1. Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, Aichi, Japan
2. Department of Radiology, Fujieda Heisei Memorial Hospital, 123-1 Mizukami, Fujieda, Shizuoka, Japan
3. Department of Radiation Oncology, Nanbu Tokushukai Hospital, 171-1 Hokama, Yaese-cho, Shimajiri-gun, Okinawa, Japan
4. Department of Radiology, Narita Memorial Hospital, 134 Haneihonmachi, Toyohashi, Aichi, Japan
5. Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1–1-1 Hirate-cho, Kita-ku, Nagoya, Aichi, Japan