1. National Cancer Center Hospital Department of Radiation Oncology, , Tokyo, Japan
2. National Cancer Center Hospital Radiation Safety and Quality Assurance Division, , Tokyo, Japan
3. Tokyo Dental College, Suidobashi Hospital Department of Oral and Maxillofacial Surgery, , Tokyo, Japan
4. National Cancer Center Hospital Department of Oral Health and Diagnostic Sciences, , Tokyo, Japan
5. National Cancer Center Hospital Department of Head and Neck Surgery, , Tokyo, Japan
6. Kansai Medical University Department of Radiology, , Osaka, Japan
7. Kyoto Prefectural University of Medicine Graduate School of Medical Science Department of Radiology, , Kyoto, Japan
8. Osaka Dental University Department of Oral Radiology, , Osaka, Japan