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					                                   AAPM Organization

TG-40 + TG-140 =~ TG-142
                                                                        Board of Directors

        Eric E. Klein, Ph.D.
                                                     Executive Committee
       Professor of Physics
       Washington University
           St. Louis, MO            Councils
                                                                                     Executive Director          Audit Commi

                                                Work Groups,                                              HQ Staff
                                                Task Groups

                               Example of
                               Working TG
                               (Linac QA):

                               To update, as
                               of Table II of the
                               AAPM TG-40
                               Report on Quality

                               2. To add
                               for Asymmetric
                               Jaws, Multileaf
                               Collimation, and
Linac QA TG-40 (1994)


                                                           The Resource Problem
                                                       Lack of adequate guidance for resource
                                                       Lack of qualified personnel
                                                       Rapid implementation of new technology
                                                           More sophisticated equipment
                                                           More resources
                                                           Clinics are under pressure to
                                                           implement new technology
                                                       Lack of timely guidelines
                 TG-58 (EPIDs) (2001)

Task Group No. 100: Method for Evaluating QA
Needs in Radiation Therapy                     Failure Modes and Effects Analysis
                                                       Three part system
    Initially “Replacement for TG-40”                    Frequency of error
    Radical departure from previous AAPM                 Severity of error
    recommendations and philosophy
                                                         Probability that an error would be
    Based on “Failure Modes and Effects                  detected
                                                     Probability of   Severity   Probability of   RPN
    Individual departments responsible for           error                       detection

    development of unique QA programs                       A                B          C           A*B*C
    Based on procedures and resources          Risk Priority Number (RPN) = Frequency*Severity*Probability
    performed at individual institutions
       Proposed Quality Assurance                           Task Group No. 142:
       Process                                              QA of Medical Accelerators
  Custom designed QA programs                                  Chair: Eric E. Klein, Ph.D., Washington University
                                                               Joseph Hanley, Ph.D., Hackensack Univ Medical Center
  AAPM Report will provide templates                           John Bayouth, Ph.D., University of Iowa
                                                               Fang-Fang Yin, Ph.D., Duke University
                                                               William Simon, M.S., Sun Nuclear Corp.
  Scoring performed by individual departments                  Sean Dresser, M.S., Northside Hospital
                                                               Christopher Serago, Ph.D., Mayo Clinic, Jacksonville
  Tolerances set by individual departments                     Francisco Aguirre, M.S., M.D. Anderson Cancer Center
                                                               Lijun Ma, Ph.D., University of California, San Francisco
  Annual evaluation and modifications based                    Bijan Arjomandy, Ph.D., M.D. Anderson Cancer Center
                                                               Chihray Liu, Ph.D., University of Florida
  on score changes                                             Consultants: Carlos Sandin (Elekta), Todd Holmes (Varian Medical

     Task Group No. 142:                                 BACKGROUND
                                                         Baseline values are entered into treatment planning systems to
     QA of Medical Accelerators                          characterize and/or model the treatment machine, and therefore can
I. INTRODUCTION                                          directly affect treatment plans calculated for every patient treated on
A. Purpose                                               that machine
B. Background
                                                         Machine parameters can deviate from their baseline values as a resu
A. General
B. Test Frequencies                                         Machine malfunction
C. Guidelines for Tolerance Values                          Mechanical breakdown
D. Ancillary Devices Not in TG-40
       Asymmetric Jaws                                      Physical accidents
       Dynamic/Virtual/Universal Wedges
       MLC                                                  Component failure
       Radiographic Imaging                                 Major component replacement
           Megavoltage Planar Imaging (Portal Imagers)
           Planar kV Imaging                                Gradual changes as a result of aging
           Serial and Cone-Beam CT
       Respiratory Gating                                These patterns of failure must be considered when establishing a
                                                         periodic QA program
QA of MEDICAL ACCELERATORS                                   Task Group No. 142:
 What This Report Doesn’t Do
   Describe the techniques for performing QA tests
                                                             QA of Medical Accelerators
   Accelerator beam data commissioning equipment and
   procedures – TG-106                                   The recommendations of this task group are not
   QA for TomoTherapy –TG-148                            intended to be used as regulations. These
   QA for Robotic Radiosurgery – TG-135
                                                         recommendations are guidelines for qualified
   QA for Non-Radiographic Radiotherapy Localization &
   Positioning Systems – TG-147                          medical physicists (QMP) to use and
 Does add Specific Recommendations / Supplements the     appropriately interpret for their individual
 Work of                                                 institution and clinical setting. Each institution
   Basic Applications of Multileaf Collimators – TG-50   may have site-specific or state mandated needs
   Clinical use of electronic portal imaging - TG-58     and requirements which may modify their usage
   Management of Respiratory Motion– TG-76
                                                         of these recommendations.
   Kilovoltage localization in therapy – TG-104

