Studies on energy dependency of biological effects of neutrons and risk estimation

我们研究了中子对中国仓鼠V79细胞的杀伤和hprt基因座突变的诱导。在广岛大学放射生物学研究加速器（HIRRAC）设施中产生了0.32、0.57和1.2 MeV的单能中子，并用于照射细胞。观察到细胞存活和hprt突变诱导终点的RBE随中子能量的变化。与137 Cs伽马射线相比，所有中子能量在细胞杀伤和诱导突变方面都更有效。在检查的中子能量的范围内，我们发现，细胞毒性增加的能量从1.2至0.32兆电子伏。相比，γ射线，在10%的生存率的细胞致死率的RBE分别为5.7，6.7和7.6为1.2，0.57，和0.32兆电子伏，分别。另一方面，突变诱导在0.57 MeV时最高，在1.2和0.32 MeV时逐渐降低。对于1.2，0.57，和0.32 MeV中子。我们从未处理的和中子处理的V79细胞中分离出hprt基因座的独立突变体。暴露的细胞，并通过多重聚合酶链反应（PCR）为基础的外显子缺失分析，确定潜在的突变的遗传变化。初步结果表明，删除模式和中子能量之间的特定关系。

We have examined the neutron energy dependency of cell killing and mutation induction at hprt locus in Chinese hamster V79 cells. Monoenergetic neutrons at 0.32, 0.57, and 1.2 MeV were generated at the Hiroshima University Radiobiological Research Accelerator (HIRRAC) Facility, and were used to irradiate cells. The variation in RBE with neutron energy for the end points of cell survival and hprt mutation induction was observed. When compared to 137Cs gamma-rays, all neutron energies were more effective at both cell killing and induction of mutation. Over the range of the neutron energies examined, we found that cytotoxicity increased as the energy decreased from 1.2 to 0.32 MeV.In comparison to gamma-rays, RBEs for cell lethality at 10% survival were 5.7, 6.7, and 7.6 for 1.2, 0.57, and 0.32 MeV, respectively. Mutation induction, on the other hand, was highest at 0.57 MeV with a gradual decrease at 1.2 and 0.32 MeV.RBEs for mutation induction were 9.7, 19.4, and 13.9 for 1.2, 0.57, and 0.32 MeVneutrons.We isolated independent V79 cell mutants at the hprt locus from untreated and neutron-exposed cells and determined the genetic changes underlying the mutation by multiplex polymerase chain reaction (PCR)-based exon deletion analysis. Preliminary results are suggestive of a specific relationship between deletion patern and neutron energy.