From Big Medical Encyclopedia

SCREENS X-RAY — devices for transformation of x-ray emission to the visible image. AA. rubles represent the plates covered with a phosphor, to-ry will transform to the public a part of the energy of x-ray emission absorbed by it.

Distinguish screens for roentgenoscopy and fluorography, X-ray intensifying screens for a X-ray analysis, and also electronic converters. For roentgenoscopic and fluorographic E. rubles use the zinc-cadmium-sulphidic phosphor activated by silver; the powder and single-crystal alkaline and haloid phosphors which are almost not absorbing own light radiation, and also powder screens on the basis of caesium, iodine, thallium and gadolinium, terbium to-rye differ in a big absorbtion coefficient of energy of x-ray emission. Use x-ray screens on the basis of zinc, cadmium, silver to the amplifiers of the x-ray image (AXRI). phosphorus with considerably smaller grains size of a phosphor.

For strengthening E. river (see. X-ray analysis) use lead and barytic, oxysulphidic, oksigalogenidny phosphors, and also a phosphor on a basis the calcium tungstate having high transparency to own light radiation. These screens are issued in couples. Strengthening E. rubles for a simultaneous tomography are intended for one-belt obtaining tomograms of several layers of an object. However intensity of x-ray emission during the passing via a number of consistently located pairs of screens (to 7) sharply decreases therefore for obtaining identical density of exhibiting of x-ray films in all layers of the cartridge weakening of radiation in screens is compensated by the corresponding increase in their luminous efficiency that is reached by a variation by phosphors. K E. rubles belong also electronic converters used to roentgenoscopy (metal x-ray screens from the TIN and LEAD, lead foil and other materials), and also flyuorimetrichesky X-ray intensifying screens from a lead foil with the phosphor applied on it, to-rye give a bigger intensification coefficient.

See also X-ray apparatus.

Bibliography: Varanetskas I. P., etc. Electroradiography, M., 1974; Gurvich of A. M. Rentgenolyuminofora and x-ray screens, M., 1976.

V. I. Belkevich.