 The objective is to assess the feasibility i.e. early toxicity of an adaptive dose escalation through 18F-FDG-PET-based dose painting by numbers in 10 HPV negative patients with locally advanced squamous cell carcinoma of the oropharynx. Treatment will be delivered with Helical Tomotherapy or volumetric-modulated arc therapy VMAT. Dose adaptation will be performed at 2 time-points with per-treatment 18F-FDG-PETCT scans. 