AAPM TG 135 ：射波刀的QA验证.docx

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1、Report of AAPM TG 135: Quality assurance for robotic radiosurgerySonja DieterichStanford University Cancer Center, Stanford, California 94305Carlo CavedonAzienda Ospedaliera Universitaria Integrata di Verona, U.O. di Fisica Sanitaria, Verona, 37126 ItalyCynthia F. ChuangUniversityof CaliforniaSan Fr

2、ancisco,Departmentof RadiationOncology,San Francisco,California94143-0226Alan B. CohenAccuray Inc, Sunnyvale, California 94089Jeffrey A. GarrettMississippi Baptist Medical Center, Jackson, Mississippi 39202Charles L. LeeCK Solutions, Inc., Edmond, Oklahoma 73034Jessica R. LowensteinUT MD Anderson Ca

3、ncer Center, Houston, Texas 77030Maximian F. dSouzaSt Anthony Hospital, Oklahoma City, Oklahoma 73101David D. TaylorJr.US Radiosurgery, Nashville, Tennessee 80304Xiaodong WuUniversity of Miami, Department of Radiation Oncology, Miami, Florida 33101Cheng YuUSC Keck School of Medicine, Los Angeles, Ca

4、lifornia 90033(Received 31 August 2010; revised 18 February 2011; accepted for publication 28 February 2011;published 25 May 2011)The task group (TG) for quality assurance for robotic radiosurgery was formed by the AmericanAssociation of Physicists in Medicines Science Council under the direction of

5、 the Radiation Ther-apy Committee and the Quality Assurance (QA) Subcommittee. The task group (TG-135) had threemain charges: (1) To make recommendations on a code of practice for Robotic Radiosurgery QA;(2) To make recommendations on quality assurance and dosimetric verification techniques, espe-ci

6、ally in regard to real-time respiratory motion tracking software; (3) To make recommendations onissues which require further research and development. This report provides a general functionaloverview oftheonlyclinicallyimplemented robotic radiosurgery device,theCyberKnifeVR. Thisreport includes sec

7、tions on device components and their individual component QA recommenda-tions, followed by a section on the QA requirements for integrated systems. Examples of checklistsfor daily, monthly,annual, andupgradeQA aregivenas guidancefor medical physicists. Areas inwhich QA procedures arestillunder devel

8、opment are discussed.VC2011AmericanAssociationofPhysicists in Medicine. DOI: 10.1118/1.3579139Key words: quality assurance, stereotactic radiosurgery, radiation therapy, robotic radiosurgeryTABLE OF CONTENTSI. INTRODUCTION .I.A. Structure of report.I.B. Record-keeping .I.C. Glossary .II. QA FOR INDI

9、VIDUAL SYSTEMCOMPONENTS .II.A. Robot and room safety .II.A.1. Mechanical safety and collisionavoidance.II.A.2. Ancillary safety systems.29152915291629162917291729172917II.A.3. Room shielding and radiation safety.II.B. Accelerator QA .II.B.1. Daily accelerator QA.II.B.2. Monthly accelerator QA .II.B.

10、3. Annual accelerator QA .II.C. Imaging subsystem .Imaging geometry.X-ray generator and sources.Amorphous silicon detectors.Patient dose due to image guidance .II.D. TreatmentplanningsoftwareQAand safety291829182918291929192920292029202921292229222914Med. Phys. 38 (6), June 20110094-2405/2011/38(6)/

11、2914/23/$30.00VC2011Am.Assoc.Phys.Med.2914Dieterich et al.: Report of AAPM TG 13529152915Medical Physics, Vol.38, No. 6, June 2011III. QA FOR INTEGRATED SYSTEMS.2924III.A. Tracking system (software and imaging).2924III.A.1. Targeting methods .2925III.A.2. Specific image guidance QA tests.2926III.A.3

12、. Practical implementation of imageguidance.2927III.B. Accuracy of radiation delivery (robot andaccelerator) .2928III.B.1. Manipulator and path calibration .2928III.B.2. Path calibration QA .2929III.C. Overall accuracy (all subsystems) .2929III.C.1. AQA test .2929III.C.2. Isocentric end-to-end (E2E)

13、 test.III.C.3. DQA plan.2930III.D. Motion tracking (synchrony) QA.2930III.E. General patient safety .2931IV. SUMMARY AND QA CHECKLISTS .2933IV.A. Summary.2933IV.B. Daily QA.2933IV.C. Monthly QA .2934IV.D. Annual QA .2934IV.E. Special considerations after upgrades .2934I. INTRODUCTIONFundamental to s

14、tereotactic radiosurgery (SRS) is the accu-rate placement of the intended radiation dose. Small errorsin the placement of radiation dose from individual beams orbeamlets can result in inaccurate estimates of accumulateddose as well as inaccurate estimates of the steepness andlocation of the high dos

