摘要
纳剂量学量正在成为新的表征辐射品质的量,也是用于精确计算相对生物学效应(RBE)的基础数据。具有相同剂量平均传能线密度(LET)离子束混合辐射场导致的生物学效应也未必相同。为研究关键纳剂量学指标[电离簇尺寸NICS≥1的条件概率密度分布的一阶矩(M^(C1)_(1))、NICS≥2的条件概率密度分布的一阶矩(M^(C2)_(1))、NICS≥2的累计概率(F^(C1)_(2))和NICS≥3的累计概率(F^(C2)_(3))]以及RBE在相同剂量平均LET混合辐射场中的分布,在蒙特卡罗(Monte Carlo,MC)模拟的基础上,结合单能离子束关键纳剂量学指标数据集,计算得到了不同能量碳离子束在不同贯穿深度处相同剂量平均LET混合辐射场中的M^(C1)_(1)、M^(C2)_(1)、F^(C1)_(2)、F^(C2)_(3)及RBE值。计算结果显示:在相同剂量平均LET混合辐射场中,不同能量碳离子束的F^(C2)_(3)没有发生显著变化,而M^(C1)_(1)、M^(C2)_(1)和F^(C1)_(2)变化显著,且随能量的增大而减小,并且随剂量平均LET的增加,M^(C1)_(1)、M^(C2)_(1)和F^(C1)_(2)变化差异逐渐变大。正是由于M^(C1)_(1)、M^(C2)_(1)、F^(C1)_(2)和F^(C2)_(3)的不同,在相同剂量平均LET混合辐射场中基于纳剂量学模型计算得到的RBE值也显著不同。这些结果表明,剂量平均LET并不能很好地用于描述离子束混合辐射场的品质,而关键纳剂量学指标则有望成为表征离子束混合辐射场品质的量。
Nanodosimetric quantities are becoming new measures to characterize radiation quality,which provide basic data for calculating Relative Biological Effectiveness(RBE).The biological effects under mixed ion-beam irradiation fields with the same dose-averaged Linear Energy Transfer(LET)value may not be the same.To study the distributions of key nanodosimetric indexes[the first moment of the conditional cluster size distribution with ionization cluster size(NICS)≥1(M^(C1)_(1)),the first moment of the conditional cluster size distribution with NICS≥2(M^(C2)_(1)),the conditional cumulative probabilities with NICS≥2(F^(C1)_(2))and the conditional cumulative probabilities with NICS≥3(F^(C2)_(3))]and RBE values in mixed ion-beam irradiation fields with the same dose-averaged LET value,a pre-calculated key nanodosimetric indexes database combined with Monte Carlo(MC)simulation was introduced to accurately calculate M^(C1)_(1),M^(C2)_(1),F^(C1)_(2),F^(C2)_(3)and RBE in mixed irradiation fields with the same dose-averaged LET value for carbon ion beams at different penetration depths.The results showed that F^(C2)_(3)for different energy carbon ion beams did not change significantly,while M^(C1)_(1),M^(C2)_(1)and F^(C1)_(2)varied remarkably,and decreased with the increase of energy.Moreover,with the increase of dose-averaged LET value,the difference between M^(C1)_(1),M^(C2)_(1)and F^(C1)_(2)increased gradually.Due to the difference of M^(C1)_(1),M^(C2)_(1),F^(C1)_(2)and F^(C2)_(3)exactly,the calculated RBE values based on the Logistic NanoDosimetry model in mixed irradiation fields with the same dose-averaged LET value for carbon ion beams were also significantly different.These results indicated that the dose-averaged LET is not a good measure to describe the quality of the mixed irradiation fields of an ion beam,and the key nanodosimetric indexes are expected to be the candidates to characterize the quality of the mixed ion-beam irradiation fields.
作者
杨静芬
张晖
刘新国
戴中颖
陈卫强
李强
YANG Jingfen;ZHANG Hui;LIU Xinguo;DAI Zhongying;CHEN Weiqiang;LI Qiang(Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China;Key Laboratory of Heavy Ion Radiation Biology and Medicine of 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)
出处
《原子核物理评论》
CAS
CSCD
北大核心
2021年第3期332-338,共7页
Nuclear Physics Review
基金
国家重点研发计划项目(2018YFC0115700)
国家自然科学基金资助项目(11875299,61631001,U1532264)
中国科学院重点部署项目(E022223Y)
中国科学院西部之光项目(29Y86205)。
关键词
纳剂量学
相对生物学效应
碳离子放射治疗
蒙特卡罗模拟
nanodosimetry
relative biological effectiveness
carbon ion radiotherapy
Monte Carlo simulation
