纳米金粒子（GNP）应用为放疗辐射增敏剂是目前国际上的一个研究热点。使用自主研发的纳剂量生物物理蒙特卡罗程序(NASIC), 模拟研究了光子照射下细胞环境中GNP的物理增敏效应和生物增敏效应。通过建立单个GNP位于细胞核中心以及多个GNP在细胞内四种理想分布的GNP-细胞模型, 分析光子能量、GNP粒子尺寸和分布对能量沉积、DNA辐射损伤和细胞存活的影响。结果表明, GNP附近约2 μm的范围内具有能量沉积的增强效应, 这主要是因为GNP内光电效应作用数目的显著增加。不同条件下细胞核内能量沉积、DSB数目和细胞存活分数增强效应的变化规律基本一致, 但增强因子呈递减趋势, 三种评价指标增强因子的最大值分别为1.55,1.32 和1.14。光子能量为40 keV、GNP直径为100 nm并分布在细胞核表面时, 相比其他参数组合具有较高的物理和生物辐射增敏效应。

Using gold nanoparticles (GNPs) as a radiation sensitizer in radiotherapy is an international research focus.The self-developed nanodosimetry biophysics Monte Carlo code NASIC was used to study both the physical and biological radiosensitization effects of GNPs in the cell environment under the irradiation of photons. GNP-cell models were built in the simulation with single GNP in the nucleus center or four different ideal distributions of multiple GNPs. The influence of photon energy, GNP size and distribution on the energy deposition, DSB number and cell survival fraction were studied. The results show that the enhancement effect of energy deposition occurs in the vicinity (~2 μm) of GNP, which is mainly due to the increase of photon interactions in the GNP. The variation trends of the total energy deposition in the nucleus, DSB number and cell survival fraction with photon energy and GNP diameter are similar, but the enhancement factors decrease with the largest values as 1.55, 1.32 and 1.14 respectively. 40 keV photon energy, 100 nm GNP diameter and GNPs distributing on the nucleus surface have advantage over other parameter values in physical and biological radiosensitization effect.