IAEAInternational Atomic Energy Agency

IAEA, the BSS and DRLs

Regional Meeting on the Establishment and Utilization of Diagnostic Reference Levels

Kampala, Uganda, 14-18 February, 2013

John Le Heron

Radiation Protection of Patients Unit

Radiation Safety and Monitoring Section

Division for Radiation, Transport and Waste Safety

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Outline

• Background & current issues

• The BSS and radiation protection in medical exposures

• IAEA activities & resources in TSA 3

• DRLs and the BSS

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Medical exposures – current usage

Every year, throughout the world, ionizing radiation is used in *:

• 4.000.000.000 diagnostic procedures

• 35.000.000 nuclear medicine procedures

• 8.000.000 radiotherapy treatment courses

* An expanding activity worldwide

Diagnostic procedure Nuclear medicine procedure Radiotherapy procedure

These bring huge benefit to healthcare

*UNSCEAR 2008

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Increasing use of radiation in medicine

• More machines, etc

• New technologies and techniques

• New roles

• Increasing complexity in the planning & delivery of the radiation

Single slice CT → Multi-Detector CTFilm → Computed & Digital RadiographyHybrid imaging, PET-CTImage-guided interventional proceduresVirtual procedures

E.g. Changes in the role of imaging: First “port of call”

A move towards “screening”, in all its guises

E.g. IMRT, IGRT, etc.

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Is this increasing use of radiation in medicine cause for concern?

What are some of the current issues

in imaging?

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Patient doses – a perspective

• Depends on the radiological procedure

• E.g. Radiology:• Radiography

• A few μSv to a few mSv, per procedure

• CT

• A few mSv to tens of mSv

• Image-guided interventional procedures

• A few mSv to tens of mSv

• Skin doses up to several 1000 mSv

• Radiation therapy• Many tens of Gy (but only to target vol) NBR, 2.4 mSv

LD50 3000 - 5000 mSv

Whole body dose

X r

ay e

xam

s

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Radiography

• Doses to the patient are typically low • Effective dose – a few μSv to a few mSv

• But variation by a factor of 20 more• Many exams lack proper justification and/or

optimization

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Image-Guided Interventional Procedures

• Increase continues, in some countries doubling every 2 - 4 years

• Doses can be high• Effective doses

• Can exceed 20 mSv

• Peak skin doses• Can exceed several Gy

• Repeat procedures – not insignificant

• Health professionals involved may not have had radiation protection training• Optimization often lacking

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CT

• Usage increasing• More scanners

• Quicker to use

• Can do more with them

• But issues with:• Justification

• Unnecessary exams

• Self-referral

• Pressure for “screening”

• Optimization• Children

• Multiple follow-up examinations

Level I - UNSCEAR 2008

43%

6%4%

47% CT

Nuclear Medicine

Interventional

Conventional Rad/f luoro

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A need for radiation protection of the patient

• ICRP principles of radiation protection• Justification

• Net benefit for the patient

• Optimization• Achieve clinical purpose with appropriate dose

management

Radiation dose Achieve clinical purpose

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RP regulatory framework for medical exposure

• The old BSS and the new BSS

• The BSS sets out the requirements for Medical Exposure

• Medical Exposure often called “TSA 3” in IAEA projects• Thematic Safety Area 3

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IAEA projects and TSA 3

• Directed at end-users – medical radiation facilities• All hospitals and medical centres in a Member State

where radiation is used in medical applications• i.e. From large teaching hospitals to small rural units

• All modalities, as applicable

• Diagnostic radiology• Radiography, fluoroscopy, CT, mammography, dental, DEXA

• Image guided interventional procedures

• Nuclear medicine

• Radiation therapy

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TSA 3 – for each medical radiation facility:

• Appropriate persons are in place to take the relevant responsibilities• Radiological medical practitioners

• Medical radiation technologists

• Medical physicists

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TSA 3 – for each medical radiation facility:

• The radiation protection principle of justification is being applied• In particular, “Level 3” for individual justification

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TSA 3 – for each medical radiation facility:

• The principle of optimization of protection is being applied to every exposure• Design considerations for equipment

• Operational considerations

• Calibration

• Dosimetry of patients

• DRLs

• Quality assurance for medical exposures

• Dose constraints

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TSA 3 – for each medical radiation facility:

