1. Department of Radiation Oncology, Daegu Fatima Hospital, Daegu, South Korea
2. Department of Radiation Oncology, Semyung Christianity Hospital, Pohang, South Korea
3. Department of Radiation Oncology, Dongguk University Gyeongju Hospital, Gyeongju, South Korea
4. Department of Radiation Oncology, Keimyung University College of Medicine, Daegu, South Korea