1. Aizawa Hospital Proton Therapy Centre, , 2-5-1, Honjo, Matsumoto, Nagano 390-8510 , Japan
2. National Institutes for Quantum Science and Technology, QST Hospital , 4-9-1, Anagawa, Inage, Chiba 263-8555 , Japan
3. University of Tsukuba Department of Radiation Oncology, Faculty of Medicine, , 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8575 , Japan
4. Hokkaido University Global Center for Biomedical Science and Engineering, Faculty of Medicine, , Kita 15, Nishi 7, Kita-ku, Sapporo, Hokkaido 060-8638 , Japan
5. University of Tsukuba Department of Biostatistics, Faculty of Medicine, , 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8575 , Japan
6. Shizuoka Cancer Center Radiation and Proton Therapy Center, , 1007 Shimonagakubo, Nagaizumi, Shizuoka 411-8777 , Japan
7. Sapporo Teishinkai Hospital Proton Therapy Center, , 3-1, Kita 33, Higashi 1, Higashi-ku, Sapporo, Hokkaido 065-0033 , Japan
8. Southern Tohoku Proton Therapy Center Department of Radiation Oncology, , 7-172, Yatsuyamada, Koriyama, Fukushima 963-8052 , Japan
9. Osaka Medical and Pharmaceutical University Department of Urology, , 2-7, Daigakumachi, Takatsuki, Osaka 569-8686 , Japan
10. Iwate Medical University Department of Urology, School of Medicine, , 1-1-1, Idaidori, Yahaba-Cho, Iwate 028-3694 , Japan
11. Hokkaido University Department of Radiation Oncology, Faculty of Medicine, , Kita 15, Nishi 7, Kita-ku, Sapporo, Hokkaido 060-8638 , Japan