| Co-Investigator(Kenkyū-buntansha) |
TAKADA Jun Hiroshima University, Research Institute for Radiation Biology and Medicine, Associate Professor, 原爆放射線医科学研究所, 助教授 (00274134)
ENDO Satoru Hiroshima University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (90243609)
ISHIKAWA Masayori Hiroshima University, Research Institute for Radiation Biology and Medicine, Research Associate, 原爆放射線医科学研究所, 助手 (80314772)
IWAMOTO Eiji Nissin Electric Co., Ltd., Head of Research, 研究部長
NITTA Yumiko Hiroshima University, Research Institute for Radiation Biology and Medicine, Research Associate, 原爆放射線医科学研究所, 助手 (60171964)
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| Research Abstract |
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
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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
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