Study of mechanism of radiation effects for low energy protons by the irradiation of neutrons

中子辐照低能质子辐射效应机理研究

基本信息

批准号：
17310034
负责人：
HOSHI Masaharu
金额：
$ 10.78万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17310034/
关键词：
proton neutron biological effect dosimetry track end of proton DNA strand break ion chamber silicon detector 影響のメカニズム

项目摘要

The study of relative biological effectiveness (RBE) of low-energy protons and neutrons attracts considerable interest for many scientific fields. The reason of expected increasing the RBE of protons in the energy range of the Bragg peak is still the matter of scientific discussion. In this institution we have been studied using the neutron generator and the Cf-252 fission neutron irradiator. The effects of neutrons were experienced in the cases of Hiroshima and Nagasaki atomic bomb and Tokai mura (JCO) accident. However effects of neutrons for people are not known well. We studied using the 2MV tandem accelerator at Tsukuba University. By using a parallel plate ion chamber and a silicon surface barrier detector we measured proton beam and studied the dosimetry in the small size like cell level to use for the study of DNA strand breaks. The other purpose was to present theoretical results on quantitative modeling of irradiation of V79 cells using track structure of slowing down protons and simulation of initial DNA breaks for investigation a variation of RBE values as a function of initial proton energy. We simulated yields of DNA breaks: SSB and DSB classified on complexity as a function of energy of proton affected straightforwardly on a DNA segment. The results are the clear illustration of the following statements: (i) sensitive sites for cell lethality (transformation) are located in the cell nucleus and (ii) the complex DSB are the most relevant initial lesions leading to cell killing or transformation. The most efficient for delivering absorbed energy in whole V79 cell nucleus are the protons with incident energy of 550 keV. At that the protons with 200 keV were found to be the most efficient in order to induce a complex double strand breaks of DNA affecting DNA straightforwardly. Those calculated numbers are in the range of experimental RBEMAX values.

低能质子和中子的相对生物有效性（RBE）的研究引起了许多科学领域的极大兴趣。期望增加布拉格峰能量范围内质子的 RBE 的原因仍然是科学讨论的问题。在该机构中，我们使用中子发生器和Cf-252裂变中子辐照器进行了研究。广岛和长崎原子弹以及东海村（JCO）事故都经历了中子的影响。然而中子对人类的影响尚不清楚。我们使用筑波大学的 2MV 串联加速器进行了研究。通过使用平行板离子室和硅表面势垒检测器，我们测量了质子束并研究了小尺寸（如细胞水平）的剂量测定，以用于 DNA 链断裂的研究。另一个目的是提出使用减慢质子的轨道结构对 V79 细胞照射进行定量建模的理论结果，并模拟初始 DNA 断裂，以研究 RBE 值随初始质子能量的变化。我们模拟了 DNA 断裂的产量：SSB 和 DSB 根据复杂性分类，作为直接影响 DNA 片段的质子能量的函数。结果清楚地说明了以下陈述：（i）细胞致死（转化）的敏感位点位于细胞核中，（ii）复杂的 DSB 是导致细胞杀死或转化的最相关的初始损伤。在整个 V79 细胞核中传递吸收能量最有效的是入射能量为 550 keV 的质子。发现 200 keV 的质子是最有效的，可以诱导直接影响 DNA 的复杂 DNA 双链断裂。这些计算出的数字在实验 RBEMAX 值的范围内。