1. Department of Radiation Oncology Niigata University Medical and Dental Hospital Chuo‐ku Niigata Japan
2. Department of Radiological Technology Niigata University Graduate School of Health Sciences Chuo‐ku Niigata Japan
3. Section of Radiology Department of Clinical Support Niigata University Medical and Dental Hospital Chuo‐ku Niigata Japan
4. Department of Radiology and Radiation Oncology Niigata University Graduate School of Medical and Dental Sciences Chuo‐ku Niigata Japan
5. Department of Radiation Oncology Niigata Neurosurgical Hospital Nishi‐ku Niigata Japan
6. Department of Radiology Nagaoka Chuo General Hospital Nagaoka Japan
7. Department of Radiation Oncology Faculty of Medicine Hokkaido University Kita‐ku Sapporo Japan