X-RAY APPARATUS — devices for receiving x-ray emission and its use in medicine for diagnosis and therapy, for X-ray diffraction and X-ray spectral analyses, and also in the industry for X-ray defectoscopy and radiation of various objects in the technological purposes.
R.'s creation and. in our country it is connected with A.S. Popov and N. G. Egorov's names, to-rye in 1896, i.e. soon after opening of x-ray emission, began to make a X-ray analysis on the first domestic R. and. — electrically not protected inductor generators of high tension feeding ionic X-ray tubes directly or via mechanical rectifiers. In 1946 under the leadership of V. V. Dmokhovsky and A. G. Sulkin the protected domestic R. was created electrically and. RUM-2 with electrovacuum rectifiers kenotrons and electronic X-ray tubes. In the domestic devices RUM-5 and RUM-10 created at the beginning of the 60th the X-ray tubes with the rotating anode which allowed to increase significantly a radiation exit of a radiator are applied. In 1968 domestic three-phase R. by ampere-second semiconductor rectifiers (RUM-16) is created.
Since 1972 R. are intensively developed and. for a computer tomography, in to-rykh on the basis of a number of mnogorakursny projections of the narrow x-ray bunch which passed through the studied object by means of the electronic digital computer the cross tomogram is synthesized (see. Tomography computer ), what allows to investigate any body part.
In R.'s structure and. one or several X-ray emitters enter; the feeding device providing with electrical energy a X-ray emitter (X-ray tube) and regulating its radiation parameters; the device for transformation x-ray emission (see), passed through the studied object, in the visible image available to observation, the analysis or fixing (the screen, the x-ray cartridge with a radiographic film, the amplifier of the x-ray image, the television video monitor, the videorecorder, cameras, movie cameras, etc.); the shtativny devices serving for mutual orientation and movement of a radiator, an object of a research and the receiver of radiation; systems of protection and management P. and. The diaphragms, tubes, filters eliminating the rasters creating radiation in space the collimators, automatic rentge-noeksponometra and stabilizers of brightness creating its flow in time are applied to formation of a flow of radiation.
River and. for the medical purposes according to the destination share on X-ray diagnostic and roentgenotherapeutic.
X-ray diagnostic devices
X-ray diagnostic devices depending on a design and external environment divide into stationary (fig. 1), intended for operation in specially equipped rooms (see. X-ray department ); mobile for operation in chambers (fig. 2), operating rooms (including traumatologic); transported on special cars (see. Fluorography ); figurative, napr, pulse (fig. 3), transported by forces no more 2nd persons. Mobile R. and. are issued also folding for a research in chambers, at home, and also in field and forwarding conditions (fig. 4).
To destination X-ray diagnostic devices divide into devices of general purpose and specialized. The last by methods and conditions of a research divide in turn on fluorographic, hl. obr. for mass preventive researches (see. Fluorography ), tomographic (see. Tomography ), simulators for planning of radiation therapy, for work in chambers, operating rooms, etc. On range of application distinguish R. and. for angiography (see), for neuroradiodiagnosis, urological a research, mammographies (see), dental, including panoramic — pan-tomographs (see. Pantomografiya ), etc.
The short technical characteristic of X-ray diagnostic devices is given in tab. 1.
On the basic flowchart of the X-ray diagnostic device (fig. 5) its basic elements are specified. The feeding tension moves in the regulator of tension, inclusion to-rogo on the set duration of exposure carry out by means of a short-time switch. Increase and straightening of tension for food of a X-ray tube is carried out in the generating device (is placed in the steel tank filled with a transformer oil) containing one - or a three-phase step-up transformer and rectifiers. Distinguish one-half-period straightening of current when rectifiers are absent, and their functions are performed by the X-ray tube having property of unipolar conductivity, napr in dental and figurative R. and.; the dvukhnoluperiodny straightening applied in folding, mobile and nek-ry stationary R. and. small power, and also six-and twelve-phase straightening of current in stationary R. and. big power, carried out by means of consistently switched on semiconductor selenic or silicon diodes. High tension from the generating device moves on a X-ray tube by means of the high-voltage cables having the outside grounded cover. A X-ray tube (fig. 6, a) — the electrovacuum device with a source of electrons (cathode) and a target, in a cut they are braked (anode). In the majority of medical X-ray tubes the thermoissue heated cathodes and the tungsten motionless or rotating anodes are used. Energy for heating of the cathode moves via the transformer of heat placed in a tank of the generating device. Control of anode current is exercised by change of current of heat. The area of the anode, on to-ruyu electrons get, call focus. Distinguish one - or bifocal anodes. In the anode of St. 95% of energy of electrons turns into the heat energy heating the anode to 2000 and more degrees. For this reason with increase in duration of exposure admissible power decreases. Protection of a X-ray tube against an overload in the form of digital or analog computers is provided, to-rye create the signal interfering giving on a X-ray tube of excessive amount of electrical energy. The X-ray tube is placed in the protection cover with a lead cover for protection against not used radiation filled with a transformer oil, containing in addition to a tube, a nest for connection of high-voltage cables and an output window, through a cut the working bunch of radiation is removed (fig. 6, b). In mobile, folding, dental R. and. the radiator (X-ray tube) is in the protection cover together with the generating device that is often called a monoblock. Characteristics of the main X-ray tubes of domestic R. and. are provided in tab. 2.
