RU2407438C1 - X-ray installation for medical diagnostics - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to field of medical equipment, namely to X-ray apparatuses intended for application both in specialized medical institutions, for instance TB dispensaries, and in general hospitals. In X-ray installation, containing located on one central optic axis X-ray radiator with slit collimator and central linear X-ray detector, mechanical scanning device with system of bringing at the level of tomographic image of X-ray radiator with slit collimator and central linear X-ray detector, footrest for patient with device for its rotation, X-ray radiator is connected to high-frequency X-ray generator and programmed control unit. Linear X-ray detector is connected with system of image conversion, registration and formation, slit collimator has two outlet windows with shutters, one of which is optically conjugated with central linear detector, and the second - with additional linear detector, installed parallel to the central one. Inlet window of additional detector is optically conjugated via the second outlet window of collimator with X-ray radiator ray, radiated at angle α=arctg s/f to the central, where s is distance between inlet windows of central and additional linear detectors, and f is distance from focus of X-ray radiator to inlet window of central linear X-ray detector on normal to its plane. Additional linear X-ray detector is connected with system of image conversion, registration and formation and has spatial resolution higher than central linear X-ray detector.

EFFECT: application of invention ensures optimal conditions of X-ray radiator operation in mode of computer tomography.

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Description

The present invention relates to the field of medical equipment, namely to x-ray diagnostic devices intended for use both in specialized medical institutions, for example, TB dispensaries, and general hospitals.

Famous low-dose digital x-ray unit (ICRC) "Siberia", developed at the Institute of Nuclear Physics. G.I. Budker (Novosibirsk) (Belova I. B., Kitaev V. M. Low-dose digital radiography. - Orel, 2001, p.29). ICRC “Siberia” contains a high-voltage generator of high-frequency type, an x-ray emitter with a slit collimator, a multi-element linear x-ray detector connected to an image recording and reproducing system, a mechanical scanning device, a protective cabin with a platform for the patient’s legs. The patient is scanned vertically with a narrow horizontal fan-shaped x-ray beam.

Also known is a radiographic scanning device (International Application WO 02/17790 A1 of 03/07/2002) containing an x-ray source, a slit collimator, and a linear x-ray receiver sequentially located on the same optical axis. The receiver and collimator are mounted on a single bracket mounted rotatably around a vertical axis passing through the focus of the x-ray source.

In contrast to the first analogue in this apparatus, the patient is scanned horizontally with a narrow vertical x-ray beam.

Also known is a radiographic installation for medical diagnostics (Patent RU 2098929 of 05.29.95, A61B 6/00) containing a high-frequency x-ray generator, an x-ray emitter with a slit collimator, an x-ray detector connected to an image recording and reproducing system, a mechanical scanning device, a protective device a cabin with a platform for the patient’s legs.

The patient is scanned vertically. X-ray radiation that has passed through the patient’s body is detected by a multi-element linear detector (MLD). The detector picks up signals that are minimally higher than the sensitivity threshold of the amplifier, due to which the background radiation is not fixed and an optimal signal-to-noise ratio is created. At the same time, the radiation dose per patient is minimized.

The information accumulated in the MLD during the exposure of the line is copied to the computer memory, and then the registration of the next vertical line begins. For this purpose, the x-ray emitter, the slit collimator, and the MLD simultaneously and uniformly move in the vertical direction during shooting. A narrow slit collimator forms a thin fan-shaped x-ray beam, which, after passing through the patient’s body, enters the MLD entrance window.

The information accumulated by the detector during the exposure of the line is transmitted to the computer. After shooting, the image matrix is formed in the computer's memory (320 × 256 numbers) containing information about the distribution of radiation after passing through the patient’s body. A digital x-ray image is displayed on a computer video monitor 5 seconds after the end of the scan.

The device is controlled by a computer. The software includes the main program that controls the device during shooting, and programs for monitoring the health of the units and the device as a whole.

All known analogues are intended primarily for X-ray examination of the lungs (fluorography) in order to timely detect tuberculosis and other diseases of the chest cavity.

The disadvantage of all known analogues is the inability to obtain a tomographic slice in the zone of interest, which complicates the diagnosis and limits the operational capabilities of the apparatus.

The closest in design to the claimed object is a radiographic unit for medical diagnostics (Patent RU 2343836 from 08/15/2007, A61B 6/00) containing a high-frequency x-ray generator, an x-ray emitter with a slit collimator, a linear x-ray detector, a mechanical scanning device, a protective cabin with a platform for the patient’s legs equipped with a patient rotation mechanism, the X-ray emitter being connected to a high-frequency X-ray generator and a programmable control unit Ia provided with a computer, control unit and a video monitor, a linear detector coupled to convert the digital electronic system, registration and imaging. An x-ray emitter with a slit collimator is optically coupled to a linear x-ray detector and mechanically connected to each other by a bracket.

