If 99mTc equate needs to be diluted to prepare other 99mTc-labeled products, what is the correct diluent?

The appropriate diluent for preparing 99mTc-labeled products is preservative-free isotonic saline. This choice is correct because it maintains the isotonicity required for intravenous administration and prevents any unwanted reactions with the radioisotope or the radiopharmaceutical.

Preservative-free isotonic saline ensures that the pH remains stable and that osmotic balance is maintained, both of which are crucial for patient safety and the integrity of the radiopharmaceutical. Using an isotonic solution minimizes the risk of hypertonic or hypotonic effects when administered, which can lead to complications.

While other options may seem relevant, they do not meet the necessary criteria for diluting radiopharmaceuticals effectively. For example, sterile saline containing thiosulfate may introduce undesired chemical interactions, and bacteriostatic saline contains preservatives that could interfere with the radiochemical purity and stability of the preparation. Sterile water, while safe for certain applications, does not provide the necessary isotonicity, which is critical for intravenous administration and could cause adverse effects.