1. Department of Radiation Oncology, Biomedical Research Institute, Pusan National University Hospital, Pusan National University School of Medicine, Busan, Korea.
2. Department of Radiation Oncology, Pusan National University Yangsan Hospital, Yangsan, Korea.
3. Department of Otolaryngology, Biomedical Research Institute, Pusan National University Hospital, Pusan National University School of Medicine, Busan, Korea.
4. Department of Otolaryngology, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea.