From Big Medical Encyclopedia

ELECTROX-RAY ANALYSIS (synonym: kseroradiografiya, kserorentgenografiya) — a method of a X-ray analysis, at Krom the x-ray image is received on the loaded semiconductor plate, and then transferred to usual paper. The carrier of the image at the same time is electrically the loaded layer of amorphous selenium (see). The image on a surface of a selenic plate appears thanks to «running off» of charges in proportion to intensity of the selenium of x-ray emission falling on a layer (see).

The first works on an electrox-ray analysis are performed in 1938 by Carlson (Ch. Carlson). However the separate parties of this process were studied in 1916 by the Russian inventor E. E. Gorin, to-ry entered the term «electrophoto» and for the first time put forward the idea of use of photosemiconductors for obtaining images. In the USSR works on an electrox-ray analysis were begun in 1949.

Electroradiographic process consists of 5 stages. The first — drawing on a selenic plate of a positive electrostatic charge therefore it becomes sensitive to x-ray emission. The second — x-ray shooting of the studied object, at a cut instead of a x-ray film use a selenic plate. At the same time under the influence of the x-ray emission passing through the studied object on a surface of a plate the electric potential (positive charge decreases) changes and thus the hidden electrostatic image is created. The third stage — manifestation, at Krom the plate is pollinated black powder. Negatively charged particles of powder settle on a surface of a plate according to the positive charge which remained on it. The fourth stage — transfer of the powder image from a plate on paper in the contact way, the fifth — fixing of the image in vapors of acetone and toluene.

All stages, except x-ray shooting, are carried out by means of the electrographic device consisting of the technological block (for charging of plates and transfer of the image from them on paper) and the block of fixing. In the USSR electrographic devices ERGA — 02 and ERGA — 03 are issued, to-rye can be used with any X-ray equipment.

Fig. It is normal of the roentgenogram of a knee joint (a side projection): and — executed by method of an electrox-ray analysis on paper; — executed on a x-ray (supersensitive) film.

AA. has a number of important differences from a usual X-ray analysis (see). In particular, at E. the so-called regional effect — - more intensive adjournment of powder on border of sites with various potentials is noted that provides sharpness of contours of a shadow, high contrast and a nek-swarm increase in the sizes of elements of the image. All this makes an impression of dimensions of details and in general increases diagnostic opportunities of a method. At a research of soft tissues it is possible to receive the image of skin, hypodermic cellulose, muscles, sheaves. In soft tissues inflammatory infiltrates, hemorrhages, cysts, the centers of calcification and ossification clearly come to light. Photographic width (leveling effect of the image) inherent E., allows to receive at the same time detailed image of the fabrics having big differences of density and thickness. So, on electroroentgenograms of a thorax elements of the pulmonary drawing, a trachea, large bronchial tubes, soft tissues of a thorax, an edge, a shovel, a backbone clearly are defined, and at a research of joints along with the joint ends of bones — elements of the copular device, a sinew, muscle (fig).

Essential advantage of a method is its profitability and speed of obtaining the image — the method allows to receive in 2 — 3 min. a dry picture (the x-ray image of an object of a research on usual paper). It gives the chance to widely use E. in out-patient and polyclinic network, travmatol. points, medical - a dignity. parts, and also in intraoperative and urgent diagnosis.

To shortcomings E. carry a possibility of distortion of the image, emergence of artifacts, «breakdowns» in the form of the black round centers with light auras, longitudinal strips and other. what is connected with repeated use of a plate, existence of bruises and scratches on its surface.

Bibliography: Kishkovsky A. N. and Tyutin L. A. Metodika and technician of an electrox-ray analysis, M., 1982; Paleev N. R., Rabkin I. X. and Borodulin V. I. Introduction to a clinical electrox-ray analysis, M., 1971.

And. X. Rabkin.