WO2025080159A1 - Target assembly for x-ray generating device - Google Patents

Abstract

The claimed devices relate to X-ray computed tomography and are used for generating X-ray radiation with a scanning electron beam. A segment of a target assembly is configured in the form of a three-dimensional part having a base made of a heat-conductive material, said base having a stepped profile in cross-section and having steps comprising arcuate plates for generating radiation, said arcuate plates being arranged at specific angles to a plane in which a tuning plate is disposed, and a platform to which a tuning plate is attached. A target assembly comprises a set of segments that are fastened with clearance from one another to an annular support plate to form arcuate targets, namely an inner target and an outer target, and one tuning target, the support plate being provided with channels for cooling of the segments. An X-ray tube comprises a vacuum chamber, electron sources, a magnetic system for rotating, focusing and deflecting electron beams, and a target assembly for generating X-ray radiation. The technical result is that of creating a reliable structure for an electron beam scanner for X-ray computer tomography, while simplifying the manufacture and assembly thereof.

Description

X-RAY GENERATING DEVICE TARGET SYSTEM

Field of technology to which the invention relates

The invention relates to X-ray computed tomography, namely devices for generating X-ray radiation with a scanning electron beam, electron beam computed tomographs, and can be used both in medicine and in the field of industrial non-destructive testing.

State of the art

An X-ray tube is an electrovacuum device that serves as a source of X-ray radiation, which occurs when electrons emitted by the cathode interact with the substance of the anode (anticathode). The energy of the electrons, accelerated by the electric field, is partially converted into the energy of X-ray radiation when interacting with the heavy metals of which the anode is made.

A typical scanner used in X-ray computed tomography (CT) consists of an X-ray tube mounted opposite one or more detectors. During scanning, the X-ray tube emits radiation that passes through the object being examined and strikes one or more X-ray detectors. The signals from the detectors are converted into data that is used to create three-dimensional images of the volume of the object being examined.

Most modern CT scanners operate on the principle of continuous rotation, in which the X-ray tube and detector are rigidly coupled, and their rotational movements around the scanned area occur simultaneously with the emission and capture of X-rays (Computer Tomography. Basic Guide, Second Edition in Russian, revised and supplemented, Matthias Hofer, Med. Lit., 2008).

However, rotating X-ray tube devices have physical limitations imposed by mechanical rotation. In particular, for medical CT scanners, the rotation speed is limited to approximately four revolutions per second, which does not eliminate the occurrence of motion artifacts during image reconstruction and increases the time required to perform the examination. Improvement of medical computer tomographs is aimed at increasing the speed of data collection, reducing radiation exposure, obtaining high-quality three-dimensional reconstruction of the object being examined, increasing the reliability, safety and durability of CT scanners.

Electron beam tomographs (e.g., CT scanner "Imatron ST-100") have higher productivity and higher quality of reconstructed images. They contain an electronic scanning system, which includes one or several stationary electron sources ("guns"), forming a flow of electrons in the direction of the target (anode). In this case, the electron beam is deflected by a magnetic system, which provides scanning and focusing of the electron beam on the target of a given geometry. The cathode unit of the gun and the extended target are in a single vacuum volume, the target, in this case, can have the shape of a ring (horseshoe) of a large radius. Thus, the movement of a beam of high-energy electrons along the target is equivalent to the movement of the X-ray source around the object under study. Since the speed of movement is limited only by transient processes of the power and control electronics, the scanning time for one revolution of the source is reduced by tens of times compared to classical mechanical CT scanners.

With such a short scanning time, to ensure sufficient X-ray output to obtain high-quality images, electron beam scanners require a significant amount of power or current. At the same time, the thermal load on the target unit also increases, which, if certain conditions are not met, can lead to the destruction of target materials. For this reason, one of the most important points in the design of electron beam devices is the development of an adequate system of target units.

