1. Department of Radiation Oncology, Chung-Ang University Hospital, Seoul, Korea.
2. Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea.
3. Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
4. Institute of Radiation Medicine, Medical Research Center, Seoul National University, Seoul, Korea.
5. Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.