1. Japan Self-Defense Forces Central Hospital Department of Radiology, , 1-2-24, Ikejiri, Setagaya-ku, Tokyo 154-8532 , Japan
2. Cancer Institute Hospital, Japanese Foundation for Cancer Research Department of Radiation Oncology, , 3-8-31, Ariake, Koto-Ku, Tokyo 135-8550 , Japan
3. University of Tokyo Hospital Department of Radiology, , 7-3-1, Hongo, Bunkyo-Ku, Tokyo 113-8655 , Japan
4. Tokyo Radiation Oncology Clinic , 3-5-7, Ariake, Koto-Ku, Tokyo 135-0063 , Japan
5. Hiroshima University Department of Radiation Oncology, Graduate School of Biomedical Health Sciences, , 1-3-2 Kagamiyama, Higashihiroshima, Hiroshima 734-8551 , Japan
6. Cancer Institute, Japanese Foundation for Cancer Research Department of Physics, , 3-8-31, Ariake, Koto-Ku, Tokyo 135-8550 , Japan
7. Cancer Institute Hospital, Japanese Foundation for Cancer Research Department of Urology, , 3-8-31, Ariake, Koto-Ku, Tokyo 135-8550 , Japan
8. Tokyo Medical and Dental University Department of Radiation Therapeutics and Oncology, , 1-5-45, Yushima, Bunkyo-Ku, Tokyo 113-8519 , Japan
9. National Cancer Center Hospital Department of Radiation Oncology, , 5-1-1, Tsukiji, Chuo-ku, Tokyo 104-0045 , Japan