What is the highest dose organ for Tc sestamibi?

• A. Kidney
• B. Large intestines
• C. Heart
• D. Bladder

Answer: (B)

The correct answer identifies the large intestines as the highest dose organ for Technetium-99m sestamibi. This radiopharmaceutical, primarily used in cardiac imaging, distributes throughout the body after administration. While the heart is the target organ for most imaging and evaluation, the biodistribution characteristics of sestamibi lead to significant uptake in the gastrointestinal tract, particularly in the large intestines.

The reason for the elevated radiation dose in the large intestines can be attributed to the metabolism and clearance pathways of the sestamibi. Following administration, some of the dose may be excreted through the gastrointestinal tract, resulting in a concentration effect that ultimately leads to the large intestines receiving a higher radiation dose compared to other organs.

Understanding which organs receive the highest dose is crucial for assessing patient safety, optimizing imaging protocols, and managing radiation exposure effectively. This knowledge plays an essential role in the development of appropriate dosimetry calculations and guidelines for the use of radiopharmaceuticals in clinical practice.