Fluorodeoxyglucose, often abbreviated as FDG, is a radiopharmaceutical used in medical imaging, particularly in positron emission tomography (PET) scans. It is a glucose analog that contains a radioactive fluorine isotope, allowing it to be tracked in the body. Cells that are more active, such as cancer cells, absorb more FDG, making it useful for detecting tumors and assessing metabolic activity. FDG is typically administered intravenously and accumulates in tissues that have high glucose metabolism. After a waiting period, a PET scan is performed to visualize the distribution of FDG in the body. This helps doctors diagnose conditions like cancer, monitor treatment response, and evaluate other diseases.