To an output window of a radiator the diaphragm limiting a bunch of radiation with the set parameters fastens. Distinguish non-regulated, adjustable and replaceable diaphragms (the last sometimes call tubes or collimators). The diaphragm can be supplied with the optical simulator for lighting by this world of the surface corresponding to a working bunch of radiation and a set of replaceable filters for change of a power radiation spectrum.
Depending on appointment modern R. and. are supplied with various shtativno-mechanical devices — columns, ceiling supports, tables and racks for pictures, rotary tables supports for raying and pictures, etc. (fig. 1) — providing carrying out corresponding rentgenol. researches.
There are special supports for a tomography, rentgenokimografiya (see), neuroradiodiagnosis, catheterization and an angiography (fig. 7, a), urological researches (fig. 7, b), etc., the mutual movements of a radiator, the patient and the receiver of radiation differing in range and special devices. Also ekranosnimochny devices, kassetosmennik, etc.
Ekranosnimochny adaptation of modern stationary R. belong to shtativno-mechanical devices and. contains a X-ray fluoroscopic screen, the moved kassetoderzhatel with the cartridge, the tube, protection devices eliminating a raster and the program control providing a possibility of receiving on one radiographic film consistently of several pictures of a smaller format (so-called aim pictures) in the course of raying. The eliminating raster (the eliminating lattice) represents a set of the thin alternating strips of the X-ray transparent and X-ray absorbing material oriented to focus of a X-ray tube. The raster is established between the patient and the receiver of radiation and serves for reduction of influence on quality of the image of secondary (scattered) radiation. In modern diagnostic R.' most and. between a raster and the cartridge with a radiographic film the camera of the X-ray exposure meter — the device is located, to-ry automatically disconnects tension on a X-ray tube at accumulation by a film of the air dose of radiation providing a preset value of density of its blackening after photo processing. In the domestic equipment rentgenoek-sponometra of the ionization RER-3, RER-ZBM-50-20 type are applied, to-rye automatically under the influence of ionization of air give in a short-time switch a signal on R.'s shutdown and. The x-ray cartridge is usually charged with the double-emulsion radiographic film and two X-ray intensifying screens located in direct contact with a film. The luminescence of X-ray intensifying screens under the influence of x-ray emission by 60 — 100 times increases sensitivity of a radiographic film, the photographic emulsion layer a cut consists of microscopic crystals of bromic silver in gelatin. At the nek-ry researches demanding special sharpness of the image (e.g., pictures of bones), make shooting and without screens. For screens use l tsy-volframatny, lead baritnye, sulphidic, oxysulphidic and oksigalogenidny phosphors — the substances shining under the influence of x-ray emission. Gradually low-silver or beeserebryany registrars of the x-ray image get a wide spread occurance.
Semiconductor converters belong to nonsilver systems of registration of x-ray emission, in quality to-rykh devices are used for electrox-ray analysis (see), the receiver of radiation in to-rykh is previously loaded kserorentge-nografichesky selenic plate which is the photoconductor. Under the influence of x-ray emission on a plate there is a formation of the hidden electrostatic image, a cut show the loaded painted powder, transfer to paper and fix on it. For this purpose the domestic elektrorentgenogra-fichesky devices ERGA-01 and ERGA-02 are issued.
For visualization of the x-ray image at raying use the fluorescent screen similar to a X-ray intensifying screen protected by lead glass. In modern R. and. instead of screens electron-optical amplifiers of the x-ray image with the television video monitor, the main part are used to-rykh the electron-optical converter is that allows to increase repeatedly brightness of the image, and to lower a dose of radiation by 4 — 5 times. At the same time identification of fine details of the x-ray image significantly improves, need for blackout of the room procedural and expenses of time for adaptation of sight of the doctor disappears. The focusing system provides transfer of the image on the output screen with the minimum distortions, and then through optical system on the television transferring tube and the screen of the video monitor. At the same time the image can be registered a photo or movie camera, register in a videomagni-tofonny tape. Domestic amplifiers of the x-ray image are used in the X-ray diagnostic RUM-20P and RUM-20M complexes.
Roentgenotherapeutic devices or complexes of devices are intended for treatment of a number of diseases of brake x-ray emission. To destination they share on: devices for superficial therapy (the max. voltage of generation is 10 — 60 kV); for vnutripolot stny therapy (the max. voltage is 60 — 100 kV); for deep therapy (the max. voltage is 100 — 300 kV). On a way of the movement of a radiator in the course of radiation distinguish devices for static and mobile (rotational, convergent and pendular) radiations.
Distinguish also roentgenotherapeutic devices for contact, blizkodistantsionny (short-distance) and dalnedistantsionny radiation therapy (see).
The principle of operation of the roentgenotherapeutic device is similar stated above, with that difference that in its flowchart there are no receivers of x-ray emission as object of influence at roentgenotherapies (see) the patient is. For automatic restriction of an exposure dose within the set level the relay of a dose is used. In roentgenotherapeutic devices X-ray tubes with the motionless anode and systems of their forced cooling by a flowing transformer oil are applied. Schemes of multiplication of tension are sometimes used: doubling, trebling etc.
