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.

对低能质子和中子的相对生物学有效性（RBE）的研究吸引了许多科学领域的兴趣。在布拉格峰的能量范围内，预期增加质子的RBE的原因仍然是科学讨论的问题。在该机构中，我们已经使用中子发生器和CF-252裂变中子辐照器进行了研究。中子的作用是在广岛和长崎原子弹和托凯·穆拉（JCO）事故中经历的。但是，中子对人的影响尚不清楚。我们使用Tsukuba University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屏障检测器，我们测量了质子束，并研究了小尺寸（如细胞水平）的剂量测定法，以用于研究DNA链断裂。另一个目的是使用减慢质子的轨迹结构和初始DNA断裂的模拟来调查RBE值随着初始质子能量的函数的变化，介绍V79细胞辐照的定量建模的理论结果。我们模拟了DNA断裂的屈服：SSB和DSB在复杂性上分类为质子的能量的函数，该质子的能量在DNA片段上直接影响。结果是以下陈述的明确说明：（i）细胞致死性的敏感部位位于细胞核中，（ii）复杂的DSB是导致细胞杀死或转化的最相关的初始病变。在整个V79细胞核中输送吸收能量的最有效效率是入射能量为550 keV的质子。在该质子上，发现具有200 KEV的质子是最有效的，以诱导直接影响DNA的复杂双链DNA断裂。这些计算的数字在实验RBEMAX值范围内。