Which tissue is the most radiosensitive?

• A. Blood-forming tissue
• B. Cerebrovascular tissue
• C. Muscle tissue
• D. Nervous tissue

Answer: (A)

Radiosensitivity tracks how actively cells divide and mature. Tissues with many immature, rapidly dividing cells are most vulnerable to ionizing radiation. Blood-forming tissue fits this pattern because hematopoietic cells in bone marrow constantly proliferate to replace blood cells; when irradiated, these cells are easily damaged, leading to impaired blood cell production. That makes blood-forming tissue the most radiosensitive among the options.

Muscle tissue consists of relatively mature, slowly dividing cells, and nervous tissue has highly specialized, largely non-dividing neurons, so both are more resistant to radiation. Brain tissue can incur damage at high doses, but its inherent sensitivity is lower than that of blood-forming tissue. Cerebrovascular tissue (brain) shares this relatively resistant profile.