This is a multi arm, single center, investigator initiated study to investigate online adaptive radiotherapy and biomarker development in patients with newly diagnosed HNSCC (Head and Neck Squamous Cell Carcinoma) receiving curative therapy. The study will consist of two prospective arms. In Arm 1 up to 100 HNSCC patients receiving (CT)RT (computed tomography-based radiation therapy) will receive up to weekly non-contrast MRI (magnetic resonance imaging) scans during treatment. Arm 2 consists of two cohorts. In cohort A up to 20 healthy volunteers will undergo non-contrast MRI at two time points. In cohort B up to 53 patients planned to receive curative (chemo) radiotherapy for HNSCC will undergo two baseline MRI scans, one MRI in week 2 and week 4, and final MRI scan 6-8 weeks after completion of treatment.