Development of an irradiation system of low-energy protons - To study the mechanism of the effects of neutrons for biological system-

低能质子辐照系统的开发 - 研究中子对生物系统的影响机制 -

基本信息

批准号：
12558061
负责人：
HOSHI Masaharu
金额：
$ 6.02万
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：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12558061/
关键词：
neutron generator energy spectrums biological effect accelerator TOF neutron

项目摘要

Relative biological effectiveness of neutrons is much higher than gamma- and beta-rays. As such cases of neutron exposure, we have experiences of atomic bomb survivors in Hiroshima and Nagasaki, and Tokai-mura accident. Neutrons when coming into human body recoil protons in hydrogen atoms which are included as a main component. Such recoil protons have charges. Therefore, as a consequence, they produce radicals, which induce DNA double strand breaks. The percentage of such proton recoils in neutron dose is 70-80% which depends on neutron energies. Almost all of such damages will be repaired; however, some of them will not be fixed, by which damages it is thought to induce cancers consequently. Recently some of the scientists proposed mat many of such damages are produced near by and that in such cases damages of DNA are become very large, which have large possibility not to be repaired. This is called as "cluster model". As the other case, neutrons have nuclear reaction and produces ra … More dioactivity. They emit particles, gamma rays and neutrons. The purpose of this study is to irradiate protons to find this part of radiation effects of neutrons using onion root top cells. Protons were produced by the Shenkel type electrostatic accelerator at Research Institute for Radiation Biology and Medicine, Hiroshima University. The irradiation system have been finished however adjustment for intensity and uniformity have not been done. Therefore we performed neutron irradiation experiment using not only onion root top cells but seeds themselves. After the irradiation seeds, they are incubated and micronucleus of the root tip cells are observed. We observed micronucleus of the root top cells by using monoenergetic neutrons of 0.2MeV, 0.5MeV, 0.8MeV and 1.0MeV from the neutron generator and average energy of 2.1MeV neutrons in Cf-252. The results of neutron RBE values are 216, 186, 180, 174 and 150 for dry seed irradiation, and 45.3, 39.1, 36.0, 31.4 and 18 for germination cells, respectively. Less

中子的相对生物有效性远高于伽马射线和β射线，就像广岛和长崎原子弹幸存者以及东海村事故中的中子进入人体时的经历一样。作为主要成分的氢原子具有电荷，因此，它们产生自由基，从而引起DNA双链断裂。中子剂量为70-80%，这取决于中子能量，几乎所有此类损伤都会被修复；然而，其中一些损伤不会被修复，最近一些科学家认为这些损伤会诱发癌症。许多这样的损伤是在附近产生的，在这种情况下DNA的损伤变得非常大，很可能无法修复，这被称为“簇模型”。产生…它们发射粒子、伽马射线和中子，本研究的目的是利用辐射研究所的申克尔型静电加速器产生的质子来寻找中子的辐射效应。广岛大学生物医学系照射系统已经完成，但尚未进行强度和均匀性的调整，因此我们使用中子照射实验。不仅是洋葱根顶细胞，还有种子本身。在照射种子后，将它们孵育，并使用 0.2MeV、0.5MeV、0.8MeV 和 0.8MeV 的单能中子观察根顶细胞的微核。来自中子发生器的 1.0MeV 中子和 Cf-252 中 2.1MeV 中子的平均能量。干种子辐照的RBE值分别为216、186、180、174和150，萌发细胞的RBE值分别为45.3、39.1、36.0、31.4和18。