Non-melanoma skin cancer (NMSC) is a term that refers mainly to basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs). NMSC is the most common form of cancer in Caucasians, with a growing incidence worldwide. Among the possible treatments, radiotherapy is often preferred as a tissue-preserving non-surgical option, which shows effectiveness in terms of cosmetic results and local control. Vessel morphologies vary with different tumour stages and as a result of treatment, so cutaneous blood flow can be used as a biomarker to diagnose NMSC. Optical coherence tomography angiography (OCTA) can visualize both the microstructure and vasculature of skin non-invasively and could thus be used in treatment planning and follow-up.