedical Engineering training programme (2) will be presented and the proposed practical implementation of the scheme will be discussed.

An over view of the final draft syllabus elements, (as shown below) will be described.

Discussion.

The CBE curriculum is aimed at developing a new consultant workforce – the vision for the new role will be discussed and contextualised within the modern healthcare system.

Conclusion.

Whilst there are already Consultant Clinical Scientists delivering Clinical Engineering Services there has

not been a national training scheme for Consultant level training. The HSST curriculum introduces a formalised training scheme, aimed at ensuring the development of a Consultant workforce capable of ensuring outcome based, patient focussed healthcare system delivery at the limits of science.

Key references.

1. Scaling the Heights, an overview of Higher Specialist Scientist Training (HSST) in Healthcare Science, Health Education England, (last accessed 13/03/2014)

http://hee.nhs.uk/wp-content/uploads/sites/321/2014/01/Scaling-the-Heights-final.pdf

2 Clinical Biomedical Engineering Higher Specialist Scientist Training Programme Curriculum, NHS Networks, Final draft v0.17 (last accessed 13/03/2014)

http://www.networks.nhs.uk/nhs-networks/msc-framework-curricula/hsst-higher-specialist-scientist-training

Comparing Training Provision for 1st Year STP Clinical Engineering Trainees at Two Centres 1 Bowers EJ, 2Stewart C, 1 Regional Medical Physics Department, Freeman Hospital, Newcastle upon Tyne 2.The Orthotic Research & Locomotor Assessment Unit, RJAH Orthopaedic Hospital, Oswestry email: e.bowers@nhs.net

Background. A large amount of the Modernising Scientific Careers Scientist’s Training Programme (STP) in Clinical Engineering is assessed by Training Centres, through competencies, Case based Discussions (CbDs), Directly Observed Practices and Observed Clinical Events. However there is no guidance for Training Centres advising what level of understanding is necessary to deem the STP Trainee satisfactory. Consequently Training Centres will not know whether they are training to the correct level until Trainees pass or fail at the end of their 3 year training period. It was due to this concern that Newcastle Training Centre (part of the Northern Training Consortium) and Oswestry Training Centre (part of the Oswestry, Wales and Liverpool network) were keen to compare training provision for 1st year STP Clinical Engineering trainees. Newcastle is an experienced Training Centre and is responsible for a range of Science and Engineering STP Trainees. Oswestry is a new Training Centre; although working with more experienced partners as part of their network, it only has contact with Clinical Engineering Trainees. Both centres took their first STP Trainees in 2012.

Methods. On Monday 16th December 2013 the Training Officer (TO) from Oswestry visited Newcastle and a return visit was made by the TO from Newcastle on Friday 20th December 2013. On both days, Training Plans were discussed, Evidence for Competencies was reviewed and CbDs attended (three in Newcastle and one in Oswestry). During CbDs each TO independently marked the trainee’s performance.

Results. Training Plans: Newcastle timetabled four separate rotations each lasting 3 months reflecting the four 1st year modules in the Learning Guide [1] in contrast to Oswestry, where the modules were not demarcated by time and time spent on each module was uneven. At Oswestry, the trainee was expected to spend a total of 3 months at three other Training Centres. The trainee was given a matrix of competencies available at each Training Centre so they could organise where and when each competency would to be fulfilled. At Newcastle each rotation had a detailed training plan outlining how each competency would be achieved and what evidence was needed.

Evidence for Competencies: Due to the guidance provided by Newcastle the evidence submitted for each competency was more focused whereas the trainee from Oswestry used competency evidence as a place to record all learning so at times produced some lengthy reports.

CbDs: At both Training Centres, all CbDs were led by the Training Supervisor of that module; in Newcastle it was also moderated by another Clinical Engineering Training Supervisor. In Newcastle the basis for CbDs were substantial pieces of work that the trainee had been involved in throughout and had already submitted as evidence for competencies. In Oswestry, however, the work was prepared solely for the CbD, contained much less detail, and although technically interesting the trainee hadn’t been involved in the whole process. The CbD formats and depths were similar. Each Training Centre assessed the CbD using between 6 and 8 assessment criteria out of the possible 13 on the Online Assessment Tool. Despite agreement as to which criteria the trainee had excelled at, or not, the average marks were different. Newcastle marked against the ultimate level expected whereas Oswestry marked on the basis of current expectation.

Discussion/Conclusion. Differences exist in training provision between the two Centres, some may reflect the amount of training experience within each Centre and the varying levels of training resources available. (The TO from Newcastle has 0.5wte dedicated time to perform this role.) In the absence of guidance, there is no single approach that can be considered correct. This comparison highlights differences between just two Training Centres, but is still able to justify the need for more detailed guidance on training provision and assessment from the National School for Healthcare Science.

[1] Work Based Learning Guide: Clinical Engineering Version 4.1 (18th October 2012) http://www.networks.nhs.uk/nhs-networks/msc-framework-curricula/stp (accessed 05/03/2014)

2nd UK Patient Specific Modelling Meeting 16th – 17th June 2014, Edinburgh

Meeting Organisers: Peter Hoskins, Edinburgh University, Pankaj Pankaj, Edinburgh University, Perumal Nithiarasu, Swansea

University

FINAL PROGRAMME

Monday 16th June

09:00 - 09:55 Coffee and registration

09:55 - 10:00 Welcome; Peter Hoskins

Session 1: Cardiovascular. Chair: Peter Hoskins

10:00 - 10:45 PLENARY: Vascular biomechanics-based methods to clinically assess the risk of rupture of abdominal aortic aneurysms Prof Christian Gasser, KTGH Royal Institute of Technology, Stockholm

10.45 - 11.15 INVITED: Effective Work Flows for Patient-Specific Haemodynamics Prof Rod Hose, University of Sheffield

11:15 - 11.45 Coffee

Session 2: Aneurysms. Chair: Perumal Nithiarasu

11.45 - 12.00 The influence of wall thickness on stress distribution in patient specific modelling of abdominal aortic aneurysm Noel Conlisk, University of Edinburgh

12.00 - 12.15 Comparison of transient and steady-state simulations of magnetic resonance elastography Lyam Hollis, University of Edinburgh

12.15 - 12.30 Centroid-symmetry correlations with aneurysm wall stress Anthony Callanan, University of Edinburgh

12.30 - 14.00 Lunch

Session 3: Cardiac. Chair: Perumal Nithiarasu

14.00 - 14.30 INVITED: Blood damage in left ventricular assist devices Dr Kate Fraser, Imperial College, London

14.30 - 14.45 Estimation of FFR using coupled 1D-0D models of the coronary circulation Etienne Boileau, University of Swansea

14.45 - 15.00 Early experience of translating patient-specific analysis towards interventional cardiology practice Claudio Capelli, University College London

15.00 - 15.15 Sizing and valvuloplasty balloon computational models: validation with in-vitro experiments Giorgia Bosi, University College London

15.15 - 15.45 Coffee

Session 4. Atherosclerosis. Chair: Peter Hoskins

15.45 - 16.15 INVITED: Translation application of the combination of MR imaging and mechanics analysis in assessing atherosclerotic plaque vulnerability Dr Zhongzhao Teng, University of Cambridge

16.15 - 16.30 Impact from the uncertainty of material properties on plaque mechanical behaviours: a 3D Fluid-Structure interaction study Jianmin Yuan, University of Cambridge

16.30 - 16.45 Comparison of different strain energy functions in describing atherosclerotic plaque mechanical behaviours Jianmin Yuan, University of Cambridge.

16.45 - 17.00 Role of Collagen Orientation in Mechanics of Carotid Atherosclerotic Plaques Graeham Douglas, University of Cambridge

Tuesday 17th June

08:00 - 08:55 Coffee and registration

08:55 - 09:00 Welcome: Pankaj Pankaj

Session 5: VPH and orthopaedic. Chair: Pankaj Pankaj

09.00 - 09.45 PLENARY: The Virtual Physiological Human: personalised modelling for in silico medicine Prof Marco Viceconti, University of Sheffield

09.45 - 10.15 INVITED: What orthopaedic surgeons want from patient specific modelling Prof Hamish Simpson, University of Edinburgh

10.15 - 10.45 Coffee

Session 6: Cancer and discussion. Chair: Permual Nithiarasu

10.45 - 11.00 Patient-specific modelling of radiotherapy dose using a biomechanics model of the rectum Michael Sutcliffe, University of Cambridge

11.00 - 11.15 Quantitative Diagnostics of Prostate Cancer using Mechanical Palpation Yuhang Chen, Heriot Watt University, Edinburgh

11.15 -

11.30 -

11.45 -

11.30

11.45

12.00

POEMS network (Predictive Modelling for Healthcare Techologies) - Richard Clayton

IPEM presentation - Steve Keevil (President IPEM)

Discussion on the future of PSM meeting, liaison with POEMS, IPEM involvement

12.00 - 13.00 Lunch

Session 7: Musculoskeletal. Chair: Pankaj Pankaj

13.00 - 13.30 INVITED: Using Patient Specific Modelling to Understand Failure Mechanisms in Metal-on-Metal Hip Resurfacing Prof Richie Gill, University of Bath

13.30 - 13.45 Towards a patient-specific combined musculoskeletal and finite element model of bone structure Claire Villette, Imperial College London

13.45 - 14.00 Validation of a finite element mouse tibia model for studying bone adaptation Yongtao Lu, University of Sheffield

14.00 - 14.15 A parametric human body modelling tool for the representation of sitting posture of individuals with profound musculoskeletal deformities Michael Voysey, University of South Wales

14.15 - 14.30 Modelling fracture fixation using extra-medullary devices: is patient specificity important? Pankaj Pankaj, University of Edinburgh

14.30 - 15.00 Coffee

Session 8: Musculoskeletal. Chair: Pankaj Pankaj

15.00 - 15.30 INVITED: Physiological challenges in musculoskeletal PSM Dr Andrew Phillips, Imperial College, London

15.30 - 15.45 A dynamic simulation approach for computing muscle synergies from experimental joint moments Ananth Gopalakrishnan, Imperial College London

15.45 - 16.00 Patient specific modelling: lessons from subject-specific animal modelling in cranial research Michael Fagan, University of Hull

16.00 Close; Pankaj Pankaj

ABDOMINAL AORTIC ANEURYSM MODELLING AND IMAGING T.Christian Gasser Department of Solid Mechanics, Royal Institute of Technology (KTH), Sweden. email: gasser@kth.se

Based on a large number of interventions, a maximum transverse diameter of, on average, 55 mm appears to be the best indicator for elective abdominal aortic aneurysm (AAA) repair. In addition to aneurysm size, other rupture risk factors such as asymmetric geometry, gender, family history, fast aneurysm expansion, a thick intra-luminal thrombus layer etc., should also be considered for the decision to perform elective AAA repair. Modern imaging modalities provide an accurate three-dimensional view of the aneurysm; information that is not being fully exploited in current clinical practice. Specifically, imaging synergistically combines with the biomechanical rupture risk assessment, where parameters like the Peak Wall Rupture Risk Index (PWRI) are computed [1]. The PWRI reflects the cumulative risk from many known risk factors, and hence, fully supports a multidimensional individual rupture risk assessment [2]. This presentation outlines the derivation of rupture risk-relevant parameters from standard Computer Tomography-Angiography (CT-A) images together with general patient data. To this end AAA geometry is reconstructed, wall stress is predicted and parameters that represent the biomechanical risk for rupture are computed with the A4clinics software (VASCOPS GmbH, Austria) [3]. This information is then compared to the average aneurysm patient, which allows a relative risk assessment that links the individual data with the clinically-established, diameter-based intervention criteria [2]. In conclusion, CT-A scanning provides much more information than is currently being considered for the decision to perform elective AAA repair. Post processing CT-A scans with the A4clinics software could significantly improve the management of AAA patients. In addition to a static view (considering image data from a single time point), the proposed concept could also be applied to monitor AAA expansion over time by means of growth-related rupture risk parameters [4].

References

[1] S. Khosla, J. V. Moxon, D. R. Morris, P. J. Walker, T.C. Gasser, J. Golledge. Comparison of peak wall stress in ruptured, symptomatic and intact abdominal aortic aneurysms: A systematic review and meta-analysis. British Journal of Surgery (in press).

[2] T.C. Gasser, A. Nchimi, J. Swedenborg, J. Roy, N. Sakalihasan, D. Böckler, A. Hyhlik-Dürr. A novel strategy to translate the biomechanical rupture risk of abdominal aortic aneurysms to their equivalent diameter risk: Method and retrospective validation. Eur. J. Vasc. Endovasc. Surg. 47(3):288-95. 2014.

[3] M. Auer and T. C. Gasser, Automatic reconstruction and finite element mesh generation of abdominal aortic aneurysms, IEEE Trans. Med. Imag. 29, 1022-1028, 2010.

[4] G. Martufi, M. Auer, J. Roy, J. Swedenborg, N. Sakalihasan, G. Panuccio and T.C. Gasser. Multidimensional growth measurements of abdominal aortic aneurysms. J. Vasc. Surg. 58, 748-55. 2013.

THE INFLUENCE OF WALL THICKNESS ON STRESS DISTRIBUTIONS IN PATIENT SPECIFIC MODELS OF ABDOMINAL AORTIC ANEURYSMS 1Conlisk N, 1Newby D E, 1Hoskins P R 1Centre for Cardiovascular Science, University of Edinburgh, UK. email: noel.conlisk@ed.ac.uk

Background: Rupture of abdominal aortic aneurysms (AAAs) is closely linked to aneurysm morphology e.g. [1, 2]. Many previous finite element (FE) studies assume a uniform aortic wall thickness in the range of 1.5 – 2 mm [3, 4]; this is necessary due to the difficulties associated with discerning wall geometry from CT. However, in reality aortic wall thickness can vary greatly e.g.[5], both regionally and between patients. This factor will likely influence both predicted stresses and conclusions drawn on rupture risk from such computational models. Therefore, the aim of this study is to quantify the exact influence of patient specific (PS) wall thickness on the resulting stress distribution in a small number of patients undergoing clinical surveillance for AAAs.

Methods: CT scans of four patients from the MA3RS clinical trial were selected for reconstruction, the criteria for selection was based on the absence of thrombus, as verified by a qualified cardiovascular surgeon on corresponding MRI scans of each patient. A total of 8 FE models were constructed, e.g. two models per patient. The key difference between these models being the assumption of a 1.9 mm uniform wall (Avg_Wall), or incorporation of variable wall thickness from CT (PS_Wall). Segmentation and meshing was carried out using commercial software (Mimics, Materialise, Belgium). Resulting FE meshes were then exported and analysed using Abaqus6.10-1 (Dassault Systemes, Simulia, Providence, RI, USA).

Results: The stress distributions for each case can be seen in the figure. At peak systolic pressure, the assumption of a uniform wall led to overestimation of peak wall stress in 3 out of 4 cases. In the remaining case (patient 4) the Avg_Wall was actually found to underestimated peak stress by as much as 40%. In all cases it can also be seen that the incorporation of patient specific wall thickness markedly influenced the resulting distribution of stress.

Discussion: This study aimed to investigate the influence of wall thickness on stress distributions. Wall thickness was found to influence both the location and magnitude of peak stresses observed. Contrary to the findings of Jiang et al. [5], the distribution of stress within the wall of the aneurysm changed dramatically with regional variations in wall thickness, possibly due to local thinning of the aortic wall in PS_Wall models, this is particularly noticeable in patient 4.

Conclusion: This study highlights the importance of accurately modelling aneurysmal wall geometry when using FE to predict clinical outcomes. All future studies should make efforts to incorporate patient specific wall data, where available, to improve accuracy of predictions. Thus far this work has focused on recruitment of thrombus free AAAs, on-going work aims to combine information from multiple imaging modalities (e.g. CT and MRI) to address the exact influence of wall thickness in aneurysms where varying amounts of intraluminal thrombus are present.

References:

1. Doyle, B.J., et al., J Biomech, 2010. 43(7): p. 1408-1416. 2. Vorp, D.A., M.L. Raghavan, and M.W. Webster,. J Vasc Surg, 1998. 27(4): p. 632-639. 3. Fillinger, M.F., et al., J Vasc Surg, 2002. 36(3): p. 589-597. 4. Raghavan, M.L., et al., J Vasc Surg, 2000. 31(4): p. 760-769. 5. Jiang, X., et al. in Biomedical Engineering and Informatics, 2009.

Comparison of Transient and Steady-State Simulations of Magnetic Resonance Elastography 1Hollis L, 1Thomas-Seale LEJ, 1Conlisk N, 2Kennedy P, 2Barnhill E, 2Roberts N, 3Pankaj P,1Hoskins PR 1Centre for Cardiovascular Sciences, University of Edinburgh, UK. 2Clinical Research Imaging Centre, University of Edinburgh, UK. 3School of Engineering, University of Edinburgh, UK email: s1160274@staffmail.ed.ac.uk

Background: Abdominal aortic aneurysm (AAA) rupture accounts for more than 8000 deaths in the United Kingdom each year however rupture occurs in only a quarter of AAAs1. Surgical intervention is currently performed if the AAA exceeds 5.5cm in diameter2 however this is seen as an unreliable predictor of AAA rupture3. Patient specific modelling (PSM) is seen as a viable alternative predictive model however one weakness is in the material properties definition. Magnetic resonance elastography (MRE), an MRI-based techniques that utilises a phase-encoding gradient to measure the wavelength of mechanically induced shear waves in order to create a map of tissue stiffness4, will be utilised to address this problem. A method of modelling MRE in silico has been created by Thomas-Seale et al. (2011)5 and is intended to be used in the development of MRE in AAA. This project aims to further develop this modelling process and investigate how various parameters affect the measurements made. Methods: Two methods of simulating MRE have been compared: transient and steady-state. Simulations have been performed on 80x80x50mm3 box with a 10mm radius cylindrical insert passed through the middle. The prescribed shear modulus of the box is 3kPa. In the first test the shear modulus of the insert is varied from 4-9kPa with vibrations being applied at 100Hz. Following this the shear modulus of the insert was fixed at 9kPa and the frequency was investigated with vibrations induced between 50-100Hz. Results: With the transient simulation good accuracy was achieved for both the background and the insert for all variations in the insert shear modulus. This was not the case when the frequency was varied however. Whilst measurements of the background shear modulus remained accurate, characterisation of the insert was poor at frequencies other than 100Hz. In the steady-state simulations the measurements made of the background and the insert were again

accurate for variations in the insert shear modulus. Measurements of the background were accurate for all frequencies. Although measurement of the insert was poor at 50Hz, the accuracy improved with increasing frequency. Discussion: Transient and steady-state offer different benefits. Whilst the steady-state simulation generally runs faster, a directional filter can be applied to the data output from the transient simulation thus limiting the effect of reflections on the measurements. The results here show that the transient simulation is unstable at different frequencies with the steady-state simulation comparing favourably here: whilst the measurement at 50Hz is inaccurate, the improvement seen with increasing frequency is expected in MRE. Conclusions: Steady state simulations of MRE are more stable at different frequencies and should therefore be used ahead of transient simulations in the in silico study of MRE in AAAs. Key references: 1. Sakalihasan, N., Limet, R. & Defawe, O. D. Lancet (2005). 2. Brewster, D. C. et al. J. Vasc. Surg (2003). 3. Vorp, D. A., Raghavan, M. L. & Webster, M. W. J. Vasc. Surg (1998). 4. Muthupillai, R. et al. Science (1995). 5. Thomas-Seale, L. et al. IAENG IJCS (2011).

