[1] Hiroshima Univ, Dept Oral & Maxillofacial Radiol, Grad Sch Biomed Sci, Hiroshima 7348553, Japan
[2] Ibaraki Univ, Sch Sci, Dept Environm Sci, Ibaraki 3108512, Japan
[3] Lawrence Berkely Natl Lab, Div Life Sci, Dept Cell & Mol Biol, Berkeley, CA 94720 USA
[4] Kyoto Univ, Ctr Radiat Biol, Kyoto 6068501, Japan
[5] Hiroshima Univ, Res Inst Radiat Biol & Med, Hiroshima 7348553, Japan