(LINAC) [Linear Particle Accelerator]
An electrical device that creates high-energy radioactive materials to treat cancers. It uses electricity to form a fast-moving linear stream of subatomic particles to collide with the target. LINACs for medical use produce a beam of 6-30 MeV energy.

An accelerator uses electrostatic or electromagnetic fields to increase the kinetic energy of charged particles (see alpha particle, beta particle) in order to produce ionization or a nuclear reaction in a target.
Accelerators (see cyclotron, linear accelerator) are used for the production of radionuclides (see Fluorine-18, Molybdenum, Technetium-99m) or directly for radiation therapy. Accelerator-produced radioactive material (ARM) is any radioactive substance that is produced by a particle accelerator. The accelerators used for radiation therapy generate gamma rays (also called Bremsstrahlung) with continuous energy by collision of high energy electrons on materials with high density (also referred as 'high z' - chemical elements with a high atomic number (Z)).
Electron accelerators with energies above 10 MeV can also produce neutrons induced by photons in the accelerator head material (mainly caused by photo nuclear reaction).

In cyclotrons charged particles are circular accelerated to bombard atoms. Short-lived positron-emitting isotopes are produced for Positron Emission Tomography (PET) imaging (e.g. F-18).

See also Linear Accelerator, Metastable Condition, Meson, Fluorodeoxyglucose, Electric Polarization.