Automated Monte-Carlo Re-calculation of Proton Therapy Plans Using Geant4/Gate: Implementation and Comparison to Plan-specific Quality Assurance Measurements
Overview
Authors
Affiliations
Objectives: Software re-calculation of proton pencil beam scanning plans provides a method of verifying treatment planning system (TPS) dose calculations prior to patient treatment. This study describes the implementation of AutoMC, a Geant4 v10.3.3/Gate v8.1 (Gate-RTion v1.0)-based Monte-Carlo (MC) system for automated plan re-calculation, and presents verification results for 153 patients (730 fields) planned within year one of the proton service at The Christie NHS Foundation Trust.
Methods: A MC beam model for a Varian ProBeam delivery system with four range-shifter options (none, 2 cm, 3 cm, 5 cm) was derived from beam commissioning data and implemented in AutoMC. MC and TPS (Varian Eclipse v13.7) calculations of 730 fields in solid-water were compared to physical plan-specific quality assurance (PSQA) measurements acquired using a PTW Octavius 1500XDR array and PTW 31021 Semiflex 3D ion chamber.
Results: TPS and MC showed good agreement with array measurements, evaluated using γ analyses at 3%, 3 mm with a 10% lower dose threshold:>94% of fields calculated by the TPS and >99% of fields calculated by MC had γ ≤ 1 for>95% of measurement points within the plane. TPS and MC also showed good agreement with chamber measurements of absolute dose, with systematic differences of <1.5% for all range-shifter options.
Conclusions: Reliable independent verification of the TPS dose calculation is a valuable complement to physical PSQA and may facilitate reduction of the physical PSQA workload alongside a thorough delivery system quality assurance programme.
Advances In Knowledge: A Gate/Geant4-based MC system is thoroughly validated against an extensive physical PSQA dataset for 730 clinical fields, showing that clinical implementation of MC for PSQA is feasible.
Burford-Eyre S, Aitkenhead A, Aylward J, Henthorn N, Ingram S, Mackay R Cancers (Basel). 2024; 16(19).
PMID: 39409935 PMC: 11475827. DOI: 10.3390/cancers16193315.
Dreindl R, Bolsa-Ferruz M, Fayos-Sola R, Padilla Cabal F, Scheuchenpflug L, Elia A J Appl Clin Med Phys. 2024; 25(5):e14328.
PMID: 38553788 PMC: 11087175. DOI: 10.1002/acm2.14328.
Rechner L, Maraldo M, Smith E, Lundgaard A, Hjalgrim L, Mackay R BJR Open. 2023; 5(1):20230012.
PMID: 37035769 PMC: 10077416. DOI: 10.1259/bjro.20230012.
The OpenGATE ecosystem for Monte Carlo simulation in medical physics.
Sarrut D, Arbor N, Baudier T, Borys D, Etxebeste A, Fuchs H Phys Med Biol. 2022; 67(18).
PMID: 36001985 PMC: 11149651. DOI: 10.1088/1361-6560/ac8c83.
A preclinical radiotherapy dosimetry audit using a realistic 3D printed murine phantom.
Biglin E, Aitkenhead A, Price G, Chadwick A, Santina E, Williams K Sci Rep. 2022; 12(1):6826.
PMID: 35474242 PMC: 9042835. DOI: 10.1038/s41598-022-10895-5.