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).

(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.

Actinides are elements in the periodic table with an equal or higher atomic number than actinium, which has an atomic number of 89 and up to 103 lawrencium, including plutonium, curium, and californium). Actinides are also called 'rare earth metals'.
Actinides include most of the well-known elements found in nuclear reactions with atomic numbers higher than 92. These elements do not occur naturally but are produced by bombarding other elements with particles in an accelerator.

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.

The duty cycle is the part of the operation cycle of an accelerator during which radiation is produced. The duty cycle is the product of the pulse duration and the pulse-repetition frequency.

See also Duty Cycle in MRI.