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, Bucheon St. Mary's Hospital, The Catholic University of Korea College of Medicine, Bucheon, Korea.
3. Department of Radiation Oncology, Ewha Woman's University School of Medicine, Seoul, Korea.
4. Department of Radiation Oncology, Kyungpook National University Hospital, Kyungpook National University School of Medicine, Daegu, Korea.
5. Department of Radiation Oncology, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.