A proton is a subatomic
particle which makes up part of the nucleus of an atom.
Protons give off more energy as they slow down, so protons
that are created in a linear accelerator can be aimed
at precise locations in radiation therapy. Proton beam
therapy is often used for delicate therapies such as
those that involve the eye or the spinal cord. Proton
beam therapy is now becoming more popular as a prostate