Figure - Elastogram from transient simulation of the 9kPa

insert at 100Hz.

CENTROID-SYMMETRY CORRELATIONS WITH ANEURYSM WALL STRESS 1Callanan A, 1Tallo N, 2Conlisk N, 1, 2Hoskins PR, 2, 3Doyle BJ 1Institute of Bioengineering, School of Engineering, The University of Edinburgh, UK 2Centre for Cardiovascular Science, The University of Edinburgh, UK 3Intelligent Systems for Medicine Laboratory, School of Mechanical and Chemical Engineering, The University of Western Australia, Australia email: anthony.callanan@ed.ac.uk

Background. Abdominal Aortic Aneurysms (AAAs) are the abnormal swelling and dilation of the abdominal aorta. This swelling is due to the degradation and weakening of the aortic wall tissue. If the swelling or weakening of the tissue becomes too severe, rupture of the AAA will occur and can result in fatalities. AAAs can be treated effectively in a number of ways, primarily through elective surgical repair or endovascular repair [1]. Unfortunately, the correct surgical intervention time is currently unknown and the method used to determine if surgical intervention is required generally do not take into account a number of factors such as patient specific geometrical and biomechanical properties. A number of tools are being developed to assist in the prediction of rupture and therefore intervention time. A recent study showed a correlation between asymmetry and stress locations [2]. This study examines a correlation between the centroid-symmetry of the AAA and the wall stress. Specifically, the distance from the centroid of the AAA to each point on the wall will be measured giving a shape plot which is compared to the stress in the same region.

Methods. Patient specific finite element (FE) models of three AAAs were reconstructed from the CT scan data of two patients from the MA3RS clinical trial. Reconstruction and meshing of aneurysm geometry was carried out using A4 clinics research edition (VASCOPS GmbH, Sweden) and FE analysis using Abaqus v6.10 (Dassault systèmes, France). Realistic arterial properties were applied to the models [3]. The numerical results of this study were formatted using MS Excel 2010 (Microsoft, USA) and Matlab R2013a (The MathWorks, Inc., USA).

Results. 2D and 3D plots of the distance from the centroid and the stress on the wall of the AAA were extrapolated. An inverse relationship was found between the stress and distance from the centroid in the models, with results for a single model shown in figure 1.

Figure 1: Line plots at the anterior (A) and posterior (B) for the distance from centroid (blue) and the wall stress (red), (B) showing the posterior stress contour plot.

Discussion. There appeared to be a clear correlation between the stress and the distance from the centroid for the models. The correlation will be further enhanced with additional models which are in the process of being analysed.

Conclusion. Finding from this initial study show some promise for this technique of centroid-symmetry to be used in conjunction with current intervention criteria.

Key references. [1] F. A. Lederle, J. A. Freischlag, T. C. Kyriakides, J. S. Matsumura, F. T. Padberg, T. R. Kohler, P. Kougias, J. M. Jean-Claude, D. F. Cikrit and K. M. Swanson, “Long-term comparison of endovascular and open repair of abdominal aortic aneurysm.,” The New England Journal of Medicine, vol. 367, no. 21, pp. 1988-1997, 2012. [2] B. J. Doyle, A. Callanan, P. Burke, P. Grace, M. Walsh, D. Vorp and T. McGloughlin, “Vessel asymmetry as an additional diagnostic tool in the assessment of abdominal aortic aneurysms.,” Journal of Vascular Surgery, vol. 49, no. 2, pp. 443-454, 2009.

Vertical Height

(A) Max Stress 0.095MPa (B) Max Stress 0.074MPa

High Stress

Low Stress

BLOOD DAMAGE IN LEFT VENTRICULAR ASSIST DEVICES Fraser K H Dept of Bioengineering, Imperial College London, UK.

email: k.fraser@imperial.ac.uk

Around 1% of the UK population suffer from heart failure. While many are treated using the available drugs, for some the only solution is a heart transplant. However, only around 120 transplants are performed in the UK each year and many patients die while waiting for a heart. Mechanical circulatory support devices have been developed to assist the circulation until a suitable donor can be found. Ventricular assist devices (VADs) are pumps which work in parallel with the native heart to augment the function of one or both of the ventricles. Compared with optimal drugs, VADs double the one year survival rate and significantly increase quality of life1. It has also been shown that in specific patient populations, VADs, in combination with drugs, can reverse end stage heart failure2,3. However there are still a number of problems. Modern VADs are small axial or centrifugal rotary pumps which supply a continuous flow of blood to the arteries. There are high shear stresses on the blood which lead to blood trauma including haemolysis, platelet activation, emboli and destruction of von Willebrand factor. In addition the steady flow has the potential to cause changes in the blood vessels.

Computational fluid dynamics studies of haemodynamics in a range of VADs were used to show how the geometry and operation of a device affect shear stresses and residence times. A numerical model for haemolysis was developed and validated against in vitro measurements and can be used to compare device prototypes. Axial flow VADs were shown to be less haemolysing than centrifugal flow VADs4. However, estimates of flow weighted residence time at a range of shear stress levels show that optimising a VAD to minimise haemolysis may not be the best approach for reducing overall blood damage.

The most common complication with VADs is non-surgical bleeding5. Future work will involve assessment of the effects of destruction of von Willebrand factor, and reduced arterial pulse, on gastrointestinal bleeding, using numerical, in vitro and in vivo models. If the current problems with VAD technology can be eliminated more patients can be supported, and more may recover from heart failure.

Key references. 1 Rose et al, 2001, NEJM 2 Birks et al, 2011, Circulation 3 Gojo et al, 2007, Ann Thorac Surg 4 Fraser et al, 2012, J Biomech Eng 5 Kirklin et al, 2013, J Heart Lung Transplant

EARLY EXPERIENCE OF TRANSLATING PATIENT-SPECIFIC ANALYSIS TOWARDS INTERVENTIONAL CARDIOLOGY PRACTICE

1,2Capelli C, 1,2Bosi GM, 1,2Biglino G, 2Khambadkone S, 2Derrick G, 1,2Taylor AM, 1,2Schievano S. 1 Institute of Cardiovascular Science, University College London, UK. 2 Great Ormond Street Hospital, NHS Foundation Trust, London, UK. email: c.capelli@ucl.ac.uk

Background.

Patient-specific models have been applied to get insights of physiology and pathology of a wide range of cardiovascular conditions [4]. Also, they have been used to test the design of existing and novel devices taking into account realistic conditions [2, 3]. Models which include individual characteristics could also be applied to address clinically relevant requests as interventional planning. However, this is currently a major challenge for the modelling community [1,5]. Over the last decade, our engineering group which is part of the Cardio-respiratory Unit in the main UK children hospital created over 700 models of cardiovascular structures and devices. This created the conditions to explore the use of such models in planning complex treatments. In this study, we report the early results of this experience of predicting outcomes of percutaneous interventions by means of patient-specific analyses.

Methods.

A small cohort of patients (n=6) who were referred to our Center for percuraneous pulmonary valve implantation (PPVI) and stenting of aortic coarctation (CoA) were included in this study. Image data were conventionally acquired for patients’ assessment, including computed tomography, magnetic resonance and echocardiographic assessment, and post-processed to reconstruct the three-dimensional anatomy of the implantation sites and translate realistic boundary conditions. For each case, patient-specific models were implemented to simulate peri- and post-operative scenarios. Different devices varying in terms of size and shape were extracted from our library and virtually implanted according to clinical indications. Finite element (FE) analyses were used to mimic the implantation and computational fluid dynamics (CFD) to investigate the hemodynamics changes. Each simulation was conducted prospectively and results were presented during the multidisciplinary meeting in our Unit to plan the intervention. Finally, clinical outcomes were compared with the model predictions.

Results.

Simulations confirmed intervention feasibility in five cases and outlined the best fitting device for each individual. Contact areas and stress distributions were quantified to assess optimal implantation strategy. Clinical procedures were decided in accordance with the computational prediction in all the cases except one PPVI, which was not performed following invasive catheterism investigation assessing large distensibility. In the CoA cases, CFD analyses were useful to highlight blood distribution before and after the intervention. The entire process, including accurate three-dimensional reconstructions, FE and CFD analyses, were completed within a week.

Discussion and Conclusion.

The early results of translating patient-specific models into clinical practice at our Center have been promising in terms of reliability of the simulations, response time, and clinical relevance. However, future studies will need to include even more realistic data about mechanical characterization of specific implantation sites and further reduce the computational costs. The translation of these technologies is crucial as it can limit the procedural risks and improve treatments as tailored on each patient characteristics.

Key references [1] Brown et al., Journal of Biomechanics, 2012

[2] Capelli et al., Annals of biomedical Engineering, 2012

[3] Schievano et al., Eurointervention, 2010

[4] Taylor and Figueroa, Annual Review of Biomedical Engineering, 2009 [5] Viceconti et al., The Journal of Physiological Sciences, 2008

SIZING AND VALVULOPLASTY BALLOON COMPUTATIONAL MODELS: VALIDATION WITH IN-VITRO EXPERIMENTS 1Giorgia M. Bosi, 1Giovanni Biglino, 2Benedetta Biffi, 2Valentina Lintas, 1Claudio Capelli, 3Spyros Tzamtzis, 3Gaetano Burriesci, 2Francesco Migliavacca, 1Andrew M. Taylor and 1Silvia Schievano 1Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science & Great Ormond Street Hospital for Children, London, UK

2Laboratory of Biological Structure Mechanics (LaBS), Chemistry, Materials and Chemical

Engineering Department "Giulio Natta", Politecnico di Milano, Italy 3Dept of Mechanical Engineering, UCL Faculty of Engineering Science, London, UK

Background Patient-specific simulations have recently been adopted to support planning of complex cardiovascular interventions [1]. However, current models do not account for realistic individual implantation site response to overload. We propose to use balloon inflation pressure and diameter changes, collected during balloon sizing and valvuloplasty, to derive this response by feeding these data into a patient-specific computational model of the procedures. In this study, we created computational models of two types of balloons and validated their behaviour using in-vitro experiments of balloon inflation first in simplified cylindrical implantation sites and then in mock arteries produced by means of rapid prototyping (RP) [2]. Methods Two balloons were analysed: Edwards non-compliant balloon used for aortic valve dilatation (23mm diameter) and NuMED compliant sizing balloon PTS405 (40mm diameter). The balloons were inflated using an ad-hoc pump system that simultaneously monitored volume (V) and pressure (P). The experiments were performed in a catheterisation laboratory to acquire biplane fluoroscopy images that allowed simultaneous measurement of balloon diameters. The experimental data were used to tune a finite element (FE) model of the balloons which were virtually inflated using fluid cavity interaction in Abaqus/Explicit. Using RP technology, a wide range of cylinders with different percentages of compliant 930TangoPlus and stiff 830VeroWhite (FullCure®), and different thicknesses was tested by inflating the samples with constant flow-rate while measuring the pressure with a fibre-optic transducer (Samba Preclin420MR, Harvard Apparatus); this allowed to derive the circumferential distensibility (D=∆V/(Vin∙∆P)) of the cylinders and identify the optimal combination of materials and thickness that replicated realistic pulmonary and aortic arteries. Two patient’s anatomies were 3D reconstructed from medical images and printed using the selected materials: an aortic root with calcified aortic valve (including leaflets and calcifications) from a transcatheter aortic valve implantation patient (Patient_A), and a pulmonary artery from a percutaneous pulmonary valve implantation candidate (Patient_B). The balloons were inflated in the in-vitro set up first inside the cylinders and then in the patient-specific mock arteries according to their applications and dimensions: Edwards23 in Patient_A and NuMED40 in Patient_B. Pressure-diameter and pressure-volume relationships were recorded. These experiments were replicated computationally. The pressure/volume loads from the cylindrical samples alone were simulated to each cylinder models. Then, balloons were virtually inflated inside the cylinders and the patient-specific FE models using a contact algorithm. Results The measured distensibilities of Edwards23 and NuMED40 were 43x10-51/mmHg and 55x10-51/mmHg respectively. The maximum pressure reached during the experiments was 6.3atm for Edwards23 and 0.4atm for NuMED40. The distensibilities of the RP cylinder samples were 2x10-3 and 7.5x10-31/mmHg for the mock aortic and pulmonary material, respectively. Balloons/cylinders interaction simulations were in good agreement with the experimental data (error<3%), while larger differences were noticed in the more complex balloons/mock arteries analyses (<10%).

Conclusion In this, study, we performed in-vitro tests to validate the computational models of balloon sizing and valvuloplasty. Diameter changes coupled with simultaneous pressure measurements during balloon inflations could be used to derive patient-specific response to overload during catheterisation procedures for more realistic computational simulations of device implantation.

References

[1] Schievano S, Taylor AM, Capelli C, Coats L, Walker F, Lurz P, Nordmeyer J, Wright S, Khambadkone S, Tsang V, Carminati M, Bonhoeffer P. A new approach to medical device development - first-in-man implantation of a novel percutaneous valve. EuroIntervention. 2010;5:745-750.

GRAFICO PV

[2] Biglino G, Verschueren P, Zegels R, Taylor AM and Schievano S. Rapid prototyping compliant arterial phantoms for in-vitro studies and device testing. Journal of Cardiovascular Magnetic Resonance 2013, 15:2

Impact from the uncertainty of material properties on plaque mechanical behaviours: a 3D Fluid-Structure interaction study Yuan J1, Teng Z1,2, HUANG Y1,Gillard JH1, 1 University Department of Radiology, University of Cambridge, UK. 2Department of Engineering, University of Cambridge, UK. email: zt215@cam.ac.uk

Background Stroke is the 3rd leading cause of death and the leading cause of disability in the world1. Carotid atherosclerotic plaque is responsible for 20-30% of all ischaemic strokes. Mechanical analysis has demonstrated the complementary value of stress in assessing the plaque vulnerability2. However, atherosclerotic plaques are non-uniform structures. As one of the key factors dominating the loading level within the fibrous cap, the material properties vary with individuals and from location to location. It is nearly impossible to quantify the local material properties in vivo and therefore there is existing uncertainty in material properties when the computational simulation is performed. However, the impact from such uncertainty on prediction of mechanical conditions within the plaque structure has been least investigated.

Methods

Carotid plaques were collected from 11 patients at endarterectomy. Media, fibrous cap (FC), lipid and haemorrhage of plaques were separated and cut into strips to perform uni-axial extension test. Each tissue type was further divided into had, median and soft according to the rank of Young’s modulus. Fluid-structure interaction (FSI) was used to assess the effect of different component stiffness on plaque mechanical behaviours.

Results

Maximum stress and stretch vary widely at different component stiffness at thin FC of 65 μm. Plaques with soft media, lipid, haemorrhage and hard FC have the largest stress of 615.2 kPa, largest stretch of 1.23, while plaques with hard media, lipid and haemorrhage and soft FC have lowest stress of 124.9 kPa. Plaques with all hard components have the smallest stretch of 1.085. At FC thickness above 1mm, maximum stress locates at FC shoulders, but at thin FC of 0.065mm, only plaques with hard media, hard haemorrhage, and soft FC show stress concentration at FC shoulders, other models show maximum stress at FC centre. Almost all the models show maximum stretch at FC shoulder.

Conclusion

Plaque component stiffness could have a large impact on plaque mechanical behaviours at thin FC (65μm). Decrease stiffness of media, lipid and haemorrhage and increase stiffness of FC can all increase the plaque maximum stress significantly (up to 392.6%). Decrease all components stiffness can increase intraplaque stretch up to 15.9%.

Key references. 1 Christopher et al, "Global mortality, disability, and the contribution of risk factors: Global Burden of

Disease Study," The Lancet 349 (9063), 1436-1442 (1997). 2 Sadat et al. "Biomechanical structural stresses of atherosclerotic plaques." Expert review of

cardiovascular therapy 8.10 (2010): 1469-1481.

Comparison of different strain energy functions in describing atherosclerotic plaque mechanical behaviours Yuan J1, Teng Z1,2*, Huang Y1, Sutcliffe MPF2, Gillard JH1, 1 University Department of Radiology, University of Cambridge, UK. 2 Department of Engineering, University of Cambridge, UK. *email: zt215@cam.ac.uk

Background

Rupture of atherosclerotic plaque is responsible for 20-30% of all ischaemic strokes and more than 60% of myocardial infarctions1. Luminal stenosis, which is the current sole criterion for assessing the disease severity, has a poor correlation with plaque vulnerabilities2. Mechanical analysis has been demonstrated to provide complementary values to luminal stenosis3. However, as one of the most important factors dominating plaque mechanical behaviours, different constitutive laws have been employed to describe the material properties of various atherosclerotic components, including modified Mooney-Rivlin (M-R), five-parameter M-R, neo-Hookean, one-term Ogden, two-term Ogden, Demiray and Yeoh strain energy density function (SEDF). However, the difference in predicting stress within the plaque structure using different type of SEDF has been least quantified.

Methods

Media, fibrous cap (FC), lipid and haemorrhage/thrombus from 11 carotid plaques, which were collected at endarterectomy were tested using uni-axial extension testing. The above mentioned seven SEDFs were used to fit the experiment data. The difference in predicting stress was assessed using: (1) analytic solutions; (2) obtained results in a 2D idealised plaque model and (3) obtained results in a 3D fluid-structure interaction (FSI) analysis with an idealised plaque model. The inherent material stability described by each SEDF was further analysed to shed light on this difference.

Results

Except for neo-Hookean, the other six SEDFs could well fit the experiment data by capturing the non-linear stress-stretch relationship in a stretch range of 1.0-1.3. The results obtained from numerical simulations using the six SEDFs were in good agreements with the analytic solutions in predicting stress distribution in a uniform long think-wall tube. However, significant differences appeared in predicting stress in idealised 2D and 3D plaque models. In 2D plaque models, one-term Ogden model predicted the maximum stress (360.3 kPa), while modified M-R model yielded the lowest stress (297.6 kPa). In 3D FSI analysis, the convergent results could be obtained from modified M-R, Yeoh and Demiray, with the largest stress in Demiray (124.5 kPa) and lowest in Yeoh (122.1 kPa). Material stability analysis indicated that one-term Ogden, two-term Ogden and five-parameter M-R were all unstable.

Conclusion

When the computational analysis is used to predict mechanical loading with plaque structures, the choice of strain energy density function needs to be carefully evaluated.

Key references 1. Casscells, Ward, Morteza Naghavi, and James T. Willerson. "Vulnerable atherosclerotic plaque a

multifocal disease." Circulation 107.16 (2003): 2072-2075.

2. Ferguson, Gary G., et al. "The North American symptomatic carotid endarterectomy trial surgical results in 1415 patients." Stroke 30.9 (1999): 1751-1758.

3. Sadat, Umar, Zhongzhao Teng, and Jonathan H. Gillard. "Biomechanical structural stresses of atherosclerotic plaques." Expert review of cardiovascular therapy 8.10 (2010): 1469-1481.

