1. Department of Radiation Oncology, National Cancer Center Hospital, Tokyo 104-0045, Japan
2. Department of Radiation Oncology, Gunma University Graduate School of Medicine, Gunma 371-8511, Japan
3. Gunma University Heavy Ion Medical Center, 3-39-22 Showa-machi, Maebashi 371-8511, Japan
4. Radiation Therapy Center, Okinawa Chubu Hospital, Okinawa 904-2293, Japan
5. Department of Radiation Oncology, Ise Red Cross Hospital, Mie 516-8512, Japan
6. Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Tokyo 104-0045, Japan
7. Department of Radiation Oncology, Saitama Cancer Center, Saitama 362-0806, Japan
8. Department of Radiation Oncology, Hyogo Cancer Center, Hyogo 673-8558, Japan
9. Department of Radiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
10. Department of Radiology, Kansai Medical University Medical Center, Osaka 573-1191, Japan
11. Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan