Electronic-optical amplifier

Electronic-optical amplifier x-ray image is a device, intended for repeated increase the brightness of the image on the x screen by converting light image in electronic and then convert it into light. This increased image in electronic-optical amplifier is achieved with the help of vacuum device, called electron-optical Converter. Power x-ray image is used mainly when the x-raying, rentgenonegativee and the use of television in x-rays .
The main advantage of the electronic-optical amplifier is the sharp reduction in the dose of x-ray radiation from diagnostic tests, especially when rentgenonegativee, and the possibility of a sharp increase in the brightness of the image to be visible in a slightly darkened room, with low power x-ray apparatus (see).

Electronic-optical amplifier x-ray image is a device for converting the x-ray image in the optical, many times superior brightness of the image on a normal x-ray screen. Increase the brightness of the image is achieved by an intermediate conversion of x-ray images in electronic and strengthening of the latter at the expense additionally supplied electric energy.
The main amplifier element of such a device is a vacuum device, called electron-optical Converter. The most widely used amplifiers with x-ray electron-optical converters (REOP). The primary receiver of x-ray radiation is in this case, the fluorescent screen of ZnS - Ag - or ZnS·CdS - Ag-phosphor inside the vacuum tube (Fig. 1). The screen is located in optical contact with translucent antimony-cesium or multiselect the photocathode. Ekrano-cathode Assembly together with cone-shaped anode and podoconiosis electrode forms a three-electrode accelerating and focusing system of the Converter. At the base of the anode of a cone is output katodolyuminestsentsii screen. On the anode is served high positive potential (25 kV) with respect to the cathode, focusing on the electrode is small capacity (200-300).

Fig. 1. Scheme of x-ray electron-optical Converter of firm Philips x-ray screen in optical contact with the photocathode: 1 - x-ray tube; 2 - the object of the research; 3 - REOP; 4 - input x screen; 5 - photocathode; 6 - podoconiosis electrode; 7 - flask; 8 - output screen; 9 - protective glass; 10 - optical system; 11 - eyes investigating; 12 - television camera; 13 - camera; 14 - wide angle camera.

The beam of x-rays, getting on the output screen, causing it to glow roentgenofluorescence). Under the action of light quanta, the photocathode emits (emitting a) the electron, and the electron density distribution in the beam plays the distribution of lighting created by the screen on the surface of the photocathode. In the light image is converted to electronic. The flow of electrons, rushing to the anode, bombards output fluorescent screen, causing it to glow. Thus, is the inverse transform electronic image in length. Increasing the brightness is achieved by accelerating electrons in an electrostatic field and electron-optical zoom, which leads to an increase in the density of electron flow. The image on the output screen, see through the optical system, increasing its size to normal. It can also be photographed on a widescreen film, film-or pass on television tube.
Modern amplifiers with REOP have a gain equal to 3000 or more. This means that the brightness of their output screen exceeds the brightness of conventional screen for x-rays of 3000 or more times. This is the main advantage of the amplifier, enabling to increase the degree of perception of the information contained in the image due to the increase of visual acuity and contrast sensitivity of the eye; to reduce the time of research; to reduce the likelihood of errors related eye fatigue; to eliminate the need for dimming and additional adaptation; to reduce the exposure of the patient during fluoroscopy; to make rentgenotechnika, and apply television installation using vidicons as transmitting tubes.
The disadvantage of the amplifier with REOP is relatively small size of the working field (technically difficult to do with REOP diameter of the output screen is more 220-230 mm). To increase the working field use amplifiers of brightness x-ray image of the other construction with the light of the electron-optical Converter (Fig. 2). This amplifier fluoroscopic screen is outside of the image intensifier, and the images on the screen, is projected on the photocathode Converter-aperture lens / mirror optics. The disadvantages of this system are cumbersome and considerable loss of light when you transfer images from the screen on the photocathode.

Fig. 2. Diagram of the device of amplifier brightness x-ray image "Cinelex" with the transfer of the image from an x-ray screen on the photocathode with the help of mirror-lens optics: 1 - x-ray tube; 2 - light electro-optical transducer; 3 - input optics; 4 - output optics; 5 - fluoroscopic screen.

Electro-optical x-ray image amplifiers used in the study of the digestive tract and cardiovascular system, for x-ray control with the introduction of
probes, catheters and radioactive drugs for quick study of traumatic injuries and in all cases where the conventional method of scanning carries the risk of excessive exposure of patients and staff.
Television installation steering allow the simultaneous observation by a team of doctors and implement radiological control operations directly from the operating table.
Rentgenotechnika using amplifier combines one of the important advantages of x-ray - a documentary with the possibility of functional studies of various organs. Dual output optical system allows you to visually control the process of filming.
Using the latest x-ray image amplifiers integral dose of x-rays in some cases decreases in 10-15 times.
The desire to minimize the exposure of patients and staff and to enhance your physical examination leads to the limitation of the scope of conventional x-ray with the replacement of its research using an electronic-optical amplifier x-ray image. Cm. also X-ray machines, X-ray Rentgenotechnika.