Proton Beam Therapy

Proton beam therapy is a form of radiotherapy that irradiates diseased tissue, most often a tumor, with a beam of protons rather than the conventional photon (X-ray) beam used in most radiotherapy machines. Because a proton loses most of its energy only after traveling a set distance into tissue, a property called the Bragg peak, physicians can aim the beam to deposit its greatest dose within the tumor itself while sparing more of the healthy tissue beyond it than conventional radiotherapy typically allows. American physicist Robert R. Wilson first proposed using proton beams for medical treatment in 1946, and the technique was first used clinically at the Berkeley Radiation Laboratory in California in 1954; it has since become an established, though still comparatively expensive and less widely available, option for treating tumors near sensitive structures such as the brain, spine and eye, and in pediatric cancer treatment where sparing developing tissue is especially important.