Role of Collagen Orientation in Mechanics of Carotid Atherosclerotic Plaques Douglas GR1,2, Teng Z2,1, Gillard JH2, Sutcliffe MPF1

1Department of Engineering, University of Cambridge, UK.

2Department of Radiology, University of Cambridge, UK. email: grd26@cam.ac.uk

Background

Arterial tissue, including atherosclerotic plaques, is fibrous and the mechanical properties are dominated by collagen4,5. While healthy tissue forms an organized pattern of concentric layers of helically oriented fibres1,2, the fibre organisation of a plaque is disrupted by features such as lipid deposits and haemorrhages. The local fibre conditions are hypothesized to have a dramatic impact on both the stress distribution and strength of the tissue4. Atherosclerosis becomes an acute disease when the fibrous cap of the plaque fractures. This releases thrombogenic lipid into the vessel, which can result in a thrombus and occlusion3. This mechanism is responsible for the majority of strokes and heart attacks. The critical event is the fracture of the fibrous cap, which is presumably from a mechanical load which exceeds the strength of the tissue6,7.

Methods

Carotid plaque specimens collected at endarterectomy are imaged using scanning electron microscopy and histology. Geometry and fibre orientation are obtained through image processing techniques from several plaques. Plaque-specific material and geometry models are then built using these images, and simulated using the finite element method. Degree of fibre organisation is modified from highly aligned to isotropic to determine the influence of this parameter.

Results

SEM

micrographs

and histolo

gy slides have been collected (left). Several have been analysed using image processing techniques to extract the geometry of the plaque and assign local fibre orientations (centre). These fibre orientations are imported to a commercially-available finite element package for local orientation assignment. The results for this simulation are compared with an isotropic material and a globally-assigned orientation (right).

Discussion and Conclusions

While models of atherosclerosis with patient-specific geometry have existed for some time, the great variability of material properties of the tissue suggests the importance for patient-specific material models. While clinical imaging is probably not yet able to assign local orientations at the discreteness of scale used here, the results of this study may find clinical utility through a classification scheme of plaques. For instance, fibre parameters at the joint between the fibrous cap and deeper tissue at the plaque's shoulder may explain this region's vulnerability to rupture.Key references

1. Clark JM, Glagov S. Arterioscler. Thromb. Vasc. Biol., 5[1]:19–34, 1985. 2. Gasser TC, Ogden RW, Holzapfel GA. J. R. Soc. Interface, 3[6]:15–35, 2006. 3. Halvorsen B, Otterdal K, et al. Prog. Cardiovasc. Dis., 51[3]:183–94, 2008. 4. Holzapfel GA, Ogden RW. Proc. R. Soc. A, 466[2118]:1551–1597, 2010. 5. Holzapfel GA. Chapter 11, Collagen: Structure and Mechanics, 2008. 6. Tang D, Yang C, et al. J. Biomech. Eng., 131[6]:1–27, 2009. Sadat U, Teng Z , Gillard JH. Expert Rev. Cardiovasc. Ther., 8[10]:1469–81, 2010.

The Virtual Physiological Human: personalised modelling for in silico medicine 1Viceconti M 1Insigneo institute for in silico medicine, University of Sheffield, UK. email: m.viceconti@sheffield.ac.uk

The Virtual Physiological Human (VPH) is a methodological and technological framework that, once established, will enable collaborative investigation of the human body as a single complex system. According to the VPH Institute, VPH models have three areas of application:

1) Digital Patient, or the VPH for the doctor

2) In silico Clinical Trials, or the VPH for the industry

3) Personal Health forecasting, or the VPH for the patient.

We summarise the development of the VPH from 2005 to date. We then focus on patient-specific modelling for diagnosis, prognosis and treatment planning, and provide some examples related to cardiovascular and neuromusculoskeletal conditions, as developed in the new Insigneo institute in silico medicine established in Sheffield, UK. As an example we discuss in detail a patient-specific modelling solution for assessing the risk of fracture in osteoporotic patients that is now entering the prospective validation phase.

Patient-specific modelling of radiotherapy dose using a biomechanics model of the rectum

MPF Sutcliffe1, JE Scaife2, K Harrison3, M Romanchikova4, MA Parker3 1 Department of Engineering, University of Cambridge 2 Department of Oncology, University of Cambridge 3 Department of Physics, University of Cambridge

4 Medical Physics Department, Cambridge University Hospitals NHS Foundation Trust, Cambridge

email: mpfs@eng.cam.ac.uk (MPF Sutcliffe)

Background: The success of radiotherapy (RT) in treating tumours depends on an accurate delivery of dose to the tumour, while avoiding damage to adjacent organs and associated toxicity. The work described here focuses on rectal toxicity associated with treatment of prostate cancer. Over the course of a treatment of typically 37 days, patient-specific changes in the shape of the rectum will result in discrepancies between the planned dose and the delivered dose. Daily computed tomography (CT) images on the treatment bed can be used to find the location of the rectum. However individual material elements within the rectum cannot be identified. Hence a biomechanics approach is proposed, using an explicit Abaqus finite element model of the rectum, to estimate the trajectory of material elements through the treatment cycle and the corresponding dose.

Methods: The set of CT patient data over the course of treatment is used to derive the outline of the rectum day-by-day. An initial tube of constant diameter following the mean centre-line of the rectum is deformed to the required shape, by inflating a dummy body within the initial tube to the target shape. Contact between the dummy internal body and the rectum wall is taken as frictionless. The resulting deformed geometry of the rectum is used to calculate the location of individual material elements through the treatment cycle. This trajectory of material movement is combined with a dose map to derive dose-volume histograms (DVH). The effect on the original planned DVH of including the rectal deformation to track material element trajectories is quantified.

Results: Figure 1 illustrates the deformed shape of the rectum for two typical days. The location of a typical element is identified by the blue asterisk on the figure. The cranial-caudal movement of material elements, which cannot be identified using the CT images directly, is significant. Figure 2 plots a histogram of the cranial-caudal position of this typical element over the 37 days of treatment. The standard deviation in the location equals 2.5 mm. The effect of material properties and boundary conditions have also been quantified. Refinements to the model are needed to improve its accuracy, including changes in the constraint associated with attachment of the rectum to surrounding organs. Validation of the model using a phantom study is in hand.

Conclusions: It is important to use a patient specific model of the rectum to model the movement of material elements and hence track radiation dose during radiotherapy.

Acknowledgements

Funding is gratefully acknowledged from Cancer Research UK for the VoxTox project, which this study is a part of.

Figure 1. Deformed geometry of rectum for two typical

days. The blue asterisk marks the same material point on

the two days.

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Quantitative Diagnostics of Prostate Cancer using Mechanical Palpation Palacio-Torralba Javier, Reuben RL, Chen YH. School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, UK email: y.chen@hw.ac.uk

1. Introduction Diagnostics of prostate cancer is usually performed by analysing the prostatic-specific antigen (PSA)

blood concentration or by digital rectal examination (DRE) tests. PSA levels vary for each patient subject

to different factors such as urinary retention, ejaculation, usage of antibiotics etc. thus becoming an

unreliable diagnostic technique. DRE is a clinical procedure where the practitioner explores the prostate,

palpating for abnormalities; however, it only provides qualitative information which may lead to poor

diagnostic and treatment decisions. In addition, to assess the presence of cancerous tissue and its stage

a biopsy is always required. Nevertheless, such procedures offer disadvantages such as false negatives,

risk of rectal bleeding, urinary tract infections etc. Mechanical palpation takes advantage of viscoelastic

properties that prostatic tissue exhibits [1] to quantitatively assess the quality of the tissue. Furthermore,

it allows determining important diagnostic features to decide optimal patient-specific treatment

procedures.

2. Methodology In this study we present a novel framework that allows quantitative tissue diagnostic measuring a

reduced set of parameters of the tissue viscoelasticity. The elastic behaviour of the material is also

obtained to enhance the diagnostic outcome. Moreover, a new approach to determine location, size and

depth of a tumour but decoupling their effects on the force feedback is proposed. It consists of palpating

the soft tissue, analysing the force feedback and comparing the results to benchmark values of healthy

and diseased tissues using finite element analysis.

3. Results and discussion A novel diagnostic framework that uses the reaction force from a mechanical palpation to quantitatively

characterise the cancerous degree of prostatic tissue using a reduced set of parameters is presented.

More importantly, it allows determining the location, depth and size of tumour. This proposed patient-

specific framework for prostate cancer diagnostics allows quantitative diagnostics when phase-shift and

amplitude measurements are not applicable due to constraints such as testing time, anatomy limitations

etc. The proposed methodology provides a quantitative tool to diagnose prostate cancer in a simple,

inexpensive and non-invasive manner.

Figure 1. In-silico model, dynamic palpation force feedback for cancerous and healthy tissue and model fitting.

4. References

1. Phipps, S., et al., Measurement of the mechanical characteristics of benign prostatic tissue: a novel method for assessing benign prostatic disease. Urology, 2005. 65(5): p. 1024-8.

Towards a patient-specific combined musculoskeletal and finite element model of bone structure Claire C. Villette, Andrew T.M. Phillips The Royal British Legion Centre for Blast Injury Studies at Imperial College London Structural Biomechanics, Department of Civil and Environmental Engineering, Imperial College London Background and Objectives: In the 1870’s, Wolff [3] formulated a ‘trajectory theory’ about trabecular bone architecture which can be succinctly written as follows: bone adapts its structure to loading conditions in a way that follows principal stress trajectories. The aim of this study was to build a predictive structural mesoscale model of a human femur based on the assumption that the bone is optimally adapted to the specific loading conditions experienced during daily activities. Methods: A generic computationally efficient structural mesoscale finite element (FE) model of a femur was built using shell and truss elements to model cortical and trabecular bone respectively, based on surface geometry information extracted from the macroCT scan of a bone surrogate. The initial thickness or radius of the structural elements was then iteratively adapted under loading conditions corresponding to walking, sit to stand, and stair ascent/descent to meet a target strain criterion. The loading conditions were obtained through musculoskeletal simulations of gait cycles recorded on a volunteer [1]. Results: A good comparison was observed in the distribution of the cortical layer thickness between the converged model and clinical images. The main trabeculae groups identified in the proximal femur by numerous studies [2] - greater trochanter group, primary compressive group and primary tensile group - were observed in this model as well, and the porosity distribution within the femur was consistent with clinical observations. It could be seen that the structure obtained from a full loading regime (including all activities) was more substantial compared to a single load case model (walking only), in particular in the distal region of the femur and the sagittal plane. It was observed that walking activities are primarily responsible for the structure of the proximal femur while sit to stand and stand to sit activities have more influence on the structure of the distal femur. Stair ascent and descent have a strengthening influence on the neck and the shaft. Fig1 shows longitudinal views of the converged model.

Fig 1: 5mm thick longitudinal slices of the converged proximal and distal parts of the femur model

with mapping of the elements according to the activity primarily responsible for their growth Discussion and future work: Using a CT of the patient bone surface and recordings of the gait cycles he is known to perform on a daily basis, this methodology has the potential to approach patient specific modelling of inner bone structure. It could also be extended to patient-specific prediction of bone reorganisation after osteotomy or following initiation of specific medical conditions such as osteoporosis. This model provides a resolution similar to a microscale continuous FE model, without the need for microscale CT imaging which could not be performed in-vivo. In addition, its computational efficiency is closer to that of a macroscale model. It is thus a powerful alternative to macro and microscale continuous FE models. References:

[1] Phillips, A.T. M. et al, (2012), Engineering and Computational Mechanics 165: 147-154

[2] Singh, M. et al., (1970). The Journal of Bone & Joint Surgery 52:3, 457–467

[3] Wolff, J. et al. (1869), Clinical Orthopaedics and Related Research, 468, 1056-1065.

Validation of a finite element mouse tibia model for studying bone adaptation 1Lu Y.T., 2,3Boudiffa M, 1Chen Y, 2,3Bellantuono I, 1Viceconti M 1Department of Mechanical Engineering and INSIGNEO Institute for in silico Medicine, University of Sheffield, Sheffield, UK. 2Bone Biology Unit, Department of Human Metabolism and INSIGNEO Institute for in silico Medicine, University of Sheffield, Sheffield, UK 3MRC-Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA) email: Yongtao.lu@sheffield.ac.uk

Background. Musculoskeletal disorders, including arthritis, osteoarthritis and osteoporosis are the most prevalent cause of work-related disease [1]. With an increasing ageing population, the size of the burden of musculoskeletal disorders is projected to increase relative to other conditions [1]. Therefore, there is an urgent need for improving our understanding of these disorders and find new therapeutic strategies in this area. To address those issues, preclinical studies using animal models are essential for the development of safer and more effective prevention and treatment [2]. However, it is time consuming and of high cost to use in vivo animal models. Computational modelling is an alternative way for studying bone adaptation and medicine intervention [3], but computational models need to be validated before use. The aim of this study is to validate a finite element (FE) mouse tibia model for studying bone adaptation.

Methods. The right tibia of a 12-week-old female mouse (C57BL6) was scanned under anaesthesia using SCANCO viva80. The µCT images with voxel size of 21µm were used to create the FE tibia model by converting each bone voxel into hexahedron (C3D8). Linear, elastic material with Young’s modulus of 21GPa and Poisson’s ratio of 0.3 was assigned [4]. The proximal articulate surface of the tibia was fully fixed. The resolved forces acting on tibia, which were 1.2N in tibia normal direction and 0.1N in anterior-posterior shear direction [5] were applied on the distal side of the tibia. The in vivo strain gauge data, measured in the mouse with the same age and the same strain during normal walking activity and at the medial and lateral surfaces of the tibia mid-shaft [6], was utilized to validate the developed tibia model.

Results. The pattern of normal strain distribution in the mouse tibia (Figure1) matched with published data [5], i.e. at the tibia mid- shaft, compressive and tensile strains at the posterior and anterior sides, respectively; maximal strains occurred at the tibia-fibular junction). FE predicted normal strains at both strain gauge sites were within 10% of experimentally measured in vivo strains (Table 1).

Discussion. Although a relatively good match of Figure 1. Distribution of normal strain in mouse tibia the FE prediction with experimental Table 1. Validation of FE predicted normal strains data was achieved, the strain gauge attachment sites were estimated in the FE model. Besides, due to the curvature of mouse tibia, the single element gauges cannot output normal strain along anatomical axis, which was the output from the FE simulation. All these issues should be investigated for a further check of the validity of the tibia FE model.

Conclusion. A finite element mouse tibia model was developed and validated against in vivo strain gauge data obtained during normal walking activity. The validated tibia model will be used for studying bone adaptation.

Key references. [1] Girgis C. et al., 2014. Current Osteoporosis Reports 16, DOI 10.1007/s11914-014-0204-5. [2] Brouwers J. et al., 2009. Osteoporosis International 20: 1823 – 1835. [3] Truessel A. et al., 2012. Annals of Biomedical Engineering 40: 2475 – 2487. [4] Patel T. et al., 2014. Journal of Biomechanics 47: 451 - 457. [5] Prasad J. et al., 2010. Journal of Biomechanics 43: 2765 - 2770. [6] De Souza R. et al., 2005. Bone 37: 810 - 818.

Strain at lateral

surface [µɛ] Strain at medial

surface [µɛ]

Experiment data 200 -300

FE prediction 182 -277

A PARAMETRIC HUMAN BODY MODELLING TOOL FOR THE REPRESENTATION OF SITTING

POSTURE OF NDIVIDUALS WITH PROFOUND MUSCULOSKELETAL DEFORMITIES 1Voysey M, 1Kulon J, 1Partlow A, 2Gibson C, 2Rogers P 1Department of Computing & Mathematical Sciences, University of South Wales, UK. 2Cardiff and Vale UHB – Rehabilitation Engineering, Rookwood Hospital, UK. email: michael.voysey@southwales.ac.uk

Background Cardiff and Vale University Health Board’s Rehabilitation Engineering Unit produce custom contoured seating-systems [1][3] &[5]. Clients with severe musculoskeletal deformities require engineers with specialised skills and extensive experience to produce seats that accommodate their shape; reduce peak pressure and provide therapeutic benefits such as improved respiratory function and posture [2][4]. After the seat geometry has been carefully designed and optimised it is often difficult to infer and visualise a client’s posture from the recorded clinical data, especially in the case of clients with complex body shapes. It will allow clinical engineers to represent the relationship between the shape of a custom contoured seat, body shape and the underlying musculoskeletal conditions. In-turn this facilitates communication of underlying conditions and the effect of a seat shape to other experts, learning from past seating designs and monitoring the progression of client's musculoskeletal conditions over time. The main aim of this study is to develop an interactive 3D digital human body model to assist clinical engineers in analysing the relationship between seat shape and musculoskeletal deformities. Methods The interactive 3D model was developed using a CAD package (SolidWorksTM) and its object-oriented application programming interface (API), coded in C#. The model supports movement and orientation of body parts both in the coronal and sagittal planes. The dimensions and description of anthropometric measurements used in the model were based on ISO-7250-1:2008 standard. The human body was partitioned into nineteen parts. The spine contains 24 vertebrae representing the cervical, thoracic and lumbar regions with each vertebrae being adjustable to different angles. The Denavit-Hartenberg inverse kinematics approach was used to calculate the position and orientation of all the joints in the hierarchy taking into consideration seat geometry, client's musculoskeletal condition and the sitting posture. Results The preliminary results showed that a 3D model is capable of representing the client’s posture corresponding to different musculoskeletal conditions. The prototype has two modes of operation automatic and manual. In automatic mode the seated shape data is processed by the algorithm to produce the visual representation of the seated posture. In manual mode the model can be manipulated through the user interface. Discussion The model is very useful from the clinical perspective; it can assist clinicians in analysing and learning from past seating designs, monitoring the progression of client's musculoskeletal condition and promoting function and comfort of the individual. Conclusion The 3D model which has been developed will be used by clinical engineers to visualise the musculoskeletal configurations of clinets with profound musculoskeletal deformities and therby inform their clinical judgements on the effectiveness and safety of a range of interventions or indeed of no intervention. Key references [1] Davies, W., 2004, The Development of the Rookwood Bead Seat System [CEng dissertation].

(Cardiff, UK: Rehabilitation Engineering Unit, Rookwood Hospital, Llandaff), p. 36.

[2] Ham, R., Aldersea, P., Porter, D. and Ham, R. 1998. Wheelchair users and postural seating: a

clinical approach. Churchill Livingstone London.

[3] Kulon, J., Partlow, A., Gibson, C., Wilson, I. and Wilcox, S. 2014. Rule-based algorithm for the

classification of sitting postures in the sagittal plane from the Cardiff Body Match measurement

system. Journal of medical engineering \& technology, 38 (1), pp. 5--15.

[4] Parsons, D. 1995. Investigation of Body Contours in Physically Disabled Seated Subjec ts. MPhil

Thesis, Department of Medical Physics & Bioenginering, University of Wales, Cardiff, Wales, UK.

[5] Partlow, A., Gibson, C., Kulon, J., Wilson, I. and Wilcox, S. 2012. Pelvis feature extraction and

classification of Cardiff body match rig base measurements for input into a knowledge-based

system. Journal of medical engineering \& technology, 36 (8), pp. 399--406.

