1. Department of Radiation Oncology Faculty of Medicine and Graduate School of Medicine Hokkaido University Sapporo Japan
2. Department of Radiation Oncology Hokkaido University Hospital Sapporo Japan
3. Global Station for Quantum Medical Science and Engineering Global Institution for Collaborative Research and Education (GI‐CoRE) Hokkaido University Sapporo Japan
4. Department of Medical Physics Hokkaido University Hospital Sapporo Japan
5. Department of Health Sciences and Technology Faculty of Health Sciences Hokkaido University Sapporo Japan
6. Department of Biostatistics Faculty of Medicine Hokkaido University Sapporo Japan
7. Department of Radiology Boston Medical Center Boston University School of Medicine Boston MA USA
8. Department of Radiation Medical Science and Engineering Faculty of Medicine and Graduate School of Medicine Hokkaido University Sapporo Japan