X-ray machines

X-ray machines (synonym x-ray equipment) devices to receive and use of x-rays in technical and medical purposes. Medical x-ray machines, depending on the destination are divided into diagnostic and therapeutic. The conditions in which they are operating, x-ray machines are divided into stationary, mobile and portable.
Stationary x-ray machines as diagnostic (Fig. 1)and therapeutic (Fig. 2), are intended for constant use in a specially designed room - x-ray room (see). Mobile x-ray units, depending on the conditions of use are divided into wards (Fig. 3)adapted to move within the medical institution with the purpose of x-ray studies of patients directly in the wards, and portable, designed for use outside of the hospital. To mobile x-ray machines are also devices (ROOM-4)that are designed to work in the field (Fig. 4). They are usually installed and transported in specially equipped vehicles, have Autonomous power and space for deployment, as well as his own photo lab. In peacetime mobile R. A. used in specially equipped vehicles, railcars and vessels of sea and river fleet (the so-called ship x-ray equipment). There are also mobile R. A., placed in a special laying boxes and transported by any kind sprung transport.
Field x-ray machines presented a number of specific requirements arising from unfavourable and difficult transportation conditions, climatic conditions and the need for frequent installation and dismantling of equipment. In particular, laying boxes must be sufficiently tight to protect the equipment from dust and moisture. Separate parts R. A. must be secured to ensure the possibility of transporting R. A. on the sprung (typically road) transport by road and dirt roads without damaging the parts R. A. Fluctuations in ambient temperature in the range from 40 to -40 degrees should not affect the quality of work and R.. during storage and transporting them in these conditions. Mounting and dismantling R. A. should be carried out by staff within half an hour without use of special tools.
In peacetime, x-ray machines field type can be used for mass surveys (see Fluorography)and for x-ray diagnostic work in remote areas.
Portable x-ray units (Fig. 5) are intended for production of the simplest kinds of radiological studies in the conditions of ambulance and emergency care, and home care. They are small, light, fit in two small bags and usually fit for carrying forces 1-2 people.
There are many types R. A., intended for different purposes. Working power produced by R. A. is determined by the product of the secondary voltage (voltage generation in kilovolts) for a current (mA)through the x-ray tube (see) in one second.
Ranges of voltage and current R. A. depending on their purpose are listed in the table.
X-ray machine consists of the following main units. 1. High-voltage device, including transformer high voltage (the so-called main transformer, transformer, a glow of x-ray tube, system, rectifying the current applied to the x-ray tube (low-power devices and rectifying unit may be absent). 2. The generator x-rays for - x-ray tube. 3. The distribution unit - control unit, regulating the operation modes of the device. 4. Tripod or group stands for mounting x
pipes, equipped with devices for installation or laying sick in the process certain types of x-ray examinations and treatment, and also means antiradiation protection.
Schematically the operating principle of the x-ray apparatus is that the power supply is supplied to the control panel, where it is controlled by autotransformer and served on the primary winding of the main transformer. The differences in the number of turns in the primary and secondary windings of the main transformer voltage in it sharply increases and served on the x-ray tube directly (the so-called half-wave R. A.) or through rectifying device (kenotron, selenium rectifiers). Adjustment of current passing through the x-ray tube, is the degree of intensity of its cathode filament.
Modern x-ray machines are equipped with very sophisticated devices for voltage and current x-ray tube, and to protect it from possible overloads. In addition to the complex of relay devices for regulation time of exposure, diagnostic devices equipped with an automatic switches modes R. A., what can be necessary, e.g. when a rapid transition from a mode of scanning mode images and back. In addition, all modern R. A. have a system of protection from unused x-ray radiation and the electric shock of high voltage.
The nature of protection against electric shock, high voltage distinguish block devices where high-voltage device together with the x-ray tube is enclosed in General grounded metal casing, cable R. A., in which the high voltage wires enclosed in insulated high voltage cables, and the tube and main transformer - in to a grounded metal housings. Block devices are usually used for mobile and portable R. A., and cable - for stationary R. A.
Diagnostic x-ray machines are supplied with the devices for imaging (see), kymography, electrotomography and other special methods of research, as well as EOP (see Electronic-optical amplifier x-ray image) (Fig. 6)to rentgenotechnika, television transmission x-ray images and provides high brightness images with a significant reduction of radiation exposure.
For the study of the individual phases of rapid processes, there are special R. A., enabling x-ray shooting at shutter speeds that make up thousandths of a second. This is achieved not by increasing the capacity (and therefore the size) R. A., and with the help of the system of capacitors that are charged from a relatively low-power transformer to the required voltage and then at the right moment instantly discharged on the x-ray tube (called a pulse x-ray units). In addition, there are devices to the usual diagnostic R. A. as set-top boxes, enabling them to shoot physiologically mobile objects (lungs, heart) into a predefined phase of activity, for example in phase inhalation or exhalation or in a particular phase of the cardiac activity.
Therapeutic x-ray machines are used for radiation therapy.
With the introduction into the clinical practice of artificial radioactive isotopes and various types of particle accelerators, linear accelerators, betatron, synchrotrons, Synchrophasotron and other role actually radiotherapy somewhat narrowed, and she currently used for radiation exposure on pathological pockets of relatively shallow location.
There are therapeutic R. A. not only the static but also for so-called rolling exposure (methods rotary and converged radiotherapy).
Depending on the depth of the location of irradiated hearth used devices for superficial x-ray therapy (Fig. 7) for static and deep therapy (Fig. 2).
In addition, produced x-ray machines for rotary (Fig. 8) and convergent (Fig. 9) therapy, which at the time of radiation exposure handset automatically sent on a predetermined path to the primary radiation beam was constantly directed the pathological focus, and the surrounding tissue and the area of skin being exposed to rays alternately. This allows, sparing the healthy skin and fabric, to bring to the hearth large doses of x-ray radiation than with static methods of irradiation.
Modern therapeutic R. A., as diagnostic, there are a number of special tools and devices that automate their work. Along with the devices for therapy with conventional automatic time relays are available R. A., in which time relays replaced on the relay dose representing integral dosimeter, automatically switching-off of high voltage at achievement of a preset value of a dose of radiation. In addition, the kit therapeutic R. A. includes special sets of tubes, diaphragms, limiting the field of radiation, and filter, screening softer part of the radiation and giving desktop bunch more homogeneous character.
Cm. also Rentgenotechnika, x-Ray, x-ray treatments.