MODELLING FRACTURE FIXATION USING EXTRA-MEDULLARY DEVICES: IS PATIENT

SPECIFICITY IMPORTANT 1Pankaj Pankaj 1Institute for Bioengineering, School of Engineering, The University of Edinburgh, UK. email: pankaj@ed.ac.uk

Background: Hospital surveys have shown that there is a wide variability in the manner different surgeons employ extra-medullary devices to treat bone fractures. A need for developing patient-specific computational models that can optimise fracture fixation is frequently voiced in the orthopaedic community. The success of fracture fixation requires that the bone-fixator construct: be able to sustain loads as the fracture heals; does not become loose and causes minimum discomfort; and promotes healing [1]. In this presentation we consider the mechanics of some of the commonly used extra-medullary devices and examine the need of patient-specific modelling with respect to the above clinical requirements.

Methods: We used basic mechanics and finite element analyses to examine the behaviour of three extra-medullary devices as shown in Fig. 1 [1-3]. In all cases we focused cases where fixators were assumed to transmit the full loads in the period following surgery and before fracture healing is initiated. We considered a range of modelling issues: manner of load application; geometrical nonlinearity of the system; bone-device interaction; anisotropic properties of bone [4]; age-dependent change in geometry and properties; and post-elastic nonlinear behaviour of bone. For modelling the post-elastic behaviour of the bone we used strain-based plasticity [5].

Results and discussion: We found that inter-fragmentary motion (IFM), which is known to be responsible for secondary healing, is strongly affected by the inclusion of geometrical nonlinearity. In particular with Illizarov fixators wherein stiffness of the construct depends on wire tension and IFM is the due to sagging of the wires geometrical nonlinearity plays a key role. IFM is also strongly influenced by the manner in which loads are assumed to act, which explains the wide variation of stiffness reported in literature. Elastic and post-elastic parameters, which are strongly patient-specific, do not play a significant role in the determination of IFM. Patient-specific material properties, however, have a key role in the prediction of damage and loosening at the pin/screw/wire-bone interface. Consequently, these predictions require nonlinear interface modelling and improved constitutive modelling of bone incorporating both anisotropy and material nonlinearity, which is patient-specific. Using patient-specific nonlinear models we show why certain fixators are more successful than others.

References

[1] MacLeod A, Pankaj P Computer simulation of fracture fixation uning-extra-medullary devices: an appraisal. In Computational Biomechanics in Medicine, Springer, in press.

[2] Donaldson FE, Pankaj P, Simpson AHRW. Bone properties affect loosening of external fixators at the pin-bone interface. Injury, 43:1764–1770, 2012.

[3] Donaldson FE, Pankaj P, Simpson AHRW. Investigation of factors affecting loosening of Ilizarov ring-wire external fixator systems at the bone-wire interface. J Orth Res, 30(5):726–732, May 2012.

[4] Donaldson FE, Pankaj P, Cooper DML, Thomas CDL, Clement JG, Simpson AHRW. Relating age and micro-architecture with apparent-level elastic constants: A μFE study of female cortical bone from the anterior femoral midshaft. J Eng Medicine, 225:585–596, 2011.

[5] Pankaj P, Donaldson FE. Algorithms for a strain-based plasticity criterion for bone. Int J Num Meth Biomedl Eng, 29:40–61, 2013.

Figure 2: Extra-medullary devices considered: locking plates;

Ilizarov fixators; and mono-lateral fixators.

Physiological challenges in musculoskeletal patient specific modelling

1Phillips A T M

1Structural Biomechanics, Department of Civil and Environmental Engineering, Imperial College London, Skempton Building, South Kensington Campus, London SW7 2AZ, UK. email: andrew.phillips@imperial.ac.uk

Different modelling approaches are often adopted in modelling the skeletal and muscular parts of the musculoskeletal system. The skeletal system is frequently modelled, using the finite element method, as a continuum at either the macroscale or microscale, with respective elements either being larger or smaller than the components of the structural system under consideration. Anatomical descriptions of the skeletal system focus on its structure and form, which may be captured using either an image based or predictive microscale continuum approach, but cannot be fully represented using an image based isotropic macroscale continuum approach. Structural modelling approaches have been presented at the microscale based on skeletonisation of micro-CT images and at the mesoscale based on structural optimisation.

Meanwhile forces exerted by the muscular system on the skeletal system are frequently extracted from musculoskeletal models with varying levels of discretisation, often utilising wrapping surfaces and via points to improve the paths of individual muscles. The musculoskeletal modelling framework in general relies on the collection of patient specific motion capture data, prior to inverse dynamics analysis and prediction of muscle forces using static optimisation with a square or cubic power cost function.

Both finite element modelling of the skeletal system and musculoskeletal modelling of the muscular system may be improved through the use of subject specific parameters and imaging. However there remain issues with the collection, reliability and variability of this data. A recent attempt at falsification of a musculoskeletal model adapted based on subject specific parameters found significant errors between predicted and measured joint contact forces.

In addition the use of combined modelling approach frameworks have highlighted implicit assumptions of both finite element and musculoskeletal modelling, which could be considered as failing to represent the physiological situation. While wrapping surfaces and via points are used in musculoskeletal models these are not in general replicated in finite element models, preventing transfer of additional compressive force onto the skeletal system. The application of muscle forces as point loads, derived from musculoskeletal models, within finite element models is also seen to be a significant simplification for large muscle attachment regions.

In the context of patient specific modelling, if the existing structure and form of the skeletal system for a patient cannot be adequately explained through predictive modelling, the question must be asked as to how effective patient specific modelling can be in assessing the potential outcome of a treatment intervention, even in circumstances where patient specific parameters and imaging are available. A predictive structural finite element modelling approach including the skeletal and muscular systems, informed by a highly discretised musculoskeletal modelling approach, is considered to have the potential to provide a robust, computationally efficient, and physiologically relevant platform, on which to base population and patient specific modelling.

A DYNAMIC SIMULATION APPROACH FOR COMPUTING MUSCLE SYNERGIES FROM EXPERIMENTAL JOINT MOMENTS 1,2Gopalakrishnan A, 3Modenese L, 1,2Phillips ATM 1The Royal British Legion Centre for Blast Injury Studies at Imperial College London, UK 2Structural Biomechanics, Department of Civil and Environmental Engineering, Imperial College London, UK 3Griffith health institute, Centre for Musculoskeletal Research, Griffith University, Australia email: a.gopalakrishnan11@imperial.ac.uk

Purpose: Experimental evidence suggests that the nervous system may be organizing and co-activating muscles in groups known as synergies as a means of simplifying the control of a musculoskeletal system containing redundant musculature [3, 6]. The synergy-specific control signals are related to individual muscle excitations through a linear combination model whose coefficients are called muscle weightings. Conventionally, statistical techniques have been used to compute synergy controls and muscle weightings from experimental EMG for a family of movements [2, 4, 5]. However these methods are affected by factors such as EMG cross-talk and the difficulties of recording deeper muscles. In this study, we present an alternative dynamic simulation approach for computing muscle synergies from subject-specific experimental kinematic and kinetic data for a family of movements (walking at 2 different speeds) instead. We apply this method to investigate whether a synergy based controller can mimic an optimal muscle recruitment strategy. Methods: A single subject walked on a treadmill at speeds of 0.7 and 1.7 m/s while kinematics and ground reaction forces were recorded. Joint moments were computed by inverse dynamics using a musculoskeletal model of the lower limb (24 muscles) that was scaled to match the subject’s dimensions. We then formulated an optimal control problem (OCP) that sought values of the muscle weightings and synergy controls that reproduced those joint moments in the model over 3 gait cycles at each walking speed. Muscle force production was governed by activation and contraction dynamics and the OCP was solved using direct collocation [1]. We then appended the OCP cost function with an additional term that minimized the sum of muscle activation squares (minimizing fatigue [1]). We compared muscle excitations resulting from this simulation (Solution 1) to those from a simulation with the same cost function, but no synergy groupings (Solution 2) – purely optimal muscle recruitment. Results: It was observed that a minimum of 5 muscle synergies were needed to reproduce experimental joint moments within a 2Nm error and hence 5 synergies were computed for Solution 1. As expected, muscle excitations in Solution 1 were generally higher than in Solution 2 for most muscles, but their patterns were very similar in magnitude and timing (see Figure 1). Discussion: The similarities in excitations from Solutions 1 and 2 imply that for an activity like walking, a synergy based neural controller could serve to simplify the process of optimally activating muscles for minimal fatigue. To investigate whether this could potentially be a more generalized neural control principle, the simulation technique needs to be applied to compute synergies for a more diverse set of movements such as walking, running, jumping etc. The capability of this method to estimate subject-specific synergies arising from inter-individual variations in kinematics and kinetics also needs to be investigated. References: [1] Ackermann, M., van den Bogert, A.J. Optimality principles for model-based prediction of human gait. Journal of biomechanics. 2010, 43, 1055-60. [2] d'Avella, A., Portone, A., Fernandez, L., Lacquaniti, F. Control of fast-reaching movements by muscle synergy combinations. The Journal of neuroscience : the official journal of the Society for Neuroscience. 2006, 26, 7791-810. [3] Saltiel, P., Wyler-Duda, K., D'Avella, A., Tresch, M.C., Bizzi, E. Muscle synergies encoded within the spinal cord: evidence from focal intraspinal NMDA iontophoresis in the frog. Journal of neurophysiology. 2001, 85, 605-19. [4] Ting, L.H., Macpherson, J.M. A limited set of muscle synergies for force control during a postural task. Journal of neurophysiology. 2005, 93, 609-13.

[5] Tresch, M.C., Cheung, V.C., d'Avella, A. Matrix factorization algorithms for the identification of muscle synergies: evaluation on simulated and experimental data sets. Journal of neurophysiology. 2006, 95, 2199-212. [6] Tresch, M.C., Jarc, A. The case for and against muscle synergies. Current opinion in neurobiology. 2009, 19, 601-7.

Figure 1: Muscle excitations of the long head of the Biceps Femoris and Soleus as computed by Solution 1 (blue line) and Solution 2 (red line) for the two walking speeds. The grey area represents experimental EMG that was collected during the

walking trials.

PATIENT SPECIFIC MODELLING: LESSONS FROM SUBJECT-SPECIFIC ANIMAL MODELLING IN CRANIAL RESEARCH 1Fagan MJ, 2Evans SE, 2Jones MEH, 3O’Higgins P, 1Watson PJ, 4Gröning F. 1 Medical and Biological Engineering, School of Engineering, University of Hull, UK 2 Research Department of Cell and Developmental Biology, University College London, UK 3 Hull-York Medical School, University of York, UK 4 Department of Anatomy, University of Aberdeen, UK email: m.j.fagan@hull.ac.uk

Background. All skulls have a common basic organisation (enclosing the brain and sense organs, supporting the mouth) and a common basic purpose (protection and feeding). This paper describes the development of complex musculoskeletal models of skulls to understand their form and function, with a long term goal to develop functioning models of the growing human skull that can be used for patient specific modelling of dental and clinical conditions and their management. This has involved a comprehensive programme of work to first develop subject-specific animal models, which provide the opportunity to measure most model parameters and undertake rigorous model validation, which is not possible to the same degree with human modelling.

Methods. Subject-specific modelling and in vivo measurements have been carried out on a number of lizard and mammal (including mouse, rabbit, sheep, pig and macaque) skulls. Model details and validation data were determined using a combination of techniques including: video fluoroscopy to record food processing and mastication activities, strain gauges attached to the cranium and mandible, and wire electrodes providing EMG information during feeding and biting on force transducers. The same individuals were imaged by MRI and microCT before and after detailed dissection to determine joint properties, soft tissue information (fascia, ligaments etc) and muscle properties (fibre lengths and angles) allowing estimation of physiological cross-sectional areas, before material testing of the soft tissues, bone and sutures.

These data were used in the construction of animal specific musculoskeletal models (using MSC ADAMS, multibody dynamics analysis (MDA) software) to provide predictions of muscle, joint and bite forces during different activities. These forces were then applied in finite element analyses (ANSYS) to predict strain values.

Results. Subject-specific MDA models of lizard skulls demonstrated that it is possible to accurately predict bite force values [1], but the models were very sensitive to changes in muscle attributes such as fibre length and intrinsic muscle strength. Bite force predictions varied considerably when these variables were altered. For example: (1) predicted bite forces using maximum fibre lengths were approximately 65% lower than those for minimum fibre lengths; (2) models without muscle wrapping predicted bite forces approximately 20% lower than those with muscle wrapping [1].

In vivo bone strain were also observed to vary considerably during apparently similar feeding activities, with unexpected variations in principal strain directions recorded with different food types suggesting different muscle activation patterns [2]. Mean principal strain orientations were consistent within an individual, but differed between individuals [2] for the same biting activity, again suggesting different modes of loading.

Conclusions. A significant amount of effort is required to create truly representative subject-specific skull models, but they can be developed and used to predict bite force and bone strain reliably. In practice it is likely that many parameters required for patient-specific models will have to be estimated. Furthermore, variability in measurements recorded in vivo for the same apparent activity suggests a normal variation in everyday life that should also be considered in any analysis. These points suggest that detailed sensitivity studies and/or probabilistic analyses should be considered in all patient-specific modelling.

Key references. [1] Gröning F, Jones MEH, Curtis N, Herrel A, O’Higgins P, Evans SE, Fagan MJ. 2013. J Roy Soc Interface 10:84, 20132016. [2] Porro LB, Ross CF, Iriarte-Diaz J, O'Reilly JC, Evans SE, Fagan MJ. 2014. J Exp Biol. In press.

Annual IPEM Technologists Study Day - Technology on the Road to Recovery – and Beyond 19th June 2014, York Racecourse Organised by the IPEM Clinical Engineering & Radiotherapy Special Interest Groups FINAL PROGRAMME

09:00 – 09:45 Registration & coffee

09:45 - 10:00 Welcome, Introduction: Jim Methven, North Cumbria University Hospital

10:00 - 10:30 Communal Lecture One: Registration & Regulation? An update from the coal face Andy Mosson, VRCT Registrar

10:30 - 11:00 Communal Lecture Two: CPD – the bane of our lives - or golden opportunity? Elizabeth Macaulay, Chair of IPEM CPD Audit Panel

11:00 - 11:30 COFFEE, EXHIBITION & POSTERS

11:30 – 12:00

Strand 1

Maintenance Issues

Strand 2 / Strand 3

Device Issues Physiological Signals and

Processes

Strand 4

Radiotherapy Planning

Strand 5

Radiotherapy Engineering/QA

Masterclass

Ultrasound Power Measurements – A Therapeutic Guide

Kirsty McNeill, NHS Lothian

Blood pressure measurement during Atrial Fibrillation (Nice recommendations) Willem Verberk & Ed Gammans, Microlife Health Management Ltd - WatchBP

Development and Implementation of Head and Neck Rotational Therapy Alan McWilliam, The Christie

Design of In-house Laser Alignment Device with demonstration

David Gaskin, The Christie

Making an In-House Equipment Management Database Really Work Robert Salter, Royal Glamorgan Hospital & Ted Stilwell, The Christie

12:10 – 12:40

Finding the Frequency: the latest on following manufacturers maintenance recommendations

Paul Blackett, Royal Preston Hospital

IT and Healthcare Integration- making devices talk to each other John Stapleton, HealthNetConnections Ltd

Pushing the boundaries: Developing the Role of Radiotherapy Engineers

Ray Lewis & Andy Garner, The Christie

12:40 – 13:40 LUNCH, EXHIBITION & POSTERS

13:50 – 14:20

Strand 1

AS ABOVE

Strand 2 / Strand 3

AS ABOVE

Strand 4

AS ABOVE

Strand 5

AS ABOVE

The Surgeon’s Dark Art (Electro-surgery)

David Dewar, Western General

14:30 – 15:00 AS ABOVE AS ABOVE AS ABOVE Hospital, Edinburgh

15:00 - 15:30 TEA, EXHIBITION & POSTERS

15:30 - 16:00 Communal Lecture Three: Technology Transforming Transplantation Dr Leslie Russell, OrganOx Limited

16:00 - 16:30 Communal Lecture Four: Give it Away or Sell it - Why Inappropriate Donating Equipment is Wrong Steven Daglish, Amalthea Trust

16:30 - 16:45 Closing Remarks

CPD – The bane of our lives – or golden opportunity? Elizabeth Macaulay, Chair of IPEM CPD Audit Panel Email: elizabeth.macaulay1@gmail.com Mention the words Continuing Professional Development (CPD) and the common reaction is a groan or a resigned sigh. Common myths abound such as “I don’t know what it is”; “I don’t need to know”; “I don’t need to do it in my job”; “I never do anything new in my job”; “I can’t go to meetings so I can’t do CPD” and the most common “I don’t have enough time to do it”. The reality is that we are learning throughout our lives, often without recognising the fact. In these days of information overload, one of the hardest things to do is to sift the information we are getting, decide whether or not we have to remember it, decide how to store that information and decide whether we need to act on it and how. As professionals, in our jobs we need to demonstrate that we are appropriately skilled and that we are continuing to be the right person for the job. Most job descriptions will state a requirement to keep up to date or will mention CPD specifically. CPD is a requirement for membership of IPEM and is a requirement for registered professionals e.g. for HCPC, CSci, RSci, RSciTech, CEng, IEng and EngTech as well as for VRCT. So, what is CPD? How do we get into the habit of taking the time we need to think about what we are learning? How does it improve or change our working practice and how is it best recorded?

Ultrasound power measurements: A therapeutic guide Kirsty McNeill, NHS Lothian Email: kirsty.mcneill@nhslothian.scot.nhs.uk Despite the substantial NHS investment in Therapeutic Ultrasound, many therapy units are poorly calibrated. Neither therapist nor the patient feel any immediate effect of the treatment, meaning units may appear to function normally while having gross faults. The role of medical physics is therefore critical in ensuring safe and effective treatment. The aim of the presentation is to give the viewer an overview of the QA systems used in Edinburgh, including explaining the importance of rigorous acceptance testing, absorbing targets, measurements of effective radiating area and simple user tests. This should give the viewer ideas about what protocols could be put into place in their workplace.

Finding the Frequency: the latest on following manufacturers maintenance recommendations Paul A Blackett, Royal Preston Hospital Email: paul.blackett@lthtr.nhs.uk Ever had the nagging feeling that you were unnecessarily servicing a medical device? Perhaps that 6 monthly service interval was a bit too often as you never actually found any adjustments had drifted? Ever wondered if you were allowed to change the service interval? This presentation explores what manufacturers, medical engineers, the MHRA and the Law says about safe maintenance. Can you safely change the frequency and what risks are involved? What does the future hold? Come along and find out!

Microlife WatchBP Home A, a blood pressure monitor with implemented atrial fibrillation detector Willem Verberk, Microlife WatchBP Solutions BV Email: willem.verberk@microlife.ch Edward Gammans, Microlife Health Management Ltd – WatchBP Email: edward.gammans@microlife.uk.com Microlife Corporation, a manufacturer of blood pressure monitors, is the patent holder of an algorithm that is called Microlife AFIB which allows atrial fibrillation (AF) detection during blood pressure measurement. The algorithm showed to allow detection of AF with high accuracy as demonstrated in several clinical studies with sensitivity and specificity values varying from 94-100% and 89-93%, respectively. The collection of clinical evidence about Microlife AFIB eventually led to recommendation of the Microlife WatchBP Home A by NICE to be used for routine blood pressure measurement in primary care. The reason for this is that NICE considers the device to have high potential in reducing the number of AF-related strokes and to decrease overall health care costs in the UK.

