基于蒙特卡罗几何分裂减方差技巧的AB-BNCT治疗室屏蔽模拟分析  

Simulation analysis of AB-BNCT treatment room shielding based on Monte Carlo geometric splitting variance reduction technique

作　　者：朱益楠 林作康[1,2] 郁海燕 余笑寒 ZHU Yinan;LIN Zuokang;YU Haiyan;YU Xiaohan(Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海应用物理研究所,上海201800 [2]中国科学院大学,北京100049

出　　处：《核技术》2025年第1期59-67,共9页Nuclear Techniques

摘　　要：硼中子俘获治疗(Boron Neutron Capture Therapy,BNCT)是一种新型二元靶向放射疗法,目前正在逐步进入商用阶段。适用于医院的BNCT中子源类型为加速器中子源,在设备运行与患者的治疗过程中,通常会伴随中子的泄漏与γ射线的污染。为了保证医用基于加速器的BNCT(Accelerator-Based Boron Neutron Capture Therapy,AB-BNCT)设备运行过程中相关人员的辐射安全,基于束流强度10 mA、能量2.8 MeV的质子中子源AB-BNCT开展屏蔽设计分析。首先以国际放射防护委员会(International Commission on Radiological Protection,ICRP)与我国现行的电离辐射防护与辐射源安全基本标准GB 18871-2002制定的公众年有效剂量限值1 mSv为参考标准,经保守估计折合成剂量率限值0.5μSv·h^(-1),利用蒙特卡罗程序进行BNCT治疗室屏蔽模拟计算分析;通过对比使用减方差技巧前后的屏蔽模拟数据结果,论证了使用几何分裂与俄罗斯轮盘赌等减方差技巧可以有效提高计算效率,获得更精确的计算结果。在模拟分析的数据基础上,给出了该AB-BNCT治疗室的屏蔽设计方案,并针对屏蔽的薄弱环节进行优化设计。最终的优化结果表明,当屏蔽墙体为60 cm的含硼重混凝土时,治疗室外侧空间的剂量率均小于0.5μSv·h^(-1),满足辐射防护要求。此外,本文也给出了剂量限值小于2.5μSv·h^(-1)时所需屏蔽墙体的厚度范围,为BNCT的商业化发展提供理论依据。[Background]Boron neutron capture therapy(BNCT)is a new type of binary targeted radiotherapy that is gradually entering the commercial stage.The accelerator-based boron neutron capture therapy(AB-BNCT)neutron sources used in hospitals are inevitably accompanied by neutron leakage and gamma-ray contamination during equipment operation and patient treatment.[Purpose]This study aims to analyze the radiation safety of public during the operation of BNCT using Monte Carlo geometric splitting variance reduction technique.[Methods]Firstly,based on a 10 mA 2.8 MeV proton accelerator neutron source,the International Commission on Radiological Protection(ICRP)and the basic standard for ionizing radiation protection and radiation source safety in China,GB 18871‒2002 was taken as the reference standard for the annual effective dose limit of 1 mSv for the public.This dose limit was conservatively estimated to be equivalent to a dose rate limit of 0.5μSv·h^(−1).Then,a water model with the size of 100 cm×30 cm×80 cm was placed at the outlet of beam shaping assembly(BSA)after neutron beam moderation and collimation,and the shielding calculations of AB-BNCT treatment room were conducted by Monte Carlo programs with various techniques.Finally,these results were comparatively analyzed to give shielding scheme design of the AB-BNCT treatment room,and the optimization design was carried out according to the weak link of the shielding.[Results]The simulation results indicate that the variance reduction techniques of geometric splitting and Russian roulette for shielding simulation calculations has higher efficiency and achieve more accurate calculation results.After optimizing the shielding design of the BNCT treatment room,the conservative calculation results prove that the total dose rate at the corridor outside the treatment room is less than 0.5μSv·h^(−1) when the shielding body is 60 cm thick boron containing heavy concrete,which meets the design requirements.In addition,the thickness range of the boron containing hea

关 键 词：硼中子俘获治疗 屏蔽设计 蒙特卡罗方法 减方差 

分 类 号：TL99[核科学技术—核技术及应用]