technetu99m

Technetium-99m, often written Tc-99m, is a metastable nuclear isomer of technetium-99 and is the most widely used radionuclide in diagnostic nuclear medicine. It has a half-life of about 6.01 hours and emits 140-keV gamma photons suitable for gamma cameras, enabling high-quality images with relatively low radiation dose.

Tc-99m is produced from a molybdenum-99 generator, in which Mo-99 decays to Tc-99m. The generator elutes as sodium pertechnetate (NaTcO4) solution, which can be chemically reduced and bound to various ligands to form technetium radiopharmaceuticals.

Tc-99m radiopharmaceuticals are used across organ systems: bone imaging with methylene diphosphonate (MDP); myocardial perfusion imaging with sestamibi or tetrofosmin; renal imaging with MAG3 or DTPA; hepatic-splenic imaging; brain perfusion imaging with HMPAO or ECD; thyroid and salivary gland imaging with pertechnetate. The choice of ligand determines the tissue distribution and imaging protocol.

Due to its short half-life and efficient detection, Tc-99m provides high-quality diagnostic information with relatively low radiation dose to patients. Handling, production, and distribution require regulated facilities and strict quality control.

Since the 1960s, Tc-99m has become the standard in diagnostic nuclear medicine; its widespread availability depends on Mo-99 production and aging reactors, with significant contributions from commercial suppliers.