task group 142 report: quality assurance of medical ... · accessory trays (i.e. port film graticle...

Chris Serago, Ph.D.Chris Serago, Ph.D.

TG 142 memberTG 142 member

Task Group 142 report: Qualityassurance of medical accelerators

2009

Many slides are borrowed from Eric Klein

2010 ACMP Annual MeetingSan Antonio, Texas

Task Group 142 report:Quality assurance of medical accelerators

Eric E. Klein, ChairWashington UniversityJoseph Hanley John BayouthHackensack University Medical Center University of IowaFang-Fang Yin William SimonDuke University Sun Nuclear Corp.Sean Dresser Christopher SeragoNorthside Hospital Mayo ClinicFrancisco Aguirre Lijun MaM. D. Anderson Cancer Center University of California, San FranciscoBijan Arjomandy Chihray LiuM. D. Anderson Cancer Center University of FloridaConsultants:Carlos Sandin Todd HolmesElekta Oncology Varian Medical Systems

Task Group ChargeTask Group Charge

Charge:Charge: 1. To update, as needed, recommendations of Table 11 of the1. To update, as needed, recommendations of Table 11 of theAAPM TGAAPM TG--40 (1994) Report on Quality Assurance. 2. To add40 (1994) Report on Quality Assurance. 2. To addrecommendations for asymmetric jaws,recommendations for asymmetric jaws, multileafmultileaf collimation, andcollimation, anddynamic/virtual wedges.dynamic/virtual wedges.

New Technology since TG 40New Technology since TG 40MLC, Asymmetric Jaws, Dynamic & virtual wedgesMLC, Asymmetric Jaws, Dynamic & virtual wedgesEPIDsEPIDsImaging: kV and cone beamImaging: kV and cone beamRespiratory gatingRespiratory gating

Clinical procedures not emphasized in TG 40Clinical procedures not emphasized in TG 40SRS, SBRT, TBI, IMRTSRS, SBRT, TBI, IMRT

Refinements to linear accelerators since TG 40Refinements to linear accelerators since TG 40

Since TG 40 (1994)Since TG 40 (1994)

TG 50: AAPM REPORT NO. 72, Basic applicationsof multileaf collimators (2001)

TG 58: AAPM REPORT No. 75, Clinical use of electronicportal imaging: (2001)

TG 76: AAPM REPORT No. 91, The management ofrespiratory motion in radiation oncology (2006)

TG 106: Accelerator beam data commissioning equipmentand procedures: A suggested protocol (2008)

TG 104: AAPM REPORT No. 104, The role of in-room kV x-ray imaging for patient setup and target localization(2009)

TG 100: Method for evaluating QA needs in radiationtherapy (Future date??)

Background to TG 142Background to TG 142

The underlying principle behind TGThe underlying principle behind TG--40 was the International40 was the International

Commission on Radiation Units and MeasurementsCommission on Radiation Units and Measurements

(ICRU) recommendation that the dose delivered to the patient(ICRU) recommendation that the dose delivered to the patient

be withinbe within ++5% of the prescribed dose.5% of the prescribed dose.

Taking into consideration the many steps involved in deliveringTaking into consideration the many steps involved in delivering dose todose toa target volume in a patient, each step must be performed witha target volume in a patient, each step must be performed with

accuracy better than 5% to achieve this recommendation.accuracy better than 5% to achieve this recommendation.

The goal of a QA program for linear accelerators is to assure thThe goal of a QA program for linear accelerators is to assure that theat themachine characteristics do not deviate significantly from theirmachine characteristics do not deviate significantly from theirbaseline values acquired at the time of acceptance andbaseline values acquired at the time of acceptance andcommissioning.commissioning.

