1. Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan.
2. Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
3. Department of Radiation Molecular Epidemiology, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan.
4. Department of Thyroid and Endocrinology, Fukushima Medical University, Fukushima, Japan.