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

   The recommendations of TG-142 should                    A Consistent beam profile is an important
   be flexible enough to take into account                 quantity for accurate and reproducible dose
                                                           delivery in radiotherapy.
   quality, costs, equipment condition,
                                                           In our tables, the monthly tolerance values are
   available test equipment, and institutional             specific to a consistent beam shape, whereby
   needs.                                                  baseline off axis factors were measured with a
   We do recommend using the tests and                     QA device immediately following
                                                           commissioning or annual data.
   frequencies outlined in the tables that
                                                           Ongoing QA measurements are compared to the
   follow, until methods such as TG-100                    baseline off axis factors.
   supersede this report.
                                                                                 Task Group No. 142:
    Task Group No. 142: General
                                                                                 QA of Medical Accelerators
Chosen O.A. point locations will generally fall within core of the field

                                                                               The types of treatments delivered with the
     1 N TPL − BPL
      ⋅∑           ⋅100% ≤ Tolerance %                                         machine should also have a role in determining
     N L =1 BPL                                                                the QA program that is appropriate for that
 where: TPL and BPL are off-axis ratios at Test and Baseline Points,           treatment machine.
 respectively, at off axis Point L
 N is the number of off-axis points
                                                                               For example, machines that are used for
 TPL = (MPL/MPC) where M represents the measurement value and C                SRS/SBRT treatments, TBI or IMRT require
 is the central axis measurement.                                              different tests and/or tolerances.
 Similarly, the baseline points are represented by BPL =

    Task Group No. 142:                                                    Task Group No. 142:
    Test Frequencies                                                            Guidelines for Tolerance Values
  In this report there are additional factors that                           Acceptance Testing Procedure (ATP) Standards
  affect the frequency of the tests, specifically:                               Acceptance testing sets the baseline for future dosimetric
  the type of treatments delivered on the machine;                               measurements for beam performance constancy, verifies that th
                                                                                 equipment is mechanically functional and operates within certai
  and the manufacturer of the machine.                                           tolerances from absolute specified values.
  For example, electron output is to be tested                               Tolerances and Action Levels
  more frequently on a Siemens machine which                                     Level 1 – Inspection Action
  possesses an electron beam specific, unsealed                                  Level 2 – Scheduled Action
  monitor chamber system, compared to the                                        Level 3 – Immediate Action or Stop Treatment Action or
  Varian machine with a multi-modality sealed                                    Corrective Action
  monitor chamber.                                                          With these 3 action levels, there is an institutional need to spec
                                                                            the thresholds associated with Levels 2 and 3. Level 1 threshol
                                                                            isn’t a critical requirement but can lead to improvements in the
                                                                            QA program.
    TG-142: Daily                                                                                               Daily
                                                                                        Tolerance                                                                                                                Tolerance
                                               Tolerance (non-   Tolerance (IMRT       (Stereotactic                                                             Tolerance (non-      Tolerance (IMRT           (Stereotactic
                  Procedure                   IMRT machines)        machines)           machines)                             Procedure                         IMRT machines)           machines)               machines)
osimetry                                                                                                   Dosimetry
  X-ray output constancy (all energies)                                                                       X-ray output constancy (all energies)
  Electron output constancy (Weekly, except                            3%                                     Electron output constancy (Weekly, except                                      3%
  for machines with unique e- monitoring                                                                      for machines with unique e- monitoring
  requiring daily)                                                                                            requiring daily)

