Implementation of the validation testing in MPPG 5.a “Commissioning and QA of treatment planning dose calculations–megavoltage photon and electron beams”

Abstract

The AAPM Medical Physics Practice Guideline (MPPG) 5.a provides concise guidance on the commissioning and QA of beam modeling and dose calculation in radiotherapy treatment planning systems. This work discusses the implementation of the validation testing recommended in MPPG 5.a at two institutions. The two institutions worked collaboratively to create a common set of treatment fields and analysis tools to deliver and analyze the validation tests. This included the development of a novel, open‐source software tool to compare scanning water tank measurements to 3D DICOM‐RT Dose distributions. Dose calculation algorithms in both Pinnacle and Eclipse were tested with MPPG 5.a to validate the modeling of Varian TrueBeam linear accelerators. The validation process resulted in more than 200 water tank scans and more than 50 point measurements per institution, each of which was compared to a dose calculation from the institution's treatment planning system (TPS). Overall, the validation testing recommended in MPPG 5.a took approximately 79 person‐hours for a machine with four photon and five electron energies for a single TPS. Of the 79 person‐hours, 26 person‐hours required time on the machine, and the remainder involved preparation and analysis. The basic photon, electron, and heterogeneity correction tests were evaluated with the tolerances in MPPG 5.a, and the tolerances were met for all tests. The MPPG 5.a evaluation criteria were used to assess the small field and IMRT/VMAT validation tests. Both institutions found the use of MPPG 5.a to be a valuable resource during the commissioning process. The validation testing in MPPG 5.a showed the strengths and limitations of the TPS models. In addition, the data collected during the validation testing is useful for routine QA of the TPS, validation of software upgrades, and commissioning of new algorithms.

Dosimetric Validation of Treatment Planning System for Volumetric Modulated Arc Therapy Using AAPM Medical Physics Practice Guideline 5.b

“…However, only 31% of the irradiations met a stricter criterion that also required adequate target coverage. The several factors associated with poor performance, such as complex delivery techniques, lack of image guidance, and errors in contouring and planning, Jacqmin et al [21] observed that tests 3 and 4 were found to be useful in the refinement of the MLC model parameters, such as the MLC transmission and dosimetric leaf gap.…”

PRIMO Monte Carlo software as a tool for commissioning of an external beam radiotherapy treatment planning system

“…Commissioning was performed following the tests described in the MPPG 5.a. guideline [ 17 ]. As part of the VMAT/IMRT recommended tests, this guideline advises planning, measuring, and comparing plans for both the Head and Neck and C-Shape mock cases of the TG-119 report, as well as performing the PSQA for at least two relevant clinical cases.…”

“…The AAPM Medical Physics Practice Guideline (MPPG) 5.a recommends checking the dose calculation accuracy of clinical plans during the commissioning of a TPS [ 17 ]. Although this recommendation refers to delivering the plan to a phantom with appropriate dosimeters enabling the user to compare planned and delivered dose distributions, a validated MC simulation system allows the dose to be accurately computed in the full three-dimensional (3D) patient geometry.…”