diagnostic radiopharmaceutical

diagnostic radiopharmaceutical,

a radioactive drug administered to a patient as a diagnostic tracer to differentiate normal from abnormal anatomic structures or biochemical or physiologic functions. Most diagnostic radiopharmaceuticals emit gamma rays. A collimated external gamma-ray detector can determine the concentration of the drug in different organs and produce low-resolution images of the organs. Some radiopharmaceuticals, such as those prepared with tritium, carbon-14, or phosphorus-32, do not emit gamma rays. Their diagnostic use involves analyzing the concentration of the isotope in a metabolic end product in the patient's blood, urine, breath, or biopsy samples. For example, when glucose containing ¹⁴C is administered, the subsequent monitoring of ¹⁴CO₂ in the patient's breath can indicate the absorption of glucose, its metabolism, and its elimination as a metabolic end product.