Development and Implementation of Head and Neck Rotational Therapy Alan McWilliam, The Christie NHS Foundation Trust, Manchester Email: alan.mcwilliam@christie.nhs.uk Rotational therapy offers benefits for both patients and staff. Patients can benefit from the improved plan quality and from the shortened treatment time. The tighter dose gradient allows greater OAR sparing, particularly in controlling the dose to the parotid glands, and PTV coverage in areas near spinal cord and brainstem to be improved. Conformity and homogeneity of the target volumes increases. The clinical benefit of moving from an IMRT technique to VMAT will be covered in this presentation. Workflow through the planning department can be improved with the implementation of VMAT. Time required for planning can be minimised and used more efficiently; plan checking can be simplified compared to IMRT plans. The impact of verification is reduced due to faster deliveries. Treatment times are typically reduced by approximately ten minutes allowing a greater throughput on the machines. The long optimisation times associated with VMAT lead to the requirement for a robust optimisation solution to allow clinical plans to be reached quickly. The development of the initial class solutions will be described along with current work to adapt this on patient specific bases. This work has created a model to predict likely achievable doses for the OAR in any given plan. These are used to adapt the class solution before optimisation in an attempt to further minimise planning time. Gaining confidence in the machine delivery is an important aspect of the commissioning process. The verification work performed during commission will be described, involving the use of an in-house anthropomorphic phantom. The current verification process and the rational behind this will also be described.

Design of In-house Laser Alignment Device David Gaskin, The Christie at Oldham Email: David.Gaskin@christie.nhs.uk To enable consistent, accurate treatments during the delivery of radiotherapy, the iso-centre of the linear accelerator and the patient positioning lasers needs to be accurately matched. The current manual methods for aligning the lasers and machine cross wires can be inconsistent due to human errors. To eliminate these errors and improve treatment accuracy an automated laser alignment device has been developed. The device uses linear optical sensors to measure both the cross wire and patient positioning lasers and automatically align the lasers to match cross wires of the Radiotherapy system. The 132-element photodiode sensors enable the crosswire and laser position to be resolved to 0.07 mm.

Developing and Maximising the Role of a Radiotherapy Engineer Ray Lewis & Andy Garner, The Christie NHS Foundation Trust, Manchester Email: andrew.garner@christie.nhs.uk and Raymond.lewis@christie.nhs.uk The role of the Radiotherapy Engineer has, and continues to evolve. The direction of that evolution is in our hands – do we stagnate and accept our current skillset or do we grasp the opportunity to develop our existing and accumulate additional skills? In the past the Radiotherapy Engineer would only be expected to fix the machines when they were broken and to do the preventative maintenance. Now, we at The Christie are more involved; branching into support of the Brachytherapy diagnostic departments; performing QC routines, Field Change Orders and upgrades. We have projects to improve the service we deliver and assist with new installs and commissioning. The future is sure to bring us Cost Improvement Programmes as well as new technologies such as Proton Therapy and advanced imaging modalities. So, do we see them as obstacles, challenges or opportunities? Engineers are problem-solvers; we build value and strive to make a difference. We should throw off the shackles of our past and dynamically build on our present skills so that we can turn the challenges of the future into opportunities. We can make a difference to patient care.

Development of SQL databases and interactive web forms to manage information within Clinical Engineering departments Robert Salter, Royal Glamorgan Hospital and Ted Stilwell, The Christie NHS Foundation Trust, Manchester Email: Robert.A.Salter@wales.nhs.uk and edmund.stilwell@christie.nhs.uk Practical demonstration of the development of simple SQL data management system and how to interface with it.

Why use SQL

Why use Web Forms

Microsoft Access database migration to SQL.

How to access your data.

Presenting your data.

Give it Away or Sell it - Why Inappropriate Donating Equipment is Wrong Steven Daglish, Amalthea Trust Email: stevend@amaltheatrust.org.uk Donations of medical equipment to developing countries is something that is done by many different organisations from around the world and in most cases it is done in the hope that the equipment will make a positive impact to the host country. However, in many cases, medical equipment donations can cause huge problems for the receiving hospitals and in many cases the equipment doesn’t come with the required training, accessories, and spare parts, meaning that the hospital quickly stops using the equipment. Resources are now available to help make sure that with proper communication and consideration, donations of medical equipment can make a positive impact on hospitals.

POSTER: Evaluation of the positional reproducibility & comfort provided by two Immobilization Systems for Head and Neck Radiotherapy Tamzin Archer, Clinical Technology, De Montfort University, Leicester and Radiotherapy Physics Weston Park Hospital Sheffield Email: Tamzin.Archer@sth.nhs.uk Background; Immobilization has become increasingly important in head and neck radiotherapy especially since the introduction of new treatment techniques such as RapidArc which uses steep dose-gradients between treatment volumes and organs at risk. Positional reproducibility and patient comfort are both important aspects of immobilization as the patient must be able to tolerate the mask throughout the course of treatment. This study was performed to evaluate and compare the two types of immobilization mask used at Weston Park Hospital with the aim of suggesting improvements for future practice in the department and deciding if it might be a viable option to discontinue using clear-plastic masks in the future.

Materials and methods; Thermoplastic (T); Using Fibreplast Variable Perf tm 3.2mm material. Clear plastic (CP); Formed from 2.5mm thick transparent Polyethylene Terephthalate Glycol (PETG). Positional shifts for all completed RapidArc treatments for H&N patients were recorded over a one-year period in three directions (laterally, longitudinally and vertically). Shift values were measured from weekly CBCT scans using OBI Varian Medical Systems registration software with independent verification by two radiographers. Data from 97 patients was collected (40 CP-masks; 57 T-masks). Questionnaires were handed out to all 97 patients resulting in the collection of 76 completed questionnaires. Questionnaires consisted of 8 tick-box style questions and an ‘additional comments’ section. Questions enquired about levels of comfort and immobilization over the course of treatment. Results; There were no significant differences observed in systematic error between the two types of mask however there was a significant difference in 3D-random error (P=0.004) with T-masks showing a smaller total range of errors and a smaller median shift. Couch-shifts were required on 4% more T-mask set-ups than CP-mask set-ups (using a 3mm shift tolerance). Questionnaire results showed a significant difference in comfort level between the two types of mask (P= 0.01) with T-masks consistently being rated as less comfortable and more claustrophobic than CP-masks. As treatment progressed the majority of patients got used to the feel of their mask (44% of CP-masks; 46% T-masks). T-mask comfort improved in 33% of cases whereas CP-mask comfort declined in 33% cases.

Discussion and conclusions; Levels of reproducibility for both CP and T-masks were comparable to those achieved at other radiotherapy centers (Humphreys 2005), however T-masks were shown to offer more reliable and accurate positional reproducibility than CP-masks in terms of random error suggesting that they are more suitable for RapidArc treatments. T-masks can be susceptible to material shrinkage (Tsai et al 1999) which is likely to have been a significant factor in the levels of claustrophobia and panic reported for this type of mask. This issue could be rectified in the future by the use of shims placed under the headrest at the impression appointment. Future improvements have been identified to improve tolerability of the masks however investigations on relative costs of immobilization should be considered before recommending a full discontinuation of CP-masks. References; 1.Humphreys M et al (2005) Assessment of a customised immobilisation system for head and neck IMRT using electronic portal imaging. Radiotherapy and Oncology 77; 39-44.

2.Tsai J-S et al (1999) A non-invasive immobilization system and related quality assurance for dynamic intensity modulated radiation therapy of intracranial and head and neck disease. International Journal of Radiation Oncology Biol. Phys., Vol. 43:2, 455-467.

POSTER: Craniospinal Radiotherapy Immobilisation Andy Baddeley & T Clarkson, St.James’s Institute of Oncology, Leeds E-mail: andy.baddeley@leedsth.nhs.uk Purpose. Local protocols for radiotherapy Craniospinal treatments require the patient to be in a prone position in order that the spine can be manipulated into the required position. Patients find this procedure uncomfortable and have restricted airways whilst lying on their chest. Paediatric patients who need to be anesthetised pose greater problems when in the prone position. Treatments in the supine would have many advantages but nothing is currently available on the market. Method. To assemble a multidisciplinary team of interested parties in order that the design, development and manufacture of a suitable device, that would allow Radiotherapy of craniospinal Patients in the supine position, could be achieved. Results. The collaboration between technical and clinical staff from the very beginning of the project has resulted in a device that has performed as expected and is being used on a regular basis for Craniospinal Radiotherapy treatments at St.James’s Institute of Oncology. Conclusions. Input from a multidisciplinary team was essential in the success of the project. The Patient experience has been much enhanced now the device is in use. Paediatric patients are much more comfortable in a supine position leading to more consistent patient positioning through out a treatment cycle.

POSTER: A dosimetric and service impact comparison of forward-planned IMRT and irregular surface compensation for whole breast radiotherapy Sadie Connelly, Clinical Technology, De Montfort University Leicester and Radiotherapy Physics, Weston Park Hospital Sheffield Email: sadie.connelly@sth.nhs.uk Background Breast cancer stands as the most common form of cancer for women globally. The primary line of treatment for most instances of early-stage breast cancer is surgical lumpectomy and post-operative adjuvant whole breast radiotherapy (WBRT). At Weston Park Hospital (WPH), these patients are typically treated using opposing tangential 6MV photon beams with a prescription of 40Gy in 15 fractions. This study looks to investigate whole breast irradiation using different planning techniques, reviewing current practise at WPH against alternative planning and delivery methods, focusing upon dosimetric and service delivery comparisons. Aims This service evaluation aimed to ascertain if there was a statistical difference between current departmental planning techniques for WBRT using forward planned FIF-IMRT and more basic, historic standard wedged methods and newer, inverse-planned electronic compensation (ISC) planning techniques. Based upon differences observed from statistical analysis of these pair-wise comparisons of the three planning techniques, clinical inferences are to be made to form the basis for recommendations regarding best practice locally. A correlative model based upon patient predictive characteristics as a way of choosing the optimal planning technique for different patient groups was also investigated. Methods A retrospective study, sampling 20 patients who had completed treatment for early-stage breast cancer locally at WPH over a one year period, was performed. Three treatment plans; SW, FIF-IMRT and ISC, were created per patient using the same planning target volume (PTV) and organs at risk (OAR) contours, field arrangements and dose reference point throughout. A dosimetric evaluation was performed looking at PTV and OAR doses, a service evaluation looked at planning calculation and treatment delivery times and a correlative model was created based upon patient measurements and plan parameters that measured dose homogeneity. Results The maximum dose was significantly reduced for FIF-IMRT when compared to SW and ISC plans. FIF-IMRT was also found to have the lowest dose homogeneity index (DHI) value across the three techniques indicating a more homogenous dose distribution across the target volume. All OAR doses were reduced using electronic compensation, though all methods met the plan quality measures for these parameters. Strong correlation was observed across all three techniques between the volume of the target (PTV) and the high dose regions delivered to 2cc of the target volume (D2). Discussion and Conclusion Statistical differences observed between the three breast radiotherapy planning techniques and the clinical inferences made in light of these, demonstrated that FIF-IMRT was dosimetrically superior to both SW and ISC. An approximate model for applying different planning techniques for different patient groups was established based upon PTV volume and the high dose, D2 region, suggesting that patients with a breast volume less than 800cm3 may be optimally treated using ISC techniques and conversely those exceeding this volume should be treated with FIF-IMRT, as this was found to yield lower D2 values within the target volume. This has been demonstrated in other studies to limit acute and long-term side-effects of early-stage breast cancer radiotherapy treatments. In conclusion, this study recommends the continued implementation of FIF-IMRT planning and delivery for early-stage breast cancer patients treated at WPH.

References 1. EMMEN, D.J. and JAMES, H.V. (2010) Irregular surface compensation for radiotherapy of the breast: correlating depth of compensation surface with breast size and resultant dose distribution. Brit J Radiol., 8: 159-165 2. GURSEL, B., MEYDAN, D., OZBEK, N. and OFLUOGLU, T. (2011) Dosimetric comparison of three different external beam whole breast irradiation techniques. Adv Ther., 28(12): 1114-1125

POSTER: The Risk of Malignancy after Gamma Knife Stereotactic Radiosurgery Alison Grainger, The National Centre for Stereotactic Radiosurgery, Royal Hallamshire Hospital NHS Foundation Trust, Sheffield Email: Alison.Grainger@sth.nhs.uk JG Rowe, AC Grainger, L Walton, MWR Radatz, AA Kemeny Objective: To assess the risk of radiosurgery to cause malignant transformation in benign tumours or in inducing new malignancies. We previously published a retrospective cohort study showing no increased risk of malignancy in UK patients treated with radiosurgery up to the end of 2004.[1] Because of the long duration after cranial irradiation before neoplastic changes may become evident, it was proposed to run this as an ongoing flagging study. To address this, we have re-analyzed the data with an additional five years of follow-up. Method: We carried out a retrospective cohort study comparing our (UK) patient database with national mortality and age and gender-matched cancer registries. This data set comprises 7998 patients and 56,788 patient-years of follow-up, with more than 1500 patients having a follow-up period of longer than ten years. Results: In this material, and including our previously reported case, we have identified four new tumours, principally astrocytomas/gliomas, developing after radiosurgery. We have not had any further malignancies in our patients with abnormal tumour suppressor genes[2]. Conclusion: No increased risk of malignancy was detected in this series, supporting the safety of radiosurgery. Pragmatically, in advising patients, the risks of malignancy would seem small, particularly if such risks are considered in the context of the other risks faced by patients with intracranial pathologies requiring radiosurgical treatments. Rowe J, Grainger A, Walton L, Silcocks P, Radatz M, Kemeny A. (2007) The Risk of Malignancy after Gamma Knife Stereotactic Radiosurgery Neurosurgery 60:60-66 Rowe J, Grainger A, Walton L, Radatz M, Kemeny A. (2007) The safety of radiosurgery applied to conditions with abnormal tumour suppressor genes. Neurosurgery 60:860-4

POSTER: The Effect of Image Slice Thickness on Volumetric Measurement Alison Grainger, The National Centre for Stereotactic Radiosurgery, Royal Hallamshire Hospital NHS Foundation Trust, Sheffield Email: Alison.Grainger@sth.nhs.uk AC Grainger, A Hampshire, P Vaughan, JG Rowe, MWR Radatz, L Walton Objective: There is a recognised need in Stereotactic Radiosurgery for the follow-up of treated lesions to assess tumour growth control. Simplistically this may be achieved by the visual comparison of follow-up scans with imaging performed on the day of treatment. More rigorous and scientific approaches involve the measurement and comparison of tumour maximum dimensions and tumour volume. Our experience suggests that some treated lesions appear to have increased in volume although visually they looked either the same or smaller. Image slice thickness was thought to affect the measured volume. Method: Existing MRI volume studies were used to reconstruct axial slices at 1mm (the slice thickness we use for planning), 2mm, 4mm, 6mm and 8mm. Five different lesions of varying size were entered into the study which consisted of three acoustic neuromas (small medium and large) and two meningiomas (small and medium). Results: Overall, the measured volumes differed by up to 80% from the baseline value. The differences were particularly pronounced in small lesions where even a 1mm increase in slice

thickness made a difference to volumetric measurement of 15%. Conclusion: We conclude that volume measurement may be unreliable as a definitive parameter of tumour growth control, unless follow-up MRI scans are acquired following strict protocols that are comparable to those used at the time of treatment.

MPE Update 8th July 2014, Centre for Life, Newcastle upon Tyne Organised by the IPEM Diagnostic Radiology Special Interest Group

FINAL PROGRAMME

09:00 – 09:55 Coffee and registration

09:55 – 10:00 Introduction

Kevin Robson, Newcastle upon Tyne

Chair: Kevin Robson

10:00 – 11:00 Update from the Department of Health Ian Chell, Department of Health

11:00 – 11:30 Coffee

Chair: Giles Morrison

11:30 – 11:50 Update on the European MPE project Steve Evans, Northampton

11:50 – 12:20 Update on Medical Physics Expert certification Claire-Louise Chapple, Newcastle upon Tyne

12:20 – 12:30 Questions/Discussion

12:30 – 13:30 Lunch

Chair: Alison Mackie

13:30 – 14:00 Nuclear Medicine: MPE involvement in the delivery of isotope therapies Jill Tipping, Manchester

14:00 – 14:30 Heard about this? Developments in research approvals Giles Morrison, Sheffield & Claire Skinner, London

14:30 – 14:45 Questions

14:45 – 15:15 Coffee

Chair: Elly Castellano

15:15 – 15:45 Diagnostic radiology: Optimisation in radiotherapy imaging: the essential role of the diagnostic radiology MPE Tim Wood, Hull

15:45 – 16:15 Radiotherapy: Image guidance in radiotherapy Ellen Donovan, London

16:15 – 16:30 Questions/discussion

16:30 Close

Update from the Department of Health Ian Chell, Department of Health Email: Ian.Chell@dh.gsi.gov.uk • Overview of the implementation of new Basic Safety Standard Directive into UK legislation • MPE Validation Framework and Competent Authority • Expert report – Justification of CT for Individual Health Assessments • DEXA Scanning for Sports Performance Assessment • Publication of COMARE CT Report (16th Report)

Update on Medical Physics Expert certification Dr Claire-Louise Chapple, The Newcastle upon Tyne Hospitals NHS Foundation Trust Email: claire.chapple@nuth.nhs.uk A steering group was established in 2012 by the Department of Health to look at developing a national framework for the education, training and recognition of the MPE that meets the requirements of the revised BSS. This presentation will give an overview of the work that has been carried out to date, including the mapping of the European MPE curriculum onto the Modernising Scientific Careers framework, and expected timeframes for developing an MPE register. Issues that remain to be addressed will also be outlined.

European Guidelines on Medical Physics Expert Stephen Evans, Medical Physics, Northampton General Hospital Email: stephen.evans@ngh.nhs.uk

The European Union Basic Safety Standards (BSS) COUNCIL DIRECTIVE 2013/59/EURATOM defines a medical physics expert as: an individual or, if provided for in national legislation, a group of individuals, having the knowledge, training and experience to act or give advice on matters relating to radiation physics applied to medical exposure, whose competence in this respect is recognised by the competent authority. The European Commission awarded a contract in 2009 to a consortium of 6 organisations within Europe to develop guidelines on the Medical Physics Expert (MPE). These Guidelines:

Detail the roles and responsibilities of the MPE,

State the qualifications and clinical training required to be an MPE, and,

Identify the number of MPEs required to provide a given service. The qualification framework for the MPE is shown below.

The talk will consider the substance of these Guidelines and how they may be interpreted with respect to the appointment of MPEs in the UK.

