A Feasibility Study on the Use of F-18-FDG-PET and Optical Imaging in Evaluation of Radiation-induced Oral Mucositis

Inclusion Criteria: * Non-operated histologically confirmed squamous cell carcinoma of the oral cavity, oropharynx (except the posterior wall) and lymph node metastases from the unknown primary tumor (CUP) * Stage T1-4; Tx N+ for the CUP * Multidisciplinary Group of Head and Neck Tumors at Ghent University Hospital decision of radical radiotherapy (±concurrent chemotherapy) * Informed consent obtained, signed and dated before specific protocol procedures. Exclusion Criteria: * Age \< 18 years * Pregnant or lactating women * Active infection or fistula in the oral/oropharyngeal mucosa * Previous cancer of the oral cavity and the oropharynx * Prior head-and-neck radiotherapy * Expectation of non-compliance with the study protocol * Known allergy for topical anesthetics (Xylocaïne)