What happens to the radionuclidic purity of 99mTc throughout the day?

The radionuclidic purity of 99mTc decreases throughout the day due to the decay of its parent radionuclide, which is molybdenum-99 (99Mo). As 99Mo decays, it produces 99mTc, but over time, the amount of 99Mo decreases, and consequently, the yield of 99mTc diminishes. This results in a gradual decrease in the overall radionuclidic purity as the concentration of 99mTc declines along with the reduction of its parent isotope. The purity is critical for ensuring the effectiveness and safety of the radiopharmaceutical, particularly in diagnostic imaging, where the presence of impurities or other radionuclides can affect the quality of the imaging results. Therefore, recognizing the decrease in radionuclidic purity is important for health professionals managing and administering radiopharmaceuticals to ensure patients receive the highest quality care.