1. Department of Microbiology, College of Medicine, Inha University, Incheon, Korea.
2. Department of Radiation Oncology, College of Medicine, Inje University, Busan, Korea.
3. Department of Therapeutic Radiology, College of Medicine, University of Ulsan, Seoul, Korea.
4. Department of Statistics College of Medicine, Inha University, Incheon, Korea.
5. Radiobiology Laboratory, Department of Therapeutic Radiology, University of Minnesota Medical School, Minneapolis, MN, USA.