This X-ray unit allows both fluorography of the lungs and transverse computed tomography in the area of interest; It is chosen by us as a prototype.

The disadvantage of the prototype is overheating of the x-ray emitter in computed tomography mode.

This is due to the fact that various technical requirements are imposed on linear X-ray detectors used in X-ray fluorography and computed tomography. The linear detector used in fluorography should have an increased spatial resolution (no worse than 2.5 pairs of lines per mm). The linear detector used in computed tomography has a spatial resolution much lower, approximately 1.0 line pairs per mm. Due to this, it has a higher optical sensitivity, which allows computed tomography with a more sparing energy load on the x-ray emitter.

That is why the use of a linear detector with a resolution of 2.5 pairs of lines per mm in computed tomography mode, as is the case in the prototype, leads to overheating of the x-ray emitter.

The aim of the invention is to provide optimal operating conditions of the x-ray emitter in computed tomography mode.

This goal is achieved by the fact that in a radiographic installation for medical diagnostics, comprising an x-ray emitter with a slit collimator and a central linear x-ray detector located on one central optical axis, a mechanical scanning device with an output system to the level of the tomographic section of the x-ray emitter with a slit collimator and a central linear x-ray the detector, the footwell of the patient with the device for its rotation, and the x-ray emitter is connected to a high-frequency x-ray generator and a programmable control unit, and a linear x-ray detector is connected to a conversion, registration and imaging system, the slit collimator has two output windows with shutters, one of which is optically coupled to a central linear detector, and the second with an additional linear detector, mounted parallel to the central one, the input window of the additional detector is optically coupled through the second output window of the collimator with an X-ray beam at an angle α = arctan s / f to the central one, where s is the distance between the input windows of the central and additional linear detectors, af is the distance from the focus of the x-ray emitter to the input window of the central linear x-ray detector along the normal to its plane, while an additional linear x-ray detector is connected to the conversion, registration and imaging system and has a spatial resolution higher than the central linear x-ray detector.

The invention is further accompanied by drawings and a description thereof. Figure 1 shows the main elements of the x-ray tripod, figure 2 - the geometry of the x-ray path from the x-ray emitter to the linear detectors, and figure 3 shows the block diagram of the x-ray unit. Figure 4 shows the position of the patient when shooting.

Tripod x-ray installation for medical diagnostics contains an x-ray emitter 1 with a slit collimator 2 and two linear x-ray detectors 3 and 4 (figure 1). As linear detectors, a matrix-type semiconductor line is used. The collimator 2 has two slots, a central 5, optically conjugated to the optical input of the central linear x-ray detector 3, and a lower 6, optically conjugated to the x-ray detector 4 (figure 2). The lower x-ray beam k passes relative to the central i at an angle α = arctan s / f, where s is the distance between the input windows of the central 3 and additional 4 linear detectors, af is the distance from the focus F of the x-ray emitter 1 to the input window of the central linear x-ray detector 3 normal to its plane. The vertex of the angle is associated with the focus F of the x-ray emitter 1.

Radiography of the lungs is usually performed at f = 1500 mm. The distance s is determined by the width of the linear detectors and is approximately 30 mm. At these values, the angle α = 1 ° 10 '.

The central i or lower k x-ray beams are turned on by a shutter 7 made of a material with a high atomic number.

The lower linear X-ray detector 4 has a spatial resolution of no worse than 2.5 pairs of lines per mm and is intended to obtain a fluorographic image of the lungs. The spatial resolution of the central linear X-ray detector 3 is approximately 1.0 line pairs per mm; it is designed to obtain a transverse computer slice in the zone of interest.

The X-ray emitter 1 is mounted on a vertical carriage 8, and the linear X-ray detectors 3 and 4 are mounted on a vertical carriage 9. The carriages 8 and 9 can synchronously and uniformly move along the guides 10 and 11, respectively, which are mounted on the trusses 12 and 13. The movement of the carriages 8 and 9 occurs when the worm shafts (not shown) rotate mechanically coupled to the reversible type electric motor 14. All these elements are part of the mechanical scanning device of the radiographic unit.

Below between the trusses 12 and 13 there is a platform 15 for the patient’s legs, equipped with a mechanism for its rotation, containing an electric motor 16, a gearbox 17 and a group of gears 18. The platform 15 is equipped with a screen 19 made of hard X-ray transparent material, such as plexiglass (Fig. 4). The chest of patient A is pressed against the screen 19 during shooting. On the platform 15 also fixed clamps for the legs and arms of patient A (not shown).

