1. Department of Radiation Oncology, Soonchunhyang University College of Medicine, Bucheon, Korea.
2. Department of Radiation Oncology, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
3. Department of Internal Medicine, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
4. CyberKnife Center, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.