X-RAY PHOTOGRAPHIC MATERIALS

From Big Medical Encyclopedia

X-RAY PHOTOGRAPHIC MATERIALS — materials for transformation of the invisible x-ray image in photographic. This process is carried out or at direct action of x-ray emission on photographic materials, or by its preliminary transformation in light by means of the x-ray luminescing screen or the electron-optical converter.

Basic element of the majority F. the river is the galoidoserebryany gelatinous emulsion applied on a transparent triatsetatny or polyester (mylar) basis. Such photographic materials are called x-ray films. They are subdivided to destination on radiographic, fluorographic, tooth and dosimetric.

Radiographic films in most cases happen bilateral (for increase in picture contrast cover with an emulsion layer both parties of a basis). Nek-ry special types of radiographic films (e.g., mammography) and all fluorographic films do unilateral. On one party of these films apply an emulsion layer, and on another of protivoskruchpvayushchiya, to-ry also the anti-shouting solo often serves.

H and shche rents of about and about r and f and h e with to 11 e i1 of l of e of N - ki (PM-I, RM-V, etc.) place in the cartridge with luminescent a Wuxi l and in and yushch to them and screens (d in a mustache of t about r about and N and e films — with two, unilateral — with one screen). The emulsion layer of such films is sensitive to the radiation of screens. Most r and the joint venture r OST r and foams of N of e with * e not and and l 11 z and r about in and N-nye of a film, the emulsion layer to-rykh is sensitive to blue, violet and ultra-violet parts of a range; such films can be developed after exposure at weak green or red light. During the use of the screens covered with the phosphors which are letting out light in a flavovirent spectral range apply the sensibilized isochromatic, panchromatic or orthochomatic films (e.g., a film of RM-6) demanding, as a rule, processing in complete darkness. For the purpose of ensuring dense contact of X-ray intensifying screens and a radiographic film, a sharp image, necessary for receiving, in x-ray cartridges use special clips (see the Roentgenogram, the X-ray analysis).

Fluorographic films produce in rolls 35, 70, 105 and 110 wide "mm (see Fluorography). Use of fluorographic films allows to save the silver which is contained in an emulsion layer of a film.

The films which are directly transforming the x-ray image to photographic are called without-ekrannymn. They are used at mammography (see), a X-ray analysis of bones of extremities (a brush, foot). Also tooth and dosimetric films are screenless (see Dosimetry of ionizing radiation).

For economy of silver special radiographic films, including films with color strengthening are created. The image on them results from interaction of the kraskoobrazuyushchy component which is contained in an emulsion layer with oxidate of developer. Use of diffusion photoprocess and a special unilateral X-ray photographic material (Polaroid type) provides bystry (apprx. 1 min.) obtaining the positive image at a smaller dose of radiation.

T. rubles are characterized by such indicators as sensitivity, contrast, photographic width, a photographic veil, etc. Sensitivity of a film is defined in units called by the return X-rays (/G1). For modern films sensitivity averages 500 — 1000 r "1. To standardize and accelerate processing F. rubles allow special pro-attendance automatic machines. Time of receiving a dry picture in such avtokhmata of 1,5 — 6 min.

Observance of rules of the address with F. the river and the recommended mode of their processing is an indispensable condition of obtaining high-quality roentgenograms.

Bibliography: At r in and the p A. M and D rubles

Sensitometrichesky characteristics of medical radiographic and fluorographic films, Medical tekhn., No. 2, page 17, 1976; Technical means of radiodiagnosis, under the editorship of I. A. Peresle-gpn, M., 1981; Meredith W. J. and. Massey J. Century of Fundamental physics of radiology, Bristol, 1977. A. M. Gurvich.

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