STANDARD PROTOCOLS FOR A GOOD

QA IN CT IMAGING

2nd Practical and Theoretical Medical Physics Course: Quality

Assurance(QA) in CT Scanner

7 AUGUST 2017

ZUNAIDE KAYUN@HJ FARNI

BAHAGIAN KAWALSELIA RADIASI PERUBATAN

KEMENTERIAN KESIHATAN MALAYSIA

OUTLINES• PURPOSES

• INTRODUCTION

• RELEVANT LAW & REGULATIONS

• MALAYSIAN ROAD MAP OF QAP

• CURENT IMPLEMENTATION OF QAP

• SUMMARY & CONCLUSION

PURPOSES

To informed to all participants in related to :

• The concepts and effectiveness of QualityAssurance Program(QAP) related toradiation protection and safety of patient

• The relevant legislative requirements andsubsidiary regulations of Act 304 related tothe QAP

• The current status on implementation of theQAP includes QC protocols byMOH’s.

THE USAGE OF RADIATION IN

MEDICAL PURPOSES

• DIAGNOSIS

• THERAPY

• PREVENTION

• FORENSIC

• MEDICAL RESEARCH

INTRODUCTION

REQUESTING REGISTRATIONSPECIAL

PROCEDURES(IF RELATED)

WAITING OF X-RAY

X-RAYREPORTING

PROCESS CHAIN OF DIAGNOSTIC RADIOLOGY SERVICES

• An individual effective dose exceeds investigation levels;

• Any of the operational parameters related to protection orsafety are out of the normal range established for operationalconditions;

• Any equipment failure, severe accident or error takes place,which causes, or has the potential to cause, a dose in excessof annual dose limits; and

• Any other event or unusual circumstance that causes, or hasthe potential to cause a dose in excess of the annual doselimits or the operational restrictions imposed on theinstallation (e.g., the significant change in workload oroperating conditions of radiology equipment).

ACCIDENTS AND INCIDENTS

To ensure protection & safety from theeffect of ionizing radiation:

(1) environmental; properties & member of public;

(2) Radiation workers/Occupational;

(3) Patient : optimization of exposure

OBJECTIVE OF RADIATION PROTECTION &

SAFETY

Cont

To ensure that the images

produced are of

diagnostic quality with

the least possible

exposure to the patient

OBJECTIVE OF RADIATION SAFETY

IN MEDICAL

(DIAGNOSTIC RADIOLOGY)

RADIATION SAFETY VERSUS QUALITY Cont

FACTORS AFFECTING IN RADIATION SAFETY FOR PATIENT

• Design;

• Operating error

• Equipment failures

• Wrong information

• Wrong patient.

MEDICAL EXPOSURECont

An organized effort by the staff operating a facility to ensure that the diagnostic images produced are of sufficiently high quality so that they consistently provide adequate diagnostic information at the lowest possible cost and with the least possible exposure of the patient to radiation

WHO DEFINITION

QUALITY ASSURANCE

PROGRAM

• Improvement in the quality of the healthcareservices in the use of radiation sources inmedicine;

• To optimized in the protection and safety ofradiation exposure on patient with the desiredclinical outcome;

• Effective use of available resources.

