Positron emission tomography/computed tomography (PET/CT) in Nepal at Purbanchal Cancer Hospital. It is a rapidly growing modality that has tremendously impacted the care of patients with cancer. PET scans use a small amount of a radioactive substance, or tracer, to show differences between healthy tissue and diseased tissue. The most commonly used tracer is 18F-FDG (Fluoro-deoxy-glucose). The combination of PET/CT provides complete information about both structure (CT) and function (PET) in human body. ย