AAPM Task Group 119 has produced quantitative confidence limits as baseline expectation values for IMRT commissioning. A set of test cases was developed to assess the overall accuracy of planning and delivery of IMRT treatments. Each test uses contours of targets and avoidance structures drawn within rectangular phantoms. These tests were planned, delivered, measured, and analyzed by nine facilities using a variety of IMRT planning and delivery systems. Each facility had passed the Radiological Physics Center credentialing tests for IMRT. The agreement between the planned and measureddoses was determined using ion chamberdosimetry in high and low dose regions, film dosimetry on coronal planes in the phantom with all fields delivered, and planar dosimetry for each field measured perpendicular to the central axis. The planar dose distributions were assessed using gamma criteria of 3%/3 mm. The mean values and standard deviations were used to develop confidence limits for the test results using the concept . Other facilities can use the test protocol and results as a basis for comparison to this group. Locally derived confidence limits that substantially exceed these baseline values may indicate the need for improved IMRT commissioning.
The authors would like to thank all the physicists and dosimetrists from these institutions who performed the planning and measurements that made this cross comparison possible, Todd Bossenberger, Shalini Pandya, and Adrian Nalichowski from Wayne State University and Amy Harrison, Kevin Fallon, and Anthony Doemer from Thomas Jefferson University. The authors would like to acknowledge their industrial consultant, Bill Simon from Sun Nuclear. They also would like to thank their reviewers from the AAPM Therapy Physics Committee and those from Medical Physics for their helpful comments and suggestions.
II. METHODS AND MATERIALS
II.B. Chamber measurements
II.C. Composite film measurements
II.D. Per-field measurements
II.E. Test suite: Planning conditions and measurement specifications
II.E.1. Test P1: AP:PA
II.E.2. Test P2: Bands
II.E.3. Test I1: Multitarget
II.E.4. Test I2: Mock prostate
II.E.5. Test I3: Mock head/neck
II.E.6. Tests I4 and I5: Cshape
III.A. Planning results
III.B. Measurement results
III.B.1. Results for preliminary test P2: Bands
III.B.2. Ion chamber results
III.B.3. Composite film measurements
III.B.4. Per-field measurements
IV.A. Test suite
IV.B. Planning results
IV.C. Ion chamber results
IV.D. Composite film measurements
IV.E. Per-field measurements
IV.F. Overall comments
IV.G. An example of the practical utility of the tests
IV.H. Comparison to other work
IV.I. Confidence limits and action levels
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