echanical                                                                                                  Mechanical
  Laser localization                               2 mm              1.5 mm               1 mm                Laser localization                                      2 mm                1.5 mm                    1 mm
  Distance indicator (ODI)@ iso                    2 mm               2 mm                2 mm                Distance indicator (ODI)@ iso                           2 mm                 2 mm                     2 mm
  Collimator size indicator                        2 mm               2 mm                1 mm                Collimator size indicator                               2 mm                 2 mm                     1 mm
afety                                                                                                      Safety
  Door interlock (beam off)                                         Functional                                Door interlock (beam off)                                                  Functional
  Door closing safety                                               Functional                                Door closing safety                                                        Functional
  Audiovisual monitor(s)                                            Functional                                Audiovisual monitor(s)                                                     Functional
  Stereotactic interlocks (lockout)                 NA                 NA               Functional            Stereotactic interlocks (lockout)                        NA                   NA                   Functional
  Radiation area monitor (if used)                                  Functional                                Radiation area monitor (if used)                                           Functional
  Beam on indicator                                                 Functional                                Beam on indicator                                                          Functional

    TG-142: Monthly
                                                                                                                                                                Tolerance (non-IMRT    Tolerance (IMRT       Tolerance Stereotacti
                                                                                                                                                                        machines)            machines)               machines

                                               Tolerance (non-   Tolerance (IMRT         Tolerance
                                              IMRT machines)        machines)      Stereotactic machines    Mechanical
                                                                                                              Light/radiation field coincidence*                                      2 mm or 1% on a side
osimetry                                                                                                       Light/radiation field coincidence*
                                                                                                               (Asymmetric)                                                           1 mm or 1% on a side
  X-ray output constancy                                                                                       Distance check device used for lasers/ODI (vs.
                                                                                                               front pointer)                                                                1mm
  Electron output constancy                                            2%
                                                                                                               Gantry/collimator angle indicators (@ cardinal
  Backup monitor chamber constancy                                                                             angles) (Digital only)                                                       1.0 deg
                                                                                                               Accessory trays (i.e. Port film graticle tray)                                2 mm
                                                                 2% (@ IMRT dose    2% (@ stereo dose          Jaw position indicators (Symmetric)3
  Typical dose rate2 output constancy               NA                                                                                                                                       2 mm
                                                                      rate)             rate, MU)              Jaw position indicators (Asymmetric)1                                         1 mm
                                                                                                               Cross-hair centering (walk-out)                                               1 mm
  Photon beam profile constancy
                                                                       1%                                      Treatment couch position indicators4                  2 mm/1 deg          2 mm/ 1 deg             1 mm/ 0.5 deg
  Electron beam profile constancy                                                                              Wedge placement accuracy                                                      2mm
                                                                                                               Latching of wedges, blocking tray5                                         Functional5
  Electron beam energy constancy
         Monthly                                                                                                              Monthly
                                              Tolerance (non-IMRT     Tolerance (IMRT      Tolerance Stereotactic
                 Procedure                                                                                                                                         Tolerance (non-IMRT     Tolerance (IMRT    Tolerance Stereotacti
                                                      machines)             machines)              machines                           Procedure
                                                                                                                                                                           machines)             machines)            machines

                                                                                                                    Respiratory gating
                                                                                                                       Beam output constancy                                                      2%
                                                                                                                       Phase, Amplitude beam control                                           Functional
                                                                                                                       In room respiratory monitoring system                                   Functional
                                                                                                                       Gating interlock                                                        Functional

