Cyclotron. View of a cyclotron machine. The cyclotron is used to radioactively label chemicals for use in medicine. This is done by accelerating high energy particles and passing them through samples of the chemicals to be made radioactive. These chemicals are used in medicine as tracers, which are injected into the body and followed using devices which can detect their radioactivity. A common use is of radioactive glucose during positron emission tomography (PET) scans of the brain. Radioactive glucose uptake in the brain is detected by a scanner, and a picture built up of which brain areas are most active. This is used to detect any abnormalities.