A stream of electromagnetic or particulate radiation that could be collimated and is generally unidirectional or divergent usually from a small source and restricted to a small-solid angle.

See also Ion Beam, Broad Beam, Useful Beam and Beam On Time.

Ion particles accelerated in a cyclotron are diverted by a magnetic field to a circular course until a desired energy is reached. The ion beam resulting from this procedure is e.g. used for the production of radionuclides.

See also Ion, Cyclotron.

A broad beam describes a radiation shielding situation in which the beam impinging on a barrier surface is laterally extensive including scattered radiation.

The useful beam refers to the part of radiation that passes through the opening in the beam-limiting device (aperture, diaphragm or collimator) and is used for imaging.

The time that the radiation source is actually producing radiation.