1. Gunma University Department of Medical Physics and Biology for Ion Therapy, Graduate School of Medicine Medical Sciences, , 3-39-22 Showa-machi, Maebashi, Gunma 371-8511 , Japan
2. Division of Biology, Gunma University Heavy Ion Medical Center , 3-39-22 Showa-machi, Maebashi, Gunma 371-8511 , Japan
3. Gunma University Graduate School of Medicine Department of Radiation Oncology, , 3-39-22 Showa-machi, Maebashi, Gunma 371-8511 , Japan
4. Gunma University Graduate School of Medicine Department of Gastroenterology and Hepatology, , 3-39-22 Showa-machi, Maebashi, Gunma 371-8511 , Japan
5. National Hospital Organization Takasaki General Medical Center Department of Clinical Research, , 36 Takamatsu-cho, Takasaki, Gunma 370-0829 , Japan