lecture 9 - quality assurance

8/17/2019 Lecture 9 - Quality Assurance

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FRCR: Physics Lectures

Diagnostic Radiology

Lecture 9Quality Assurance (QA) of radiographic

systems

Dr im !ood

Clinical "cientist


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#$er$ie%

& !hat is QA'

& he life cycle of ray imaging systems

* he critical e+amination

* Acceptance testing * Commissioning

* Routine performance testing

& ,P-. Report 9/

* Recommended tests 0y modality * a %histle stop tour

& he role of .edical Physics in Diagnostic

Radiology


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!hat is QA'

& Quality as·sur·ance

& A programme for the systematic

monitoring and e$aluation of the $arious

aspects of a pro1ect2 ser$ice or facility to

ensure that standards of 3uality are 0eing

met

.erriam!e0ster4s .edical Dictionary2 5 6778 .erriam!e0ster2 ,nc


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!hat is QA'

& ,t is a re3uirement under the Ionising Radiations

Regulations 1999 (Reg 6()(;)) to<

* ‘… make arrangements for a suitable quality

assurance programme to be provided in respect of

the equipment or apparatus for the purpose of

ensuring that it remains capable of restricting so far

as is reasonably practicable exposure to the extent

that this is compatible with the intended clinical

purpose or research obective!"


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!hat is QA'

& Regulation 6 also re3uires=

* Ade3uate testing 0efore entering clinical ser$ice

(commissioning)

* Ade3uate testing at appropriate inter$als and afterany ma1or maintenance procedure (routine)

* .easurements at suita0le inter$als to ena0le

assessment of representati$e doses to persons

undergoing medical e+posures


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!hat is QA'

& he regulations use lots of $ague terms li>e?suita0le@2 ?ade3uate@ and ?appropriate@ * Deli0erate due to range of e3uipment the regulations

ha$e to co$er

& he ?Appro$ed Code of Practice@ gi$es slightly more detail * Depends on the nature and range of e3uipment in use * he QA programme should specify the fre3uency of

any testing and appropriate actions le$els

* In establishing these levels the employer shouldtake into account guidance established byrelevant professional bodies about criteria ofacceptability


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!hat is QA'

& ,n de$ising the QA programme2 pay specialattention to e3uipment for= * Children * ealth screening programmes

* igh dose procedures2 such as inter$entionalradiology2 C or radiotherapy

& he employer should consult their RPA %hende$ising the QA programme

& Bote QA2 does not 1ust co$er the e3uipment2 0utalso procedures2 etc (as re3uired under,R(.-)R)


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he life cycle of ray imaging

systems

& here are essentially four stages of chec>s

applica0le to ray imaging systems=

* Critical e+amination

* Acceptance * Commissioning

* Routine performance testing

& .aintenance is $ital throughout


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he life cycle of ray imaging

systems


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he Critical -+amination

& nder ,RR 99 Reg /(6)2 the installer isre3uired to perform a critical examination ofany ne% installation

& he purpose of the ?crite+@ is to ensure all safety

features and %arning de$ices %or> correctly * Also includes tu0e lea>age2 total filtration2 etc

& Primarily related to radiation protection featuresthat affect staff and $isitors2 0ut some impact on

patient safety too& -mployer must not allo% the e3uipment to gointo clinical ser$ice until the results of the crite+are satisfactory


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Acceptance testing

& erify that the contractor has supplied all thee3uipment specified and has performedade3uate tests to demonstrate specifiedre3uirements are met

& .ay 0e a simple chec> list

& .echanical and electrical safety chec>s alsore3uired


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Commissioning

& "et of tests performed 0y a representati$e of the

employer (usually .edical Physics)2 to ensure

the e3uipment is ready for clinical use2 and to

esta0lish 0aseline $alues against %hich routineQA can 0e compared

& Commissioning tests may need to 0e repeated

during the life of the system if any ma1or

maintenance is underta>en eg ne% ray tu0e * Be% 0aselines may need to 0e esta0lished