To increase the speed of examination, the electron beams generated by the cathode are usually used for high-energy bombardment of a polycrystalline tungsten or tungsten-rhenium alloy target. In this case, a decrease in the focal spot size leads to a significant increase in the energy density on the target, which can lead to overheating and destruction of the target surface, and, as a consequence, to failure of the X-ray tube. An increase in the focal spot leads to a loss in the sharpness of the image of the object section. Thus, heating of the target often limits the intensity of the generated X-ray beam. In X-ray tubes used today, this problem is often solved by using a rotating anode. The overheating problem is also solved by increasing the mass and size parameters of the anode, using heat exchangers surrounding the vacuum shell of the X-ray tubes.

A number of patents (e.g. US4352021, US7872241) disclose a design for a CT scanner with a scanning electron beam, which uses several large mass targets arranged in four rows, which are cooled by running water, which solves the heat removal problem. In particular, in the mentioned publications, the target unit includes four semicircular target rings, each of which has a cooling coil. In publication US7872241, the target has a horseshoe shape formed as a single unit, or can be formed by straight sections connected together to form a polygonal shape. In one particular embodiment, the target includes a metal back part, active and inactive sections connected to the back part, for example, by soldering, wherein the active section is designed with the possibility of generating X-rays when an electron beam hits it, the inactive section is intended, on the contrary, to suppress the generation of X-rays. The outer diameter of the active section is approximately equal to the inner diameter of the inactive section. Another embodiment of the invention is possible using two electron sources and a target with two active sections separated by a small gap, designed to generate X-rays when an electron beam hits them. The active sections of the target are made of a refractory metal, such as tungsten, molybdenum and/or one of their many alloys, and have flat upper surfaces. During operation of the X-ray tube, focusing units alternately move electron beams from the two electron sources along the first and second active sections. As a result of reducing the power level of the inactive beam, heating of the target is reduced, as well as the total power required from the high-voltage power source.

The closest to the proposed group of inventions are the target system of an electron-beam computer tomograph and the electron-beam scanner, known from patent US8530849. The electron-beam scanner includes a vacuum chamber; at least two electron sources located on the rear side of the vacuum chamber; a magnetic system of rotation, focusing and electron beam deflections; a system of targets generating X-ray radiation, located in the front part of the vacuum chamber; X-ray exit windows; a detector of the generated radiation. In this case, the target system is formed by two tungsten targets located concentrically relative to the detector. The ends of each of the targets are superimposed on at least part of the detector along the circumference. Due to the different diameters of the targets, the electron beam generated by one of the sources collides with one target without touching the other target. In this case, the targets are located at an angle of approximately thirty-six degrees relative to the detector. The scanner uses a detector divided by a gap into two detector rings, each of which is formed by a pixel matrix (matrix of photosensors). The use of the known solution makes it possible to obtain high power X-ray radiation and ensure an acceptable service life of X-ray tubes. However, this publication does not describe the design of the target unit, which has a significant impact on the reliability of the device and the quality of the reconstructed image. The task of improving the target unit system is also relevant for this technical solution.

Thus, the problem of ensuring the durability and reliability of targets, as well as improving their characteristics, continues to be relevant.

The technical problem that the present invention is aimed at solving is the creation of a target system for a device for generating X-ray radiation with at least two electron sources, as well as an electron beam scanner based on it, characterized by reliability and durability, allowing for fast and efficient generation and detection of X-rays, while simplifying the manufacturing and assembly technology.

Disclosure of invention

The technical result is the creation of a reliable design of an electron beam scanner for X-ray computed tomography, characterized by a scanning area length of at least 16 cm, and ensuring the receipt of a high-quality (defect-free) reconstructed image of an object while simplifying the manufacturing and assembly technology.

The technical result is achieved by creating a design for a segment of the target system of a device for generating X-ray radiation, made in the form of a volumetric part containing a base made of heat-conducting material with a stepped cross-section profile, having an external and internal longitudinal surfaces, mating end surfaces, external and internal mounting surfaces, wherein the base is provided on the side of the internal mounting surface with at least two steps with internal and external arc-shaped plates fixed thereto for generating X-ray radiation, and a platform located parallel to the external mounting surface, with an adjustment plate fixed thereto, where the first step of the base with the internal plate fixed is located at an angle a relative to the plane of the adjustment plate, and the second step with the external plate fixed is located at an angle 0 relative to the plane of the adjustment plate, where 0<ос; the base is provided with at least four mounting holes, two of which are located between the internal and external plates, and the other two are between the adjustment plate and the external longitudinal surface of the base.

