Which organ is primarily affected by the highest dose from heat damaged Tc RBCs?

• A. Liver
• B. Spleen
• C. Lungs
• D. Kidneys

Answer: (B)

The spleen is primarily affected by the highest dose from heat damaged technetium-labeled red blood cells (Tc RBCs). When these radiopharmaceuticals are subjected to heat damage, the integrity of the red blood cells is compromised, leading to their sequestration and breakdown. The spleen plays a critical role in filtering blood, particularly the removal of damaged or old red blood cells.

Due to its function and anatomical position, the spleen is particularly sensitive to changes in red blood cell integrity. When heat-damaged Tc RBCs circulate in the bloodstream, the spleen recognizes them as abnormal and actively filters them out, exposing itself to a localized higher dose of radiation from the radioisotope. This preferential uptake and processing in the spleen make it the organ most affected by such damaged cells.

Other organs like the liver, lungs, and kidneys do also play roles in blood filtration and processing, but they do not specifically target damaged red blood cells in the same manner as the spleen and therefore would not be as significantly impacted by the radiation from heat damaged Tc RBCs.