Bone marrow is used as a somatic dose indicator. Radiation can cause depression in blood cell production. Which category best describes this depression?

• A. Hematological depression
• B. Nervous depression
• C. Dermal depression
• D. Muscular depression

Answer: (A)

Radiation primarily affects rapidly dividing cells, and bone marrow is the key site of blood cell production. When marrow is irradiated, it slows or stops producing red cells, white cells, and platelets, leading to a drop in all blood cell counts. This specific decline is best described as hematological depression because it reflects impairment of the hematopoietic (blood-forming) system. The other body systems—nervous, skin, and muscle—aren’t the primary sites of hematopoiesis, so their “depressions” aren’t the appropriate way to describe this marrow-related effect. In this context, observing a hematological depression serves as a useful indicator of the dose absorbed by bone marrow.