敏感域的形状选取对微剂量动力学模型参数的影响  

Influence of selection of domain shape on parameters of microdosimetric kinetic model

作　　者：严南 周云 孙向上 廖文涛 刘俊雅 蒲越虎 Yan Nan;Zhou Yun;Sun Xiangshang;Liao Wentao;Liu Junya;Pu Yuehu(Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China;Medical equipment Innovation Research Center,West China Hospital,Sichuan University,Chengdu 610041,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 [3]四川大学华西医院医学装备创新研究中心,成都610041

出　　处：《中华放射医学与防护杂志》2023年第3期209-215,共7页Chinese Journal of Radiological Medicine and Protection

基　　金：国家重点研发计划(2016YFC0105400)。

摘　　要：目的基于粒子径迹结构模型,利用三重积分计算粒子在球状敏感域(domain)内的单次事件剂量加权平均比能,并探讨敏感域的形状对微剂量动力学模型(MKM)参数带来的影响及其对应的物理意义。方法分别假定敏感域为圆柱状和球状。α_(0)、域半径r_(d)和细胞核半径R_(n)为待定系数,3种带电粒子(^(3)He、^(12)C、^(20)Ne)的核电荷数、动能及其对应的传能线密度(LET)为自变量,D10为因变量。以D10计算值与实验值的残差均方值J^(2)为优化目标,采用稳健最小二乘法分别得到人类唾液腺肿瘤(HSG)细胞和中国仓鼠肺(V79)细胞对应待定系数的最优拟合值即为MKM最优模型参数值。结果对于HSG细胞,圆柱状敏感域:α_(0)=0.073/Gy,r_(d)=0.29μm,R_(n)=4.1μm,J^(2)=0.0397 Gy^(2);球状敏感域:α_(0)=0.023/Gy,r_(d)=0.29μm,R_(n)=4.4μm,J^(2)=0.0393 Gy^(2);对于V79细胞,圆柱状敏感域:α_(0)=0.114/Gy,r_(d)=0.25μm,R_(n)=3.8μm,J^(2)=0.0974 Gy^(2),球状敏感域:α_(0)=0.095/Gy,r_(d)=0.26μm,R_(n)=4.1μm,J^(2)=0.0969 Gy^(2)。结论对于同一种细胞,分别选取圆柱状和球状的敏感域,最终计算拟合得到的MKM参数存在明显差异,其中两种形状的敏感域半径拟合值r_(d)相差不大,而球状敏感域拟合得到的α_(0)更小,细胞核半径R_(n)更大,更接近于荧光显微镜观察的细胞核尺寸。在低LET(<20 keV/μm)区域,根据两种形状敏感域所得参数计算的D10存在明显差异,所以敏感域形状选取会对质子放疗在布拉格峰附近区域的相对生物效应(RBE)计算造成影响。Objective To calculate the single-event dose-averaged specific energy of particles delivered in spherical domains based on the track structure model and using triple integration,and to investigate the influence of the domain shape on the key model parameters of microdosimetric kinetic model(MKM)and its corresponding physical significance.Methods The domains are assumed to be cylinders and spheres,respectively.Withα_(0),domain radius,r_(d),and nucleus radius,R_(n),as undetermined coefficients,the nuclear charge numbers,kinetic energies and their corresponding LETs of three kinds of charged particles(^(3)He、^(12)C、^(20)Ne)as independent variables,D10 as dependent variable,the mean value of squared residuals,J^(2),between the D10 calculated values and D10 experimental values as the optimization objective,the final fitting values of the above undetermined coefficients of human salivary gland(HSG)cells and Chinese hamster lung(V79)cells obtained after iteration by the robust least square method are the optimal model parameter values of MKM.Results For HSG cells,cylindrical domain:α_(0)=0.073/Gy,r_(d)=0.29μm,R_(n)=4.1μm,J^(2)=0.0397 Gy^(2);spherical domain:α_(0)=0.023/Gy,r_(d)=0.29μm,R_(n)=4.4μm,J^(2)=0.0393 Gy^(2);For V79 cells,cylindrical domain:α_(0)=0.114/Gy,r_(d)=0.25μm,R_(n)=3.8μm,J^(2)=0.0974 Gy^(2);spherical domain:α_(0)=0.095/Gy,r_(d)=0.26μm,R_(n)=4.1μm,J^(2)=0.0969 Gy^(2).Conclusions For the same type of cells,cylindrical and spherical domains were selected respectively,and there are significant differences in MKM parameters obtained by fitting.The fitting values of the domain radius,r_(d) of the two shapes of domains show no significant difference,while the fitting values ofα_(0) of spherical domains are smaller than those of cylindrical domains,the fitting values of nucleus radius,R_(n),of spherical domain are larger than those of cylindrical domains,closer to the nucleus radius observed by fluorescence microscopy.In the low LET(<20 keV/μm)region,D10 calculated accor_(d)ing to the paramet

关 键 词：微剂量动力学模型 剂量加权平均比能 敏感域 传能线密度 

分 类 号：R144.1[医药卫生—公共卫生与预防医学]