Multi-modality imaging changes during radiotherapy. A case of a patient with a poorly differentiated squamous cell carcinoma of the base of tongue, T2N2bM0 treated with concurrent chemoradiotherapy to a dose of 70 Gy in 35 fractions over 7 weeks with concurrent cisplatin 100 mg/m2 days 1 and day 29. Imaging was acquired at baseline, fraction 11 and fraction 21 timepoints. Representative axial images at each timepoint are shown, illustrating CT, T2-weighted MRI, DW-MRI, DCE-MRI, and FDG PET-CT images. Colourwash panels show intensity of FDG uptake and PF.