1. Department of Radiation Oncology, Hokkaido University Faculty of Medicine and Graduate School of Medicine, Sapporo, Japan
2. Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
3. Department of Radiation Oncology, Hokkaido University Hospital, Sapporo, Japan
4. Global Center for Biomedical Science and Engineering, Hokkaido University Faculty of Medicine, Sapporo, Japan
5. Institute of Health Science Innovation for Medical Care, Hokkaido University Hospital, Sapporo, Japan