1. Department of Clinical Studies, Radiation Effects Research Foundation, Hiroshima, Japan.
2. First Department of Internal Medicine, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
3. Department of Statistics, Radiation Effects Research Foundation, Hiroshima, Japan.
4. Hakujuji Hospital, Fukuoka, Japan.
5. Saiseikai Nagasaki Hospital, Nagasaki, Japan.