• Unintended and accidental medical exposures are being addressed• Means for minimizing their likelihood

• If they occur:• Appropriate investigations

• Appropriate corrective actions

• Written records

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Some IAEA activities to help Member States with radiation protection of the patient

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Dedicated website

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Dedicated website – rpop.iaea.org

Updated monthly

Information for• Health

professionals• Member States• Patients

Additional resources• Publications• Safety

Standards• Training material

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Developing Standards

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The new BSS

• Basis for RP in medical exposures

• Safety Guide• RP in medical facilities (being developed)

• Safety Report Series

• Newer medical imaging techniques

• Guidelines for the release of patients after radionuclide therapy

• Establishing guidance levels in X ray guided medical interventional procedures

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All available from RPoP website

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Promoting Education and Training

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Promoting Education and Training

• Development of standard packages for training in the application of the safety standards • Approved training packages on:

• Radiation protection in:

• Diagnostic and interventional radiology• Nuclear medicine• Radiotherapy• Cardiology• PET/CT• Paediatric radiology

• Prevention of accidental exposure in radiotherapy

• Dissemination of training material• Downloadable from RPoP website or available as CD

• Organization of training courses

Approved Training Package

IAEA Training Material onRadiation Protection in Cardiology

Version: April 2009Training material also available for free download from

http://rpop.iaea.org

in collaboration with

Thicker tissue masses absorb more radiation

Physical factors and challenges to Physical factors and challenges to radiation managementradiation management

proper filtering

improper filtering

THE USE OF THE

ANTISCATTER GRID

INCREASES PATIENT

ENTRANCE DOSE BY A

FACTOR OF 2 TO 6

Factors affecting patient Factors affecting patient doses (I)doses (I)

Threshold

Preventable

Lessons from injured patients:

Cumulative buildup of dose for steeply angled high-dose beam through large patient not recognized.

Lesion required grafting.

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Technical Assistance

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Technical Cooperation

• Through regional and national projects:• Procurement for Member States

• QC kits, phantoms, dosimeters, publications, etc

• Fellowships & Scientific Visits

• Expert missions

• Regional & national training courses

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Diagnostic Reference Levels & the BSS

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The advent of DRLs

• Large variations in patient doses for the same exam have been long documented• Many factors influence patient dose and image quality

• The need for improvement long recognized

• Various approaches advocated in 70s, 80s • E.g. Patient exposure guides (USA)

• International recommendations• ICRP first mentioned “DRLs” in Publication 60, 1990

• Elaborated in Publication 73, 1996

0

20

40

60

80

100

120

0 - 1.0 - 2.0 - 3.0 - 4.0 - > 5.0

Effective dose (mSv)

Nu

mb

er

Abdomen AP – NZ, 1983

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The IAEA and DRLs

• The International BSS, 1996• Introduced Guidance Levels for medical exposure

• Concept same as DRLs

• Revised International BSS, 2011• DRLs continue as an important tool for

optimization of patient radiation protection in imaging

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What does the new BSS require?

• 2 aspects• Establishing (national) DRLs

• Using the DRLs

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Establishing national DRLs - BSS

• Who?

• Government as the facilitator• Health Authority

• Professional Bodies

• Regulatory Body

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Establishing national DRLs - BSS

• For what procedures?

• Medical imaging• Including image guided interventional procedures

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Using national DRLs - BSS

• The (radiation protection) Regulatory Body mandates the use of the nationally established DRLs

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Using national DRLs - BSS

• At each medical radiation facility• Local assessments of typical doses for common

procedures

• Results compared with relevant DRLs, and if:• Exceed the relevant DRLs; or

• Substantially below the relevant DRL and images not of diagnostic quality

• Review of adequacy of optimization of patient radiation protection• Corrective action, if indicated

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How DRLs work – a trigger for review

• National DRLs have been established

• Typical doses at a facility are periodically compared with the relevant DRLs• If exceeds DRL, or

• If significantly below DRL and there are IQ problems

• Investigate and if needed improve optimization

DRL based on 75th percentile

Note: if below DRL, still may not be optimized

Average ESD Room AA = 4.4 mGy

Average ESD Room BB = 6.9 mGy

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What are the features of DRLs?

