tecnecio99m

Technetium-99m, often abbreviated as Tc-99m and sometimes referred to in Spanish-language contexts as tecnecio-99m, is a metastable nuclear isomer of technetium-99 used extensively in diagnostic nuclear medicine. It emits a gamma photon with an energy of about 140 keV and has a half-life of approximately 6 hours, which provides high-quality imaging while limiting the radiopharmaceutical’s overall radiation dose. Tc-99m decays to the ground-state technetium-99 through an isomeric transition.

Production and availability of Tc-99m rely on molybdenum-99 in a Mo-99/Tc-99m generator system. Molybdenum-99 is typically produced in nuclear reactors or accelerator facilities and then loaded onto collapsible generators. Clinicians administer Tc-99m on-site from the generator, enabling rapid, on-demand access to the isotope at hospitals and imaging centers.

Tc-99m is used in a wide range of radiopharmaceuticals that target specific organs or physiologic processes. Pertechnetate (TcO4-) is used for thyroid, salivary glands, and gastric studies. Tc-99m-labeled compounds such as sestamibi or tetrofosmin are employed for myocardial perfusion imaging; exametazime (HMPAO) for cerebral perfusion; and various agents (DTPA, MAG3, DMSA, MAA, MDP) for renal, lung, bone, and renal cortical imaging. The choice of agent determines the organ or system being investigated.

Tc-99m remains favored in diagnostic imaging due to its favorable imaging characteristics, relatively short half-life, and compatibility with standard gamma cameras and SPECT systems. Safety and regulatory oversight require trained personnel and licensed facilities, with administered activities tailored to the specific examination.