Question

Why are the alpha particles not used in radiotherapy?​

Answer 1

Radiotherapy is a therapy that uses ionizing power of radiation to treat cancer. An Alpha particle rapidly dissipates its energy as it moves through a medium due to its high mass and size.​

Therefore, its penetrating power is quite small. It can penetrate only through 3 to 8 cm in air and can easily be stopped by a paper and cannot be used to irradiate a tumor from outside of one’s body. Thus, alpha particles cannot be used for radiotherapy. ​