1 Department of Radiation Oncology, Kochi Medical School, Kochi University, Oko-cho, Nangoku-shi, KohasuKochi, 783-8505, Japan. tkkimura@kochi-u.ac.jp.
2 Department of Radiation Oncology, Kochi Medical School, Kochi University, Oko-cho, Nangoku-shi, KohasuKochi, 783-8505, Japan.
3 Department of Radiation Oncology, Hiroshima Red Cross Hospital and Atomic-Bomb Survivors Hospital, 1-9-6 Sendamachi, Naka-ku, Hiroshima, 730-8619, Japan.