Optimisation in radiotherapy imaging: the essential role of the diagnostic radiology MPE Wood T J Radiation Physics Department, Hull and East Yorkshire Hospitals NHS Trust, Castle Hill Hospital, Cottingham, HU16 5JQ. email: tim.wood@hey.nhs.uk

With the increased utilisation of X-ray imaging techniques in radiotherapy, the role of the diagnostic radiology (DR) MPE has become more important in the delivery of safe and effective treatments. By exploiting the DR MPEs specific knowledge and skills for monitoring and optimising various x-ray imaging techniques, in conjunction with the radiotherapy MPEs practical experience of how these images should be used, it is possible to make the most of all imaging performed in the radiotherapy department whilst ensuring patient doses remain as low as reasonably practicable (consistent with the intended purpose). This talk will discuss the way in which the diagnostic radiology MPE has become an essential contributor to all uses of x-ray imaging techniques in the Radiotherapy Department at Castle Hill Hospital. The structure that has been established to ensure DR MPE advice and practical skills are available when introducing new techniques and optimising current practice will be briefly discussed. This will be followed with some discussion of specific examples of how DR MPE input has proved vital in the delivery of optimised imaging at each stage of the patient’s treatment from planning CT to verification CBCT.

Image Guidance in Radiotherapy Donovan EM Joint Dept of Physics, Royal Marsden Foundation Trust, UK. email: ellen.donovan@nhs.net

Background. Image guidance is increasingly important for radiotherapy and this will continue. It is a crucial part of the radiotherapy chain and is integrated within high quality radiotherapy treatment. It is the role of image guidance in ensuring highly accurate and precise radiotherapy treatment which provides its justification. The National Advisory Group Report to Ministers in 2007 [6] set as an aspiration that ‘image guided four-dimensional adaptive radiotherapy is the future standard of care for radical radiotherapy’. In 2012 the Department of Health Cancer Policy Team [1] state ‘All patients should have a form of image guidance as part of their radiotherapy treatment episode’. ‘Image guidance’ has been defined in a variety of ways. The scope of image guidance covered in this presentation arises from the definition given in the National Radiotherapy Implementation Group Report 2012 [7] which states ‘Image guided Radiotherapy (IGRT) is any imaging at pre-treatment or delivery …that improves or verifies the accuracy of radiotherapy’. Image Guided Radiotherapy Equipment The presentation summarises the commercially available equipment used in image guidance, and covers systems using ionising and non-ionising radiation plus the use of fudicial marker, which is an important component of image guided radiotherapy for some treatment sites. Appropriate modifications should be made to the standard imaging protocols set up on IGRT equipment when it is installed. These should focus on providing the image quality necessary to achieve an accurate radiotherapy delivery. Work by Harrison et al [4,5] Donovan et al [2] and Shah et al [9] demonstrates that > 80% of the total dose to an organ results from the radiotherapy exposure even with intensive use of image guidance. Appropriate use of verification protocols is good practice, and can reduce the imaging dose component of total organ dose, if this is of concern. Impact of image guidance. It is obvious that image guidance is necessary in radiotherapy. Two studies to be presented show this explicitly. Hawkins et al [8] report that using cone beam CT image sets from the first week of treatment to refine a planning target volume in oesophageal cancer can reduce this volume by half with dose sparing to the heart and lungs of 6Gy for an imaging dose spend of ~ 0.2Gy. Donovan et al [3] demonstrate a reduction of up to 190 cc in breast tissue within a high dose volume for a complex plan, with modest reductions in heart and lung doses, for a similar imaging dose spend of ~ 0.3 Gy. Summary Image guidance is essential to high quality radiotherapy and contributes to improving the therapeutic ratio. Key references. 1. Department of Health ‘Radiotherapy Services in England 2012’ 2. Donovan et al Med. Phys. (2012) 39 (10) 5814-5820. 3. Donovan et al Clin. Oncol. (2014) http://dx.doi.org/10.1016/j.clon.2014.05.013 4. Harrison et al Br. J. Radiol. (2006) 79 487-496. 5. Harrison et al Br. J. Radiol. (2007) 80 989-995. 6. National Radiotherapy Advisory Group, Report to Ministers ‘Radiotherapy : Developing a World Class Service for England’ 2007 7. National Radiotherapy Implementation Group, ‘Implementing Image Guided Radiotherapy’,2012. 8. Hawkins et al Int J Rad Oncol Biol Phys (2010) 77(2) 378-383 9. Shah et al Rad. Oncol. (2012) 105 139-144.

RPA Update 9th July 2014, Centre for Life, Newcastle upon Tyne Organised by the IPEM Radiation Protection Special Interest Group FINAL PROGRAMME

09:00 – 09:55 Coffee & Registration

09:55 – 10:00 Introduction Dr Phil Orr, Belfast Health and Social Care Trust

Chair: Jennifer Poveda

10:00 – 10:20 Issues in Estimating Epidemiological Effects: Lessons Learnt from Recent CT Studies Dr Mark Pearce, Newcastle University

10:20 – 10:40 Update from the HSE James Taylor, Health & Safety Executive

10:40 – 10:55 Questions

10:55 – 11.25 Coffee & Exhibition

Chair: Jim Thurston

11:25 – 11:45 Dental CBCT and Hand Held X-ray Systems: An Update Andrew Gulson, Public Health England

11:45 – 12:05 Dental Radiation Protection – Issues and Controversies Graham Hart, YourRPA

12:05 – 12:25 Influencing radiation protection culture Andrew Gibson, Studsvik UK

12:25 – 12:40 Questions

12:40 – 13:40 Lunch & Exhibition

Chair: John Saunderson

13:40 – 14:00 Potential for High Skin Doses arising from contamination in Radiopharmacy and Patient administration in Nuclear Medicine Janice O’Neill, Ninewells Hospital & Medical School Dundee

14:00 – 14:20 A Survey of Restrictions for I131 for Thyrotoxicosis Dr Bill Thomson, City Hospital, Birmingham

14:20 – 14:40 Radiation Safety Culture – Medical Sector: The Bonn Call for Action Dr Penelope Allisy OBE

14:40 – 14:55 Questions

14:55 – 15:25 Coffee & Exhibition

Chair: John Crossman

15:25 – 16:10 Roundtable Discussions

1. I want to hold your hand… How far should RPA advice go?

2. Competing Legislation: Radiation Protection vs Infection Prevention in Theatres

3. Who is responsible for Emergency plans when transporting Radioactivity?

16:10 – 16:25 And Finally….Radiation Protection of the Future?!? Dr Phil Orr, Belfast Health and Social Care Trust

16:25 Close

Issues in Estimating Epidemiological Effects: Lessons Learnt from Recent CT Studies Mark S. Pearce, Institute of Health & Society, Newcastle University Email: mark.pearce@newcastle.ac.uk Although computed tomography (CT) has great clinical utility, serious concerns have been raised about the potential cancer risks from the associated ionising radiation, particularly for children, who are more radiosensitive. To date, there have been two epidemiology studies of cancer risks following CT scans in early life using empirical data, the first from the UK, the second from Australia. Both will be discussed, alongside the studies that have used a risk modelling approach. Within the UK CT Scan Study, the cohort comprised patients without previous cancer diagnoses, aged <22 years at first CT, scanned in Great Britain between 1985-2002 and followed up to 2008. The absorbed brain and red bone marrow doses were estimated per scan in milligray (mGy) and analysed in relation to cancer outcomes using Poisson relative risk models. The initial results of the UK CT Scan Study were published in the Lancet in 2012. They showed significantly increased risks of both leukaemia and brain tumours with increasing red bone marrow and brain dose, respectively. Compared to less than 5mGy, the RR for a cumulative dose of 30+mGy (mean=50mGy) was 3.18 (95%CI:1.46-6.94) for leukaemia and for 50-74mGy (mean=60mGy) the RR was 2.82 (95%CI:1.34-6.03) for brain tumours. For perspective, in children currently 5-10 head CTs gives approximately 50mGy cumulative red bone marrow dose and 2-3 head CTs approximately 60mGy cumulative brain dose. The Australian study showed excess risks for most cancer types. The results of the studies so far suggest that there are, small, increased risks of subsequent cancers with increasing radiation doses from CT. Research in this area is ongoing, so an update on progress on other studies will be given, along with an insight into what else needs to be done in this area, in particular to address suggested biases.

Dental CBCT and Hand Held X-ray Systems: An Update 1Gulson, A D 1Dental X-ray Protection Services, Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Leeds, UK. email: andrew.gulson@phe.gov.uk

This presentation covers two recent innovations in dental radiography, both of which presented new problems in terms of radiation protection and compliance with the Ionising Radiations Regulations 1999 (IRR99), and require new approaches to support their safe use in general dental practice. The first is dental cone-beam CT (CBCT) equipment which is now in widespread use in hospitals and private dental practices and continues to increase in number. This new technology delivers radiation doses to patients, and potentially operators, that can be significantly higher than from conventional dental X-ray equipment. The Health Protection Agency (as it was then) convened a Working Party in 2008 to investigate the radiation protection issues associated with dental CBCT and subsequently produce guidance, which resulted in two publications in 2010: HPA-RPD-065, which addresses issues of facility design and testing requirements, and HPA-CRCE-010 which deals with these and all other radiation protection issues. Four years on, the technology has developed and PHE has collated a large amount of testing data. Also, there is now sufficient experience from RPAs (and others) of applying the guidance in the real world, to justify a critical review of the HPA guidance. This presentation is made at the start of this process, which will aim to identify whether it would be useful to make any amendments to the guidance. Unlike dental CBCT, hand held dental intra oral X-ray equipment is a new form of an imaging modality that is very familiar to dentists, and indeed one of the oldest radiographic techniques. However, the relocation of the X-ray tubehead from its traditional wall-mounted position at least 1.5 metres away from the operator to being held in their hands, changes the situation from the perspective of radiation safety. As with dental CBCT, the new technology is rapidly becoming established in UK dental practice in a vacuum of guidance regarding how dentists should work with it to ensure their safety and compliance with IRR99. PHE has tested several hand held devices that are currently available on the UK market, and used this, together with experience of acting as RPA to dental practices with hand held equipment, to draft new guidance. The second half of the presentation summarises PHE’s findings to date and briefly discusses the likely content of the forthcoming ‘Guidance on the Safe Use of Hand Held Dental X-ray Equipment.’

Dental Radiation Protection – Issues and Controversies Graham Hart, YourRPA, Morecambe, Lancashire Email: YourRPA@yahoo.co.uk

Although radiation doses from dental radiography are low in comparison with other hospital-based radiological techniques such as CT, they remain the most frequent radiological examination. Despite the Ionising Radiations Regulations and Ionising Radiation (Medical Exposure) Regulations having been statutory requirements for well over a decade, HSE found a low level of compliance with the Regulations during a round of inspections. In addition, the General Dental Council have five hours of mandatory training on radiation protection issues as part of every five year CPD cycle. However, significant inconsistencies remain in the advice dental care professionals receive from Radiation Protection Advisers and dental trainers. These include:

- Shielding for walls and doors in dental surgeries. Some agencies and dental equipment installers routinely recommending lead lining, which goes against the advice in the recent update to the BIR Shielding Report;

- Use of thyroid shields and lead aprons for patients. The UK and European Guidance for dental professionals is quite clear on this issue, although recent US Guidance differs, along with some dental CPD trainers in suggesting a more widespread use of thyroid shields;

- Radiation monitoring for dental staff. Some dental CPD trainers advise that pregnant dental staff should be monitored for their radiation dose as a reassurance exercise, despite published data showing staff doses to be well below any significant level in routine practice;

- Testing of x-ray sets (both critical examination and routine QA tests). A wide variety of approaches to the responsibility for and range of tests performed, for both intra-oral and CBCT x-ray sets;

These key issues will be discussed in this paper, with suggestions as to how moves towards a consensus opinion might be achieved.

Influencing radiological Safety Culture Andrew Gibson, MRF Radiation Protection Adviser, Studsvik UK Ltd, Workington, Cumbria Email: andrew.gibson@studsvik.co.uk Culture is a set of beliefs, values, and customs held by a group of people and which form the unwritten rules of an organisation. The culture is supported by the organisation’s written rules, such as policies, procedures, and systems. As RPAs we can influence the culture by both developing and implementing effective systems, but also by actively engaging with the workforce and giving them the information they need to make informed decisions about what is right and wrong. This presentation will provide examples of how RPAs can both influence, and be influenced by, the culture of an organisation.

Potential for high Skin Doses arising from contamination in Radiopharmacy and Patient administration in Nuclear Medicine. 1O’Neill J, 2Robertson J, 1Grieve N, 1Medical Physics, Ninewells Hospital & Medical School Dundee, UK. 2 Health Physics, NHS Greater Glasgow & Clyde, UK. email: Janice.oneill@nhs.net,

Aim: Estimate potential occupational doses arising from Tc-99m contamination, and consider if classification of staff is necessary, based on potential for occupational skin doses to exceed 3/10ths of equivalent dose limit for the skin/extremity. Consider two separate cases. Case A radiopharmacy dispensary workers and Case B nuclear medicine staff administering Tc-99m radiopharmaceuticals to patients. In 2 of the 5 Scottish radiopharmacies, dispensary staff are designated classified workers based on extremity dose. In 3 centres, personal monitoring has demonstrated extremity doses are < 150 mSv per annum and staff remain non-classified. Nuclear medicine staff are in general, non-classified on basis of low extremity and whole body doses and IRR99 Risk assessments [1]. Method: Estimation of external skin dose by calculation arising from contamination using published dose rates for two geometries [2] is considered. A) Droplet contamination model (gloved hand) for radiopharmacy dispensers, and B) Uniform wide area deposition on the skin surface for nuclear medicine staff performing Tc-99m patient injections. For A) short term contamination of gloved hand is estimated by calculation and verified by experiment. For B) both short term contamination (droplet) and long term uniform residual contamination of skin modelled mathematically. For an initial dose-rate do decaying with a half-life τ½, the dose incurred in a time T is

wheredttdT

oo ,exp =

½

693.0

= 1.44 od τ ½ ½/693.0exp1 T (1)

Results: A) Calculated extremity dose (droplet model) for Tc-99m eluate (100GBq) is 73 mSv over 5 minutes. For typical activity of 2GBq, an extremity dose of 88mSv per 15 min interval is estimated. Verification by experiment. B) Extremity doses using uniform deposit model [2] and Eq (1) result in doses to the skin of approx 260mSv for handling 0.6GBq with 600 kBq contamination and 20% (120 kBq) remaining after attempted decontamination. Discussion: A) Doses > 150mSv constraint for the skin can be obtained in a single contamination incident over 15 minutes. For repeated droplet contamination, accumulated over the year from lower activities and combined with the external dose measured at the same point, annual finger doses for radiopharmacy staff easily exceed 3/10ths of the annual extremity dose limit. In B) risk is from uniform fixed Tc-99m contamination (120kBq) on uncovered skin surface of arm resulting in dose to skin of 260mSv. Conclusion: A) The results of both the calculations and experimental dose measurement for short term droplet contamination onto gloved hands, has demonstrated that radiopharmacy staff are at risk from potential extremity doses in excess of 3/10th of UK dose limits. We recommend these staff are classified workers and highlight need for frequent contamination monitoring ( ≤15 minute intervals). B) Nuclear medicine staff routinely administering patient doses of Tc-99m (600 MBq per injection) are at risk of extremity (skin) doses arising from direct contamination of the outer surface of the skin. Doses > 3/10ths of the UK dose limit for skin for persistent contamination. We recommend such staff wear disposable sleeves to avoid potential for long term low level skin contamination. References. Personal communication from Scottish RPA group [1], ICRU Radionuclide Handbook 2002 [2].

A Survey of Restrictions for I131 for Thyrotoxicosis WH Thomson, City Hospital, Birmingham Email: bill.thomson@nhs.net A survey of certain restrictions and advice for I131 therapy patient for thyrotoxicosis was carried out. Following a request on the Physics mailbase, 49 centres completed a questionnaire. Some centres completed for more than one administered activity level giving 65 total entries, however not all questions were answered by all centres. Most questions are of relevance to RPAs, covering comforter and carers, partner sleeping restrictions, partner restrictions when pregnant , family restrictions and work restrictions (based on an office worker, a food preparation worker and school teacher), and travel restrictions. Expected values of dose constraint were also requested. An outline of some examples of results is given below. These will be presented in relation to expected dose constraint levels, noted dose constraints and also annual limits. Only 4 centres routinely use the ‘comforter and carer’ designation. Other centres are therefore generally relying on 1mSv / year or ‘5mSv in 5 years’ limit. For these centres the partner sleeping restriction periods were analysed to give the partner dose, and a median dose value for the daytime component added. Only 5/59 values were <1mSv. However 38/59 were <1.6mSv, allowing up to 3 treatments in 5 years, and 45/59 were <2.5mSv allowing a repeat treatment. 12/51 centres considered they were working to a dose constraint of 0.3mSv, and 37/51 were working to 1mSv, figures incompatible with the restrictions as noted. For the office restriction situation given, 44/59 noted they worked to a constraint of 0.3mSv, whereas the advice given indicated that 26/59 exceeded 0.3mSv, although only 4/59 exceeded 1mSv. For the travel restriction (a 3 hour flight) , 15/56 indicated they used a constraint of 1mSv ,with others indicating 0.3mSv. However the restriction times given covered a broad range ( 0 to 60 days) , and for 46/56 departments were well within the 0.3mSv restriction. The above results demonstrate that there is a wide range of advice being given to I131 patients. With a few exceptions, advice is consistent with Guidance although for the situation of the patient’s partner and family, and for the office worker, the guidance is not compatible with the intended dose constraint. Travel restriction advice generally exceeded required values.

Radiation Safety Culture in the Medical Sector – Bonn call-for-action Allisy, P J EUTERP Secretary email: penelope.allisy@gmail.com

The IAEA/WHO instigated a series of global actions and sub-actions resulting from a conference on issues in radiation medicine that was held in Bonn, Germany in 2012. One of the ten actions calls for a global strengthening of radiation safety culture in the medical sector. The various sub-actions proposed by this particular Bonn call-for-action will be presented with outline suggestions for possible ways to implement these in the UK.

And Finally…The Future of Radiation Protection?!? 1 Orr P A 1 Regional Medical Physics Service, Belfast Health and Social Care Trust, UK. email: Philip.orr@belfasttrust.hscni.net

At the end of the ITN 10 o’clock news there always used to be an “And Finally…” story to pick up the spirits of viewers after the rigours of the hard hitting stories delivered in the previous 25 minutes of news. Following the in-depth, hard-hitting presentations of the RPA Update, this talk aims to finish the day with a light hearted look at four vignettes of research that may have an impact on radiation protection of the future including some unusual sources of radiation and even more unusual radiation detectors.

