1. Department of Radiation Oncology, Graduate School of Biomedical Health Sciences, Hiroshima University, 1-2-3 Kasumi, Hiroshima, 734-8551, Japan
2. Department of Physics, Cancer Institute, Japanese Foundation for Cancer Research , 3-8-31 Ariake , Koto-ku, Tokyo 135-8550, Japan
3. Department of Radiology, Japan Self-Defense Forces Central Hospital , 1-2-24 Ikejiri , Setagaya-ku, Tokyo 154-8532, Japan
4. Department of Radiology, University of Tokyo Hospital , 7-3-1, Hongo , Bunkyo-ku, Tokyo 113-8655, Japan
5. Tokyo Radiation Oncology Clinic , 3-5-7, Ariake , Koto-ku, Tokyo 135-0063, Japan
6. Department of Radiation Oncology, National Cancer Center Hospital , 5-1-1, Tsukiji , Chuo-ku, Tokyo 104-0045, Japan
7. Radiation Oncology Department, Cancer Institute Hospital, Japanese Foundation for Cancer Research , 3-8-31 Ariake , Koto-ku, Tokyo 135-8550, Japan