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Routine testing

& Regular tests throughout the lifetime of thee3uipment

& Loo>ing for changes in performance thatindicates remedial action re3uired

& Eenerally2 routine are a su0set of thecommissioning tests


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,P-. Report 9/

& he ,nstitute of Physics and-ngineering in .edicine (,P-.)produce a series of reports relatedto medical e3uipment QA

& he most useful for DiagnosticRadiology is ,P-. Report 9/ * Recommended standards for the

routine performance testing ofdiagnostic #$ray imaging systems

(677)& Relates primarily to imaging

performance and radiation safetychec>s


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,P-. Report 9/

& he report is split into chapters on differentmodalities

& -ach chapter starts %ith a summary ta0le of= * The physical parameter to be tested

* Frequency * $aries from daily to three yearly * Priority * le$el / is essential for ?good practice@= le$el

6 is not essential2 0ut considered ?0est practice@ * Level of expertise required * le$el A applies to

fre3uent and relati$ely 0asic tests performed 0y

Radiographers= le$el G tests are less fre3uent2 0utre3uire greater e+pertise and more comple+e3uipment (.edical Physics tests)

* ction levels * split into ?Remedial@ and ?"uspension@(see later)


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,P-. Report 9/

& -ach test is then descri0ed 0riefly2%ith appropriate references to otherdocuments2 such as the ,P-. Report6 series * hese are a series of reports that gi$e

much greater detail on the method fortesting systems eg ray tu0es andgenerators2 fluoroscopy2 C2 etc


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,P-. Report 9/

& !emedial Level:

* A le$el of performance at %hich remedial

action is re3uired2 0ut the unit may continue to

0e used in the meantime * he action %ill 0e 0ased on a ris> assessment

of the e3uipments performance and the ris>

arising should it continue to 0e used

* Follo%ing assessment2 a timescale must 0e

agreed and restrictions on its use follo%ed


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,P-. Report 9/

& "uspension Level:

* A le$el of performance at %hich it is

recommended the e3uipment is remo$ed from

clinical use immediately * Bot all tests ha$e suspension le$els set due

to the su01ecti$e nature of the test eg image

3uality


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,P-. Report 9/

& ,P-. 9/ also emphasises that= * A senior radiography or other suita0le person should

0e appointed to super$ise the QA programme

* ime should 0e allocated to staff and e3uipment for

testing * ll Q tests should be documented as part of the

Q programme * may 0e re3uired as e$idencepresented to the "- inspectors

* Results and remedial actions must 0e follo%ed uppromptly

* est e3uipment should 0e a$aila0le and %ithincali0ration (annual recali0ration usually re3uired fordosemeters)


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A %histle stop tour of ,P-. 9/


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ray tu0es and generators(Chapter )

& Level

* rayHlight 0eam alignment and centring

* Light 0eamH0uc>y centring

* Field siIe cali0ration

* Distances and scales

* Radiation output repeata0ility and

reproduci0ility (small range of settings)


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ray tu0es and generators(Chapter )

& Level #

* Radiation output repeata0ility and

reproduci0ility (larger range of settings)

* -+posure time * u0e potential


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FilmHscreen radiography2

processors and A-Cs

(Chapter ;)

& Level

* De$eloper temperature2 fog2 film speed2

contrast inde+2 replenishment2 p2 sil$ercontent

* ,ntensifying screens and dar>room chec>s

* A-C guard timer and resulting film #D


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FilmHscreen radiography2

processors and A-Cs

(Chapter ;)

& Level #

* #nly A-C tests

* Consistency 0et%een cham0ers

* Repeata0ility and reproduci0ility

* Receptor dose


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CR and DR(Chapters and J)

& Level $

* Detector dose indicator monitoring

* niformity

* Condition of image plates (CR only)

* Lo% contrast sensiti$ity

* Limiting spatial resolution


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CR and DR(Chapters and J)

& Level #$ (in con1unction %ith ,P-. 6 Part ,,) * DD, repeata0ility and reproduci0ility

