1. Department of Radiation Oncology, Konkuk University College of Medicine, Seoul, Korea.
2. Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea.
3. Institute of Radiation Medicine, Medical Research Center, Seoul National University College of Medicine, Seoul, Korea.
4. Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
5. Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.