Which organ is generally less radiosensitive than the breasts?

• A. Kidneys
• B. Stomach
• C. Bladder
• D. Brain

Answer: (D)

The main idea here is how different tissues respond to radiation based on their cell biology. Tissues with high cell turnover, like the mucosa of the stomach and the lining of the bladder, are generally more radiosensitive because many cells are actively dividing and more vulnerable to DNA damage. The brain, however, is made mostly of non-dividing neurons and relatively quiescent cells, so it tends to be more resistant to radiation effects—especially at diagnostic or lower therapeutic doses. That makes the brain generally less radiosensitive than breast tissue, which has more radiosensitive glandular and ductal cells and a higher risk of radiation-induced effects. So the brain is the best choice as the organ that’s generally less radiosensitive than the breasts.