RWA Update 10th July 2014, Centre for Life, Newcastle upon Tyne Organised by the IPEM Radiation Protection Special Interest Group FINAL PROGRAMME

09:00 – 09:55 Coffee and registration

09:55 – 10:00 Introduction

Chair: Jennifer Poveda, Nottingham University Hospitals, Organiser

10:00 – 10:30 Considerations for BATs for Medical Cyclotrons Jan Passchier, Imanova

10:30 – 11:00 Regulatory Requirements for the Transport of Radioactive Material Jon Hursthouse, Office for Nuclear Regulation

11:00 – 11:30 Coffee

Chair: Jennifer Poveda

11:30 – 12:00 Radiological Assessments Amber Bannon, Environment Agency

12:00 – 12:30 Interactive tutorial session of IRAT model Amber Bannon, Environment Agency

12:30 – 12:40 Questions

12:40 – 13:30 Lunch

Chair: Kate Griffith

13:30 – 13:50 Dose considerations for Sewerage workers upstream of the Water Treatment plant Anna Louise Bradley, University of Manchester & Jennifer Poveda, Nottingham University Hospitals

13:50 – 14:10 Partial Surrender of an EPR permit Rosemary Morton & Stephen Dainty, Medical Physics, University Hospital of North Staffordshire, Stoke-on-Trent

14:10 – 14:30 Radiation protection issues due to activated linac components Philip Orr, Belfast Health and Social Care Trust

14:30 – 14:50 I131 thyrotoxic Therapy patients and ‘stress’ incontinence pads. A survey of disposal advice and mechanisms

Bill Thomson, City Hospital, Birmingham

14:50 – 15:00 Questions

15:00 – 15:20 Coffee

Chair: Philip Orr

15:20 – 15:40 Implications for disposals from new molecular therapy isotopes Julie Robinson, Guy's and St Thomas' NHS Foundation Trust

15:40 – 16:15 Round table discussion

Implications for disposals from new molecular therapy isotopes

16:15 – 16:30 Questions/discussion

16:30 Close

Regulatory Requirements for the Transport of Radioactive Material Jon Hursthouse, ONR Inspector, Office for Nuclear Regulation - Cross ONR Programme, Office for Nuclear Regulation, Rose Court, 2 Southwark Bridge, London SE1 9HS Email: jon.hursthouse@onr.gsi.gov.uk The presentation outlines the regulatory structure for the transport of dangerous goods in the UK, with particular emphasis on radioactive material. It gives an overview of the requirements of the regulations, and the duties of various participants in the transport chain. The process of transporting radioactive material is described, including the organisational pre-requisites, package selection, consignment documentation, marking, labelling, placarding and training. Finally, common issues identified during inspections are discussed.

Radiological Assessments Amber Bannon, Senior Radioactive Substances Regulation Technical Specialist, Environment Agency, North London, Hertfordshire and Kent, SRP Honorary Secretary Email: amber.bannon@environment-agency.gov.uk The Environmental Permitting Regulations provides a framework for controlling the generation and disposal of radioactive waste by requiring the prior permitting of discharges of radioactive waste in to the environment. Radiological assessments are a key element in determining whether discharges should be permitted. The Environment Agency must ensure that doses to members of the public and population as a whole are ALARA (As Low As Reasonably Achievable) and must ensure the sum of doses from such exposures does not exceed public dose limits. In 1999 the Environment Agency initiated an agreed approach between relevant regulatory and advisory bodies and developed an initial assessment system, now known as IRAT (Initial Radiological Assessment Tool). This presentation outlines the usefulness of IRAT and some important factors that can be considered to refine the assessment. An interactive session follows the presentation, giving a practical demonstration showing how those factors affect the assessment outcome.

Dose considerations for Sewerage workers upstream of the Water Treatment plant Anna Louise Bradley, University of Manchester, Jennifer Poveda, Nottingham University Hospitals Email: jennifer.poveda@nuh.nhs.uk This project work was completed by Anna Louise Bradley for submission towards her MSC in Nuclear Science and Technology from the University of Manchester under the Viridian EMPower scheme. This work was carried out in consultation with the medical physics staff from NUH, the staff from the local environment agency office and representatives from Severn Trent Water Ltd. Models used to assess the environmental impact of radioactive discharges entering the sewage network address the dose to the sewage workers at the water treatment works. The water treatment plant workers are assumed to be the critical receptor group due to their regular exposure throughout their working hours. However, water treatment works are often several hours downstream of the origin of the radioactive discharges. Radionuclides used in medical treatment and especially diagnosis have half-lives measured in hours or days. This may lead to higher doses than the workers at the water treatment works if access was required and work carried out in sewage pipes upstream of the water treatment plant and close to the origin of the discharges. The City Campus of Nottingham University hospital is a large teaching hospital with multiple departments using unsealed sources and a co-located PET/CT facility. The aim of this project was to ascertain whether radiation doses upstream of the treatment works could be significant enough to require regulation. To that end two scenarios were considered: man- access in a large diameter pipe near the origin of the discharges and doses from a small diameter pipe upstream of the main pipe accessed by surface digging. Based on estimates of activity discharges and time spent working around the radioactivity, the worker in the large pipe would receive ~6µSv in two hours and the worker above the small pipe would receive ~1.4 µSv in 30 minutes. For comparison, the sewage treatment plant worker was estimated to receive ~2.5 µSv annually.

PARTIAL SURRENDER OF AN EPR PERMIT Morton R, Dainty S, Eatough J, Williams C, Baker M Medical Physics, University Hospital of North Staffordshire, Stoke-on-Trent, UK. email: rosemary.morton@uhns.nhs.uk; stephen.dainty@uhns.nhs.uk

Background. The University Hospital of North Staffordshire has historically provided care from both the Royal Infirmary (RI) and City General Hospital (CGH) sites, half a mile apart. Over the years there has been a gradual migration of services from RI to the CGH with the last clinical service involving radioactivity leaving the RI site April 2013. This ended a long history of radioactivity usage at the RI that started in 1938 and included sources used for Brachytherapy, Radiotherapy, Nuclear Medicine, and PET, (not to mention decoration of walls). In October 2013 an application was submitted to the Environment Agency to surrender the part of the permit relating to the RI. The permit surrender was finally agreed in March 2014. This presentation looks at the work involved in preparing this partial surrender application. Aim. Demonstrate that there is no significant residual radiation risk from the activities carried out on site. Methods. Reviewing the history of activities carried out on site; through document archives, and from talking with long serving members of staff. Identifying a list of potential contaminants and areas that might be contaminated. Removing all known radioactive materials including waste, and approximately 20,000 radioactive decorative tiles containing NORM U-238. Monitoring potentially contaminated working areas and sewer routes, using appropriate contamination monitors for the isotopes suspected in each area. Where long lived beta sources (e.g. C-14) had been in use wipe testing was performed and the wipes were counted for beta and gamma emissions. Removing all warning signs relating to radiation hazards or radioactive materials from roofs, drains, basements, and department doors and walls. Consideration of other potential uses of radioactivity on site, such as in lightening conductors. Results. Radioactive contamination was found on some of the lead forming the safe in the Radiotherapy hot lab. This was identified as Ra-226. All other working areas, remaining equipment, work surfaces, and sewer routes were found to be out of scope. Many warning signs were discovered and removed from “legacy” locations. The confirmation of tile composition was obtained as 6.7 Bq/gram of NORM U-238. Discussion. The Ra-226 contaminated items were able to be removed and disposed as very low level waste. The activity concentration within the tiles was identified as being in scope, but suitable for general landfill. The partial surrender was able to be granted with the tiles still in situ, with the condition that they either are disposed of prior to sale of the site, or handover arrangements are put in place. Other relevant issues include site security, and a theft of lead from site occurred before the surrender had been granted. Conclusion. Documentation of the decontamination of the site to a satisfactory level to surrender the permit has been accepted by the Environment Agency.

Decommissioning Dilemmas – Radioactive Waste Issues due to Activated Linac

Components 1 Orr P A, Mooney R B, Grattan M, Hounsell A, Frew L 1 Regional Medical Physics Service, Belfast Health and Social Care Trust, UK. email: Philip.orr@belfasttrust.hscni.net

Aim: Activation within linacs is a well documented phenomenon [1-7], however, there appears to be little work on the radioactive waste implications following their decommissioning. Following the detection of elevated dose-rates from components of a decommissioned Varian Clinac kept for teaching purposes, the composition and level of activated radioactive contamination within the Target and a Flattening Filter from the Clinac were estimated to determine the best method of safe storage, handling and eventual disposal of the components. Method: Liquid scintillation (Perkin Elmer Tricarb 2900 TR) and high resolution gamma-ray spectrometry (Ortec HPGe) of surface wipes, as well as low resolution gamma-ray spectrometry (Exploranium Identifier GR-135) of the Clinac components directly, were used to determine the activation radioisotopes present as well as estimate their abundance. Results: A range of radioisotopes with varying activities were identified as shown in Table 1 below.

Estimated Activity [kBq]

Target Filter

Radioisotope Half-life (Days) November 2012 November 2012

Co-57 * 77 9 14

Co-58 * 71 1 11

Co-60 * 1925 1 1.2

Cu-67 * 0.88 8 7

Ta-182 * 114 2 3

W-181 + 121 5000 70

W-185 + 75 5000 70

W-187 * 1 4 -

Au-196 * 6.2 50 5

Table 1: Identified activation radioisotopes with estimated activities at time of measurement. Discussion: While the results obtained are only estimates and could vary by an order of magnitude, they do indicate the presence of long-lived activation radioisotopes within components of a linac. While dose rates from the components measured were relatively low and, if handled appropriately, would not cause a significant risk to staff, they are potentially radioactive materials and would fall under the Radioactive Substances Act 1993 if ever removed from site. If removed from site before 10 weeks after last beam on, they would need to be registered. If removed more than 10 weeks after last beam on they could be held under the 2010 Northern Ireland Exemption Order but would not be out of scope for 20 years (target) to 30 years (filter). If declared as waste, the components could be disposed of to the dustbin (<40kBq) after 8 months (filter) and 2.5 years (target). Conclusion: If the components are kept on site they are out of scope of RSA93 due to the 2010 Northern Ireland Exemption Order. If however, they are removed, they could be held without a certificate provided the appropriate conditions of the exemption order are followed. If declared waste they could be disposed of to the bin after 2.5 years. References. [1] L. Ahlgren and L. E. Olsson, Phys. Med. Biol., 33, 351-354 (1988) [2] Y. Z. Wang et al., Med. Phys., 32, 2899-2910 (2005) [3] H. W. Fischer et al., Phys. Med. Biol., 51, N461-466 (2006) [4] Y. H. Cho et al., Nucl. Instr. Meth. Phys. Res. B, 265, 615–620 (2007) [5] J. Kwak et al., Progress in Nuclear Science and Technology, 1, 525-528 (2011) [6] J. A. Kalef-Ezra, Rad. Prot. Dos., 147, 281–286 (2011) [6] K. Polaczek-Grelik et al., Applied Radiation and Isotopes, 70, 2332–2339 (2012) I131 thyrotoxic Therapy patients and ‘stress’ incontinence pads. A survey of disposal advice and mechanisms.

WH Thomson, City Hospital, Birmingham Email: bill.thomson@nhs.net A survey of certain restrictions and advice for I131 therapy patient for thyrotoxicosis was carried out. Following a request on the Physics mailbase, 49 centres completed a questionnaire. Two questions related to the situation of ‘stress’ incontinence in patients, where pads may be radioactive. The advice for a patient in their own home and in a care-home was requested. The responses indicated that 3/49 would not treat such patients , 20/49 would advise the patient to dispose of the pads immediately, 7/49 recommend a weeks storage and disposal, 7/49 recommend 2weeks storage and disposal, 6/49 recommended a period of storage between 4 to 12 weeks and disposal. 6/49 indicated that they would recommend some storage decay and then for the pads to be picked up for disposal at the department. The issues of a patient in a nursing home were noted by several replies, regarding HSE notification, considerations under EPR. 9 departments indicated they would not treat such patients in the care home, either not treat at all or consider as an inpatient. 9 centres would also recommend storage and then collect for disposal at the centre. However the aspects of complying with Transport regulations was not mentioned specifically. These aspects will be covered. Clearly the issues of I131 low activity pads creates a difficulty for departments leading to a difference in practice. It would seem wrong for a patient not to get the appropriate treatment. However it is hoped that this review may help with discussion at the RWA meeting on possible common advice that might help with compliance with current legislation.

Implications for disposals from new molecular therapy isotopes Julie Robinson, Guy's and St Thomas' NHS Foundation Trust Email: julie.robinson@gstt.nhs.uk With the recent research and application of molecular therapy isotopes for the treatment of neuroendocrine tumours and advanced, resistant prostate cancer, comes the inevitable issues regarding unexpected patient death and risk planning. This talk will aim to address the issues faced when a patient recently treated with Ra-223 Xofigo unexpectedly passes away. Issues with regards to location of the body, handling the body, solid and aqueous waste, post mortems and possible embalming. In addition the deceased patient (or relative’s) wish for cremation or burial will be covered. Considerations for Lu-177 and Y-90 deceased patients will also be touched on briefly.

Physics in Doppler Ultrasound 22nd July 2014, Royal Berkshire Hospital, Reading Organised by the IPEM Ultrasound & Non-Ionising Radiation Special Interest Group FINAL PROGRAMME

09:00 – 09:55 Coffee and registration

09:55 – 10:00 Introduction

Chair: James Goracy

10:00 – 10:30 Doppler Ultrasound: A Clinical Perspective Dr Paul Williams, Cardiff & Vale University Health Board

10:30 – 10:45 Plane Wave Ultrasound Imaging Velocimetry Chee Hau Leow, Imperial College London

10:50 – 11:05 Small Vessel Doppler Applications: Influence of Beam Shape on Capillary Doppler Sensitivity Philip Coulthard, Northern Physics Services

11:10 – 11:45 Coffee

Chair: Mike Lynn

11:45 – 12:00 How does Crystal Drop-Out affect the quality of Colour Doppler in terms of Signal-to-Noise Ratio? Dr Jacinta Browne, Dublin Institute of Technology, Ireland

12:00 – 12:15 Doppler QA with minimal funding Dr Nick Dudley, United Lincolnshire Hospitals NHS Trust

12:15 – 12:30 Questions

12:30 – 13:30 Lunch

Chair: Nick Dudley

13:30 – 14:00 A Review Of Doppler Ultrasound QA Dr Jacinta Browne, Dublin Institute of Technology, Ireland

14:00 – 14:15 Experiences at the Royal Surrey County Hospital Designing and Constructing an In-house Built Doppler String Phantom Pedrum Kamali-Zonouzi, Royal Surrey County Hospital

14:20 – 14:35 Rotating Doppler Phantom: An Investigation of the Performance and Accuracy of Colour Flow Doppler Imaging James Goracy, Royal Berkshire Hospital

14:35 – 14:45 Questions

14:45 – 15:05 Coffee

Chair: James Goracy

15:05– 15:20 Use of a Mini-Doppler flow phantom to evaluate system performance as part of a tender evaluation process Dr Fiammetta Fedele, Guy’s and St Thomas’ NHS Foundation Trust

15:20 – 15:35 Towards using Doppler testing as a routine quality assurance tool: practical experience Dr Vincent Pelling, Brighton and Sussex University Hospitals NHS Trust

15:35 – 15:50 Doppler phantoms and velocity measurements in preclinical ultrasound Dr David A Kenwright, University of Edinburgh

15:50 – 16:05 The ‘Leicester’ Electronic Doppler Phantom Michael Lynn, Royal Berkshire Hospital

16:05 – 16:30 Questions/discussion

Doppler Ultrasound: A Clinical Perspective Dr Paul Williams, Cardiff & Vale University Health Board email: Paul.Williams13@wales.nhs.uk

The Doppler effect has many uses, from weather forecasting to aviation safety. It has been used in medicine for many years to detect and measure tissue motion, and is commonly applied to monitor the fetal heart rate during labour. Vascular ultrasound uses the Doppler effect to determine the presence or absence of blood flow and its direction, speed and character. Some of the clinical applications of Doppler ultrasound are: stenosis or occlusions of major arteries in the abdomen, upper or lower limbs; sites of reflux for varicose vein surgery; location of a deep vein thrombosis (DVT); assessment of arterio-venous fistula; carotid arteries; detection of true and false aneurysms and endovascular aneurysmal repairs (EVAR). The different Doppler techniques, such as colour flow Doppler, power Doppler, and broadband Doppler give the user a visual and dynamic representation of blood flow, and the choice of which technique to use depends on various clinical parameters. The use of Colour Doppler and spectral Doppler are well established techniques in the investigation of carotid stenosis, and the need to obtain accurate and reliable clinical data is of utmost importance as many surgeons will base their patient management decisions on the carotid duplex result alone. Therefore, it is vitally important that the technologies used to obtain data used for clinical decision making are entered into a routine quality assurance programme to ensure the information we pass on to clinicians is accurate and evidence-based.

Plane Wave Ultrasound Imaging Velocimetry 1Chee Hau Leow, 2Robert J. Eckerley, 1Meng-Xing Tang* 1Department of Bioengineering, Imperial College London, UK. 2Department of Biomedical Engineering, King’s College London, UK. *email: c.leow12@imperial.ac.uk

Background. Ultrasound Imaging Velocimetry (UIV) generates flow vectors by tracking microbubbles within flow over frames. It has been limited by low temporal resolution, limited field of view[2], [3], and measurement error associated with conventional line by line beamforming[1]. This can be improved by using plane wave imaging[4], a promising technique that can dramatically increase the imaging frame rate. In this study, a plane wave UIV system is developed and compared with Doppler measurement.

Methods. Microbubbles were injected to a fully developed laminar flow in a 6mm diameter latex tube with average velocity of 24cm/s or peak velocity of 48cm/s. Images were acquired using plane wave pulse inversion techniques at 555 frames per second over a depth of 5cm. The images were analysed using an UIV algorithm and compared with Doppler measurement.

Results. The figure (a) and (b) show the displacement vector and velocity profile obtain using a plane wave UIV, while (c) show the centreline velocity measure using spectral Doppler.

Figure: (a) Vector image of the tube flow obtained using a plane wave UIV system. (b) Velocity profile taken from the centre of the vector image and black line represent the analytical flow profile. (c) Spectral Doppler measurement at the centre of the flow.

Discussion. Plane wave UIV is able to track the flow with good resolution and accuracy regardless of flow directions. The very high frame rate enables tracking of a very fast flow and acceleration. The results correspond well with the measurement obtained using Doppler ultrasound.

Conclusion. Plane wave UIV is a promising flow quantification tool.

Key references. [1] B. Zhou. Ultrasound Med. Biol., vol. 39, no. 9, pp. 1672–1681, Sep. 2013. [2] F. Zhang, Ultrasound Med. Biol., vol. 37, no. 3, pp. 450–464, Mar. 2011. [3] L. Liu.” Phys. Med. Biol., vol. 53, no. 5, pp. 1397–1412, Mar. 2008. [4] M. Tanter. Ultrason. Ferroelectr. Freq. Control IEEE Trans. On, vol. 61, no. 1, pp. 102–119, 2014.

c)

a) b)

The effect of Beam Form Factor on Doppler sensitivity 1Philip Coulthard, 1Georg Doblhoff, 2Jaroslav Satrapa 1Northern Physics Services, Hexham, UK. 2 TCC Consulting TimelKam Austria. email: phil@northernphysics.co.uk

Background Form factor or radiative transfer, is the proportion of energy transmitted by the ultrasound probe which can be transferred to the object of interest in this case the blood inside of the vessel. Thus, the beam form factor will vary the Doppler sensitivity. This is because the energy lost, in side lobes, grating lobes and real beam cross section (footprint) compared to the object size, means less energy is available for the useful Doppler signal. At depth, only a portion of the main beam targets the active area, where blood flow is to be detected and the Doppler return signal is generated. Method One method to observe the effect of beam form factor, is to study the “footprint” produced using matrix probes. A Random void phantom ( RVP) is able to quantify the influence of the beam shape on the form factor, as it changes with depth, which is useful for both 2D and Doppler imaging. The main contributor reducing the visibility of small voids, in the Random Void phantom are footprint size. Result We have found, in practice, predicted Doppler sensitivity, due to beam shape agrees with clinical study. Discussion. If part of the acoustic beam picks up any of the void periphery, this will show. For good and efficient Doppler detection it is important that the beam picks up only signal from the blood cells. Any other signal will contribute to Doppler noise in some way. The information from the RVP and software can help determine applicability of the scanner for Doppler measurement. Also when poor Doppler sensitivity needs investigation, it is possible to split the problem between beam formation and Doppler related effects.