Linac QA TGLinac QA TG--40 (1994)40 (1994)

Daily

TG 40 Monthly

TG 40 Annually

MLC QA per TG-50 (2001)

TG-58 (EPIDs) (2001)

TheThe Resource ProblemResource Problem

Lack of adequate guidance for resourceLack of adequate guidance for resourceallocationallocation

Lack of qualified personnelLack of qualified personnel

Rapid implementation of new technologyRapid implementation of new technology

–– More sophisticated equipmentMore sophisticated equipment

–– More resourcesMore resources

–– Clinics are under pressure toClinics are under pressure toimplement new technologyimplement new technology

Lack of timely guidelinesLack of timely guidelines

Task Group No. 100: Method for Evaluating QA Needs inTask Group No. 100: Method for Evaluating QA Needs inRadiation TherapyRadiation Therapy

InitiallyInitially ““ReplacementReplacement for TGfor TG--4040””

New approach compared to previous AAPMNew approach compared to previous AAPMrecommendations and philosophyrecommendations and philosophy

Based onBased on ““Failure Modes and EffectsFailure Modes and EffectsAnalysisAnalysis””

IndividualIndividual departments responsible fordepartments responsible fordevelopment of unique QA programsdevelopment of unique QA programs

Based on procedures and resourcesBased on procedures and resourcesperformed at individual institutionsperformed at individual institutions

Failure Modes and Effects AnalysisFailure Modes and Effects Analysis

Three part systemThree part system

–– Frequency of errorFrequency of error

–– Severity of errorSeverity of error

–– Probability that an error would be detectedProbability that an error would be detected

Probability ofProbability oferrorerror

SeveritySeverity Probability ofProbability ofdetectiondetection

RPNRPN

AA BB CC A*B*CA*B*C

Risk Priority Number (RPN) = Frequency*Severity*Probability

Proposed Quality AssuranceProposed Quality AssuranceProcessProcess

Custom designed QA programsCustom designed QA programs

AAPM Report will provide templatesAAPM Report will provide templates

Scoring performed by individual departmentsScoring performed by individual departments

Tolerances set by individual departmentsTolerances set by individual departments

Annual evaluation and modifications basedAnnual evaluation and modifications basedon score changeson score changes

Task Group No. 142:Task Group No. 142:

QA of Medical AcceleratorsQA of Medical AcceleratorsI. INTRODUCTIONI. INTRODUCTIONA. PurposeA. PurposeB. BackgroundB. Background

II. QUALITY ASSURANCE OF MEDICAL ACCELERATORSII. QUALITY ASSURANCE OF MEDICAL ACCELERATORSA. GeneralA. GeneralB. Test FrequenciesB. Test FrequenciesC. Guidelines for Tolerance ValuesC. Guidelines for Tolerance ValuesD. Ancillary Devices Not in TGD. Ancillary Devices Not in TG--4040

Asymmetric JawsAsymmetric JawsDynamic/Virtual/Universal WedgesDynamic/Virtual/Universal WedgesMLCMLCTBI/TSETTBI/TSETRadiographic ImagingRadiographic Imaging

Megavoltage Planar Imaging (Portal Imagers)Megavoltage Planar Imaging (Portal Imagers)Planar kV ImagingPlanar kV ImagingSerial and ConeSerial and Cone--Beam CTBeam CT

Respiratory GatingRespiratory Gating

III. SUMMARY OF RECOMMENDATIONS/IMPLEMENTATION SCHEMEIII. SUMMARY OF RECOMMENDATIONS/IMPLEMENTATION SCHEME

BACKGROUNDBACKGROUNDBaseline values are entered into treatment planning systems toBaseline values are entered into treatment planning systems tocharacterize and/or model the treatment machine, and therefore ccharacterize and/or model the treatment machine, and therefore canandirectly affect treatment plans calculated for every patient tredirectly affect treatment plans calculated for every patient treated onated onthat machinethat machine

Machine parameters can deviate from their baseline values as a rMachine parameters can deviate from their baseline values as a resultesultof many reasonsof many reasons

–– Machine malfunctionMachine malfunction

–– Mechanical breakdownMechanical breakdown

–– Physical accidentsPhysical accidents

–– Component failureComponent failure

–– Major component replacementMajor component replacement

–– Gradual changes as a result of agingGradual changes as a result of aging

These patterns of failure must be considered when establishing aThese patterns of failure must be considered when establishing aperiodic QA programperiodic QA program

