基于 OpenMC 的 BNCT 剂量计算研究

硼中子俘获治疗(boron neutron capture therapy, BNCT)是通过中子与 $ ^{10} $B反应产生α、 $ ^{7} $Li重离子杀死癌细胞的二元疗法,其剂量成分较为复杂,包含快中子、热中子、α与 $ ^{7} $Li、γ射线,各成分的相对生物学效应不尽相同,开展BNCT剂量计算方法研究对临床照射剂量的评估具有重要应用价值。文章基于OpenMC蒙特卡洛粒子输运程序进行剂量计算方法研究,并验证其在BNCT剂量计算中应用的可行性和有效性。建立Snyder人体头部的解析几何模型;利用质子与锂反应获得中子能谱、强度和角度等中子源项数据,提供OpenMC源项建模;基于OpenMC网格计数统计BNCT中子剂量,并与MCNPX和FLUKA程序进行比较。利用OpenMC程序计算BNCT的剂量分布结果,与MCNPX模拟计算结果相比,粒子通量误差为0.59%;与FLUKA计算结果相比,粒子通量误差为9.18%,硼剂量最大误差为2.30%。尽管与MCNPX和FLUKA在仿真参数设置及数据后处理上存在差异,但OpenMC在BNCT剂量计算方面是可行且有效的,可为未来发展的BNCT治疗计划系统剂量的精确计算与治疗策略的优化选取提供可靠的软件工具。

Boron neutron capture therapy (BNCT) is a binary therapy that kills cancer cells through the reaction of neutrons with $ {}^{10} $B which produces $ \alpha $ and $ {}^{7} $Li heavy ions. Its dose components are complex, including fast neutrons, thermal neutrons, $ \alpha $ and $ {}^{7} $Li particles, and $ \gamma $-rays. The relative biological effectiveness of each component differs. Therefore, research on BNCT dose calculation methods holds significant application value for the evaluation of clinical irradiation doses. This paper investigates the dose calculation method based on the OpenMC Monte Carlo particle transport code and validates its feasibility and effectiveness for BNCT dose calculations. An analytical geometric model of the Snyder human head phantom was established. Neutron source term data, including neutron energy spectrum, intensity, and angular distribution, were obtained using the proton-lithium reaction to provide source term modeling for OpenMC. BNCT neutron doses were tallied using OpenMC's mesh-based counting and compared with those from the MCNPX and FLUKA codes. Compared with the MCNPX simulation. tion results, the particle flux error of the BNCT dose distribution calculated by the OpenMC code is 0.59%; compared with the FLUKA results, the particle flux error is 9.18%, and the maximum error of the boron dose is 2.30%. Despite differences in simulation parameter settings and data post-processing relative to MCNPX and FLUKA, OpenMC proves to be feasible and effective for BNCT dose calculations. It can provide a reliable software tool for accurate dose calculation in future BNCT treatment planning systems and for the optimization of treatment strategies.