How does Crystal Drop-Out affect the quality of Colour Doppler in terms of Signal-to-Noise Ratio? 1,2A Bryan, 1,3P Lespiau and 1JE Browne 1 School of Physics, Dublin Institute of Technology, Ireland 2 Radiation Physics, Hull and East Yorkshire Trust, 3 IUT Universite Boradeaux 1, France email: jacinta.browne@dit.ie

Background: Colour Doppler has become an integral part of many clinical ultrasound investigations and therefore, it is important that an understanding of the quality of the Doppler signal is established. The aim of this study was to develop a quantitative analysis technique for Colour Doppler Signal–to-Noise Ratio (SNR) and to test it with a group of scanners. Methods: A series of ten images were taken for a flow phantom for each of the ultrasound control settings and experimental set-ups1. The effect of crystal drop-out was evaluated to determine the impact of Colour Doppler SNR. The images were analysed using the in-house developed Matlab program to obtain the Colour Doppler SNR value. The SNR of the Colour Doppler signal was determined by the MATLAB program analysing the variation in the Colour Doppler signal within a region of interest (mean velocity/variation of velocity). Results: The results indicated that the Colour Doppler control had a significant impact on the quality of the corresponding Colour Doppler SNR. Also, the test was found to be sensitive to changes in transducer performance through the incremental degradation of the crystal performance by placing layers of insulating tape over the transducer face. Simulated crystal drop-out In order to simulate “crystal drop-out”, 1, 2 and 3 layers of insulating tape were placed over the Curvilinear C4-2 transducer and the results obtained are presented in Figure 7. The colour Doppler SNRs for two regions was determined were the area under the tape and to the side of the tape. The results at the optimised setting areas expected demonstrating that the area that is covered by the tape has a lower colour Doppler SNR while the area not covered by the insulating tape but to the side of the tape is still affected by the tape due to crystal cross over in forming the scan lines of the image.

Conclusions: The Colour Doppler SNR test demonstrated the potential to challenge modern ultrasound scanners and to highlight problems associated with crystal drop-out. Furthermore, this test could be incorporated into routine ultrasound quality assurance in a clinical environment to monitor any changes in performance over time.

Key references.

1 Teirlinck, C. J., et al 1998, “Development of an example flow test object and comparison of five of these test objects, constructed in various laboratories”, Ultrasonics, vol 36, no. 1-5, pp 653-66.

Doppler QA with minimal funding Dudley NJ Medical Physics Department, United Lincolnshire Hospitals NHS Trust, UK. email: nick.dudley@ulh.nhs.uk

Doppler testing is an important element of Ultrasound QA, but the cost of test equipment is high and many departments are unable to carry out such tests. The aim of this study was to determine which tests may be performed without test equipment and to assess the feasibility of building a very low cost string phantom.

The majority of recommended Doppler QA tests were performed without any test equipment, using spectral and colour flow images from the tester. A “proof of principal” string test object was constructed at a materials cost of under £50.

Doppler QA is possible with minimal funding. The lack of test equipment should no longer be an obstacle to offering a Doppler QA service.

Experiences at the Royal Surrey County Hospital Designing and Constructing an In-house Built Doppler String Phantom 1Kamali-Zonouzi P, 1Fynn M, 1 Leavesley L, 1 Pryor M 1Medical Physics, Royal Surrey County Hospital, UK. email: p.kamali@nhs.net

Abstract . The aim of this project was to develop a Doppler QA testing programme whilst reducing costs by designing and constructing an in-house Doppler QA string phantom. The phantom was designed and parts were priced to determine the cost benefits of designing such a phantom and it was deemed that this was more cost effective than purchasing a Doppler phantom. The phantom design and construction was based on a number of recommendations in IPEM Report 102. Following construction the motor that drives the string was calibrated using methods outlined in the literature. IPEM Report 102 suggests that Doppler testing using a QA string phantom should be performed at a string velocity of 50cm.s-1. The string Rotations Per Minute (RPM) required to rotate the string at a velocity of 50cm.s-1 was calculated and compared with the motor software RPM. The integrity of the software RPM calibration was tested for velocities raging between 10-90cm.s-1. Doppler measurements were then performed using the phantom on a Philips iu22 ultrasound machine at the Royal Surrey County Hospital to identify potential practical issues. The motor software was well calibrated and was found to be linear as a function of string velocity with a maximum percentage difference from the measured RPM of -3.0%. Probe positioning and signal issues were encountered when performing Doppler measurements on the Philips iu22 system. The signal was found to be very dependent on the position of the probe and to obtain the optimal signal the probe should be positioned close to the string. The phantom is currently being redesigned to ensure that the probe can be secured in a reproducible setup and that a useful Doppler signal is achievable.

Rotating Doppler Phantom: An Investigation of the Performance and Accuracy of Colour Flow Doppler Imaging James Goracy, Royal Berkshire Hospital, Reading Email: James.goracy@royalberkshire.nhs.uk

Colour Flow Imaging began in the mid 1970’s but became a standard tool in the 1990’s. A clinical ultrasound scanners ability to accurately describe blood flow jets can be influenced by the acquisition frame rate of the colour flow imaging [1]. Methods and schedule for the performance testing of clinical ultrasound Doppler have been described in the updated IPEM report 102[2]. Current phantoms do not allow the user to fully evaluate the effect of frame rate and the accuracy of the colour flow over a large area. The scope of this presentation is to report on current developments to design and build a phantom for the use of performance testing and verification of clinical ultrasound scanners Doppler function. It will primarily focus on the performance of colour flow Doppler. Spectral Doppler accuracy will be assessed by checking the peak flow rate with rotational/linear velocity. The accuracy of the colour flow Doppler will be assessed by mapping the colour pixel intensity which is proportional to the flow velocity. The phantoms design has been based on the rotating Perspex cylinder by Andrew Walker [3]. A working phantom with variable speed has been constructed in order to assess and investigate colour flow Doppler in clinical ultrasound units. References [1] T. UTSUNOMIYA, T. OGAWA, S. W. KING, E. SUNADA, S. M. LOBODZINSKI, W. L. HENRY, and J. M. GARDIN, “Pitfalls in the Display of Color Doppler Jet Areas: Combined Variability Due to Doppler Angle, Frame Rate, and Scanning Direction,” Echocardiography, vol. 7, no. 6, pp. 739–745, 1990. [2] IPEM, “Quality Assurance of Ultrasound Imaging Systems Report 102,” 2010. [3] A. Walker, E. Henriksen, I. Ringqvist, and P. Ask, “A Rotating Cylinder Phantom for Flow and Tissue Color Doppler Testing,” Ultrasound Med. …, vol. 25, no. 2, pp. 788–791, 2009.

Case Study: Use of a Mini-Doppler flow phantom to evaluate system performance as part of a tender evaluation process Fedele F Medical Physics, Guy’s and St Thomas NHS Foundation Trust, UK. email: Fiammetta.Fedele@gstt.nhs.uk

Background.

These days ultrasound images (US) are the first line of diagnostic in most clinical specialities [1] The cost of a top of the range scanner is in the region of hundreds thousand pounds; and the acquisition of such a system has to be subject to a rigorous tender process.

A key part of the process is the pre-evaluation and comparison of systems from different manufactures that have nominally comparable performances and price.

Generally this test is done directly on patients and can be quite time consuming.

The aim of this case study was to show that Performance characterization by mean of a mini-Doppler phantom testing can be a valid alternative when clinical testing is not possible.

Methods.

The Doppler performance of 4 different US systems was evaluated independently by 5 clinicians and one Medical Physicist. The Physicist exploited a 1430 LE mini Doppler flow phantom and a protocol based on IPEM recommendations [2-3] and phantom user manual [4].

The Phantom was used in the continuous flow modality and flows varying between 0-5 ml/s.

The features tested were: Spectral and Colour Doppler sensitivity, Doppler congruency, angular correction and velocity estimation.

Results.

The case study shows a good agreement (p=0.2) between the clinical and the Doppler phantom scoring.

Discussion.

The case study has been limited to obstetrics scanners. The method should be validated on scanners optimised for other modalities.

Conclusion.

This suggests that Doppler phantom testing might be a valid support for those Departments that do not have the possibility to test system in a clinical environment.

Key references. [1] Wells, P. N. T. "Ultrasound imaging." Physics in medicine and biology 51.13 (2006): R83.

[2] IPEM Report 102. Quality Assurance of Ultrasound Imaging Systems. (2010) [3] IIPEM Report 70. Testing of Doppler Equipment,(1994) [4] Gammex Ultrasound QA Cookbook.

Towards using Doppler quality assurance testing as a routine tool Dr Vincent Pelling, Radiological science and safety service, Brighton and Sussex University Hospitals NHS Trust Email: Vincent.Pelling@bsuh.nhs.uk

In 2012 a Doppler quality assurance testing of a number of machines at BSUH NHS trust was undertaken using a Gammex 1430 flow phantom. The protocol was based on methods subsequently published in IPEM Report 102, and, practical experience of testing using a CIRS string phantom. Sensitivity and noise measurements in three Doppler modes were shown to be easy additions to a standard quality assurance protocol. Some factors did not show any variability across machine models e.g. lowest detectable velocity. Parameters such as maximum velocity at 10ml/s and spectral broadening showed differences that could be ascribed to performance differences or differences in scanning technique or settings. Doppler testing was shown to be practicable, requiring some adaptation, with a need further use to validate its effectiveness as a quality assurance tool.

Doppler phantoms and velocity measurements in preclinical ultrasound David A Kenwright, Tom Anderson, Carmel M Moran, Patrick W Hadoke, Gillian A Gray, Peter R Hoskins Department: University/BHF Centre for Cardiovascular Science, University of Edinburgh email: david.kenwright@ed.ac.uk

Background

Doppler ultrasound provides a measurement of blood velocity, from which related quantities including volumetric flow and wall shear stress can be derived. Changes in these quantities can provide powerful non-invasive data directly related to the extent and effect of arterial disease and of the effect of other diseases on flow. However, it is known that clinical Doppler ultrasound velocity measurement errors may be large (>100%) if inappropriate or manufacturer-recommended protocols are used, but that considerable reduction in error may be achieved using modified protocols. As small-animal (preclinical), high-frequency ultrasound systems are increasingly used for measurement of blood velocity and its related quantities, it is important to investigate these errors.

Methods

We have used a rotating phantom to assess errors in velocity measurements at a range of Doppler angles using the IEC-recommended agar-based tissue-mimicking material. We have also created a wall-less flow phantom with vessel dimensions equivalent to small animal arteries using a stronger tissue-mimicking material. We have characterised the acoustic properties of this material at the preclinical frequency range at two both the Edinburgh Preclinical Imaging Facility and a newly-developed high-frequency characterisation facility at the National Physical Laboratory.

Results

These phantoms provide known values of velocity with which the measured values from preclinical ultrasound can be compared. We have found that the maximum velocity was overestimated by up to 158% by spectral Doppler from measurements using the rotating phantom. We have characterised the acoustic properties of a konjac-carrageenan-based tissue mimicking material, and found that it is suitable for use in high-frequency ultrasound applications. We were able to successfully create a flow phantom with vessel diameters down to 1mm at a depth of 1mm with steady flow of approx. 20cm/s, equivalent to the rat carotid and femoral arteries.

Discussion

The errors in velocity measurement using Doppler ultrasound are shown to be consistent with geometric spectral broadening. Due to the physically-robust nature of the konjac-carrageenan tissue-mimicking material, the flow phantom design has the potential to be modified into more complex geometries such as stenosis and bifurcation models, providing a useful tool in preclinical ultrasound validation.

Conclusion

With this knowledge, errors in preclinical ultrasound Doppler measurements can be corrected. The outcome of this work will be well-validated test tools and measurement protocols that will improve the reliability of measurements made in preclinical investigations.

The ‘Leicester’ Electronic Doppler Phantom Michael Lynn, Ultrasound and Non-ionising radiation specialist, Dept of Physics and Clinical Engineering, Royal Berkshire NHS Foundation Trust, RG1 5AN Email: michael.lynn@royalberkshire.nhs.uk

Electronic Doppler Phantoms (EDP) have the possibility to be more compact and convenient than ‘mechanical’ phantoms which involve water filled tanks and pipes with synthetic blood. Early versions of EDP were based on analogue circuitry; it is now possible to construct an EDP based on a digital signal processor and this presentation describes the invention of an EDP by physicists at Leicester Royal Infirmary and the subsequent construction and testing of this design by an MSc student (now an STP trainee). Acknowledgement must be made of the generosity of the Medical Physics Dept at Leicester Royal Infirmary in making available details of the hardware and software to enable the student to construct the phantom. An advantage of EDP is precise control of frequency, amplitude and timing of test signals and the design also allows actual ‘clinical’ waveforms to be used as the test source. An attenuator can be used to vary the strength of the test signal and verify the sensitivity of the system under test (SUT). Another possibility is to introduce ‘clutter’ signals to further challenge the SUT. The hardware and software components are described. Some examples are shown of the capabilities of the EDP. Delegates will be able to try out an EDP during the workshop section of this conference on the 23rd July 2014.

INDEX OF PRESENTING AUTHORS

A

Allisy, Penelope ..................................................................... 143 Archer, Tamzin ....................................................................... 123 Ashmore, Jonathan ........................................................... 44, 48 Ashworth, David ....................................................................... 13

B

Baddeley, Andy ...................................................................... 125 Bannon, Amber ...................................................................... 147 Barnes, Anna ............................................................................ 52 Blackett, Paul .......................................................................... 116 Bosi, Giorgia ................................................................................. 96 Bowers, Emma ................................................................... 83, 86 Browne, Jacinta ..................................................................... 157 Budgell, Geoff ..................................................................... 22, 27 Bull, Victoria .............................................................................. 45 Burniston, Maria ....................................................................... 60

C

Callanan, Anthony ................................................................... 93 Capelli, Claudio ........................................................................ 95 Castellano, Elly ......................................................................... 63 Chapple, Claire-Louise ......................................................... 132 Charnock, Paul ......................................................................... 65 Chell, Ian .................................................................................. 131 Chen, Yuhang ......................................................................... 103 Conlisk, Noel ............................................................................. 91 Connelly, Sadie ...................................................................... 126 Coulthard, Philip .................................................................... 156 Cournane, Seán ............................................................................ 76 Cross, Timothy ......................................................................... 72

D

Daglish, Steven ...................................................................... 122 Dainty, Stephen ...................................................................... 149 Darekar, Angela ........................................................................ 47 De Vita, Enrico .......................................................................... 54 Donovan, Ellen ....................................................................... 135 Douglas, Graeham ................................................................. 100 Downes, Patrick ....................................................................... 77 Driver, Ian .................................................................................. 16 Duane, Simon ........................................................................... 23 Dudley, Nick ............................................................................ 158

E

Esmail, Alikhan ......................................................................... 29 Evans, Stephen ....................................................................... 133 Eyles, Hannah ........................................................................... 34

F

Fagan, Michael ........................................................................ 111 Fedele, Fiammetta .................................................................. 161 Frame, John ............................................................................... 21 Fraser, Kate ............................................................................... 94

G

Garner, Andy ........................................................................... 120 Gaskin, David .......................................................................... 119 Gasser, T Christian .................................................................. 89 Gibson, Andrew ...................................................................... 140 Gillett, Daniel ............................................................................... 9 Gopalakrishnan, Ananth ...................................................... 109 Goracy, James ........................................................................ 160 Gowland, Nigel .......................................................................... 82 Grainger, Alison ............................................................. 128, 129 Green, Martin ............................................................................. 71 Gulson, Andrew ...................................................................... 138

H

Hart, Graham ........................................................................... 139 Hollis, Lyam ............................................................................... 92 Hooper, Susan ............................................................................ 6 Hughes, Anthony ..................................................................... 15 Hursthouse, Jon ....................................................................... 146

I

Iball, Gareth ............................................................................... 66

J

Jefferies, Anita .......................................................................... 11 Jones, David .............................................................................. 74 Jones, Stephen ......................................................................... 69

K

Kamali-Zonouzi, Pedrum ...................................................... 159

Kauppinen, Risto A ................................................................. 51 Kenwright, David A................................................................ 163 Kerry, Joanne ........................................................................... 10

L

Lechner, Wolfgang .................................................................. 25 Leow, Chee Hau ..................................................................... 155 Lewis, Ray ............................................................................... 120 Lu, Yongtao ............................................................................. 105 Lynn, Michael .......................................................................... 164

M

Macaulay, Elizabeth .............................................................. 114 McCool, Daniel ......................................................................... 12 McGarry, Bryony L .................................................................. 55 McNeill, Kirsty......................................................................... 115 McWilliam, Alan ...................................................................... 118 Metwaly, Mohamed .................................................................. 24 Monaghan, Niall ....................................................................... 68 Moore, Craig .............................................................................. 64 Moreton, Amanda .................................................................... 59 Morton, Rosemary ................................................................. 149 Murphy, Kevin..................................................................... 58, 61 Murray, Louise .......................................................................... 31

N

Novak, Jan ................................................................................. 49

O

O’Neill, Janice ......................................................................... 141 O'Brien, Joseph .......................................................................... 5 Orr, Philip ......................................................................... 144, 150

P

Pankaj, Pankaj ........................................................................ 107 Paynter, David .................................................................... 20, 37 Pearce, Mark S ........................................................................ 137 Pelling, Vincent ...................................................................... 162 Perry, Laura ................................................................................. 4 Phillips, Andrew ..................................................................... 108 Poveda, Jennifer .................................................................... 148 Prince, Jennie ........................................................................... 14

Puxeu Vaque, Josep ................................................................ 38

R

Robinson, Julie ....................................................................... 152

S

Sakhardande, Christine .......................................................... 79 Salter, Robert .......................................................................... 121 Scott, Richard ........................................................................... 84 Smith, Suzanne ............................................................. 33, 40, 42 Spendley, David ........................................................................ 75 Stacey, Christopher ................................................................. 41 Stilwell, Ted ............................................................................. 121 Sutcliffe, Michael .................................................................... 102

T

Thompson, Christopher ......................................................... 36 Thomson, William H ...................................................... 142, 151

V

Verbakel, Wilko ......................................................................... 35 Verberk, Willem ...................................................................... 117 Viceconti, Marco ..................................................................... 101 Villette, Claire C ...................................................................... 104 Voysey, Michael ...................................................................... 106

W

Ward, Matthew ............................................................................ 8 Wheller, Bob .............................................................................. 70 Wilkins, Hugh ............................................................................ 57 Williams, Paul .......................................................................... 154 Wood, Bryony J ........................................................................ 50 Wood, Tim .......................................................................... 62, 134

Y

Young, Joanne .......................................................................... 80 Yuan, Jianmin ..................................................................... 98, 99