Purpose: To commission a Monte Carlo beam modelling and dose calculation platform for a proton therapy system under installation, to be used to assist in TPS commissioning and independent plan dose calculations.
Methods: TOPAS software is used in the Monte Carlo modeling of ProBeam machine model. A set of demonstration machine beam data in Eclipse treatment planning system (TPS) provided by the vendor was used to fine tune TOPAS phase space parameters , so that the beam profiles and IDDS are matched between Monte Carlo simulation and TPS beam data. Beam modelling was verified by generating SOBP curves in water and comparing to TPS calculations. Beam data for our own ProBeam machine obtained during acceptance test are subsequently used to further fine tune the beam modeling, in developing a platform for independent dose calculation for treatment planning.
Results: Results of TOPAS Monte Carlo model are in good agreement with those of Eclipse treatment planning system with IDD curves within 2% and ranges within 0.5mm. Beam spot profiles in air are within 3%, with spot size within 0.2mm. SOBPs calculated by TOPAS are within 5% of Eclipse calculations and is to be further fine-tuned. Further development on generating beam data for TPS commissioning and plan dose calculation are in progress.
Conclusion: Using TOPAS software a Monte-Carlo model for pencil beam scanning of a ProBeam system was developed and will be used to generate and verify beam data for TPS commissioning and independent dose calculation for future treatment planning QA.
Not Applicable / None Entered.