radiotracer

A radiotracer is a radioactive substance used to study biological processes by tracing its distribution and movement within an organism. In nuclear medicine, radiopharmaceuticals labeled with a radionuclide are administered to patients to image organs or to measure function.

The isotope decays to emit gamma rays or positrons; detectors capture the emitted radiation to form images. The data reflect physiology such as perfusion, metabolism, and receptor expression.

Common radionuclides include technetium-99m, fluorine-18, iodine-123, gallium-68, carbon-11, and copper-64. Examples: 18F-FDG for glucose metabolism in PET; 99mTc-labeled compounds for bone, liver, and thyroid imaging; 123I-MIBG for adrenergic heart and neural imaging.

Usage: diagnostic imaging, functional assessment, and research. Radiotracers are often used with anatomical imaging modalities such as CT or MRI to provide structural context and enable kinetic analysis.

Production and safety: radiotracers are produced in cyclotrons or generator systems and must be prepared as sterile, pyrogen-free solutions. Short half-lives require rapid use and centralized radiopharmacies. Administration follows radiation safety principles and regulatory oversight.

Note: radiotracers differ from radiopharmaceuticals. A radiotracer is any radioactive substance used to trace a biological process; a radiopharmaceutical is a radiotracer designed as a drug intended for diagnosis or therapy.