Question

A woman with endometrial carcinoma is undergoing radiotherapy. Which of the following is true?

• A. Intensity is inversely proportional to the square of the distance from the source
• B. Small blood vessels are most radioresistant
• C. Rapidly proliferating cells are most radioresistant
• D. Small intestinal mucosa is most radio-resistant

Answer 1

The Correct Option is A

To address the scenario involving the radiotherapy for a woman with endometrial carcinoma and determine the truth among the given statements, we can apply the principles of radiotherapy and radiobiology:

• The principle that "Intensity is inversely proportional to the square of the distance from the source" is based on the inverse square law. This law states that the intensity of radiation decreases with the square of the distance from the source, which is true and a fundamental concept in radiotherapy. Therefore, this option is correct.
• The statement "Small blood vessels are most radioresistant" is incorrect. While tissues with less vascular supply can be radiobiologically resistant due to nutrients, small blood vessels are generally radiosensitive.
• The assertion "Rapidly proliferating cells are most radioresistant" is false. Rapidly proliferating cells are usually more radiosensitive because they are more likely to be in radiosensitive phases of the cell cycle, such as G2 and M phases.
• The claim "Small intestinal mucosa is most radio-resistant" is incorrect. The small intestinal mucosa is radiosensitive as the gastrointestinal lining contains rapidly dividing cells.

In conclusion, the correct statement is that the "Intensity is inversely proportional to the square of the distance from the source."