@misc{oai:repo.qst.go.jp:00071273,
 author = {Kakinuma, Shizuko and Shang, Yi and Amasaki, Yoshiko and Hirano, Shinobu and Sawai, Tomoko and Takabatake, Takashi and Sawa, Yurika and Shirakami, Ayana and Sunaoshi, Masaaki and Morioka, Takamitsu and Tani, Shusuke and Blyth, Benjamin and Nishimura, Mayumi and Imaoka, Tatsuhiko and Daino, Kazuhiro and Takeda, Shino and Iwata, Ken-ichi and Yamada, Yutaka and Shimada, Yoshiya and 柿沼 志津子 and 尚 奕 and 甘崎 佳子 and 坂入 しのぶ and 澤井 知子 and 高畠 貴志 and 澤 百合香 and 白神 綾奈 and 砂押 正章 and 森岡 孝満 and 谷 修祐 and Ｂｌｙｔｈ Ｂｅｎｊａｍｉｎ and 西村 まゆみ and 今岡 達彦 and 臺野 和広 and 武田 志乃 and 岩田 健一 and 山田 裕 and 島田 義也},
 month = {Sep},
 note = {There are insufficient data at present to inform cancer risk after radiation exposure, during fetal and childhood periods, especially for heavy ions and neutrons.  Using animal models, we studied the age-at-exposure effect of radiation on cancer induction and lifespan shortening, in order to propose age-weighting factors and relative biological effectiveness (RBE) of heavy ions for radiation protection of fetuses and children. 
Fifty female and male B6C3F1 mice per group were exposed to gamma rays (137Cs), carbon ions (13 keV/µm) generated from Heavy Ion Accerelator in Chiba (HIMAC), or neutrons (average energy, 1-2 MeV) from Neutron Exposure Accelerator System for Biological Effect Experiments (NASBEE), at various ages from fetal to mature adult periods.  Mouse ages at the time of irradiation included 3 days post-conception (dpc), 13 dpc, 17 dpc, and 1 week, 3 weeks, 7 weeks and 15 weeks after birth. The doses ranged between 0.2 and 4 Gy for gamma rays, 0.2 and 2 Gy for carbon ions, and 0.05 and 1 Gy for neutrons. Mice were observed until moribund and their lifespan and tumor burden were analyzed.
Female mice appeared to be more susceptible to radiation-induced lifespan shortening than male mice. The effect of gamma-rays on lifespan shortening was more pronounced when irradiated at 1 week rather than 7 weeks of age. Surprisingly, irradiation with gamma rays at the late fetal stage had little influence on lifespan shortening compared to infant and adult exposures. Carbon ions and neutrons were more potent in reducing lifespan than gamma rays when 1 week-old mice and fetuses were exposed. These results on lifespan shortening suggest the highest RBE value were obtained for neutrons. Currently, pathological examination is undertaken to clarify the cause of life shortening., 59ｔｈ　Annual Meeting　of the Radiation Research Society},
 title = {Lifespan shortening after exposure of mice to gamma-rays, carbon ions and neutrons during fetal, childhood and adult periods},
 year = {2013}
}