What is the energy level of Tc-99m?

• A. 80 keV
• B. 140 keV
• C. 200 keV
• D. 300 keV

Answer: (B)

The energy level of Tc-99m is 140 keV, which is significant in the context of its applications in nuclear medicine. Tc-99m is a metastable isotope of technetium that decays by emitting gamma radiation, specifically at this energy level, which is optimal for imaging purposes. The 140 keV gamma photons have a favorable balance of sufficient penetration power for imaging organs and tissues while minimizing patient radiation dose, making it widely used in diagnostic imaging procedures such as single-photon emission computed tomography (SPECT).

The high energy of 140 keV also aids in achieving high-quality images, as this energy allows for better detection clarity and contrast when using gamma cameras. This characteristic is crucial for physicians in diagnosing various medical conditions through imaging techniques. Therefore, the designation of 140 keV as the energy level of Tc-99m highlights its importance in the practical applications of radiopharmaceuticals in medical diagnostics.