• To comply with the regulatory requirementsunder the Act 304

OBJECTIVES OF QAP

• REGULATORY INFRASTRUCTURE

• OCCUPATIONAL EXPOSURE

• MEDICAL EXPOSURE

• PUBLIC EXPOSURE

• EMERGENCY PREPAREDNESS &

RESPONSE

THEMATIC SAFETY AREA OF IAEA

MILESTONE OF IAEA

Cont

RELEVANT LAW AND REGULATIONS

ACT

SUBSIDIARY REGULATIONS

CIRCULARS/ STANDARDS*/

GUIDELINES*

*LOCAL RULES/

INSTRUCTION MANUALS

1

2

3

4

Mandatory/Legally Bound

Advisory

* Not regulatory by itself but becomes mandatory if linked to Regulations/Acts

HIERARCHY OF ACT AND REGULATION

SUBSIDIARY REGULATIONS

1. RADIATION PROTECTION (LICENSING)REGULATIONS 1986

2. RADIATION PROTECTION(TRANSPORT) 1989

3. ATOMIC ENERGY LICENSING (BASIC SAFETYRADIATION PROTECTION) REGULATIONS2010

4. RADIATION PROTECTION (RADIOACTIVEWASTE MANAGEMENT) REGULATIONS 2011

Conthttps://radia.moh.gov.my/

SYSTEM OF RADIOLOGICAL PROTECTION

• Justification of practice

• Optimization of protection and safety

• Dose limitation

• Justification of medical exposure

• Optimization of protection frommedical exposure

REGULATION 4

REGULATION 5

REGULATION 6

REGULATION 42

REGULATION 43

OPTIMIZATION• Take steps to restrict the necessary exposure

in order that : - the magnitude of individual doses, - the number of people exposed, and - the likelihood of incurring exposures

be kept to as low as is reasonably achievable (ALARA), economic and social factors taken into account

• Optimization balance between image quality and radiation dose to patient.

• Optimization means that minimum risk and maximum benefits should be achieved.

BENEFIT

RISK

REG.5 OF BSRP 2010

OPTIMIZATION OF PROTECTION FROM MEDICAL EXPOSURE

The requirements of the optimization ofprotection from medical exposure shallinclude:• Design considerations • Operational considerations • Calibration of radiation source & equipment• Quality Assurance Program • Guidance level/Diagnostic reference level

REG.43 OFF BSRP 2010

REGULATION 44

REGULATION 44 ,48 and 49

REGULATION 51

REGULATION 41&53

REGULATION 54

ATOMIC ENERGY LICENSING(BASIC SAFETY RADIATION PROTECTION)

REGULATIONS 2010Reg. [41]

Every licensee or employer shall ensure that:-

(d) for diagnostic uses of radiation, the QAP specified bythe appropriate authority is conducted by or underthe supervision of a qualified expert in medical physics

(e) for therapeutic uses of radiation including teletherapyand brachytherapy, the calibration, dosimetry andQAP specified by the appropriate authority isconducted by or under the supervision of a qualifiedexpert in medical physics

ContRESPONSIBILITIES OF LICENSEE/EMPLOYER

53. (1)

The licensee shall establish a comprehensive QAP for medical exposure

with the participation of appropriate qualified experts in the relevant fields

as specified by the appropriate authority.

QUALITY ASSURANCE FOR

MEDICAL EXPOSURE

(a) the measurement of the physical parameters of the irradiatingapparatus, imaging devices and irradiation installations at the timeof commissioning and periodically after the commissioning;

(b) verification of the appropriate physical and clinical factors used inpatient diagnosis or treatment;

(c) written records of relevant procedures and results;

(d) verification of the appropriate calibration and conditions ofoperation of dosimetry and monitoring equipment

53(2) The QAP for medical exposure shall include:

Cont

(a) corrective action is taken as necessary if doses or

activities fall substantially below the guidance levels

and the exposures do not provide useful diagnostic

information and do not yield the expected medical

benefit to patients; and

(b) review is considered if doses or activities exceed

the guidance levels as an input to ensuring

optimized protection of patients and maintaining

appropriate levels of good practice.

GUIDANCE LEVELS FOR MEDICAL EXPOSURE

REG. 54(1) OF BSRP 2010

As a guide by approved registered medical practitioners,

in order that :

Cont

RECORDS

RECOMMENDED DIAGNOSTIC REFERENCE LEVEL FOR COMPUTED TOMOGRAPHY

Examination TypeDRLs in CTDIw

(mGy)DRLs in DLP (mGy.cm)

Abdomen 12.8 450

Brain 46.8 1050

Cardiac 11.8 870

Chest 19.9 600

Pelvis 39.1 730

Spine/Musculo-Skeletal 16.3 390

Thorax 21.3 420

Others 12.3 380

ACCEPTABLE AND INTERVENTION (or investigation) LEVELS

+ intervention level

+ tolerated level

guidance level

- tolerated level

- intervention level

time

(Immediate action required)

