1. Department of Radiation Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, Japan
2. Department of Radiation Oncology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi Maebashi, Gunma, Japan
3. Department of Gynecologic Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, Japan