15、e gradient regions that may bedesigned to protect adjacent critical structures and organs atrisk.The Accuray CyberKnifeVRRobotic Radiosurgery sys-tem13isat the timeof publicationtheonly robotic radiosur-gery device in clinical use. It consists of a compact x-bandlinear accelerator mounted on an indu

16、strial robotic manipu-lator arm. The manipulator arm is configured to direct theradiation beams to the region of beam intersection of two or-thogonal x-ray imaging systems integrated to provide imageguidance for the treatment process. The patient under treat-ment is positioned on an automated roboti

17、c couch such thatthe target to be treated is located within this radiation beamaccessible region. The movements of the robotic manipulatorarm and the robotic patient support assembly are under thedirect control of a computer system that is in turn controlledby the radiation therapist (during patient

18、 treatments) or themedicalphysicist(forqualityassurancemeasurementpurposes).Thetreatmentplanning system fortheCyberKnifeVRis de-vice-specific. It is an inverse planning system which uses lin-ear optimization to optimize the beam angle and beammonitor units (MU). The user selects the preconfigured tr

19、eat-ment path, collimator size, dose calculation algorithm (ray-tracing or Monte Carlo), and sets the dose constraints.Whilemost CyberKnifeVRtreatments are nonisocentric,there is a reference point in the room which serves as the ori-gin for several coordinate systems used within theCyberKnifeVRappli

20、cation, and to whichtherobot and imag-ing calibration is defined. This point in space is defined byan “isocrystal” which is mechanically mounted on the“isopost.” In this report, this point in space is defined asthe “geometric isocenter.” It must not be confused with the“treatment isocenter,” which r

21、efers to an isocentric treatmentto a target which may be located at a distance from the geo-metricisocenter.While asmall fraction of CyberKnifeVRtreatments are either isocentric or an overlay of isocentricshots of different collimator sizes, the majority of treatmentsare “nonisocentric.” This means

22、that beams are pointingaway from the geometric isocenter to create highly irregulartarget shapes that can contain surface concavities.This document will covertheaspects oftheCyberKnifeVRsystem that were well established at the time this report wentto review, and therefore excludes devices or softwar

23、e whichhad a very limited user base (e.g., IRISTMcollimator, Monte-Carlo dosecalculation,InTempoVC, and external phy- sicianworkstations).This report aims to define standards for an institutionalquality assurance (QA) protocol for robotic radiosurgery. Ef-ficacy and efficiency are key considerations

24、 in our process ofdeveloping the QA methodology. This report intends to giveguidelines on setting up a comprehensive quality assurance(QA) program for robotic radiosurgery systems to comple-ment the vendor guidelines. Acceptance testing and commis-sioning are outside the scope of this report; thisre

25、portfocuses on routine QA after commissioning and serves as asupplement to TG 142.4Each institution should develop a comprehensive QA pro-gram for their robotic radiosurgery program that is custom-ized to the unique nature of this treatment delivery system. Itis incumbent upon the physicist to devel

26、op and implementsuch a program, based on how the equipment is to be used.In this task, he/she should refer to professional guidelinessuch as this document, manufacturers recommendations,and the experience of other users. Any program must mini-mally meet state and federal regulatory requirements.In t

27、he following sections of this report, the wordsshallandmustare italicized to emphasize that they are being usedin the special sense conveyed by the definition given below.“Shall” and“must” are used when the activityis requiredby various regulatory agencies, or may be essential tomeet currently accep

28、ted standards.“Recommend” and “should” are used when the task groupexpects that the procedure should normally be followed asdescribed.However,equivalentprocesses,criteriaormethodologies may exist whichcanproducethesameresult.I.A.Structure of reportThis report is structured in five parts: an introduc

29、tion, twomajor parts discussing QA, a summary section including QAchecklists, and references. Section II is titled “QA for Indi-vidual System Components.” Each of the subsystems (robotand room, accelerator, imaging subsystem, and software)Dieterich et al.: Report of AAPM TG 13529162916Medical Physic

30、s, Vol.38, No. 6, June 2011will be described and QA recommendations developed. Sec-tionIII is titled“QA for IntegratedSystems.” Inthis sectionwe will discuss how the individual components are linkedand describe the QA to check the various links between sub-systems, leading to overall system QA. Sect

31、ion IV containstabulated checklists for daily, monthly, and annual QA, aswell as recommendations for special situations.I.B.Record-keepingIn the current environment, technology is rapidly evolv-ing. Hence, thorough quality assurance (QA) and qualitycontrol (QC) become an essential component in treat

32、ingpatients safely. With the arrival of new treatment techniquesand modalities it is very important that the new proceduresfor QA tests and QC are well documented. Good record-keeping5can increase work efficiency and reduce the risk ofmaking errors for newly implemented QA tests. It will alsomake it

33、 easier to compare the test results to previous testresults and ensures easy repeatability by multiple individu-als, thus limiting the potential for errors.For every QA test, there should be a written guidelinewhich clearly defines the objective, lists the action levels forthe test, and corrective a