The steps of the base, as well as the platform for placing the tuning plate, can be provided with stop projections for the plates. In a preferred embodiment of the invention, the angle a can be made equal to 17°, the angle 0 can be made equal to 13°.

The inner plate can be made with a radius of curvature of the inner surface from 628 mm to 631 mm, the outer plate can be made with a radius of curvature of the inner surface from 660 mm to 663, the tuning plate can be made with a radius of curvature of the inner surface from 713 mm to 715.

The lower boundary of the outer plate may be located at a height hl, which is from 4.25 mm to 4.55 mm from the lower boundary of the tuning plate, the lower boundary of the inner plate may be located at a height h3, which is from 24.35 mm to 24.65 mm from the lower boundary of the tuning plate; in this case, the lower boundary of the outer plate may be removed from the lower boundary of the inner plate at a distance of from 19.95 mm to 20.25 mm in projection onto the plane of the tuning target.

The thickness of the plates can be from 0.6 to 0.9 mm, the width of the inner and outer plates can be from 14.5 to 15 mm, the width of the tuning plate can be from 29.5 to 30 mm.

The base can be made of oxygen-free copper, and tungsten-rhenium plates can be used as plates.

The target system segment may also contain at least two tungsten W-shaped sensors for tracking the position of the electron beam on the tuning plate, fixed on a heat-conducting base with a gap relative to the tuning plate. The use of tungsten W-shaped sensors is one of the alternative methods for adjusting the beam parameters. At the same time, such adjustment can be implemented by other methods and means, for example, using test objects with subsequent adjustment of the parameters of the resulting beam.

The technical result is also achieved by creating a target system of the device for generating X-ray radiation, containing a set of the above-described segments, fixed on a ring-shaped plate with the formation of at least two arc-shaped targets - internal and external, and one tuning target, wherein the segments are fixed on the plate with a gap relative to each other, ensuring the exclusion of damage to the segments during their thermal expansion during operation of the device, the plate is provided with channels for cooling the segments of the target system, located with the formation of at least two cooling sections, as well as input and output openings for the cooling medium.

In a preferred embodiment of the invention, the target system includes 12 segments.

The channels for cooling the segments of the target system can be made with a rectangular cross-section profile and can be located parallel to the arcuate targets at an equal distance from each other, forming two cooling sections symmetrical with respect to the vertical axis passing through the center of the annular plate.

In particular embodiments of the invention, the number of channels in each section can be selected to be no less than 7, with the width and height of the channels preferably being no less than 4 mm, and the distance between adjacent channels being no less than 14 mm.

The gap between adjacent segments of the target system can be from 0.35 to 0.45 mm, for example, 0.4 mm.

The technical result is also achieved by creating a device for generating X-ray radiation (an X-ray tube) comprising a vacuum chamber; at least two electron sources located on the rear side of the vacuum chamber; a magnetic system for rotating, focusing and deflecting electron beams; the above-described system of targets for generating X-ray radiation outlet located in the front part of the vacuum chamber; X-ray exit windows.

The technical result is also achieved by creating an electron-beam scanner (scanning system) that includes the above-described device for generating X-ray radiation, a detector system, and a collimator located between the target system and the detector system, all mounted on a supporting frame. The detector system is formed by a set of scintillation matrices fixed to a frame provided with a gap and dividing the detector system into two ring-shaped sectors. The frame is made with side walls, one of which is removable, and is provided with a mechanism for fastening and adjusting the detector system, which also ensures fixation of the frame to the supporting frame with the side walls located on opposite sides from the supporting frame. The target system is fixed to the supporting frame with an annular plate with cooling channels placed on it. In this case, the frame is located concentrically relative to the target system with the gap located opposite the output window of the device for generating X-ray radiation, with one sector of the detector system located with the possibility of detecting radiation from the internal target, and the other - from the external one, where the internal and external targets are located with the provision of passage of the generated radiation into the frame gap. The internal diameter of the detector system frame is not less than 1040 mm.