(Corrective action recommended)

test

valu

e

ContREG. 54(1) OF BSRP 2010

INVESTIGATION, NOTIFICATION AND

REPORTING OF ACCIDENTAL MEDICAL

EXPOSURES

(1)The licensee shall notify the appropriate authority ofaccidental medical exposure within 24 hours after theoccurrence of such medical exposure

(2) The licensee shall immediately investigate the followingaccidental medical exposures

(3) Submit to the appropriate authority, as soon as possibleafter the investigation specified by a written reportwithin 30 days after the completion of the investigationstating the cause of accidental medical exposure

(4) Inform the patient about the incident.

REG. 57 OF BSRP 2010 Cont

RADIATION SAFETY REQUIREMENTS

• RADIATION SHIELDING OF PREMISES

• QUALITY CONTROL MEASUREMENTS OF IRRADIATING APPARATUS AND ASSOCIATED FACILITIES

• QUALIFIED PERSONNEL & RADIATION WORKERS;

• PROGRAMME & PROCEDURES FORRADIATION SAFETY.

Cont

CURRENT CONTROL OF RADIATION PROTECTION AND SAFETY

• Radiation Protection Program (RPP) –

occupational exposure

• Quality Assurance Program(QAP) – patient

exposure

• Standard Operating Procedures (SOP) – safe

handling to the patient and workers during

operational of IR facilities.

APPROPRIATE RADIATION PROTECTION AND SAFETY PROGRAM

1985

QAP Strategic Plan in Healthcare

1996

MS ISO 9000 Quality Management System

1999

QAP in Diagnostic Radiology (under Act 304)

2013

QAP in Nuclear Medicine and Radiotherapy under Act 304 (Voluntary Implementation)

201x

Implementation of New QAP

Indicator in Diagnostic Radiology,

RT & NM under Act 304

MALAYSIAN ROAD MAP OF QAP IN HEALTHCARE

APPROACHES• The Manual for the Implementation of QAP was

established and a joint working group of members.

• References were mostly based on the IAEAdocuments.

• With the consultation of the National RadiologicalAdvisory Committee (RAC).

• The quality indicator also sent to National QAPSteering Committee for endorsement.

• Disseminate the manual to all relevant institutions

• Voluntary basis during early stages prior to mademandatory

28

IMPLEMENTATION OF QAP

• Performance indicator

• The measurement of physical parameters

of the irradiating apparatus, imaging

devices and irradiating installation;

• Regular and quality audit reviews of

QAP.

• Training of personnel & CME/CPD

CONTINUE/…

Cont

ELEMENTS OF QAP IN DIAGNOSTIC RADIOLOGY

• QC of IR equipment & associated facilities;

• Indicator of QAP

• Quality Audit

• Continuous Medical Education(CME)

CONTINUE/…

Cont

PROPOSED INDICATOR OF QAP PATIENT EXPOSURE FOR RADIOLOGY SERVICES

MODALITY INDICATOR

General Radiography Percentage of radiographs rejected is < 5%

Digital Radiography Proportion of retakes for digital images is ≤ 2.5%

Fluoroscopy Percentage Of Fluoroscopic Procedures Where Patient DoseExceed The Malaysian Diagnostic Reference Level (DRL) is ≤ 20%

CT Scanner Percentage Of Dose Length Product (DLP) for Adult CT BrainExamination that Exceeds Malaysian Diagnostic Reference Level(DRL) is≤ 10% exceed Malaysian DRL values(The DLP value for CT Brain examination is 1050 mGy.cm).

Mammography Percentage Of Rejected Mammography Films or Images is < 3 %

Cont

The manual guide for the implementation of QAP

Established and a joint working group of members.

Consultation of the National Radiological Advisory Committee

(RAC).

The quality indicator also sent to National QAP Steering

Committee for endorsement.

Provides more detailed guidance

The measurement of physical parameters of the irradiating

apparatus, imaging devices and irradiating installation;

Regular and quality audit reviews

Training of personnel

Voluntary basis during early stages prior to made mandatory.