QA of MEDICAL ACCELERATORSQA of MEDICAL ACCELERATORSWhat This Report DoesnWhat This Report Doesn’’t Dot Do–– Describe the techniques for performing QA testsDescribe the techniques for performing QA tests (TG 198)(TG 198)

–– Accelerator beam data commissioning equipment and proceduresAccelerator beam data commissioning equipment and procedures ––TGTG--106106

–– QA for TomoTherapyQA for TomoTherapy ––TGTG--148148

–– QA for Robotic RadiosurgeryQA for Robotic Radiosurgery –– TGTG--135135

–– QA for NonQA for Non--Radiographic Radiotherapy Localization & PositioningRadiographic Radiotherapy Localization & PositioningSystemsSystems –– TGTG--147147

Does add Specific Recommendations / Supplements theDoes add Specific Recommendations / Supplements theWork ofWork of–– Basic Applications of Multileaf CollimatorsBasic Applications of Multileaf Collimators –– TGTG--5050

–– Clinical use of electronic portal imagingClinical use of electronic portal imaging -- TGTG--5858

–– Management of Respiratory MotionManagement of Respiratory Motion–– TGTG--7676

–– Kilovoltage localization in therapyKilovoltage localization in therapy –– TGTG--104104

TG198TG198 -- An implementation guide for TGAn implementation guide for TG--142: QA of medical linear accelerators142: QA of medical linear accelerators

1)1) Provide specific procedural guidelines forProvide specific procedural guidelines forperforming the tests recommended in TGperforming the tests recommended in TG--142.142.

2)2) Provide estimate of the range of times,Provide estimate of the range of times,appropriate personnel and qualificationsappropriate personnel and qualificationsnecessary to complete the tests in TGnecessary to complete the tests in TG--142. 3)142. 3)Provide Sample Daily/Weekly/Monthly/AnnualProvide Sample Daily/Weekly/Monthly/AnnualQA forms.QA forms.

Task Group No. 142:Task Group No. 142:QA of Medical AcceleratorsQA of Medical Accelerators

“The recommendations of this task group are notintended to be used as regulations. Theserecommendations are guidelines for qualified medicalphysicists (QMP) to use and appropriately interpret fortheir individual institution and clinical setting. Eachinstitution may have site-specific or state mandatedneeds and requirements which may modify their usageof these recommendations.”

Task Group No. 142:Task Group No. 142:Guidelines for Tolerance ValuesGuidelines for Tolerance Values

The recommendations of TGThe recommendations of TG--142 should be142 should beflexible enough to take into account quality,flexible enough to take into account quality,costs, equipment condition, available testcosts, equipment condition, available testequipment, and institutional needs.equipment, and institutional needs.We do recommend using the tests andWe do recommend using the tests andfrequencies outlined in the tables that follow,frequencies outlined in the tables that follow,until methods such as TGuntil methods such as TG--100 supersede this100 supersede this

report.report.

Task Group No. 142: GeneralTask Group No. 142: General

AA Consistent beamConsistent beam profileprofile is an importantis an importantquantity for accurate and reproducible dosequantity for accurate and reproducible dosedelivery in radiotherapy.delivery in radiotherapy.In our tables, the monthly tolerance values areIn our tables, the monthly tolerance values arespecific to a consistent beam shape, wherebyspecific to a consistent beam shape, wherebybaseline off axis factors were measured with abaseline off axis factors were measured with aQA device immediately followingQA device immediately followingcommissioning or annual data.commissioning or annual data.Ongoing QA measurements are compared to theOngoing QA measurements are compared to thebaseline off axis factors.baseline off axis factors.

