photon beam radiation therapy
Pronunciation: (FOH-ton beem RAY-dee-AY-shun THAYR-uh-pee)
A type of radiation therapy that uses x-rays or gamma rays that come from a special machine called a linear accelerator (linac). The radiation dose is delivered at the surface of the body and goes into the tumor and through the body. Photon beam radiation therapy is different from proton beam therapy.
Source: NCI Dictionary of Cancer Terms2006-04-14 Date last modified: 2010-08-27