1. Radiation Therapy Section, Division of Clinical Support, Hiroshima University Hospital, Hiroshima, Japan
2. Medical and Dental Sciences Course, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
3. Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
4. Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
5. Department of Nuclear Engineering and Management, School of Engineering, University of Tokyo, Tokyo, Japan
6. Departments of Diagnostic Radiology and Radiology, Hiroshima University, Hiroshima, Japan