利用纳米颗粒的光核反应实现原位活化治疗的可行性研究

Feasibility of using photo-nuclear reaction of nanoparticles to achieve in situ activation therapy

目的:利用蒙特卡罗程序Geant4模拟13.5 MeV和6 MeV X射线照射细胞内的纳米颗粒,分析其光核反应的剂量贡献份额。方法:以纳米金颗粒(GNP)为例,分别模拟6 MeV和13.5 MeV照射细胞内的GNP,给出各自条件下由GNP造成的剂量贡献。创建水模体(0.426 mm×0.426 mm×0.426 mm),包含1 103个细胞,作为GNP的载体。在6 MeV和13.5MeV下分别模拟细胞中包含和不包含GNP所造成的剂量沉积。结果:13.5 MeV X射线照射,其由GNP造成的剂量贡献为5.12 cGy,细胞总能量沉积为25.37 cGy,由GNP引起的剂量贡献占20.19%;6 MeV X射线照射,其由GNP造成的剂量贡献为2.87 cGy,细胞总能量沉积为23.05 cGy,由GNP造成剂量贡献约为12.46%。与6 MeV相比,13.5 MeV下由GNP光核反应造成的剂量贡献占7.7%。结论:对于细胞模型内纳米金的研究表明,GNP确实能引起额外的剂量贡献。由于GNP光核反应引起的剂量贡献很低,难以作为能够被原位激活的放射源使用。

Objective To simulate the nanoparticles inside the cells that are irradiated by 13.5 MeV and 6 MeV X-rays by Monte Carlo toolkit Geant4,and to explore the dose contributions coming from the nanopaticles activated by photo-nuclear reaction.Methods Taking gold nanoparticles(GNP)as the example,the situations that the GNP inside the cells were irradiated by 13.5 MeV and 6 MeV X-rays were simulated,and the dose depositions caused by GNP were studied.Awater tank(0.426 mm×0.426 mm×0.426 mm)that contained 1103 cells was taken as the container of GNP.Based on the irradiation by 6 MeV and 13.5 MeV X-rays,the dose depositions in two kinds of cell models(with and without GNP)were analyzed.Results The dose contribution of GNP irradiated by 13.5 MeV X-rays reached 5.12 cGy which was 20.19%of the total dose deposition(25.37 cGy),while the dose contribution of GNP irradiated by 6 MeV X-rays reached 2.87 cGy which was 12.46%of the total dose deposition(23.05 cGy).Compared with the dose contribution under the irradiation by 6 MeV X-rays,the dose contribution coming from GNP activated by photo-nuclear reaction under the irradiation by 13.5 MeV X-rays accounted for about 7.7%.Conclusion The study on the GNP in cell models shows that GNP does lead to additional dose depositions.Because of the low dose contribution caused by photonuclear reaction,it is impossible to take the GNP activated by photo-nuclear reaction as in situ activated radiation source.