Task Group No. 142: GeneralTask Group No. 142: General

Chosen O.A. point locations will generally fall within core oChosen O.A. point locations will generally fall within core of the fieldf the field

where:where: TPTPLL andand BPBPLL are offare off--axis ratios at Test and Baseline Points,axis ratios at Test and Baseline Points,respectively, at off axis Point Lrespectively, at off axis Point LN is the number of offN is the number of off--axis pointsaxis pointsTPL = (TPL = (MPMPLL//MPMPCC) where M represents the measurement value and C) where M represents the measurement value and Cis the central axis measurement.is the central axis measurement.Similarly, the baseline points are represented bySimilarly, the baseline points are represented by BPBPLL ==((MBPMBPLL//MBPMBPCC))

1

1100% %

NL L

L L

TP BPTolerance

N BP=

−⋅ ⋅ ≤∑

Task Group No. 142:Task Group No. 142:QA of Medical AcceleratorsQA of Medical Accelerators

The types of treatments delivered with the machineThe types of treatments delivered with the machineshould also have a role in determining the QAshould also have a role in determining the QAprogram that is appropriate for that treatmentprogram that is appropriate for that treatmentmachine.machine.

For example, machines that are used for SRS/SBRTFor example, machines that are used for SRS/SBRTtreatments, TBI or IMRT require different tests and/ortreatments, TBI or IMRT require different tests and/ortolerances.tolerances.

Task Group No. 142:Task Group No. 142:Test FrequenciesTest Frequencies

In this report there are additional factors that affect theIn this report there are additional factors that affect thefrequency of the tests, specifically: the type offrequency of the tests, specifically: the type oftreatments delivered on the machine; and thetreatments delivered on the machine; and themanufacturer of the machine.manufacturer of the machine.

For example, electron output is to be tested moreFor example, electron output is to be tested morefrequently on a Siemens machine which possesses anfrequently on a Siemens machine which possesses anelectron beam specific, unsealed monitor chamberelectron beam specific, unsealed monitor chambersystem,system, compared to the Varian machine with a multicompared to the Varian machine with a multi--modality sealed monitor chamber.modality sealed monitor chamber.

Task Group No. 142:Task Group No. 142:Guidelines for Tolerance ValuesGuidelines for Tolerance Values

Acceptance Testing Procedure (ATP) StandardsAcceptance Testing Procedure (ATP) Standards–– Acceptance testing sets theAcceptance testing sets the baselinebaseline for future dosimetricfor future dosimetric

measurements for beam performancemeasurements for beam performance constancyconstancy, verifies, verifiesthat the equipment is mechanically functional and operatesthat the equipment is mechanically functional and operateswithin certain tolerances from absolute specified values.within certain tolerances from absolute specified values.

Tolerances and Action LevelsTolerances and Action Levels–– Level 1Level 1 –– Inspection ActionInspection Action–– Level 2Level 2 –– Scheduled ActionScheduled Action–– Level 3Level 3 –– Immediate Action or Stop Treatment Action orImmediate Action or Stop Treatment Action or

Corrective ActionCorrective Action

With these 3 action levels, there is an institutional need to spWith these 3 action levels, there is an institutional need to specifyecifythe thresholds associated with Levels 2 and 3. Level 1 thresholdthe thresholds associated with Levels 2 and 3. Level 1 thresholdisnisn’’t a critical requirement but can lead to improvements in thet a critical requirement but can lead to improvements in theQA program.QA program.

TGTG--142: Daily142: Daily

ProcedureTolerance (non-IMRT machines)

Tolerance (IMRTmachines)

Tolerance(Stereotactic

machines)

Dosimetry

X-ray output constancy (all energies)

Electron output constancy (Weekly, exceptfor machines with unique e- monitoringrequiring daily)

3%

Mechanical

Laser localization 2 mm 1.5 mm 1 mm

Distance indicator (ODI)@ iso 2 mm 2 mm 2 mm

Collimator size indicator 2 mm 2 mm 1 mm

Safety

Door interlock (beam off) Functional

Door closing safety Functional

Audiovisual monitor(s) Functional

Stereotactic interlocks (lockout) NA NA Functional

Radiation area monitor (if used) Functional

Beam on indicator Functional

DailyDaily

ProcedureTolerance (non-IMRT machines)


Tolerance(Stereotactic

machines)

Dosimetry

X-ray output constancy (all energies)

Electron output constancy (Weekly, exceptfor machines with unique e- monitoringrequiring daily)

