Moskvin Vadim P, Faught Austin, Pirlepesov Fakhriddin, Xie Fang, Al-Ward Shahad, Cohilis Marie, Souris Kevin, Merchant Thomas E, Hua Chia-Ho
Department of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, TN, United States of America.
Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, Brussels, Belgium.
Biomed Phys Eng Express. 2025 Jul 8;11(4). doi: 10.1088/2057-1976/ade9c8.
This study presents the implementation and validation of the fast, simplified open-source MC code MCsquare as a secondary dose calculation engine for intensity-modulated proton therapy with narrow beams (the Gaussian-shaped beam spot with standard deviations as small as 1-2 mm) produced by a synchrotron-based system with minibeam modification. A proton therapy system was modeled with MCsquare, using commissioning data, and with TOPAS, an explicit multi-particle MC code. The computed dose distributions were compared with the patient-specific quality assurance (QA) measurements (203 measurements for 94 treatment fields), using gamma analysis with criteria of 3% and 3 mm. The dose distributions in the patient geometry defined by computed tomography (CT) images were simulated with MCsquare and TOPAS and compared. For the main beam, the gamma passing rates of the patient-specific QA averaged 99.4% and 97.9% for MCsquare and 99.2% and 98.5% for TOPAS, with and without range shifter use, respectively. For minibeams, the rate was 100% for both MC codes. The dose distributions calculated with TOPAS and MCsquare on the patient's CT were identical, within the statistical error of the simulation. The simulation time with MCsquare varied between 1 and 25 min per plan on a 16-core workstation with a 2% statistical error. The fast, simplified MCsquare and the slower TOPAS using explicit multi-particle transport produced statistically identical dose distributions. The results support using MCsquare as a secondary dose engine for narrow beams.
本研究展示了快速、简化的开源蒙特卡罗代码MCsquare作为二次剂量计算引擎的实现与验证，该引擎用于基于同步加速器系统并经微束修正产生的窄束（高斯形状束斑，标准差小至1 - 2毫米）调强质子治疗。使用调试数据，用MCsquare对质子治疗系统进行建模，并使用显式多粒子蒙特卡罗代码TOPAS进行建模。使用3%和3毫米标准的伽马分析，将计算得到的剂量分布与患者特定的质量保证（QA）测量结果（94个治疗野的203次测量）进行比较。使用MCsquare和TOPAS模拟并比较了由计算机断层扫描（CT）图像定义的患者几何结构中的剂量分布。对于主束，在使用和不使用射程移位器的情况下，MCsquare的患者特定QA伽马通过率平均分别为99.4%和97.9%，TOPAS分别为99.2%和98.5%。对于微束，两种蒙特卡罗代码的通过率均为100%。在模拟的统计误差范围内，TOPAS和MCsquare在患者CT上计算得到的剂量分布相同。在具有2%统计误差的16核工作站上，每个计划使用MCsquare的模拟时间在1至25分钟之间变化。快速、简化的MCsquare和使用显式多粒子输运的较慢的TOPAS产生了统计上相同的剂量分布。这些结果支持将MCsquare用作窄束的二次剂量引擎。
