BEAM (redirected from beam down)

beam

Etymology: ME, beem, tree

1 a bedframe fitting for pulleys and weights, used in the treatment of patients requiring weight traction. See Balkan traction frame.

2 (in radiology) the primary beam of radiation emitted from the x-ray tube.

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BEAM

[bēm, bē′ē′ā′em′]

abbreviation for brain electric activity map.

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beam,

n a stream or approximately unidirectional emission of electromagnetic radiation or particles.

beam, central,

n the center of the beam of roentgen rays emitted from the tube.

beam, useful,

n the part of the primary radiation that passes through the aperture, cone, or other collimator.

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beam

a unidirectional emission of electromagnetic radiation. See also x-ray.

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external beam therapy

radiotherapy in which the source is at a distance from the patient, e.g. orthovoltage, cesium-137, cobalt-60 or linear accelerator.

beam limitation

restriction of the divergent beam as it appears from the tube window by a lead plate or cone or a light beam diaphragm located at the window.

primary beam

the radiation beam as it passes through the window of the x-ray tube and before it is modified by extra-tube devices.