3%

Mechanical

Laser localization 2 mm 1.5 mm 1 mm

Distance indicator (ODI)@ iso 2 mm 2 mm 2 mm

Collimator size indicator 2 mm 2 mm 1 mm

Safety

Door interlock (beam off) Functional

Door closing safety Functional

Audiovisual monitor(s) Functional

Stereotactic interlocks (lockout) NA NA Functional

Radiation area monitor (if used) Functional

Beam on indicator Functional

TGTG--142: Monthly142: Monthly

ProcedureTolerance (non-

IMRT machines)Tolerance (IMRT

machines)Tolerance

Stereotactic machines

DosimetryX-ray output constancy

Electron output constancy

Backup monitor chamber constancy

2%

Typical dose rate2 output constancy NA2% (@ IMRT dose

rate)2% (@ stereo dose

rate, MU)

Photon beam profile constancy

Electron beam profile constancy1%

Electron beam energy constancy 2%/2mm

MonthlyMonthly

MechanicalLight/radiation field coincidence* 2 mm or 1% on a side

Light/radiation field coincidence*(Asymmetric) 1 mm or 1% on a side

Distance check device used for lasers/ODI (vs.front pointer) 1mmGantry/collimator angle indicators (@ cardinalangles) (Digital only) 1.0 deg

Accessory trays (i.e. Port film graticle tray) 2 mm

Jaw position indicators (Symmetric)3 2 mm

Jaw position indicators (Asymmetric)1 1 mm

Cross-hair centering (walk-out) 1 mm

Treatment couch position indicators4 2 mm/1 deg 2 mm/ 1 deg 1 mm/ 0.5 deg

Wedge placement accuracy 2mm

Latching of wedges, blocking tray5 Functional5

Localizing lasers ±2 mm ±1 mm <±1 mm

ProcedureProcedureTolerance (nonTolerance (non--

IMRTIMRTmachines)machines)

Tolerance (IMRTTolerance (IMRTmachines)machines)

ToleranceToleranceStereotacticStereotactic

machinesmachines

MonthlyMonthly





machinesmachines

MonthlyMonthly





machinesmachines

Respiratory gating

Beam output constancy 2%

Phase, Amplitude beam control Functional

In room respiratory monitoring system Functional

Gating interlock Functional

TGTG--142: Annual142: AnnualProcedure

Tolerance (non-IMRT machines)


ToleranceStereotactic

machines

Dosimetry

X-ray flatness change from baseline 1%

X-ray symmetry change from baseline ±1%

Electron flatness change from baseline 1%

Electron symmetry change from baseline ±1%

Monitor units set vs.delivered:1.0 MU or

2% (whichever isgreater)SRS Arc rotation mode (range: 0.5 to 10

MU/deg )NA NA

Gantry arc set vs.delivered: 1.0 deg or

2% (whichever isgreater)

X-ray/electron output calibration (TG-51) ±1%(absolute)

Spot check of field size dependent outputfactors for X-ray (2 or more FS)

2% for field size < 4x4 cm2, 1% ≥4x4 cm2

Output factors for electron applicators(spot check of 1 applicator/energy)

±2% from baseline

X-ray beam quality (PDD10, TMR1020) ±1% from baseline

Electron beam quality (R50) ±1mm

Transmission factor constancy for alltreatment accessories

±1% from baseline

Physical wedge transmission factorconstancy

±2%

AnnualAnnualProcedureProcedure

Tolerance (nonTolerance (non--IMRTIMRT

machines)machines)



machinesmachines

X-ray monitor unit linearity [output .constancy ]

±2% ≥5MU±5% (2-4 MU), ±2%

≥5MU±5% (2-4), ±2%

≥5MU

Electron monitor unit linearity [output .constancy ]