TG-142: Annual                                                                                                      Annual
                                               Tolerance (non-       Tolerance (IMRT
                 Procedure                                                                     Stereotactic                                                        Tolerance (non-IMRT     Tolerance (IMRT    Tolerance Stereotacti
                                              IMRT machines)            machines)                                                     Procedure
                                                                                                machines                                                                   machines)             machines)            machines
  X-ray flatness change from baseline                                        1%
                                                                                                                       X-ray monitor unit linearity [output .                            ±5% (2-4 MU), ±2%     ±5% (2-4), ±2%
  X-ray symmetry change from baseline                                        ±1%                                                                                      ±2% ≥5MU
                                                                                                                       constancy ]                                                             ≥5MU               ≥5MU
  Electron flatness change from baseline                                     1%
  Electron symmetry change from baseline                                     ±1%                                       Electron monitor unit linearity [output .                             ±2% ≥5MU
                                                                                                                       constancy ]
                                                                                           Monitor units set vs.
                                                                                           delivered:1.0 MU or         X-ray output constancy vs dose rate                                ±2% from baseline
                                                                                            2% (whichever is           X-ray output constancy vs gantry angle                             ±1% from baseline
  SRS Arc rotation mode (range: 0.5 to 10                                                        greater)
                                                      NA                    NA                                         Electron output constancy vs gantry
  MU/deg )                                                                                                                                                                                ±1% from baseline
                                                                                            Gantry arc set vs.
                                                                                           delivered: 1.0 deg or
                                                                                            2% (whichever is           Electron and X-ray Off-axis factor
                                                                                                                                                                                          ±1% from baseline
                                                                                                                       constancy vs gantry angle
  X-ray/electron output calibration (TG-51)                             ±1%(absolute)
                                                                                                                       Arc mode (expected MU, degrees)                                  ±1% from baseline
  Spot check of field size dependent output                2% for field size < 4x4 cm2, 1% ≥4x4 cm2                    TBI/TSET Mode                                                       Functional
  factors for X-ray (2 or more FS)
  Output factors for electron applicators                                                                              PDD or TMR and OAF constancy                       1% (TBI) or 1mm PDD shift (TSET) from baseline
                                                                      ±2% from baseline
  (spot check of 1 applicator/energy)                                                                                  TBI/TSET Output calibration                                      2% from baseline
  X-ray beam quality   (PDD10, TMR1020)                               ±1% from baseline                                TBI/TSET accessories                                             2% from baseline
  Electron beam quality (R50)                                              ±1mm
  Transmission factor constancy for all                               ±1% from baseline
  treatment accessories
                                              Tolerance (non-IMRT         Tolerance (IMRT        Tolerance Stereotactic             Dynamic/Universal/Virtual Wedges
                                                      machines)                 machines)                machines

Mechanical                                                                                                                   Dynamic-incl. EDW (Varian), Virtual (Siemens), Universal (Elekta) Wedge quality assurance
  Collimator rotation isocenter                                       ±1 mm from baseline
  Gantry rotation isocenter                                           ±1 mm from baseline
                                                                                                                                        Frequency                      Procedure                   Tolerance
  Couch rotation isocenter                                            ±1 mm from baseline                                                                                                Dynamic Universal Virtual
  Electron applicator interlocks                                          Functional
                                                                                                                                                                        Morning Check-out
   Coincidence of radiation and mechanical        ±2mm from
                                                                      ±2mm from baseline         ±1mm from baseline                          Daily                                                          Functional
   isocenter                                       baseline                                                                                                              run for 1 angle
   Table top sag                                                         2mm from baseline
                                                                                                                                                                                                            C.A. Axis
   Table Angle                                                                1 degree                                                                                                           Axis 45º              5% from
                                                                                                                                                                                                            45º or 60°
   Table travel maximum range movement                                                                                                                                   Wedge factor for         or 60°                 unity,
                                                                                 ±2mm                                                       Monthly                                                            WF
   in all directions                                                                                                                                                      all energies             WF                  otherwis
   Stereotactic accessories, lockouts, etc                          NA                                Functional                                                                                             (within
                                                                                                                                                                                                 (within                  2%
Safety                                                                                                                                                                                                        2%)*
   Follow manufacturers test procedures                                      Functional
Respiratory gating                                                                                                                                                        Check of wedge
   Beam energy constancy                                                         2%                                                                                      angle for 60°, full     Check of Off-center ratios @ 80%
   Temporal accuracy of Phase/Amplitude
                                                                         100 ms of expected                                                 Annual                       field & spot check       field width @ 10cm to be within
   Calibration of surrogate for respiratory
                                                                         100 ms of expected
                                                                                                                                                                           for intermediate                     2%
                                                                                                                                                                           angle, field size
   Interlock testing                                                         Functional
                                                                                                                          * Recommendation to check 45º if angles other than 60º are used.