IMPLEMENTATION OF QUALITY

ASSURACE PROGRAM(QAP)

Cont

QC PROTOCOLS

Test for QC of monitors and laser printers

Test for QC of geometry influoroscopy

Test for QC of radiography

Test for QC in mammography

Cont

CIRCULARS/GUIDELINES/MANUALS RELATED TO QAP AND QUALITY CONTROL(QC)

YEAR

Manual Pelaksanaan Program Jaminan Mutu(QAP)dalam Perkhidmatan Perubatan Nuklear

2013

Manual Pelaksanaan Program Jaminan Mutu(QAP)dalam Perkhidmatan Radioterapi

2013

Technical Quality Protocol(QC) Handbook ForComputed Tomography

2015

Technical QC Protocol Handbook For Dental X-rayTechnical QC Protocol Handbook For FluoroscopyTechnical QC Protocol Handbook For RadiographyTechnical QC Handbook for Computed RadiographyTechnical QC Handbook for Digital Radiography

2015

2015

2015

2015

Manual Pelaksanaan Program Jaminan Mutu(QAP)dalam Perkhidmatan Radiologi

2017

DIGITAL IMAGING PROCESS

WHAT’S QC

1) QC is regulatory process through which theactual quality performance is measured,compared with existing standards and theactions necessary to keep or regainconformance with the standards;

2) QC is concerned with operational techniquesand activities used :

* To check quality requirements are met

* To adjust and correct performance ifrequirement found not to have been met.

Cont

2. QC.doc

TECHNICAL QUALITY CONTROL HANDBOOK COMPUTER TOMOGRAPHY SYSTEM

• Unit Assembly Evaluation• X-Ray Generator• Radiation Dosimetry• Scan Localisation• Image Scan Width (Sensitivity Profile)• Radiation Dose Profile (Irradiated Beam Thickness)• Image Display• Image Quality• Quantitative Accuracy• Leakage Radiation• Scatter Radiation

Cont“TECHNICAL QUALITY PROTOCOL HANDBOOK FOR CT SYSTEM”

PHYSICAL PARAMETERS OF CT IMAGE

Image quality– May be expressed in terms of physical parameters such as

uniformity, linearity, noise, spatial resolution, low contrast resolution

– It depends on the technological characteristics of the CT scanner, the exposure factors used and image viewing conditions.

– Quality may be assessed by quantitative measurement using test phantoms, and by the appearance of artifacts.

– Measurements should be conducted regularly

Scanner performance: technical parameters (I)

Test Phantoms:– Test phantoms of a standardized human shape

or test objects of a particular shape, size andstructure, are used for the purposes ofcalibration and evaluation of the performancesof CT scanners

– They should allow for the parameters to bechecked: CT number; uniformity; noise; spatialresolution; slice thickness; dose; positioning ofcouch

18: Optimization of protection in CT scanner

41

Minimum requirements: CT scanner (I)• Image noise

The Standard Deviation of CT numbers in the central 500 mm2 ROI for a water or tissue equivalent phantom should not deviate more than 20% from the baseline.

• CT number values

The deviation in the CT number values for water or tissue equivalent material and materials of different densities should <±20 HU or 5%.

• CT number uniformity

The SD of the CT number over a 500 mm2 region of interest for water or tissue equivalent material at the center and around the periphery of phantoms < 1.5% of the baseline

Minimum requirements: CT scanner (II)

• Computed tomography dose index (CTDI)

The CTDI for a single slice for each available beam shaping filter and for each available slice thickness should not deviate more than ± 20% from the baseline.

• Irradiated slice thickness

The FWHM of the dose profile should not differ more than ± 20% from baseline.

• High contrast resolution (spatial resolution)

The FWHM of the point spread function of a pin, or the edge response function of an edge should not differ more than ± 20% from baseline.

• Low contrast resolution

Polystyrene pins of 0.35 cm diameter inserted in a uniform body water phantom should be visible in the image.

