1. Department of Head and Neck Surgery, Atubetu Otolaryngeal Hospital
2. Department of Otolaryngology, Sapporo JR Hospital
3. Department of Otolaryngology, Head and Neck Surgery, Faculty of Medicine, Sapporo Medical University
4. Department of Head and Neck Surgery, Sapporo Teishinkai Hospital
5. Sacramento Otolaryngology
6. Department of Radiation Oncology, Keiyukai Sapporo Hospital
7. Department of Radiation Oncology, Sapporo City General Hospital
8. Department of Radiation Oncology, Hokkaido Cancer Center