* .easured uniformity

* hreshold contrast detail detecta0ility

* -rasure cycle efficiency (CR only)


* "caling errors

* Dar> noise

* .odulation transfer function (.F)

* Bormalised noise po%er spectrum (BBP")

* A-C tests


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,mage display(Chapter 8)

& Film vie%ers * Level * general condition * Level # * luminance2 uniformity2

$ariation 0et%een $ie%ers2 room

illumination& &onitors * Level * general condition2

greyscale and resolution %ith testpatterns

* Level # * D,C#. greyscalecali0ration2 test patterns2 uniformity2$ariation 0et%een monitors2 roomillumination


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.ammography(Chapter K)

& "ee also ,P-. Report K9 ?%he commissioningand routine testing of mammographic #$ray

systems@ and the latest B"G"P reports

& B"G"P -3uipment Report 7J7; for full fielddigital testing

& Lots of testing re3uired

* Radiographer testing daily2 %ee>ly2 monthly

* Physics testing e$ery J months


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.ammography(Chapter K)

& -+ample tests include= * Processing2 %here applica0le

* A-C


* ,mage 3uality %ith test phantoms

* .ED to standard 0reast

* ray 0eam alignment

* Compression force

* > accuracy (specific cali0rations)

* niformity

* Radiation output repeata0ilityHreproduci0ility

* And much more<


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Dental Radiography(Chapter 9)

& Processing tests * emperature2 solutions2 step

%edge2 light proofing

& '(ray)detector tests * u0e $oltage2 e+posure time2collimation2 dose at collimator tip

for ,#2 DAP for #PE2 detector

condition2 clinical image 3uality

compared %ith reference


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Fluoroscopy(Chapter /7)

& Level

* Dose rate reproduci0ility under AGCHA-C

* Display monitor setup


* hreshold contrast

* RadiationHimage field siIe


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Fluoroscopy(Chapter /7)

& Level #

* Dose rate at the entrance surface of a

phantom under AGCHA-C

* Dose rate at the input face of the detectorunder AGCHA-C


* hreshold contrast


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Fluorography(Chapter //)

& Level

* Dose per image under A-C


* hreshold contrast


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Fluorography(Chapter //)

& Level #

* Dose per image at the input face of the

detector under A-C

* Limiting spatial resolution * hreshold contrast

* Dynamic range


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Patient dose measurements(Chapter /)

& Perform dose audits and)or Q measurements * ,ndi$idual radiographic e+posures

& -ntrance surface dose or DAP M Diagnostic Reference Le$els (DRLs)

* Complete e+aminations

& DAP M DRLs

* .ammography& .ED to standard 0reast M6 mEy per film

& .ED to patients M mEy per film

* Dental Radiography& ,# dose at collimator tip M DRL

& #PE dose M DRL

* Fluoroscopy& Dose at entrance surface of phantom M 7 mEyHmin

& DAP M DRL


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C(Chapter /6)

& Craig to co$er<


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QA is important 0ecause<

& QA is important 0ecause< * Can identify e3uipment deterioration

* Can 0e used to achie$e ALARP

*-nsures patient (and staff) safety

* -nsures legislati$e compliance

& Final thought<

* Although it@s not your responsi0ility to chec>

e3uipment2 you should ensure that the ray sets you

use ha$e 0een chec>ed for your o%n safety2 as %ell

as the patient@s

h l f . di l Ph i i


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he role of .edical Physics in


& Q * Le$el G tests * Ad$ising on QA programme and monitoring performance

& !adiation protection and physics advice

*!P)&P+, * -nsuring compliance %ith rele$ant regulations eg ris>

assessments2 controlled areas2 dose monitoring2 etc * ,RR and ,R(.-)R audits * ma>e sure %e@re ready if the

inspector calls

* Be% installations shielding2 testing2 etc * Botification of incidents to the CQC2 "-2 -A2 Police2 etc

