1. Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
2. Graduate School of Health Sciences, Hokkaido University, Sapporo, Japan
3. Sanda City Hospital, Sanda, Japan
4. School of Medicine, Hokkaido University, Sapporo, Japan
5. Hiroshima Heiwa Clinic High-Precision Radiotherapy Center, Hiroshima, Japan