PERFORMANCE & SAFETY STANDARDS FOR COMPUTED TOMOGRAPHY

NO. PROCEDURE TOLERANCE FREQUENCY

1. Unit Assembly Evaluation Ensure all mechanicalmovements and locks arefunctioning properly

Annually

2. X-Ray Generator

2.1 Accuracy of kVp

(a) Tube potential < 100 kV Maximum deviation ≤ ±5 kV Annually

(b) Tube potential ≥ 100 kV Maximum deviation ≤ ±5%

2.2 Accuracy of exposure timer Maximum deviation ≤ 10% Annually

2.3 Coefficient of linearity ≤ 10% Annually

Cont

NO. PROCEDURE TOLERANCE FREQUENCY

3. Radiation DosimetryPatient dosimetry(CTDI)

≤ 20% of baseline ormanufac-turer referencevalue

Annually

Cont

Dosimetry - CTDI in airDosimetry - CTDI in Perspex Phantoms

NO. PROCEDURE TOLERANCE FREQUENCY4. Scan Localisation Annually

4.1 Axial scan localisation lightaccuracy

Maximum deviation≤ 2 mm

Annually

4.2 Isocenter alignment,sagittal and coronallocalisation light accuracy

Maximum deviation ≤ 5 mm

Annually

4.3 Gantry tilt accuracy Maximum deviation ≤ 30 of intended

Annually

4.4 Table position Maximum deviation≤ 2.0 mm

Annually

4.5 Table index Maximum deviation≤ 0.5 mm

Annually

4.6 Gantry MovementAccuracy

Maximum deviation≤ 2.0 mm

Annually

4.7 Accuracy of scan prescriptionfrom scout localisation image

Maximum deviation 1.0 mm Annually

Cont

Z

X

Pin pricks made in

film at position of

scan plane light

X-ray beam

exposure

Congruence of the scan localization light and scan plan(Co-incidence of internal scan plane lights and scan plane)

Axial scan localisation light accuracy(Scan Localisation)

Isocentre Alignment of indicating lights with scan, coronal and sagittal planes

• Several methods can be used to perform these tests

• The techniques described here are straightforward to implement and require little specialist test equipment.

Scan field and the localization light are centered at the same location

Gantry Tilt Accuracy

Accuracy of gantry tilt indicators and that specified at position tilt position

Table Positioning(Couch travel accuracy for helical scans)

Accuracy of longitudinal Table Motion

Table Index

Accuracy of Table Movements Indicator

NO. PROCEDURE TOLERANCE FREQUENCY5. Image Scan Width

(Sensitivity Profile)

5.1 For ≥ 5 mm prescribedscan width

Maximum deviation ≤ 1 mm Annually

5.2 For < 5 mm prescribed scanwidth

Maximum deviation ≤ 0.5 mm Annually

Cont

Z-Sensitivity (Imaged slice width)

Determine the actual width of the imaged slice

(Plan view of a test object used to measure imaged slice widths for axial

scans)

NO. PROCEDURE TOLERANCE FREQUENCY6. Radiation Dose Profile

(Irradiated Beam Thickness)Maximum deviation ≤ 1 mm or within manufacturer’s specifications for multi-slice CT

Annually

Measurement of

irradiated slice

widths for a range

of nominal slice

width settings

Determine the accuracy of pre-patient collimator setting

NO. PROCEDURE TOLERANCE FREQUENCY7. Image Display

7.1 Visual display (SMPTE Pattern) Lumi-nanceand contrast not signifi-cantlydifferent from hard copy output;

Daily

Geomet-ric distor-tion not excee-ding 1 mm;

5% and 95% patches must bevisible;

No notice-able artifacts

Cont

NO. PROCEDURE TOLERANCE FREQUENCY7. Image Display

7.2 Hard copy display Lumi-nance contrast not signifi-cantly different from visual output Monthly

Geomet-ric distor-tion not exceed 1 mm

5% and 95% patches must be visible

No notice-able artifacts

Optical density values must bewithin speci-fied range

Cont

NO. PROCEDURE TOLERANCE FREQUENCY8. Image Quality

8.1 CT number uniformity

Monthly

a) head phantom ≤ 5 HU

b) body phantom ≤ 20 HU

8.2 Image noise Standard deviation of CT numbersvaries as reciprocal square root ofmAs

8.3 Image artifacts (transaxialscan localisation images)

No significant artifacts

Cont

Axial image

of an

homogenous

phantom

CT number uniformity

Image Uniformity – ROI at Centre and Periphery

CT number uniformity

Region of

interest (ROI)

