标题：Relative Biological Effectiveness of Fission Neutrons for Producing Micronuclei in the Root-tip Cells of Onion Seedlings after Irradiation as Dry Seeds
其他标题：Relative Biological Effectiveness of Fission Neutrons for Producing Micronuclei in the Root-tip Cells of Onion Seedlings after Irradiation as Dry Seeds
摘要：The relative biological effectiveness (RBE) of mixed neutron and gamma-ray radiation emitted at a 252 Cf source at the Research Institute for Radiation Biology and Medicine, Hiroshima University, compared with 60 Co gamma-ray radiation was determined. The tissue-absorbed dose contribution of the accompanying gamma radiation was about 35.7% to the total tissue-absorbed dose from the 252 Cf mixed radiation. The 252 Cf mixed radiation and 60 Co gamma rays produced approximate linear changes in the frequency of micronuclei induced in root-tip cells of Allium cepa L. onion seedlings after irradiation as dry dormant seeds with varying absorbed doses in onion seeds. Therefore, the RBE for radiation-induced micronuclei was calculated as the ratio of the slopes for the 252 Cf mixed radiation and the 60 Co gamma rays. The deduced RBE value of 252 Cf mixed radiation to 60 Co gamma rays to induce micronuclei in dry dormant onion seed cells was about 90.5 ± 3.6 (± 1σ); the RBE of neutrons from the 252 Cf mixed radiation was about 150 ± 6 (± 1σ). Furthermore, the sensitivity ratio of the induction rate of micronuclei in dry dormant seeds to that in seedlings by neutrons from 252 Cf mixed radiation was significantly different from that by 60 Co gamma rays. From these results, we concluded that the repair efficiency of DNA damage induced by neutrons may be different from that by gamma rays.
