Radioguided surgery uses a radiolabelled tracer administered prior to surgery to guide lesion resection. Preferential tracer uptake by the tumour helps the surgeon to identify tumour residuals, target sentinel lymph nodes and hopefully achieve complete tumour resection. Current methods mostly use gamma-emitting tracers, but the high penetration of gamma photons through tissue means that any tracer uptake in nearby healthy tissue generates a non-negligible background signal. This approach also exposes medical personnel to radiation. Read more.