Question

Why are the alpha particles not used in radiotherapy?

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

Answer 1

The correct option is C

Alpha particles cannot penetrate the human skin

Explanation for correct option:

(C) Alpha particles cannot penetrate the human skin

Alpha Particles:

• The composite particle known as an alpha particle is made up of two protons and two neutrons that are closely bonded.
• They are released from the nucleus of certain radionuclides during an alpha-decay process, a kind of radioactive decay.
• A doubly ionised helium atom, which has an atomic mass of four, is equivalent to the nucleus of an alpha particle.
• The first type of nuclear radiation to be recognised was alpha particles, often known as alpha radiation or alpha rays. Beta particles and gamma rays followed shortly after.

Figure: Alpha Particle

• $\alpha$-particles are a weakly penetrating type of particle radiation that is strongly ionising.
• By a few centimetres of air or by the skin, they can be halted. i.e., they are not employed in radiotherapy since they cannot penetrate human skin.

Explanation for incorrect options:

(A) Alpha particles cannot penetrate the bones

• Though alpha particles cannot penetrate the bones but the radiotherapy is used for the treatment of cancer.
• Cancer tissues needs to be destroyed and the major part of cancer is of skin tissues only and no bone is involved.

(B) Alpha particles can penetrate the human skin

• Alpha particles cannot penetrate human skin.
• They are a weakly penetrating type of radiation.

(D) Alpha particles are not radio waves

• Alpha particles are a type of radiation categorized under radio waves.
• These are also emitted from radioactive elements.

Hence, the correct option is (C).