1. Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
2. Department of Radiation Oncology, Wonkwang University College of Medicine, Iksan, South Korea
3. Department of Pathology, Yonsei University Wonju College of Medicine, Wonju, South Korea
4. Department of Radiation Oncology, Kosin University College of Medicine, Busan, South Korea