Question

Cancer patient undergoes radiotherapy, pick the true statement for radiosensitivity of tissues ?

• A. Rapidly dividing cells are resistant to radiation
• B. GI mucosa is one of the most radioresistant tissues in the body
• C. The intensity of radiation is inversely proportional to the square of distance from the source
• D. Small blood vessels are least resistant to radiation

Answer 1

The Correct Option is C

In the context of radiotherapy, it is essential to understand the concepts of radiosensitivity and radiation physics. The correct statement pertains to a fundamental principle known as the Inverse Square Law. This law states:

• The intensity of radiation is inversely proportional to the square of the distance from the source. Mathematically, this is expressed as:

I ∝ 1/d²

Where:

• I = intensity of radiation
• d = distance from the source of radiation

This principle explains that as the distance from a radiation source increases, the intensity of radiation decreases exponentially. Therefore, when treating cancer patients with radiotherapy, accurately measuring the distance from the source is crucial for effective dosimetry and minimizing harm to healthy tissues.

Options	Radiosensitivity
Rapidly dividing cells	Highly radiosensitive, not resistant
GI mucosa	Radiosensitive, not radioresistant
Small blood vessels	Moderately radiosensitive

Therefore, the correct statement regarding radiation physics and its impact on tissues in radiotherapy is indeed the principle of the inverse square law.