±2% ≥5MU

X-ray output constancy vs dose rate ±2% from baseline

X-ray output constancy vs gantry angle ±1% from baseline

Electron output constancy vs gantryangle

±1% from baseline

Electron and X-ray Off-axis factorconstancy vs gantry angle

±1% from baseline

Arc mode (expected MU, degrees) ±1% from baseline

TBI/TSET Mode Functional

PDD or TMR and OAF constancy 1% (TBI) or 1mm PDD shift (TSET) from baseline

TBI/TSET Output calibration 2% from baseline

TBI/TSET accessories 2% from baseline

AnnualAnnualProcedureProcedure

Tolerance (nonTolerance (non--IMRTIMRT

machines)machines)



machinesmachines

MechanicalCollimator rotation isocenter ±1 mm from baseline

Gantry rotation isocenter ±1 mm from baseline

Couch rotation isocenter ±1 mm from baseline

Electron applicator interlocks Functional

Coincidence of radiation and mechanicalisocenter

±2mm frombaseline

±2mm from baseline ±1mm from baseline

Table top sag 2mm from baseline

Table Angle 1 degree

Table travel maximum range movementin all directions

±2mm

Stereotactic accessories, lockouts, etc NA Functional

SafetyFollow manufacturers test procedures Functional

Respiratory gatingBeam energy constancy 2%Temporal accuracy of Phase/AmplitudeGate-on

100 ms of expected

Calibration of surrogate for respiratoryphase/amplitude

100 ms of expected

Interlock testing Functional

Dynamic/Universal/Virtual WedgesDynamic/Universal/Virtual Wedges

Dynamic-incl. EDW (Varian), Virtual (Siemens), Universal (Elekta) Wedge quality assurance

ToleranceFrequency Procedure

Dynamic Universal Virtual

DailyMorning Check-out

run for 1 angleFunctional

MonthlyWedge factor for

all energies

C.A.Axis 45ºor 60°WF

(within2%)*

C.A. Axis45º or 60°

WF(within2%)*

5% fromunity,

otherwise2%

Annual

Check of wedgeangle for 60°, fullfield & spot checkfor intermediateangle, field size

Check of Off-center ratios @ 80%field width @ 10cm to be within

2%

* Recommendation to check 45º if angles other than 60º are used.

Multileaf CollimationMultileaf CollimationMulti-leaf collimation quality assurance (with differentiation of IMRT vs. non-IMRT machines)

Frequency Procedure Tolerance

Weekly (IMRT machines)Qualitative test (i.e. matched

segments, aka, “picket fence”)

Visual inspection for discernabledeviations such as an increase in

interleaf trransmission

Setting vs. radiation field fortwo patterns (non-IMRT)

2mm

Backup diaphragm settings(Elekta only)

2mm

Travel speed (IMRT) Loss of leaf speed > 0.5 cm/secMonthly

Leaf position accuracy (IMRT)

1mm for leaf positions of anIMRT field for 4 cardinal gantryangles. (Picket fence test may be

used, test depends on clinicalplanning – segment size)

Multileaf CollimationMultileaf Collimation: Annual Tests: Annual Tests

MLC Transmission (Average of leaf andinterleaf transmission), All Energies ±0.5% from baseline

Leaf position repeatability ±1.0 mm

MLC spoke shot ≤1.0 mm radius

Coincidence of Light Field and X-ray Field(All energies) ±2.0 mm

Arc dynamic leaf-speed test <0.35 cm Max Error RMS, 95% of errorcounts <0.35 cm (Varian)

Arc dynamic interlock trip test Leaf position interlock occurs (Varian)

Arc dynamic typical plan test <0.35 cm Max Error RMS, 95% of errorcounts <0.35 cm (Varian)

Segmental IMRT (Step and Shoot) Test <0.35 cm Max Error RMS, 95% of errorcounts <0.35 cm (Varian)

Moving window imrt (4 cardinal gantryangles)

<0.35 cm Max Error RMS, 95% of errorcounts <0.35 cm (Varian)

Imaging Tests: DailyImaging Tests: Daily

Procedure Non-SRS/SBRT ApplicationsTolerances

SRS/SBRT ApplicationsTolerances

Daily

MV imaging (EPID)

Collision interlocks Functional Functional

Spatial linearity1 (x and y) (single gantryangle)

< 2 mm ≤ 1 mm

Imaging & Treatment coordinatecoincidence (single gantry angle)

