1. Department of Radiation Oncology, Korea Institute of Radiological and Medical Sciences, 75, Nowon-ro, Nowon-gu, Seoul 01812, Republic of Korea
2. Department of Radiation Oncology, Haeundae Paik Hospital, Inje University School of Medicine, 875, Haeun-daero, Haeundae-gu, Busan 48108, Republic of Korea
3. Department of Biostatistics, Soonchunhyang University College of Medicine, Bucheon, 170 Jomaru-ro, Wongmi-gu, Bucheon-si 14584, Gyeonggi-do, Republic of Korea
4. Department of Radiation Oncology, Soonchunhyang University College of Medicine, Bucheon, 170 Jomaru-ro, Wongmi-gu, Bucheon-si 14584, Gyeonggi-do, Republic of Korea
5. Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Republic of Korea