PIRATES: Image-guided Hyper-fractioned Dose-escalation With Proton Therapy for Head and Neck Cancer

Inclusion Criteria: In order to be eligible to participate in this study, a subject must meet all of the following criteria: * Biopsy proven diagnosis of squamous cell carcinoma originating in the oropharynx. * Routine staging procedures, including CT of the head and neck region and chest, head and neck FDG-PET/CT and MRI (treatment planning allowed), and endoscopic evaluation when indicated. * Negative for p16 * Locally advanced disease, specifically meeting all following criteria: * Stage III-IV * T-stage 2-4 * All N-stages (N0-3) * M0 * Eligible for primary concurrent chemoradiation using conventionally fractionated radiotherapy 70 Gy combined with weekly cisplatin * Eastern Cooperative Oncology Group (ECOG) performance score ≥2 * Age ≥18 years * Written informed consent Exclusion Criteria: A potential subject who meets any of the following criteria will be excluded from participation in this study; patients that: * underwent definitive resection of their primary tumor or nodal disease, except for incisional or excisional biopsies. received radiation therapy in the head and neck area in the past * have no detectable tumor anymore at both the primary site and lymph nodes at week 4 in treatment, because there will not be a volume to boost. * are unable or unwilling to give written, informed consent * have contra-indications for chemotherapy. This is at the discretion of the treating medical oncologist. * are unable to tolerate intravenous contrast for both CT and MRI, having an estimated GFR \< 60 ml/min/1.73 m2 or any contraindications to gadolinium-based contrast agents. * have any evidence of iron overload on pre-imaging laboratory studies. * have other serious illnesses or medical conditions present at entry in the study, including (but not limited to): immunodeficiency virus (HIV) infection or other conditions of persistent immunodeficiency, neurologic or psychiatric disorders, active disseminated intravascular coagulation, unstable cardiac disease despite treatment or uncontrolled diabetes mellitus. * Women who are pregnant or breast feeding