# STEREOX-RAY ANALYSIS

STEREOX-RAY ANALYSIS (Greek stereos firm, volume, space + a X-ray analysis) — the way of a X-ray analysis of a motionless object from two certain positions providing the subsequent visual reconstruction according to two roentgenograms of the volume (stereoscopic) image of the finished shooting object. The Page is the cornerstone the principle of the stereoscopic effect connected with properties solid vision (see).

The idea of use of stereoscopic effect in a radiology arose at the end of 19 century. E. Mach in 1896 offered S.'s idea, and after Levi-Dorn (M. of Levy-Dorn) developed S.'s technique and applied it for practical purposes.

The essence of a technique of S. is in what is made by two pictures (a so-called stereo pair) of the motionless studied object, displacing a X-ray tube in an interval between the first and second pictures in the plane parallel to the plane of the cartridge with a film. The distance between points of shooting (basis of shooting) is usually equal to 60 — 70 mm, i.e. visual basis (to distance between visual axes of eyes of the person). During the shooting of stereo pairs use special two-pipe stereographic X-ray apparatus or move the same X-ray tube at a size of basis of shooting. Sometimes for receiving a stereo pair of roentgenograms use the phenomenon of parallactical shift of the image (see Skialogiya) arising at rotation of an object. The size of basis of shooting is determined by a formula:

d = [N (N + E)] / 50E

where d — basis of shooting; N — distance from focus of a X-ray tube to the cartridge; E — thickness of the studied object.

For change of films at a X-ray analysis use an automatic prefix or the tunnel cartridge. The tunnel cartridge consists of three departments; average department of the cartridge misses x-ray emission, two other departments (extreme) are screened sheet lead. After receiving the first picture the exhibited x-ray film is stretched in a screened part of the cartridge, and in the unprotected part there is not exhibited part of a film again, on to-ruyu later shift of a X-ray tube and do the second picture, receiving thus a stereo pair.

For the purpose of obtaining stereoeffect received by the specified way of the roentgenogram consider on the stereonegatoscope.

In the analysis of roentgenograms on the special stereonegatoscope — the stereocomparator it is possible to make rentgenogrammetriya (see) structural elements of an object. For increase in accuracy and convenience of measurements create additional reference points, applying them on a body surface of the patient or entering X-ray contrast tags into hollow bodies.

In a crust, S.'s time apply seldom. Resort to it only in some cases at a contrast rentgenol. a research of a bronchial tree (see. Bronchography ), veins (see. Flebografiya ), at fistulografiya (see), in obstetric and gynecologic practice, at establishment of localization of metal foreign bodys (see), in the topometric analysis rentgenol. pictures of intracranial structures (e.g., Turkish saddle).

Bibliography: Bondarev I. M., etc. Studying of some indicators of function of bronchial tubes by method of a stereorentgenogrammet-riya, Vestn. rentgenol. and radio-gramophones., No. 4, page 20, 1975, bibliogr.; Poluektov JI. Century, etc. A clinical use of a stereox-ray analysis during the studying of venous system of the lower extremities, in the same place, No. 3, page 36, 1981, bibliogr.; Feoktistov V. I. The x-ray image, its metric properties and their use in clinic, L., 1966, bibliogr.; P e r N and y A. N. Use of a stereophotogrammetric method of a research in a medical radiology, Geodesy and aerial photography, century 5, page 119, 1971.

I. P. Korolyuk.