Open AccessMoving GPU ‐Open CL ‐based Monte Carlo dose calculation toward clinical use: Automatic beam commissioning and source sampling for treatment plan dose calculation
Author(s) -
Tian Zhen,
Li Yongbao,
HassanRezaeian Nima,
Jiang Steve B.,
Jia Xun
Publication year - 2017
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1002/acm2.12049
Subject(s) - truebeam , linear particle accelerator , monte carlo method , beam (structure) , variance reduction , physics , nuclear medicine , computer science , sampling (signal processing) , radiation treatment planning , optics , computational physics , materials science , mathematics , statistics , medicine , detector , radiation therapy
We have previously developed a GPU ‐based Monte Carlo ( MC ) dose engine on the Open CL platform, named go MC , with a built‐in analytical linear accelerator (linac) beam model. In this paper, we report our recent improvement on go MC to move it toward clinical use. First, we have adapted a previously developed automatic beam commissioning approach to our beam model. The commissioning was conducted through an optimization process, minimizing the discrepancies between calculated dose and measurement. We successfully commissioned six beam models built for Varian TrueBeam linac photon beams, including four beams of different energies (6 MV, 10 MV, 15 MV, and 18 MV) and two flattening‐filter‐free ( FFF ) beams of 6 MV and 10 MV. Second, to facilitate the use of go MC for treatment plan dose calculations, we have developed an efficient source particle sampling strategy. It uses the pre‐generated fluence maps ( FM s) to bias the sampling of the control point for source particles already sampled from our beam model. It could effectively reduce the number of source particles required to reach a statistical uncertainty level in the calculated dose, as compared to the conventional FM weighting method. For a head‐and‐neck patient treated with volumetric modulated arc therapy ( VMAT ), a reduction factor of ~2.8 was achieved, accelerating dose calculation from 150.9 s to 51.5 s. The overall accuracy of go MC was investigated on a VMAT prostate patient case treated with 10 MV FFF beam. 3D gamma index test was conducted to evaluate the discrepancy between our calculated dose and the dose calculated in Varian Eclipse treatment planning system. The passing rate was 99.82% for 2%/2 mm criterion and 95.71% for 1%/1 mm criterion. Our studies have demonstrated the effectiveness and feasibility of our auto‐commissioning approach and new source sampling strategy for fast and accurate MC dose calculations for treatment plans.