In a preferred embodiment, the detector system includes scintillation matrices of at least 16x32 in size with a pixel size of no more than 1.06 mm by 1.12 mm. In this case, the annular sector is made with a diameter of at least 1175 mm and a width of at least 235 mm. The gap in the annular frame can be made with a width of 16.5 to 17 mm and is removed from the lower boundary of the internal target at a distance of no more than 50 mm.

The present scanner is an improvement over the scanner described in US Patent No. 8,530,849, which is characterized by high scanning speed, allowing to obtain high-quality images, including when examining the heart, and at the same time is more technologically advanced and reliable.

The claimed configuration of the target system segments, due to improved heat dissipation, ensures a reduction in temperature loads on the target at the points where X-ray sources are formed and allows the most energy-intensive scanning mode to be maintained without the risk of target overheating, while due to the precise positioning of the segments on the cooling plate, the the probability of occurrence of defects in reconstructed images of objects (shading zones) associated with poor normalization of target gaps. Organization of the target cooling system in the form of a system of flowing water channels made in the cooling plate, in combination with the design of the heat-conducting base, also ensures a reduction in cooling time and the achievement of greater uniformity in cooling all segments of the targets with minimal production and operating costs.

The declared parameters of the target are optimal, ensure manufacturability in the manufacturing and assembly process, while the implementation of the target system from separate blocks (modules) ensures convenience and the least labor intensity in the assembly process, simplifies the process of manufacturing an electron beam computed tomograph.

The claimed configuration of the target system segment allows to create a design of the target unit of the electron beam tomograph, in which the radiation-generating plates are precisely positioned on the base with the formation of a flat, shift-free radiating surface of the target, the radius of curvature and slope of which provide the possibility of using this target together with a radiation detector with an increased diameter and width, which also allows to increase the aperture (air gap) of the electron beam computed tomograph to 1 m in diameter, to expand the length of the continuous scanning area of the object under study within one scan to 16 cm. Increasing the aperture expands the possibilities of using the electron beam computed tomograph, including for conducting studies of patients with injuries, and also provides convenient access during manipulations and intravenous administration of drugs during the study.

The modular design principle of the target system ensures increased technological efficiency of the device during the production of segments and assembly.

Brief description of the drawings

The invention is illustrated by Figures 1-15, which serve only to illustrate embodiments and should not be considered as limiting the present invention. Figure 1 shows a general view of the target system on heat-conducting blocks; Figure 2 is a general view of one assembly unit of the target system (a segment of the target system); Figure 3 is a fragment of the target system mounted on a cooling plate (Cold Plate), where the angles of inclination of the plates relative to the isocenter axis (OZ) are indicated; Figure 4 shows embodiments of channels for cooling liquid, general view; Fig. 5 - base of the target segment; Fig. 6 - section of the target segment along line A-A in Fig. 5 indicating the linear arrangement of the platforms (steps) of the target plates; Fig. 7 - enlarged view of section of the target segment indicating the angular arrangement of the platforms (steps) of the target plates; Fig. 8 - general view of the cooling plate from the side of installation of the target segments; Fig. 9 - general view of the cooling plate from the side of the cooling channels; Fig. 10 - section of the plate along line H-H in Fig. 9 indicating the geometry of the cooling channels; Fig. 11 - general view of the soldering device with the target system assembly unit fixed thereto; Fig. 12 - general view of the X-ray radiation source; Fig. 13 - supporting frame with installed vacuum chamber, detector system frame, collimator; Fig. 14 is a general view of an electron beam computed tomograph with the equipment necessary for its operation; Fig. 15 shows the arrangement of the target system in the device for generating X-ray radiation and in the electron beam scanner.