Fig. 1. Stationary diagnostic x-ray machine type RUM-5.
Fig. 2. X-ray machine type RUM-11 for static deep x-ray therapy.
Fig. 3. Ward x-ray machine.
Fig. 4. General view of the x-ray machine ROOM-4.
Fig. 5. Portable x-ray machine.
Fig. 6. Electron-optical Converter (EOP) with a mirror for visual observations, a video camera and television transmitting camera.
Fig. 7. X-ray machine type RUM-7 for skin and contact therapy.
Fig. 8. X-ray machine for rotational therapy.
Fig. 9. X-ray machine for converged therapy.

X-ray units is a device for obtaining x-ray radiation and its application in medicine and technology. Medical x-ray machines on purpose divided by diagnostic (Fig. 1) and therapeutic (Fig. 2), and the conditions - stationary, mobile and portable. Stationary x-ray units are placed in a special x-ray rooms. Mobile x-ray units are of two types: demountable, intended for working externally (Fig. 3), and ward (Fig. 4) - for x-ray care in hospitals at the bedside. Portable x-ray units (Fig. 5) is used for simple x-ray examinations at home (domestic portable device RU-560 with all accessories are placed in two suitcases and has a total weight of about 45 kg). Range of voltage and current x-ray units, depending on their purpose is given in the table.

Ranges of voltage and current x-ray units
Types of vehicles Voltage (kV) Current (mA)
Diagnostic
Stationary
Mobile
Portable

Therapeutic
Stationary
Mobile

100-150
60-125
50-85


60-400
15-150

60-1000
10-300
5-15


20-30
5-50
x-ray machineFig. 1. Stationary diagnostic x-ray machine type RUM-5.
Fig. 2. X-ray machine type RUM-11 for deep x-ray therapy.

Fig. 3. Sectional x-ray machine type ROOM-4.
Fig. 4. Ward x-ray machine.
portable x-ray machine
Fig. 5. Portable x-ray machine.

Arranged in an x-ray machine, as follows: high voltage on the x-ray tube (see) is served from the step-up transformer (the so-called main transformer), to the secondary winding of which the pipe is connected either directly (in low power portable and mobile devices), or by rectifier - kenotron or semiconductor valve (see Rectifiers). Power the heaters cathode x-ray tube is made from a step-down transformer heat. As the anode x-ray tube is usually grounded, and the cathode is high voltage transformer heat is high voltage insulation. High-voltage circuit elements of the x-ray apparatus are grounded casing and connected with electrodes protective x-ray tube by means of high-voltage cables (cable x-ray machines). In the so-called block devices high voltage part together with a tube is placed in a metal casing, filled with mineral insulation oil.
High voltage is normally regulated with the help of autotransformer (see), included in the primary circuit of the main transformer. A special switch that is attached to different taps autotransformer, allows to change smoothly or step the voltage at the primary and, consequently, on the secondary side of the main transformer. The current intensity of x-ray tube set using resistor in the circuit of transformer primary winding calibre. Anode tube current depends on the size of the filament current, which is caused by the voltage electric networks: change of voltage in the network, for example, 5% change anode current 2 times. Power supply reduced by the incorporation of the x-ray machine, and therefore for stabilization of heat pipes have to install a transformer (compensator) or special ferro-resonant stabilizer. Autotransformer with switches dimmer adjustment of the filament current, control devices, voltage regulation and overload protection and short circuit are low-voltage part of the x-ray machine and placed in a special remote control. The unit is usually carried out by stages: the first includes the supply voltage, then the intensity of x-ray tube and kenotron and finally, high voltage. Disabling is in the reverse order. Part x-ray unit also includes a tripod (or group of stands) for fixing the x-ray tube, fittings for fixing of patients in the process of examination or treatment, x-ray screens (see x-ray Screens) and means antiradiation protection of the patient and doctor. X-ray machines are equipped with special devices (relays) to automatically switch off of high voltage after a given exposure. In therapeutic x-ray machines are used Electromechanical relays with a maximum shutter speed of 10-30 minutes, which are driven by a small electric motor. In portable and mobile diagnostic x-ray machines are used for manual relay, driven by a spring, and in the steady - condensing relay with a minimum shutter speed of about 0.01 sec.

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