Authors' contributions
The study concept was conceived by TY, SZ, TK, and NK. The study was designed by TY, SZ, TK, NK, RT, YF, and KW. TY, SZ, TK, and NK are the primary authors of the protocol; however, all authors have contributed in this regard to some extent. TY, SZ, TK, and NK wrote the manuscript. RT, YF, NK, and KW play central roles in radiological physics, procedures for the evaluation of the swallowing function, quality-of-life assessment, and procedures for the evaluation of the hearing function, respectively. All the authors have read and approved the final manuscript.