What is the therapeutic ratio in radiotherapy?
AThe ratio of abnormal cells killed to normal cells killed
BThe ratio of the patient's height to their weight
CThe number of treatment sessions divided by the tumor's size
DThe ratio of X-ray energy to visible light energy
Answer & Solution
Correct answer: A. The ratio of abnormal cells killed to normal cells killed
1. Radiotherapy aims to damage cancer cells heavily while sparing normal tissue as much as possible.
2. The ratio of abnormal cells killed to normal cells killed is called the therapeutic ratio.
3. All radiotherapy techniques are designed specifically to enhance that ratio.
4. Patient height and weight, treatment count, and X-ray-to-light energy ratios are not what this term describes.
5. So the ratio of abnormal to normal cells killed is correct.
_Source: OpenStax Physics (CC BY 4.0), Ch 22 "The Atom", section 22.5 Medical Applications of Radioactivity: Diagnostic Imaging and Radiation_
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