intensifying screen (redirected from intensity of a radiographic beam)

intensifying screen

[inten′sifī′ing]

Etymology: L, intensus, tighten, facere, to make; ME, screne

a device consisting of fluorescent material, which is placed in contact with the film in a radiographic cassette. Radiation interacts with the fluorescent phosphor, releasing light photons. These photons expose the film with greater efficiency than would the radiation alone. Thus patient exposure to radiation can be reduced.

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screen [skrēn]

1. a framework or agent used as a shield or protector; called also protectant and protective.

2. to separate well individuals in a population from those who have an undiagnosed disease, defect, or other pathologic condition or who are at high risk by means of tests, examinations, or other procedures. See also screening.

Bjerrum screen tangent screen.

fluoroscopic screen a phosphorescent screen that shows the movement and relationship of organs and structures in fluoroscopy.

intensifying screen a fluorescent screen used in conjunction with x-ray film to enhance the effect of the radiation and reduce dosage to the patient. The screen must be matched to the emissivity range; the emissivity of phosphorus is similar to that of the human eye, so that phosphors absorb x-ray energy and convert it to visible light.

tangent screen a large square of black cloth with a central mark for fixation; used with a campimeter in mapping the field of vision.

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intensifying screen,

n See screen, intensifying.

intensity of a radiographic beam,

n the amount of energy in a radiographic beam per unit volume or area.

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intensifying screen

calcium tungstate screens which fluoresce and transform the invisible x-ray image to a fluorescent blue or ultraviolet one. This reduces the exposure time a great deal. The image is intensified. Rare-earth intensifying screens are more modern and produce more intensification. They also produce different colored light, depending on the rare earth used.

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rare-earth intensifying screen

faster than the standard calcium tungstate screens but much more usable at high kV range. They require the use of special film and safelights.