< 2 mm ≤ 1 mm

Positioning/repositioning < 2 mm ≤ 1 mm

KV imaging2


Imaging & treatment coordinatecoincidence

< 2 mm ≤ 1 mm


Cone-beam CT (kV & MV)



Imaging Tests: MonthlyImaging Tests: MonthlyProcedure

Non-SRS/SBRTApplications Tolerances


MV imaging (EPID)

Imaging & treatment coordinatecoincidence (4 Cardinal angles)

< 2 mm ≤ 1 mm

Scaling3 < 2 mm < 2 mm

Spatial resolution Baseline4 Baseline

Contrast Baseline Baseline

Uniformity and noise Baseline BaselinekV imaging

Imaging & treatment coordinatecoincidence (4 Cardinal angles)

< 2 mm ≤ 1 mm

Scaling < 2 mm ≤ 1 mm

Spatial linearity (x and y) (single gantryangle)

< 2 mm ≤ 1 mm

Spatial resolution Baseline Baseline


Uniformity and noise Baseline BaselineCone-beam CT (kV & MV)

Imaging & treatment coordinatecoincidence

< 1.5 mm ≤ 1 mm

Geometric distortion < 2 mm ≤ 1 mm

Spatial resolution Baseline Baseline


HU constancy Baseline Baseline

Uniformity and noise Baseline Baseline

Spatial linearity (x and y) (single gantryangle)

< 1 mm ≤ 1 mm

Imaging Tests: AnnualImaging Tests: Annual

Procedure Non-SRS/SBRTApplications Tolerances


MV imaging (EPID)

Full range of travel SDD ±5 mm ±5 mm

Imaging dose5 Baseline Baseline

Beam quality / energy Baseline BaselinekV imaging

Beam quality / energy Baseline Baseline

Imaging dose Baseline Baseline

Cone-beam CT (kV & MV)

Imaging dose Baseline Baseline

SUMMARY OF RECOMMENDATIONS/SUMMARY OF RECOMMENDATIONS/IMPLEMENTATION SCHEMEIMPLEMENTATION SCHEME

The tabulated items of this report have been considerablyexpanded as compared with the original TG 40 report andthe recommended tolerances accommodate differencesin the intended use of the machine functionality (non-IMRT, IMRT, and Stereotactic Delivery).


1) A QA team support all QA activities and draft policiesand procedures. The policy should establish roles andresponsibilities. For QA measurements, detailedinstructions on equipment use, cross-calibration,measurement frequency, and documentation of theresults should be provided.

2) The 1st step is to establish institution-specific baselineand absolute reference values. The QA team needs tomeet and monitor the results against the establishedvalues.


3) A QMP should lead the QA team. The QMP providesaction level and methods of notification when tolerancesare exceeded.

4) Daily QA tasks may be carried out by a RTT using across-calibrated dosimetry system that is robust andeasy-to-setup. Correction factors should be documentedin a permanent electronic or hardcopy format forinspection purposes. The QMP should review and sign offon the reports at least once per month.


5) Monthly tasks should be performed by (or directlysupervised by) a QMP. It is recognized there is overlap oftests for daily, monthly, and annual. This overlap shouldhave independence achieved with independentmeasurement devices. This will identify trends that may goundetected.

6) It is recommended annual measurements be performed bya QMP. QA devices should be checked prior tomeasurements. The measurements should be carried outusing commissioning quality equipment as recommendedthe TG-106 report.


7) End-to-end system checks ensure fidelity of overallsystem. This can be done by creating plans typical of thefacility’s clinic, transferring the plan data across the datanetwork, and delivering them.

8) During the annual QA, absolute outputs should becalibrated as per TG51. Subsequently, all secondary QAdosimeters should be cross-checked against suchcalibrations.


Upon completion of the measurements, an annual QAreport be generated. The report should statesignificant findings based on tolerance values. Thereport can be divided into sections; (1) Dosimetry,(2) Mechanical, (3) Safety, (4) Imaging, and (5)Special Devices/Procedures. The QA report shouldbe signed and reviewed by the QMP and filed forfuture machine maintenance and inspection needs.

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