1. Department of Radiation Oncology, Seoul St. Mary's Hospital, The Catholic University of Korea College of Medicine, Seoul, Korea.
2. Department of Radiation Oncology, Yeungnam University College of Medicine, Daegu, Korea.
3. Department of Radiation Oncology, Incheon St. Mary's Hospital, The Catholic University of Korea College of Medicine, Incheon, Korea.
4. Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea.
5. Department of Radiation Oncology, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
6. Department of Radiation Oncology, Pusan National University Hospital, Pusan National University School of Medicine, Busan, Korea.
7. Department of Radiation Oncology, Yeouido St. Mary's Hospital, The Catholic University of Korea College of Medicine, Seoul, Korea.
8. Department of Radiation Oncology, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.
9. Department of Radiation Oncology, Proton Therapy Center, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
10. Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
11. Department of Radiation Oncology, Ajou University School of Medicine, Suwon, Korea.
12. Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea.
13. Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Korea.
14. Department of Radiation Oncology, Chungnam National University School of Medicine, Daejeon, Korea.
15. Department of Radiation Oncology, Chung-Ang University Hospital, Seoul, Korea.