1. Department of Radiation Oncology, Graduate School of Biomedical Health Sciences, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan
2. Department of Nursing, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan
3. Department of Otorhinolaryngology, Head and Neck Surgery, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan
4. Department of Radiotherapy, National Cancer Center of Mongolia, Nam-Yan-Ju Street, Bayan Zurkh District, Ulaanbaatar 13370, Mongolia