34、ction(s) to be taken when these lev-els are exceeded. The QA guideline should include all testsnecessary to evaluate equipment safety, patient safety, andoverall treatment accuracy. In addition, the guideline mustalso meet state, federal, and/or any other regulatory agencyrequirements. It is essenti

35、al to keep either a handwritten re-cord or electronic record in a well-organized file. This filewill provide documentation for a site visit or a departmentaudit, as well as educate new personnel to the status andservice history of the equipment.A good record allows another physicist to come into acl

36、inic and completely understand what has been done previ-ously and to recreate the tests performed.6,7There should bea clear and concise description of each test. Theresultsshould be legible (if one is keeping paper copies) and shouldbe compared to data which is clinically relevant. The compar-ison s

37、hould clearly state if the result is or is not within therequired criteria level. If it is outside the criteria level then itshould clearly state what corrective action was taken, when,and by whom. Also, if the procedure has several differentaction levels (i.e., morning checks) it should clearly def

38、ineeach step and who should be notified at each of the differentaction levels. All documents should be dated and have alegible (if applicable, digital) signature of the person whocompleted the test. If a second check is made by anotherphysicist then it should be clearly signed and dated by thatphysi

39、cist.I.C.GlossaryAQA “Auto QA,” a Robot pointing test: The center-ing of a radiographic shadow of a 2 cm diame-ter tungsten ball hidden in a cubic phantom ismeasured on a pair of orthogonal films.CNRContrast-to-noise ratio.Code ofPractice:DQADRRE2EEMOEPOIGRTGeometricIsocenterTreatmentIsocenterIsocry

40、stalMCMTFMUOCRPDDQAQCSADSNRSRSTGTPRTPSA systematic collection of rules, standards, andother information relating to the practices andprocedures followed in an area.Delivery Quality Assurance: The DQA planis an overlay of a patient plan on a phantom.The plan is delivered and the measured dosein the p

41、hantom can be compared with thecalculated dose for quality assurance,typi-cally by using a gamma-index pass/fail crite-ria. The DQA assesses both spatial and dosi-metric accuracy of delivery, and is the mostcomprehensive,overallassessmentofthesystem.Digitally reconstructed radiograph.End-to-End test

42、. A phantom containing a hid-den target and orthogonal films is taken fromsimulation through treatment delivery. Thespatial distribution of delivered dose is com-pared to the plan dose for the 70% isodose line.The E2E test is performed using an isocentrictreatment plan. Its purpose is to be a more s

43、o-phisticated WinstonLutz test,8checking spa-tial delivery accuracy together with trackingmodality accuracy. Unlike the DQA test, theE2E does not have a patient-specific dosimetrycomponent.Emergency Motion Off.Emergency Power Off.Image-Guided Radiation Therapy.A point in space defined by the positio

44、n of theisocrystal.ThecommoncrossingpointoftheCyberKnifeVRbeams in an isocentric (singlecenter) treatment plan. This point isnotrequired to be coincident with the GeometricIsocenter.A light-sensitive detector of about 1.5 mm di-ameter mounted at the tip of a rigid post whoseposition of peak internal

45、 sensitivity marks thealignment center for the ideal pointing direc-tion ofthecenter ofallCyberKnifeVRradiationbeams as defined by the position of the center-line laser.Monte Carlo.Modulation transfer function.Monitor unit.Off-center ratio.Percent depth dose.Quality assurance.Quality control.Source-

46、to-axis distance.Signal-to-noise ratio.Stereotactic radiosurgery (including stereotac-tic radiotherapy, SRT).Task group.Tissue-phantom ratio.Treatment planning system.Dieterich et al.: Report of AAPM TG 13529172917Medical Physics, Vol.38, No. 6, June 2011II.QA FOR INDIVIDUAL SYSTEM COMPONENTSII.A.Ro

47、bot and room safetyAny robotic system that causes the motion of either thepatient couch or treatment apparatus in the immediate vicin-ity of a patient must have collision safeguards to prevent apotential collision with the patient. The details of how colli-sion safeguards are implemented vary with t

48、he componentand the overall system configuration. In general, collisionsafety precautions are dealt with in three stages in the use ofa robotic radiosurgery system:(1)Design specification: Adequate space for all systemcomponents such that clearance issues for both theequipment and patient are verifi

49、ed prior to and during fa-cility design and construction.(2)System installation, acceptance, commissioning, andupgrades: Items that are fixed by system design are veri-fied as functional and adequate. In this category are ele-ments of electrical safety (emergency offs,systemmotion disable, etc.), pa

50、tient and robot movementrestrictions, patient safety zones where robotic motion isexcluded for patient safety, etc.(3)On-going system accuracy and safety testing: The peri-odic testing of safety systems to document the on-goingfunction of system components.II.A.1.Mechanical safety and collision avoi