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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学效应（RBE）的研究在许多科学领域引起了广泛的兴趣。在布拉格峰的能量范围内，质子的RBE预期增加的原因仍然是科学讨论的问题。在这个机构中，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。在广岛、长崎原子弹爆炸和东海村核电站事故中，人们都经历了中子的影响。然而，中子对人类的影响还不清楚。我们使用筑波大学的2 MV串列加速器进行了研究。利用平行板电离室和硅面垒探测器测量了质子束流，研究了用于DNA链断裂研究的小尺寸细胞水平的剂量学。另一个目的是目前的理论结果的定量建模的照射V79细胞使用的轨道结构的减慢质子和模拟的初始DNA断裂的调查RBE值的变化作为初始质子能量的函数。我们模拟了DNA断裂的产率：SSB和DSB分类的复杂性作为一个函数的能量的质子直接影响的DNA片段。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是导致细胞杀伤或转化的最相关的初始病变。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。在此，发现具有200 keV的质子是最有效的，以诱导直接影响DNA的复杂的DNA双链断裂。这些计算值在实验RBEMAX值的范围内。