Monte Carlo模拟在细胞辐射损伤中的应用

Application of Monte Carlo simulation in cell rdiation damage

本文利用Monte Carlo方法模拟细胞辐射损伤过程,以提供精确微观的数字化损伤产额结果。采用MCDS/MCER/VC系列程序模拟研究了电子束照射下DNA损伤产额随能量的变化,结果表明低能电子更容易造成DNA双链断裂。依据MCDS/MCER输出的SSB和OTHER产额,计算了酶解DSB产额,结果显示,入射能量变化对酶解DSB产额影响很小,但不同的修复机制却对其存在显著影响。采用能谱加权的方法得到了5种β放射性核素(Lu-177,Cu-67,Re-186,Re-188和Y-90)对DNA损伤的产额,结果表明低能核素Lu-177,Cu-67的DSB损伤产额略大,而SSB、OTHER和ALL产额略小。5种核素对DSB产额的影响相对最大,对SSB产额的影响相对最小。基于实验数据,利用VC程序得到两种模型细胞的存活曲线及相关参数。在此模型基础之上,模拟了修复时间对细胞存活曲线的影响。

BCRT （Biologically Conformal Radiotherapy ） is a hotspot in modem radiotherapy research. The implementation of BCRT concept is based on the rich knowledge on the radio-sensitivity of the cells in target. Monte Carlo method can simulate the radiation damage process economically, and output the rigorous, numeric and microcosmic damage yields. The work calculated the variation of DNA damage yields with energy of irradiation electrons using Monte Carlo codes, MCDS/MCER/VC. The results show that it is easier for the low energy electrons to damage DNA by DSB （double-strand break）. The enzymatic DSB has been calculated in the base of the combination of MCDS and MCER, which show that the influence of incident electron energy variation on enzymatic DSB yield is very little, but that of different base excision repair mechanism is notable. The damage yields of 5 13-emitter radionuelides （Lu-177, Cu-67, Re-186, Re-188, and Y-90） have been deduced by weighted energy spectra, which show the Lu-177, Cu-67 with a bit lower energy than the others have a little higher DSB damage yield and lower SSB, OTHER and ALL yields. It also shows that the influence of these 5 radionuclides on DSB yield is relatively the more, but on SSB yield is relatively the less. The cell surviving fraction and the key parameters for two models have been obtained by VC code based on measured data, on which the influence of the repairing time on surviving fraction has been studied.