The fundamental difference between cancer cells and normal cells is their uncontrolled and rapid proliferation. This high metabolic activity requires them to consume more energy and building blocks than normal cells. PET/CT imaging works by introducing substances like sugar, proteins, and specific molecules, which cancer cells heavily utilize, into the body after they have been radioactively tagged. The intense uptake of these tagged substances by cancerous tissues is detected by the device, thereby locating the cancerous regions.