Oxygen-18 is an important precursor for the production of fluorodeoxyglucose (FDG) used in positron emission tomography (PET). Generally, in the radiopharmaceutical industry, concentrated water (H₂O) is bombarded with hydrogen ions in a cyclotron or linear accelerator to produce fluorine-18. FDG is then synthesized and injected into patients. When combined with tritium (H₃O), it can also be used to produce an extremely heavy form of water: ₃H₂O or T₂O. It is also primarily used for isotope tracing.
