论文部分内容阅读
采用Geant4-DNA低能物理模型研究了污染电子在细胞DNA水平上的物理作用和能量沉积。利用密度聚类算法分析了损伤产额分布;并结合皮肤细胞辐射敏感性参数和临床表征剂量,探讨了低能电子对皮肤细胞的损伤特征。模拟发现,产生的DSB中约20%是cDSB;DSB产额是SSB的约4%;损伤聚类包含的SSB一般3个,20 keV和100 keV电子也可造成5个SSB的聚类损伤;晚反应、高α值的组织更应注意防护低能电子辐射;由于LQ模型中剂量平方项的影响,cDSB损伤致死系数ε随入射电子数目的增加而增大。当105个电子入射时,ε的数值可较单个电子增大3%～15%。可通过调节直接电离损伤概率弥补间接损伤产额,研究细胞辐照损伤的内在机理。本工作建立的低能电子对细胞DNA的损伤模型及结果,可用于评价放疗中低能污染电子对皮肤细胞的损伤效应。
The Geant4-DNA low energy physical model was used to study the physical effects and energy deposition of polluted electrons on cellular DNA levels. The distribution of damage yield was analyzed by density clustering algorithm. Combined with the skin cell radiation sensitivity parameters and clinical characterization dose, the damage characteristics of low energy electrons on skin cells were discussed. The simulation found that about 20% of the DSBs produced were cDSBs; the DSB yield was about 4% of SSBs; the SSBs contained in the damage clusters were generally three, with 20 keV and 100 keV electrons also causing cluster damage of five SSBs; Late response, high α value of the organization should pay attention to the protection of low-energy electron radiation; due to the impact of dose squared terms LQ model, cDSB damage lethal factor ε increases with the number of incident electrons. When 105 electrons are incident, the value of ε can be increased by 3% ~ 15% compared with that of single electron. By adjusting the probability of direct ionization injury to make up for the indirect damage yield, we study the intrinsic mechanism of radiation injury. The model and result of DNA damage induced by low-energy electrons established in this work can be used to evaluate the damage effect of low-energy contaminated electrons on skin cells in radiotherapy.