Particle Therapy

Particle therapy is a form of external beam radiotherapy that uses beams of energetic neutrons, protons or other heavier positive ions for cancer treatment; the most common type of particle therapy, as of August 2021, is proton therapy. In contrast to the X-ray photon beams used in older radiotherapy, particle beams exhibit a Bragg peak in energy loss as they pass through the body, delivering their maximum radiation dose at or near the tumor and minimizing damage to surrounding normal tissue. Particle therapy is also referred to, more technically, as hadron therapy, a category that excludes photon and electron therapy and also excludes neutron capture therapy, which depends on a secondary nuclear reaction; muon therapy, a rare type of particle therapy outside those categories, has also been studied theoretically, though muons remain most commonly used for imaging rather than treatment.