What is the machine called that scans you when you have cancer? how does it work?

PET scan: Positron emission tomography (PET) is a nuclear medicine imaging technique. It pairs gamma rays emitted indirectly by a positron-emitting radionuclide. By choosing fluorodeoxyglucose (FDG), an analogue of glucose, the concentrations of tracer imaged will indicate tissue metabolic activity in most malignancies since they actively utilize glucose uptake as part of their anaerobic metabolic pathway