Yuki Hiroshima1, Takeo Kato1, Katsushi Tajima1,2. 1. a Department of Neurology , Hematology, Metabolism, Endocrinology and Diabetology (DNHMED), Yamagata University School of Medicine , Yamagata , Japan. 2. b Department of Radiation Emergency Medicine , National Institute of Radiological Sciences , Chiba , Japan.