Inclusion Criteria:  ECOG Performance status 0 to 2 Life expectancy > 12 months Histological proven squamous cell carcinoma of the pharynx, larynx or oral cavity Locally advanced stage disease classified as T3-T4 or N1-3 Radical radiotherapy +/- chemotherapy indicated as the primary treatment modality Visible disease at the primary site on imaging performed within 4 weeks of starting treatment Adequate liver function Adequate renal function for infusion of iv. contrast for CT-scan and MRI-scan Adequate bone marrow function Written informed consent No previous radiation therapy on head and neck region  Exclusion Criteria:  Inability to provide informed consent Presence of distant metastases Previous radiation therapy on head and neck region Pregnant or breastfeeding patients Prior malignancy within the last five years (except adequately treated basal cell carcinoma of the skin or in situ carcinoma of the skin or in situ carcinoma of the cervix, surgically cured, or localized prostate cancer without evidence of biochemical progression) Mental conditions rendering the patient incapable to understand the nature, scope, and consequences of the study Allergy or contraindication to contrast agents General contraindications to MRI ECOG PS >=3