& +ducation * FRCR2 pdate raining2 etc

h l f . di l Ph i i


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he role of .edical Physics in


& -ptimisation * !e aren@t 1ust here to interfere and police the

regulations

* "ignificant part of the Radiation Physics groups %or>

is loo>ing at ho% %e can get the most out of our ray

imaging systems

* Rely on feed0ac> and cooperation from Radiology to

ensure %e are optimising e+posures

* !e@re here to help<


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Recent pu0lications

& #eavis2 . "aunderson2 N !ard 2!-EGRA7J: Cali0rating an ,onisation Cham0er: Eaining -+perience sing a Dosimetry ?flight "imulator@2 .ed Phys 92 987 (67/6)

& /" &oore2 E A$ery2 " Galcam2 L Beedler2 A "%ift2 0 #eavis1 .!"aunderson 2 se of a digitally reconstructed radiograph 0ased computersimulation for the optimisation of chest radiographic techni3ues for

computed radiography imaging systems 2 Gr N Radiol 67/6=K eJ7eJ9& T. 0ood1 0 2avis1 /" &oore1 0 #eavis 3 .! "aunderson 2

alidation of a Large"cale Audit echni3ue for C Dose #ptimisation 2Radiat Prot Dosimetry (67/6) /7(;): ;68;

& /" &oore1 4P Liney1 0 #eavis1 .! "aunderson2 A method to produceand $alidate a digitally reconstructed radiograph0ased computer simulationfor optimisation of chest radiographs ac3uired %ith a computed radiography

imaging system2 Gritish Nournal of Radiology2 K; (67//)2 K97976& &L 0ilson1 0P /olley 3 0 #eavis 2 he effect of the car0on fi0re insert

for the arian -+actO couch on the attenuation and 0uildup of high energyphoton 0eams2 Nournal of Radiotherapy in Practice (67//) /72 88K

http://www.aapm.org/meetings/2012AM/PRAbs.asp?mid=68&aid=18282http://www.aapm.org/meetings/2012AM/PRAbs.asp?mid=68&aid=18282http://online.medphys.org/resource/1/mphya6/v39/i6/p3970_s2?isAuthorized=nohttp://online.medphys.org/resource/1/mphya6/v39/i6/p3970_s2?isAuthorized=nohttp://bjr.birjournals.org/content/85/1017/e630.abstracthttp://bjr.birjournals.org/content/85/1017/e630.abstracthttp://bjr.birjournals.org/content/85/1017/e630.abstracthttp://rpd.oxfordjournals.org/content/150/4/427.abstracthttp://rpd.oxfordjournals.org/content/150/4/427.abstracthttp://bjr.birjournals.org/cgi/content/abstract/84/1006/890http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8316032&fulltextType=RA&fileId=S1460396910000373http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8316032&fulltextType=RA&fileId=S1460396910000373http://bjr.birjournals.org/cgi/content/abstract/84/1006/890http://rpd.oxfordjournals.org/content/150/4/427.abstracthttp://rpd.oxfordjournals.org/content/150/4/427.abstracthttp://bjr.birjournals.org/content/85/1017/e630.abstracthttp://bjr.birjournals.org/content/85/1017/e630.abstracthttp://bjr.birjournals.org/content/85/1017/e630.abstracthttp://online.medphys.org/resource/1/mphya6/v39/i6/p3970_s2?isAuthorized=nohttp://www.aapm.org/meetings/2012AM/PRAbs.asp?mid=68&aid=18282http://www.aapm.org/meetings/2012AM/PRAbs.asp?mid=68&aid=18282


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Current Pro1ects

& Further de$elopment of our dose audit soft%are

& C A-C optimisation %ith a custom 0uilt phantom

& De$elopment of a high s>in dose reporting system

for inter$entional procedures& De$elopment of a ne% test o01ect for routine

image 3uality assessment in digital

mammography

& And many more< %%%hullradorgu>
http://www.hullrad.org.uk/http://www.hullrad.org.uk/

lecture 9 - quality assurance

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