1. Hospital of the National Institute of Radiological Sciences National Institutes for Quantum and Radiological Sciences and Technology Chiba Japan
2. Department of Radiology Hyogo Ion Beam Medical Center Tatsuno Japan
3. Gunma University Heavy Ion Medical Center Maebashi Japan
4. Ion Beam Therapy Center SAGA‐HIMAT Foundation Tosu Japan
5. Department of Oral Pathobiological Science and Surgery Tokyo Dental College Tokyo Japan
6. Department of Radiation Oncology, Faculty of Medicine Yamagata University Yamagata Japan