NCIt definition : A type of external beam radiation therapy using a beam of protons. It has the advantage
of precisely localizing the radiation dose on the targeted tissue and avoiding damage
to the healthy surrounding tissues.;
Alternative definition : NCI-GLOSS: A type of radiation therapy that uses streams of protons (tiny particles
with a positive charge) that come from a special machine. This type of radiation kills
tumor cells but does not damage nearby tissues. It is used to treat cancers in the
head and neck and in organs such as the brain, eye, lung, spine, and prostate. Proton
beam radiation is different from x-ray radiation.;