1. Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
2. Department of Radiation Oncology, Konyang University College of Medicine, Daejeon, Republic of Korea
3. Department of Radiation Oncology, Wonkwang University School of Medicine, Iksan, Republic of Korea
4. Department of Radiation Oncology, Inje University Busan Paik Hospital, Busan, Republic of Korea
5. Department of Radiation Oncology, Chung-Ang University Hospital, Seoul, Republic of Korea