Operation of X-ray apparatus
Main characteristics of R. and. GOST 7248 — 75 «X-ray apparatus are normalized. General technical specifications». The main safety requirements are stated in GOST 12.0018.06. SSBT «X-ray apparatus. Safety requirements».
At R.'s operation and. careful observance of the maintenance instruction is necessary. Nek-ry elements P. and. are exposed to the increased wear and demand timely periodic replacement. About need of replacement it is possible to judge by decline in quality of the received image. It belongs first of all to X-ray tubes, endurance to-rykh is limited by a certain number of inclusions (15 — 20 thousand). In the course of work of a X-ray tube under the influence of electronic bombing there is a destruction of the anode and the flow of x-ray emission decreases. Also X-ray intensifying screens, kserorentgenografiche-sky selenic plates of electro-radiographic devices are subject to periodic replacement, etc.
Field X-ray diagnostic devices
Are intended for X-ray inspection of wounded and patients in field conditions. These are rather powerful, rather easy and reliable R. and., providing inspection of the big contingents of victims in various climatic conditions. Distinctiveness of field R. and. the possibility of their bystry assembly and disassembly without use of special tools (up to 30 min.), resistance to long transportations, reliability of protection against unused and scattered x-ray emission is. Domestic field X-ray apparatus of RUM-4 (RUM-4m) and RUM-24 are issued in box laying or in the set placed in a body of the special car (autox-ray).
The device RUM-4m (fig. 8) electrically is safe, expected food from low-power sources of alternating current. Main parts of the device: the operating console, the folding universal support and a monoblock containing the high-voltage transformer, the transformer of heat of a tube and a X-ray tube to-rye are placed in the protection cover with a transformer oil. In the scheme P. and. the electronic switch of time for implementation of a X-ray analysis with excerpts from 0,04 to 10 sec. is switched on. The support of the device allows to carry out roentgenoscopy and a X-ray analysis in vertical and horizontal provisions of wounded (patient), and also in lateroposition (with the eliminating lattice or without it). Protection of the doctor against secondary x-ray emission is carried out by a three-blade subscreen apron from the leaded rubber and the screen attached to a rack of a support.
The device RUM-24 represents more perfect model of a field X-ray apparatus (fig. 9). Has big power at rather small dimensions and simple management. Electrically it is safe. For food use the ordinary electric alternating current main or the benzoelek-trichesky unit. R.'s design and. allows to carry out quickly assembly and dismantling of its main nodes. RUM-24 consists of a monoblock, a universal support and the operating console. It is supplied with an ostrofokusny X-ray tube with the rotating anode, an optical centralizer with a slit diaphragm and rents-genoeksponometrom. Rentgenol. the research can be executed in vertical, horizontal provisions and lateroposition, and also directly on a stretcher. Movement of a support from vertical position in horizontal and giving of cartridges for a X-ray analysis are carried out automatically. Sufficient power of a X-ray tube allows to receive good pictures of all anatomic areas at rather short endurance. Short technical characteristic of domestic field R. and. it is presented in tab. 3.
The devices RUM-4m and RUM-24 can be operated with the electron-optical URI-60 and URI-135 amplifier, and also in a complex with the large picture frame photofluorograph and polevgm the electroradiographic device ERGA-megapixel, to-ry is carried out in the form of a prefix to R. and. It is intended for bystry obtaining electroroentgenograms in field and stationary conditions (fig. 10). Consists of three blocks. It can be developed in one or two workplaces. Gross weight (weight) of the device in boxes with account property on 3000 electroroentgenograms of 300x400 mm in size makes about 200 kg. The weight of the device unpacked — 53,2 kg. Can eat from network of alternating single-phase current or mobile power plant. The maximum power consumption — 600 W. The special plates covered with the photosemiconductor (selenium), powder for manifestation, fixer of the image and the writing paper are included in the package. From one picture it is possible to receive 3 — 4 prints, productivity of the device of 30 roentgenograms an hour. Use of the device allows to simplify and accelerate significantly inspection of wounded in field conditions.
Field R. and. are used in medical institutions of hospital bases. Their operation shall be carried out in strict accordance with the instructions attached to them. At the same time long trouble-free operation at mass inspection of wounded and patients in field conditions is guaranteed.
R.'s storage and. it is carried out, as a rule, in the dry heated rooms.
Transportation can be made by any kinds of transport at a temperature of an ambient air from — 60 to +60 °C observance of the established rules of packaging and processing of uncolored details protective lubricants.
Table 1. SHORT TECHNICAL CHARACTERISTIC of the MAIN DOMESTIC X-RAY DIAGNOSTIC DEVICES (COMPLEXES)
Table 2. CHARACTERISTICS of the MAIN X-RAY TUBES of DOMESTIC X-RAY APPARATUS
&Table 3nbsp; SHORT TECHNICAL CHARACTERISTIC of DOMESTIC FIELD X-RAY DIAGNOSTIC DEVICES
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