1. Department of Radiation Oncology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea;
2. Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Republic of Korea;
3. Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea;
4. Department of Radiation Oncology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea;
5. Department of Neurosurgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea;
6. Department of Neurosurgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea;
7. Department of Neurosurgery, SMG-SNU Boramae Medical Center, Seoul, Republic of Korea;
8. Department of Neurosurgery, Keio University School of Medicine, Tokyo, Japan;
9. Department Radiation Oncology, SMG-SNU Boramae Medical Center, Seoul National University College of Medicine, Seoul, Republic of Korea