TEPC壁对重离子束微剂量学测量及相对生物学效应计算的影响  

Influence of TEPC Wall on Microdosimetric Measurement and Relative Biological Effectiveness Calculation of Heavy Ion Beam

作　　者：戴天缘 刘新国[1,2,3] 戴中颖 贺鹏博[1,2,3] 马圆圆 申国盛[1,2,3,4] 张晖 陈卫强[1,2,3] 李强 DAI Tianyuan;LIU Xinguo;DAI Zhongying;HE Pengbo;MA Yuanyuan;SHEN Guosheng;ZHANG Hui;CHEN Weiqiang;LI Qiang(Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China;Key Laboratory of Heavy Ion Radiation Biology and Medicine,Chinese Academy of Sciences,Lanzhou 730000,China;Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine,Gansu Province,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院近代物理研究所,甘肃兰州730000 [2]中国科学院重离子束辐射生物医学重点实验室,甘肃兰州730000 [3]甘肃省重离子束辐射医学应用基础研究重点实验室,甘肃兰州730000 [4]中国科学院大学,北京100049

出　　处：《原子能科学技术》2019年第6期1127-1134,共8页Atomic Energy Science and Technology

基　　金：国家重点研发计划资助项目(2017YFC0107500);国家自然科学基金资助项目(11875299)

摘　　要：组织等效正比计数器(TEPC)广泛应用于重离子束微剂量学测量,提供用于计算相对生物学效应(RBE)的基础数据。为研究TEPC壁对重离子束微剂量学测量及RBE计算的影响,在蒙特卡罗(MC)模拟中引入理想组织等效正比计数器(Ideal-TEPC),精确计算得到碳离子束不同水等效深度处的微剂量学量及RBE。Ideal-TEPC和常规TEPC的计算结果表明:TEPC壁会使碳离子束产生较大的辐射场畸变,且会使TEPC测量结果及RBE计算结果产生较大偏差,该偏差随贯穿深度的增加而增大。将TEPC壁视为具有固定水等效厚度的水层可在数值上抵消TEPC壁对RBE计算的影响,但在展宽Bragg峰(SOBP)后端会产生过修正现象。Ideal-TEPC结合MC模拟能有效避免TEPC壁效应及TEPC壁引起的辐射场畸变对重离子束微剂量学量和RBE计算的影响。Tissue equivalent proportional counter(TEPC)is widely used for microdosimetric measurements in heavy ion beams,which provides basic data for calculating relative biological effectiveness(RBE).To study the influence of TEPC wall on microdosimetric measurements and RBE calculations of heavy ion beams,an Ideal-TEPC combined with Monte Carlo(MC)simulation was introduced to accurately calculate the microdosimetric quantities and RBE at different water equivalent depths of carbon ion beams.The results using Ideal-TEPC and general TEPC show that the TEPC wall produces serious irradiation field distortions for the carbon ion beams,and leads to deviation for the results of TEPC measurements and the RBE calculations.The deviation increases with the penetration depth.Treating the TEPC wall as a water layer with a fixed water equivalent thickness could numerically offset the influence of the TEPC wall on the RBE calculation,but over-correction occurs at the distal end of the spread-out Bragg peak(SOBP).Using Ideal-TEPC combined with MC simulation,the influence of wall effect and irradiation field distortions caused by TEPC wall on microdosimetric measurements and RBE calculations of heavy ion beam can be effectively avoided.

关 键 词：组织等效正比计数器 微剂量学 相对生物学效应 重离子 蒙特卡罗模拟 

分 类 号：TL811.2[核科学技术—核技术及应用]