The following are designated by the positions in Fig. 1-15:

1 - target system;

2 - segment (section) of the target system;

3 - base of the target system segment made of heat-conducting material;

4 - internal plate for generating X-rays;

5 - outer plate for generating X-rays;

6 - tuning plate;

7 - outer longitudinal surface of the base;

8 - inner longitudinal surface of the base;

9 - mating end surface;

10 - internal mounting surface;

11 - external mounting surface;

12 - step on the base for placing plate 4;

13 - step on the base for placing plate 5;

14 - platform for the adjustment plate on the inner mounting surface of the base;

15 - mounting hole in the base;

16 - thrust projection from the side of the inner end surface of the base (mounting flange);

17 - W-shaped sensor;

18 - cooling plate; 19 - internal target;

20 - external target;

21 - tuning target;

22 - gap between segments;

23 - channel for cooling medium;

24 - cooling section;

25 - coolant inlet;

26 - outlet for coolant;

27 - holes in the plate for fastening segment 2;

28 - clamping device;

29 - clamping element;

30 - clamp;

31 - hairpin;

32 - supporting frame;

33 - vacuum chamber;

34 - electron source;

35 - magnetic system for rotation, focusing and deflection of electron beams;

36 - X-ray output window;

37 - detector system;

38 - collimator;

39 - detector system frame;

40 - gap in frame 39;

41 - side wall of frame 39;

42 - mechanism for fastening and adjusting the detector system;

43 - gantry;

44 - patient table;

45 - power distribution system;

46 - power supply and energy storage system;

47 - high voltage power supply;

48 - beam sweep control electronics;

49 - computer control system server;

50 - a block including a data collection system and a data reconstruction system;

51 - chiller;

52 - electrocardiograph; 53 - lower border of the inner plate;

54 - lower border of the outer plate;

55 - lower limit of the tuning plate;

56 - plate cover 18.

Implementation of the invention

Below is a more detailed description of the implementation of the claimed group of inventions, which does not limit the scope of the claims of the inventions, but demonstrates the possibility of their implementation with the achievement of the claimed technical result.

The target system 1, intended for generating X-ray radiation, according to the proposed invention, consists of individual assembly units, forming, in the preferred embodiment of the invention, twelve segments 2 (sections). Each segment 2 comprises a base 3 made of a heat-conducting material (for example, copper, graphite), preferably made of oxygen-free high-conductivity copper (OFHC), with three soldered plates made of a heavy metal alloy (tungsten, rhenium, etc.), preferably made of a tungsten-rhenium alloy, at least two of which are intended for generating X-ray radiation - the inner 4 and outer 5, and one is a tuning (calibration) plate 6. Plates 4, 5, 6, when assembling a target system from segments 2, form at least an inner 19 and outer 20 arc-shaped targets (active), which are affected by an electron beam generated by an electron source, as well as a tuning (calibration) target 21, respectively. The deflection (scanning) of the electron beam along the entire length of the arc-shaped targets provides the number of images (sections) required to form a three-dimensional image (thermogram) of the object's area of interest. The length of the targets is preferably no less than 2/3 of the length of the arc of the circle along which they are located.

The base 2 is made with a stepped cross-section profile and is formed by external 7 and internal 8 longitudinal surfaces, mating 9 end surfaces, as well as internal 10 and external 11 mounting surfaces. From the side of the internal mounting surface 10, the base 3 is made with at least two steps 12, 13, on which the internal 4 and external 5 arc-shaped plates for generating X-ray radiation are fixed, and is also provided with a platform 14 located parallel to the external mounting surface 11, on which the tuning plate 6 is fixed. In this case, the step 12 with the plate 4 is located at an angle a with respect to the plane the location of the tuning plate, and the stage 13 with the plate 5 - at an angle 0 to the said plane, where 0 < a. Thus, the plates for generating X-ray radiation are oriented at different angles to the axis of the scanning X-ray tube. The angles between the plates of the arc-shaped targets are calculated based on the geometry of the location of the electron sources, targets, the size of the X-ray output window and the location of the detectors to expand the continuous scanning area of the object under study within the framework of one scan. In one of the particular embodiments of the invention, the angle between the inner plate 4 and the plane parallel to the outer mounting surface 11 of the base of the segment of the target system is 17 degrees, the angle between the outer plate 5 and the plane parallel to the outer mounting surface is 13 degrees.

