What determines tissue sensitivity to radiation?

• A. The tissue's color
• B. The tissue's age
• C. Susceptibility of the tissue's cells
• D. The patient’s height

Answer: (C)

Tissue sensitivity to radiation is determined by how susceptible the tissue’s cells are to ionizing damage. Radiosensitivity is highest in cells that divide rapidly and have high metabolic activity, and lowest in mature, differentiated cells with low turnover. This relationship is captured by the principle that radiosensitivity increases with proliferative activity and metabolic rate, and decreases with differentiation. Therefore, tissues with high cell turnover (like bone marrow, intestinal lining, and reproductive tissues) are more sensitive, while tissues composed of largely non-dividing cells (like nerve or muscle) are less sensitive. The choice highlighting the susceptibility of the tissue’s cells best reflects this concept, whereas color, overall tissue age, or patient height do not determine how radiation affects tissue.