Question:medium
A cancer patient undergoes radiotherapy. Pick the true statement regarding radiosensitivity of tissues:
A cancer patient undergoes radiotherapy. Pick the true statement regarding radiosensitivity of tissues:
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One option is a pure physics law about distance and dose; the others misstate which tissues are sensitive.
Updated On: Jun 23, 2026
- Rapidly dividing cells are resistant to radiation
- GI mucosa is one of the most radioresistant tissues in the body
- The intensity of radiation is inversely proportional to the square of the distance from the source
- Small blood vessels are least resistant to radiation
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The Correct Option is C
Solution and Explanation
Option-elimination first. Bergonie and Tribondeau tells us that tissues which divide rapidly and are poorly differentiated are the most radiosensitive. That single rule kills three options: rapidly dividing cells are sensitive (not resistant), the high-turnover GI mucosa is highly radiosensitive (not radioresistant), and slowly dividing structures like small mature blood vessels are comparatively radioresistant (so they are not the least resistant).
The only survivor is the inverse square law, a fixed physics fact: dose is proportional to $\dfrac{1}{r^{2}}$. Move twice as far from a point source and the dose drops to a quarter. This underlies the radiation-protection mantra of maximizing distance from the source.
Hence option 3 is the true statement.
Ref: Inverse square law in medical physics.
The only survivor is the inverse square law, a fixed physics fact: dose is proportional to $\dfrac{1}{r^{2}}$. Move twice as far from a point source and the dose drops to a quarter. This underlies the radiation-protection mantra of maximizing distance from the source.
Hence option 3 is the true statement.
Ref: Inverse square law in medical physics.
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