Question

Why are the alpha particles not used in radio therapy?

• A. Alpha particles can penetrate the human skin
• B. Alpha particles are not radio waves
• C. Alpha particles cannot penetrate the bones
• D. Alpha particles cannot penetrate the human skin

Answer 1

The correct option is D Alpha particles cannot penetrate the human skin

$\alpha$-particles are a highly ionizing form of particle radiation, and have low penetration depth. They are able to be stopped by a few centimeters of air, or by the skin. i.e., they cannot penetrate the human skin, so are used in radio therapy.