1. Department of Radiation Oncology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
2. Department of Radiation Oncology, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
3. Department of Thoracic and Cardiovascular Surgery, Severance Hospital, Yonsei University School of Medicine, Seoul, Korea.
4. Department of Radiation Oncology, Wonkwang University School of Medicine, Iksan, Korea.
5. Department of Radiation Oncology, Wonju Severance Christian Hospital, Wonju, Korea.
6. Department of Radiation Oncology, Ewha Womans University Hospital, Seoul, Korea.
7. Department of Radiation Oncology, Jeju National University Hospital, Jeju University College of Medicine, Jeju, Korea.