    Multileaf Collimation                                                                                                   Multileaf Collimation: Annual Tests
       Multi-leaf collimation quality assurance (with differentiation of IMRT vs. non-IMRT machines)                           MLC Transmission (Average of leaf and
                                                                                                                                                                                          ±0.5% from baseline
                                                                                                                                interleaf transmission), All Energies
                   Frequency                            Procedure                               Tolerance

                                                                                   Visual inspection for discernable                  Leaf position repeatability                                 ±1.0 mm
                                               Qualitative test (i.e. matched
        Weekly (IMRT machines)                                                     deviations such as an increase in
                                              segments, aka, “picket fence”)
                                                                                        interleaf trransmission                            MLC spoke shot                                      ≤1.0 mm radius

                                                                                                                             Coincidence of Light Field and X-ray Field
                                               Setting vs. radiation field for                                                                                                                    ±2.0 mm
                                                                                                  2mm                                      (All energies)
                                                two patterns (non-IMRT)
                                                                                                                                                                               <0.35 cm Max Error RMS, 95% of error
                                                Backup diaphragm settings                                                            Arc dynamic leaf-speed test
                                                                                                  2mm                                                                                 counts <0.35 cm (Varian)
                                                      (Elekta only)

                                                   Travel speed (IMRT)                Loss of leaf speed > 0.5 cm/sec               Arc dynamic interlock trip test             Leaf position interlock occurs (Varian)
                                                                                                                                                                               <0.35 cm Max Error RMS, 95% of error
                                                                                     1mm for leaf positions of an                   Arc dynamic typical plan test
                                                                                   IMRT field for 4 cardinal gantry
                                                                                                                                                                                      counts <0.35 cm (Varian)
                                              Leaf position accuracy (IMRT)        angles. (Picket fence test may be                                                           <0.35 cm Max Error RMS, 95% of error
                                                                                    used, test depends on clinical             Segmental IMRT (Step and Shoot) Test
                                                                                                                                                                                      counts <0.35 cm (Varian)
                                                                                      planning – segment size)
 Imaging Tests: Daily                                                                                   Imaging Tests: Monthly                             Non-SRS/SBRT           SRS/SBRT Applications
                                                                                                                                                        Applications Tolerances        Tolerances
                                                                                                         MV imaging (EPID)
                                                Non-SRS/SBRT Applications      SRS/SBRT Applications
                Procedure                                                                                  Imaging & treatment coordinate
                                                       Tolerances                   Tolerances                                                                  < 2 mm                    ≤ 1 mm
                                                                                                           coincidence (4 Cardinal angles)
                                                     Daily                                                 Scaling3                                             < 2 mm                    < 2 mm
MV imaging (EPID)                                                                                          Spatial resolution                                   Baseline4                Baseline
  Collision interlocks                                  Functional                   Functional            Contrast                                             Baseline                 Baseline
                                                                                                           Uniformity and noise                                 Baseline                 Baseline
  Spatial linearity1 (x and y) (single gantry
                                                         < 2 mm                       ≤ 1 mm             kV imaging
                                                                                                           Imaging & treatment coordinate
                                                                                                                                                                < 2 mm                    ≤ 1 mm
  Imaging & Treatment coordinate                                                                           coincidence (4 Cardinal angles)
                                                         < 2 mm                       ≤ 1 mm
  coincidence (single gantry angle)                                                                        Scaling                                              < 2 mm                    ≤ 1 mm
                                                                                                           Spatial linearity (x and y) (single gantry
  Positioning/repositioning                              < 2 mm                       ≤ 1 mm                                                                    < 2 mm                    ≤ 1 mm
                                                                                                           Spatial resolution                                   Baseline                 Baseline
KV imaging2
                                                                                                           Contrast                                             Baseline                 Baseline
  Collision interlocks                                  Functional                   Functional            Uniformity and noise                                 Baseline                 Baseline
  Imaging & treatment coordinate                                                                         Cone-beam CT (kV & MV)
                                                         < 2 mm                       ≤ 1 mm               Imaging & treatment coordinate
  coincidence                                                                                                                                                   < 1.5 mm                  ≤ 1 mm
  Positioning/repositioning                              < 2 mm                       ≤ 1 mm               Geometric distortion                                 < 2 mm                   ≤ 1 mm
                                                                                                           Spatial resolution                                   Baseline                 Baseline
Cone-beam CT (kV & MV)                                                                                     Contrast                                             Baseline                 Baseline
  Collision interlocks                                  Functional                   Functional            HU constancy                                         Baseline                 Baseline
  Positioning/repositioning                              < 2 mm                       ≤ 1 mm               Uniformity and noise                                 Baseline                 Baseline
                                                                                                           Spatial linearity (x and y) (single gantry
                                                                                                                                                                < 1 mm                    ≤ 1 mm

   Imaging Tests: Annual                                                                               SUMMARY OF RECOMMENDATIONS/
                                                                                                       IMPLEMENTATION SCHEME
                                                   Non-SRS/SBRT             SRS/SBRT Applications
  MV imaging (EPID)
                                                Applications Tolerances          Tolerances
                                                                                                        The tabulated items of this report have
     Full range of travel SDD                            ±5 mm                       ±5 mm
     Imaging dose5                                       Baseline                   Baseline
                                                                                                        been considerably expanded as
    Beam quality / energy
  kV imaging
                                                         Baseline                   Baseline
                                                                                                        compared with the original TG 40
                                                         Baseline                   Baseline
    Beam quality / energy
    Imaging dose                                         Baseline                   Baseline            report and the recommended
  Cone-beam CT (kV & MV)
     Imaging dose                                        Baseline                   Baseline            tolerances accommodate differences
                                                                                                        in the intended use of the machine
                                                                                                        functionality (non-IMRT, IMRT, and
                                                                                                        Stereotactic Delivery).
                                                        3) A   QMP should lead the QA team. The QMP
1) A QA team support all QA activities and draft
  policies and procedures. The policy should                 provides action level and methods of
  establish roles and responsibilities. For QA               notification when tolerances are exceeded.
  measurements, detailed instructions on                4) Daily QA tasks may be carried out by a
  equipment use, cross-calibration,
                                                          RTT using a cross-calibrated dosimetry
  measurement frequency, and documentation of
  the results should be provided.                         system that is robust and easy-to-setup.
                                                          Correction factors should be documented
2) The 1st step is to establish institution-specific
                                                          in a permanent electronic or hardcopy
  baseline and absolute reference values. The
  QA team needs to meet and monitor the results           format for inspection purposes. The QMP
  against the established values.                         should review and sign off on the reports
                                                          at least once per month.

                                                       7)    End-to-end system checks ensure fidelity of overall
) Monthly tasks should be performed by (or directly         system. This can be done by creating plans typical of the
 supervised by) a QMP. It is recognized there is            facility’s clinic, transferring the plan data across the data
 overlap of tests for daily, monthly, and annual.           network, and delivering them.
 This overlap should have independence achieved        8) During the annual QA, absolute outputs should be
 with independent measurement devices. This will          calibrated as per TG51. Subsequently, all secondary QA
                                                          dosimeters should be cross-checked against such
 identify trends that may go undetected.
6) It is recommended annual measurements be            Upon completion of the measurements, an annual QA report
  performed by a QMP. QA devices should be               be generated. The report should state significant findings
  checked prior to measurements. The                     based on tolerance values. The report can be divided into
  measurements should be carried out using               sections; (1) Dosimetry, (2) Mechanical, (3) Safety, (4)
                                                         Imaging, and (5) Special Devices/Procedures. The QA
  commissioning quality equipment as                     report should be signed and reviewed by the QMP and filed

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