In a preferred embodiment of the invention, the steps 12, 13 of the base 3, as well as the platform 14 for placing the tuning plate 6, are provided with stop projections 16, ensuring the fixation of the plates on the base during the soldering process.

In addition, the base 3 is provided with at least four mounting holes 15, two of which are located between the inner 4 and outer 5 plates, and the other two are located between the adjustment plate 6 and the outer longitudinal surface 7 of the base 2.

In one embodiment of the invention, the overall dimensions of the base 3 may be from 277.5 to 278.5 mm in length, from 128.5 to 129.5 mm in width, and from 47.5 to 48.5 mm in height. The inner plate 4 may be made with a radius of curvature of the inner surface of at least 625 mm, the outer plate 5 - with a radius of curvature of the inner surface of at least 660 mm, and the tuning plate 6 - with a radius of curvature of the inner surface of at least 710 mm. In this case, the lower boundary 54 of the outer plate 5 is located, preferably, at a height hl, which is no more than 3.5 mm from the lower boundary 55 of the tuning plate 6, and the lower boundary 53 of the inner plate 4 is located at a height h3, which is no more than 24 mm from the lower boundary of the tuning plate 6. The lower boundary of the outer plate 5 is removed from the lower boundary of the inner plate 4 by a distance, preferably, no more than 32 mm in projection onto the plane of the location of the tuning target 6, and from the tuning plate - by a distance of no more than 53.5 mm. The thickness of the plates is, preferably, from 0.6 to 0.9 mm. The use of thinner plates to improve contact with the base can lead to a reduction in the service life of the target. The width of the inner and outer plates in particular embodiments of the invention is from 14.5 to 15 mm, the width of the tuning plate is from 29.5 to 30 mm. The target segments can be equipped with tungsten W-shaped sensors for tracking the position of the electron beam on the tuning plate. The W-shaped sensor in a specific embodiment of the invention can have a rod diameter of 0.76 mm, a length of the outer rods of 59 mm, a length of the central rod of 43 mm, which are fixed on a heat-conducting base with a gap relative to the tuning plate of approximately 10 mm.

During the generation of X-ray radiation, the electron beam moves at a high speed along the surface of targets 19, 20, causing local heating to high temperatures, potentially dangerous for the integrity of the target materials. The base 3 made of heat-conducting material ensures heat dissipation of the structure, eliminating its deformation during overheating. In addition, the design of the target system provides for a cooling system located on the side of the outer mounting surface 11 of the base 3 and representing a set of flow channels 23 for the circulation of the cooling medium (cooling fins), made in the cooling plate 18, and forming at least two cooling sections 24, an example of the implementation of which is shown in Figs. 9, 10.

In one of the particular embodiments, the optimal parameters of the channels (channel profile shape, width, height, distance between adjacent channels) of the cooling system were determined, ensuring the best heat removal efficiency. In particular, the channels can be made with a rectangular cross-section profile or have a cross-sectional shape in the form of a trapezoid, preferably with a wall inclination angle of 5°-10°. The required profile of the cooling system channels can be implemented using milling during the manufacturing process of the cooling plate. It is preferable to arrange the cooling system channels parallel to the arcuate targets at an equal distance from each other. In this case, in the preferred embodiment of the invention, the thickness of the cooling plate is from 21 to 23 mm, the height and width of the channels in the cooling plate are from 3 to 5 mm, the distance between adjacent channels is from 13 to 15 mm. The number of channels can be at least 7. Part of the plate 18 in the area of fastening the segments is made wider than its arcuate upper part.