• Applicable to a country or region within a country

• Values established, in consultation, by• Professional bodies, Health Authority, RP Regulatory Body

• For common examinations

• In setting values, the following must be considered• Clinical requirements – general or specific

• Adequate image quality

• Use of easily measured dose quantities

• Data from wide-spread surveys

• Standardised patient or phantom

• Need for revision as technology and techniques improve

All of these will be discussed many times this week

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In setting DRLs

• Adequate image quality

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Example – Image Quality & Mammography

• 1990s, MGD increased• Image quality demands,

including• Need for higher contrast

• New film developed, higher density needed

• Clinical requirements must be the driver

• DRLs must not be an impediment to such developments

* D Spelic, et al. Biomed Imaging and Interv 2007; 3(2):e35

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Setting a DRL value for a procedure performed with different technologies and techniques

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Example – Dental intra-oral radiography

• Most common dental exam is the posterior “bitewing” view• Direct exposure film

• D-speed

• E/F-speed

• Digital imaging• DR (mainly)

• CR

www.michigan.gov/mdch/0,1607,7-132-27417_35791_35798-46657--,00.htm M Alcaraz et al. Radiation Protection Dosimetry (2010) 140(4),391-5

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Dental doses – intra-oral

• Depends on the image receptor

• Depends on the kVp, etc.• Factor of 5 in the example

• Should the setting of DRLs accommodate all current practice or be technology specific?

• National DRLs are based on wide-spread surveys• Blunt instrument

• In parallel, the professional bodies must take the initiative • e.g. American Dental Association

• Dentists should use E/F-speed film

• In time, DRLs would reflect this professional body guidance

http://www.michigan.gov/mdch/0,1607,7-132-27417_35791_35798-46657--,00.html

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• DRLs reflect immediate-past practice in a given country, “warts and all”, applied prospectively

• Therefore, the periodic review of DRLs is very important

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Patient size

• The concept of a DRL is based on a typical patient, either:• A phantom, or

• Patients selected on basis of some criteria

• Does “looking after” this standardised patient ensure that all patients are ok?• Does an adult DRL help ensure optimization for a child?

• Experience has shown that the answer is “No”• There is a need for a range of “standardised patients”

• E.g. several paediatric sizes

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Setting DRL values – not all exams are equal

• DRLs for projection radiography are relatively easy

• But with other modalities it is more difficult• Image Guided Interventional Procedures (IGIPs)

• Factors include• Operator skill and experience

• Patient size and anatomy

• Complexity of the task

• Equipment

• Routine versus emergency

• DRLs for IGIPs need to reflect the overall system

• DRLs for IGIPs are not appropriate for deterministic effects• DRLs are not used for individual patients

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DRL values and the new BSS

• The new BSS gives no values• The old BSS did (Schedule III)

• The new Safety Guide will discuss values of DRLs in use

• Preference is for each country (or region in a country) to have their own• Based on the practice in their country

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Do DRLs work – Trends with time

• UK has > 20 years of experience with DRLs• Reviews in 1995, 2000, 2005 and 2010

• 2010 review showed for radiography:• On average about 16% lower than 2000 review

• Typically less than 50% of original DRLs

Trend due to better optimization, including regular monitoring of patient doses

HPA-CRCE-034, Health Protection Agency, UK, 2012

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Implementation around the world

• Still a long way to go• Many countries have introduced DRLs, but the

level of utilization varies widely• Between countries, and within countries

• IAEA regional projects in patient protection• Developing Member States in:

• Africa, Asia, Europe, Latin America

• Includes setting up DRLs

• Level of achievement to date is low

At RAF9044 RCM, DRLs were identified as the number 1 priority

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Regional meeting, Kampala, 18-22 Feb

• Aim• To describe, using teaching, practical work and

group discussion, the concepts and methodologies that will enable participants to facilitate in their own countries the: • Establishment (and periodic review) of national DRLs,

and

• Application and use of DRLs in their country’s hospitals

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Summary

• BSS sets out the requirements for patient radiation protection

• Optimization of protection is a cornerstone of patient radiation protection

• DRLs are an important tool for optimization• Need to be established

• Need to be used

• Need to be reviewed periodically