What is the half-life of Tc-99m?

• A. 2 hours
• B. 6 hours
• C. 12 hours
• D. 24 hours

Answer: (B)

The half-life of Technetium-99m (Tc-99m) is approximately 6 hours. This relatively short half-life makes Tc-99m particularly advantageous for medical imaging and diagnostic purposes. Its rapid decay allows for a quick accumulation of sufficient radioactivity for imaging while minimizing the radiation exposure to the patient. In practice, this means that the radiopharmaceutical can be effectively used for procedures such as single photon emission computed tomography (SPECT) imaging without significant long-term radiation concerns.

The short half-life of 6 hours also facilitates the timely scheduling of imaging studies, as Tc-99m can be produced in a generator and used within a few hours to allow for efficient patient turnover and imaging workflows in clinical settings. This characteristic is a key reason why Tc-99m is the most widely used radioisotope in nuclear medicine.