恒健质子治疗装置的辐射与屏蔽设计

Radiation and Shielding Design of Hengjian Proton Medical Facility

恒健质子治疗装置(HJPMF)是广东省在建的首台质子治疗装置。为确保该装置的辐射安全,采用经验公式计算和蒙特卡洛程序模拟两种方法,对该装置的瞬发辐射和感生放射性进行了计算分析,并按剂量限值对原屏蔽结构进行了优化设计。结果表明:装置的原屏蔽结构基本满足瞬发辐射防护要求,外混凝土屏蔽墙厚度可充分利用土壤屏蔽优化替换以节省成本,部分迷宫和屏蔽墙的厚度可进行优化;加速器室部件和治疗室病人的感生放射性剂量率较大,需严格管理。研究表明了经验公式和FLUKA、MCNPX程序都可用来对质子治疗装置进行辐射防护设计,但在面对复杂结构和涉及感生放射性问题时,蒙特卡洛程序更为适用。

Hengjian Proton Medical Facility （HJPMF） is the first proton therapy device being built in Guangdong province. To ensure the radiation safety of HJPMF, two methods of emprical formulas calculation and Monte Carlo codes simulation were used to calulate and analyze its prompt radiation and induced radioactivity, and optimization design for its original shielding structure was conducted according to dose limit. The results shown that, the original shielding structure basically satisfies the requirement of shielding prompt radiation, but the thickness of outer concrete wall can be optimized and decreased greatly by soil shielding to save cost, and the thickness of several mazes and shielding walls can be optimized. The results also shown that, the induced dose rates from compo-nents in cyclotron room and from patients in treatment room are comparatively large and should be governed strictly. The research proved that both the empirical formulas and FLUKA or MCNPX code can be used to shielding design for proton medical facility, but the Monte Carlo codes are more suitable to the situations with sophisticated structure and induced radioactivity.