1. Department of Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan;
2. Department of Statistics, Radiation Effects Research Foundation, Hiroshima, Japan;
3. Department of Clinical Studies, Radiation Effects Research Foundation, Hiroshima, Japan;
4. Department of Clinical Studies, Radiation Effects Research Foundation, Nagasaki, Japan;
5. Associate Chief of Research, Radiation Effects Research Foundation, Hiroshima, Japan