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

J Appl Clin Med Phys. 2017 Jan;18(1):115-127. doi: 10.1002/acm2.12015. Epub 2016 Dec 5.

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.

Keywords: beam modeling; commissioning; dosimetric accuracy; treatment planning system.

Publication types

  • Validation Study

MeSH terms

  • Algorithms
  • Electrons / therapeutic use*
  • Health Plan Implementation*
  • Humans
  • Models, Theoretical*
  • Monte Carlo Method
  • Neoplasms / radiotherapy*
  • Particle Accelerators / instrumentation
  • Phantoms, Imaging
  • Photons / therapeutic use*
  • Practice Guidelines as Topic / standards
  • Quality Assurance, Health Care / standards*
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted / methods
  • Radiotherapy Planning, Computer-Assisted / standards*
  • Radiotherapy, Intensity-Modulated / methods