Imaging performance (Noise)

Noise level for different scanning parameters

Can cause:- Ring artifacts- Non-Uniformity

Artifacts- Aliasing Artifacts

NO. PROCEDURE TOLERANCE FREQUENCY8.4 Low contrast resolution ≤ 5 mm for 0.3% of nominal target

contrast

Cont

Typical image

of the

Catphan LCR

insert

NO. PROCEDURE TOLERANCE FREQUENCY8.5 High contrast resolution ≥ 5 lp/cm

Cont

• The number of line pairs per cm just visible in the image is approximately equivalent to the 2% value of the MTF

• This result can then be compared with the 2% MTF, if this is quoted in the manufacturer’s specification

NO. PROCEDURE TOLERANCE FREQUENCY9. Quantitative Accuracy

9.1 Accuracy of distance measurements (transaxialand scan localisationimages)

Maximum deviation≤ 1 mm

Annually

9.2 CT number value Water: 0 5 HU Annually

Air: – 1000 10HU

Cont

NO. PROCEDURE TOLERANCE FREQUENCY9.3 CT number constancy Value and standard deviation for

water remains relatively constantDaily

9.4 CT number dependence on: Water: 0 5 HU Semi-annually, Annually

a) Scan thickness

b) Reconstruction algorithm

c) kV

9.5 CT number dependence on phantom size

Maximum deviation ≤ 20 HU Semi-annually, Annually

9.6 CT number dependence on phantom position

15 HU Annually

9.7 CT number linearity CT number shall change linearly with linear attenuation coefficient of different material

Annually

Cont

NO. PROCEDURE TOLERANCE FREQUENCY10. Leakage Radiation

Exposure from the leakage radiation at 1 meter from the x-ray tube in an hour at every rating specified by the manufacturer

≤ 0.1 mGy (≤ 10 mR) Annually

11. Scattered RadiationExposure rate in one week at every occupied area outside the x-ray room and at the position normally occupied by the operator at the control area

≤ 0.1 mGy (≤10 mR) Annually

Notes:

All tests shall be carried out during commissioning and after replacement of major components.

Cont

• Acceptable Level: Level at which the performance of that parameter is

within stipulated requirements.

• Remedial Level: Level at which the performance of that parameter is

not within the stipulated requirements where corrective action shall be

taken within a prescribed time period.

• Suspension Level: Level at which the performance of that parameter is

not within stipulated requirements where the equipment shall be

removed from clinical use immediately until appropriate corrective action

is taken.

• Baseline: The value of a parameter (unless specified otherwise), which

is determined at the time of commissioning (for new equipment) or as

determined for the first time of the QC. This is to determine whether

there are any changes in the performance of equipment over time.

LATEST QAP IN RADIOLOGYPERFORMANCE LEVEL OF IRRADIATING APPARATUS

COMMISSIONING

Commissioning is the process of acquiring all the data from equipment that is required to make it clinically useable in a specific department. This commissioning test will give the baseline values for the QC procedures

Cont

CRITERIA FOR CLASS H(CERTIFICATION) ON RADIATION SAFETY PERFORMANCE UNDER ACT

3O4

• Part 2 :Quality Control Test byapproved “Technical SupportStaff”

• Part 1: Radiation Protectionand Safety by approvedpersonnel “Medical PhysicsConsultant” or Qualified Expert

Cont

OUR WEB SITE

https://radia.moh.gov.my/

SUMMARY AND CONCLUSION

• QAP as one of the planned program to further

upgrade and enhance the quality, safety and

efficacious of radiological services;

• The co-operations from regulator, users and

clinical auditors will be the paramount

importance to ensure the successful

implementation of the programme to

guarantee the quality of radiological services

in the related medical centres nationwide.

TERIMA KASIH

zunaide@moh.gov.my

https://radia.moh.gov.my/