1. Department of Radiation Oncology, Inje University College of Medicine, Busan, Korea.
2. Department of Radiation Oncology, Dong-A University College of Medicine, Busan, Korea.
3. Department of Biochemistry, Kangwon National University, Chuncheon, Korea.
4. Radiobiology Laboratory, Department of Therapeutic Radiology, University of Minnesota Medical School, Minneapolis, MN, USA.