1. Department of Radiation Oncology, Yonsei Cancer Center, Brain Korea 21 Project for Medical Science, Kyonggi, Korea
2. Department of Yonsei University College of Medicine, Seoul, and Department of Radiation Oncology, National Health Insurance Cooperation, Ilsan Hospital, Kyonggi, Korea
3. Department of Pathology, National Health Insurance Cooperation, Ilsan Hospital, Kyonggi, Korea
4. Department of Otorhinolaryngology, National Health Insurance Cooperation, Ilsan Hospital, Kyonggi, Korea