1. Research Institute of Clinical Medicine, Kyung Hee University Hospital at Gangdong, Seoul, Korea.
2. Department of Radiation Oncology, Kyung Hee University Hospital, Seoul, Korea.
3. Division of Medical Radiation Equipment, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
4. Department of Nuclear Engineering, Kyung Hee University, Yongin, Korea.
5. Department of Radiation Oncology, Kyung Hee University Hospital at Gangdong, Seoul, Korea.