Dosimetric Evaluation of a Treatment Planning System Using the Aapm Medical Physics Practice Guideline 5.a (MPPG 5.a) Validation Tests

In this work, the AAPM Medical Physics Practice Guideline 5.a (MPPG 5.a) validation tests package was used to evaluate the dosimetric performance of a new version of the Eclipse treatment planning system (TPS) algorithms. A series of tests were developed and comparisons between TPS calculated and corresponding beam data measurements have been performed for basic beam validation, heterogeneity correction and IMRT/VMAT dose validation tests. Measurements were performed using a Varian IX Linear Accelerator with the 6 MV, 6MV FFF and 18 MV photon beams, and 6, 9, 12, 16, 20 MeV electron beams. Results for basic dose validation tests yielded differences within 3% for all point doses and pass rate greater than 95% for all depth profiles using 3%/3mm criteria. For testing the ability of the TPS in accounting for tissue inhomogeneity, corresponding comparisons were performed with the presence of a heterogeneous media to simulate an air inhomogeneity. Results showed a mean deviation between the TPS calculated and measured of 1.9%, reaching a maximum of 2.8% for the AAA algorithm. For IMRT/VMAT validation tests, our local criteria passing rate of 95% was used, but no consensus of the tolerance exists. Our results agree well with the data reported accuracy in previous studies of Eclipse TPS. In summary, the AAPM MPPG 5.a validation tests are a valuable package for evaluating dose calculation accuracy and are very useful for TPS upgrade checks, commissioning tests and routine TPS QA.