Final answer:
Technetium-99m macroaggregated albumin (99mTc-MAA) is a metastable nuclear imaging agent with a short half-life of 6 hours, used in nuclear medicine to image various organs with minimal radiation exposure to the patient.
Step-by-step explanation:
The compound 99mTc-MAA (technetium-99m macroaggregated albumin) is frequently used in nuclear medicine imaging procedures. The 'm' in Tc-99m stands for 'metastable', indicating an unstable, high-energy state. When 99mTc decays, it emits a single gamma ray with an energy of 0.142-MeV, which makes it ideal for diagnostic imaging purposes due to its detectability and relatively low radiation dose to the patient. This low radiation dose is due in part to the isotope's short half-life of approximately 6 hours, limiting the time it remains active within the body.
99mTc-MAA can be administered to patients positioned in various ways, with the supine position being common for certain diagnostic tests. The isotope can be linked to different compounds to allow imaging of the skeleton, heart, lungs, kidneys, and so forth. Through neutron activation of molybdenum, 99mTc is conveniently and continuously produced on-site, making it readily available for medical use in imaging applications such as checking cardiac damage, blood flow in organs, or identifying issues like hypothyroidism or cancerous growths.