Question

Which statements describe the use of gamma rays to treat cancer? Check all that apply.

Gamma rays have low energy and a source must be placed in the body.
Gamma rays are absorbed by only the cancer cells.
High-energy gamma rays are directed at a tumor from outside of the body.
Gamma rays kill cancer cells in a tumor.
Gamma rays are applied to a large area of the body.

Answer 1

Correct choices: 3 and 4.

Brief explanations:
- 1 is false — gamma rays are high-energy; while internal (brachytherapy) sources can be used, the statement as written is incorrect.
- 2 is false — gamma rays damage both cancer and normal cells; therapy is aimed to maximize tumor dose and minimize healthy tissue dose.
- 3 is true — external beam therapy uses high-energy photons (X-rays or gamma rays) directed at the tumor from outside the body.
- 4 is true — gamma rays kill cancer cells by damaging their DNA.
- 5 is false (generally) — radiation is usually targeted to the tumor; whole-body irradiation is only used in special cases (e.g., pre-transplant conditioning).