The x-ray installation includes a system for outputting the scanning device to the level of the tomographic slice, including a coordinate gauge 20, mechanically connected to the electric motor 14 of the scanning device, and electrically through a computer 21 with a video monitor 22 (Fig. 3).

The apparatus is controlled by a computer 21 from the programmed control unit 23. The software contains the main control program for obtaining a standard digital x-ray image, a test program for monitoring the health of the units and the apparatus as a whole, and an additional program for obtaining transverse tomographic images. High voltage to the x-ray emitter 1 is supplied from the high-frequency generator 24 by command of the computer 21.

Upon receipt of a standard digital x-ray image, the radiation distribution in the horizontal direction (row) is measured using a multi-element linear detector 4. The lines are “stitched” into the frame by mechanical scanning of the patient’s body in the vertical direction. For this purpose, the x-ray emitter 1 with a slit collimator 2 and the detector 4 simultaneously and uniformly move in the vertical direction during shooting. A collimator 2 with a slit width of 0.5 to 2.0 mm forms a thin fan-shaped oblique x-ray beam k, which, after passing through the patient’s body A, enters the input window of the linear detector 4. The detector 4 is connected to an electronic system for converting, recording and reproducing a digital image 25 connected to the computer 21. The information accumulated in the receivers of the multi-element linear detector 3 during the exposure of the line is written to the memory of the computer 21, after which the registration of the next vertical rock. After shooting the frame, a digital image-matrix of numbers is accumulated in memory, which describes the distribution of radiation after passing through the patient’s body.

The first raw image on the video monitor occurs simultaneously with the scan. The video monitor screen displays an X-ray image of the patient’s internal organs, such as the lungs, and a coordinate scale that allows you to determine the position of a structural element of the body by height (in the coordinate system of the device).

In case of detection of a pathological formation, for example, a tuberculous cavity in the lung, the radiologist points the “floating mark” of the video monitor to the target image point and presses the corresponding button on the keyboard 26 of the video monitor 22. In this case, firstly, an additional program is activated on the programmable control unit 23 obtaining a transverse tomographic slice, and secondly, the signal through the computer 21 and the coordinate gauge 20 is fed to the electric motor 14 of the scanning system, resulting in an x-ray emitter 1 with evym collimator 2 and the detector 3 are displayed on the level of the tomographic slice. The shutter 7 of the collimator 2 is moved to the upper position, in which the horizontal x-ray beam i is opened, which goes to the detector 3 (see Fig. 2). The detector 3 is connected to an electronic system for converting, recording and reproducing a digital image 26 connected to a computer 21. In addition, an electric motor 16 is turned on, which determines the uniform rotation of the pad 15, for example, at a speed of 1 revolution per second. Patient A is given the command “take a deep breath and do not breathe”. After that, the x-ray emitter 1. The computer 21 processes the signal coming from the linear detector 3, and a tomographic slice matrix is formed, which is displayed on the screen of the video monitor for visual analysis.

To obtain one tomographic slice, digital information obtained by a computer for one revolution of the carriage (360 °) is sufficient. With an exposure of one line of 0.015 s per one revolution of the carriage, 67 scans (line scans) are performed. If a multi-element linear detector contains 400 sensors, then upon receipt of one tomographic slice the computer processes 26800 discrete signals.

The proposed technical solution allows patients to freely pass through the unit and exit the X-ray room through a door opposite the entrance, which accelerates the process of fluorography. This possibility is especially important in mass fluorography of the population.

Claims (1)

A medical diagnostic x-ray system, comprising an x-ray emitter with a slit collimator and a central linear x-ray detector located on the same central optical axis, a mechanical scanning device with an output system to the level of the tomographic section of the x-ray emitter with a slit collimator and a central linear x-ray detector, a patient’s foot platform with the device of its rotation, and the x-ray emitter is connected to a high-frequency x-ray the generator and the programmable control unit, and the linear X-ray detector is connected to a conversion, registration and imaging system, characterized in that the slotted collimator has two output windows with shutters, one of which is optically coupled to a central linear detector, and the second with an additional linear with a detector mounted parallel to the central one, the input window of the additional detector is optically coupled through the second output window of the collimator with the beam of the x-ray emitter, at an angle α = arctan s / f to the central one, where s is the distance between the input windows of the central and additional linear detectors, af is the distance from the focus of the x-ray emitter to the input window of the central linear x-ray detector along the normal to its plane, while the additional linear x-ray the detector is connected to a conversion, registration and imaging system and has a spatial resolution higher than the central linear X-ray detector.

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