Adaptive, Image-guided, Intensity-modulated Radiotherapy for Head and Neck Cancer in the Reduced Volumes of Elective Neck

Inclusion Criteria: * Histologically confirmed squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx and larynx. * Primary non-resected tumor and/or patients refused surgery * Stage T1-4, N0-3; for cancer of the glottis T3-4 or T any N1-3 * Decision of curative radiotherapy or radiochemotherapy made by a Multidisciplinary Group of Head and Neck Tumors at UZ Gent and UZ Gasthuisberg Leuven * Karnofsky performance status \>= 70 % * Age \>= 18 years old * Informed consent obtained, signed and dated before specific protocol procedures Exclusion Criteria: * Treatment combined with brachytherapy * Prior irradiation to the head and neck region * Surgery of the primary tumor except lymph node dissection prior to radiotherapy * induction chemotherapy * history of prior malignancies, except for cured non-melanoma skin cancer, curatively treated in-situ carcinoma of the cervix or other cancer curatively treated and with no evidence of disease at least 5 years * Distant metastases * Creatinine clearance (Cockroft-Gault) =\< 60 milliliter/minute before treatment or creatinine value \> 1,3 milligram/deciliter * Known allergy to the CT-contrast agents * Pregnant or lactating women * Mental condition rendering the patient unable to understand the nature, scope and possible consequences of the study * Patient unlikely to comply with protocol, i.e. uncooperative attitude, inability to return for follow-up visits and unlikely to complete the study