Inclusion Criteria:  Patients > 18 years Head and neck cancer: (upper aerodigestive tract, cavum, facial sinus, skull base, brain) operated Surgery for complete tumour resection or with microscopic residue R1 All possible histologies: squamous cell carcinoma, undifferentiated carcinoma of the nasopharyngeal type (UCNT), adenocarcinoma, adenoid cystic carcinoma, chordoma, chondrosarcoma, other tumours Patients undergoing exclusive postoperative radiotherapy with a minimum total dose of 60 Gy of X-ray photon radiation or equivalent proton radiation. Patient affiliated to a social security scheme Signature of the informed consent before any specific procedure related to the study  Exclusion Criteria:  Macroscopic postoperative tumour residue R2 Previous cancer within 5 years (except treated basal cell skin carcinoma and treated cervical cancer). Previous radiotherapy (except brachytherapy of the cervix or prostate) Chemotherapy or other systemic oncological treatment (cetuximab) concomitant with radiotherapy Long-term immunosuppressive or corticosteroid therapy Patient deprived of liberty or under guardianship, protected adult Patient unable to undergo trial monitoring for geographical, social or psychopathological reasons Pregnant or breastfeeding woman Emergency situations