1. Department of Radiation Oncology , Samsung Medical Center, School of Medicine, , Seoul , Korea
2. Sungkyunkwan University , Samsung Medical Center, School of Medicine, , Seoul , Korea
3. Departments of Radiation Oncology , School of Medicine, , Daegu , Korea
4. Kyungpook National University , School of Medicine, , Daegu , Korea
5. Healthcare Review and Assessment Committee, Health Insurance Review and Assessment Service , Seoul , Korea