In one of the particular embodiments of the invention, the inlet openings 25 for the cooling liquid are located in the central part of the ring of the plate 18 (its lower part), and the outlet openings 26 are at the ends of its wide part, while the circulation of the cooling liquid is carried out in two parts of the plate - the cooling sections. 24, symmetrical with respect to the vertical axis passing through the center of the annular plate 18. The cooling plate is provided with covers 56, ensuring the tightness of the cooled sections 24. The described variant of the design of the cooling system ensures the optimal density of the ribs, which leads to a decrease in the costs of mechanical processing, while achieving a coolant flow rate of approximately 3 gallons per minute. This coolant flow rate and its operating temperature of about 20 ° C are sufficient to achieve complete cooling of the structure after a period of 450 s. Increasing the flow rate and preliminary cooling of the liquid do not provide additional advantages in the operation of the cooling system.

To improve heat removal from the heated parts of the structure, a substrate made of interface material can be used, located between the bases 3 of the segments 2 and the cooling plate 18, which increases the heat exchange capacity in the high vacuum environment inside the chamber. Pyrolytic graphite, for example, can act as a substrate material. The cooling plate is provided with holes for its fastening to the supporting frame of the electron beam scanner.

The segments 2 of adjacent heat-conducting bases are located with a small gap relative to each other, formed between the mating side surfaces 9, and calculated based on the linear expansion of the heat-absorbing structure made of high-conductivity oxygen-free copper (the total increase in the entire length of the ring of heat-conducting blocks based on the calculated deformation of each edge of the segment by less than 0.2 mm under a thermal load for 6 seconds). To compensate for this deformation, the heat-absorbing structures contain gaps, preferably from 0.35 to 0.45 mm (for example, 0.4 mm), located radially between adjacent bases of the segments of the target system. The arrangement of the target segments with a gap relative to each other by a value less than the calculated one can lead to their mechanical damage as a result of the expansion of the target segments when exposed to the energy of electrons. The arrangement of target segments with a gap relative to each other by a value greater than the calculated value can lead to the occurrence of defects (inhomogeneities) in the resulting X-ray images of the objects being studied.

The process of soldering the plates for generating X-ray radiation to a heat-conducting base is carried out in a vacuum furnace, for example, models Ipsen Turbo Treater. To ensure precision and tight fit of the plates to the base during soldering, the device 28 shown in Fig. 11 can be used. This device ensures precise soldering without the formation of voids and without deformation of the surface of the plates.

Below is a description of an example of the implementation of the target system assembly.

Bag-8 plates 0.1 mm thick are cut and used as solder during soldering. The dimensions of the solder must match the dimensions of the tungsten-rhenium plates. The tungsten-rhenium plates are nickel-plated and the parts of the device are cleaned with acetone. The plates are installed on a heat-conducting base (copper block), after which the solder is placed between the base and the plates, after which this structure is fixed in device 28. In this case, the base is bolted to a stainless steel plate to maintain flatness during the soldering process. Using graphite clamping elements 29, the tungsten-rhenium plates are pressed to the base using clamps 30 and studs 31 made of stainless steel. This allows the tungsten-rhenium plates to take the shape of the copper block during the soldering process. Since precision cutting produces a straight edge on the tungsten-rhenium alloy parts, a chamfer is preliminarily cut on the inner edge (the edge located at the mounting flange) of the tungsten-rhenium alloy parts on a belt grinder to ensure a complete fit of the tungsten-rhenium plates on the copper block in the area of the mounting flange. The entire structure is placed in a vacuum furnace. The furnace is heated in stages to 885°C, which is approximately 93°C higher than the melting point of Bag-8 solder (780°C), and the structure is quickly cooled by introducing argon. The structure is then slowly cooled for an hour before being removed from the furnace and cooled in air. The tungsten-rhenium alloy to copper connection is checked for unsoldered voids (e.g., by ultrasonic flaw detection). If necessary, the target segment is cut to a size that ensures the most accurate and flattest profile of the target ring located inside the vacuum chamber. Copper blocks with soldered plates are placed in an ultrasonic bath for cleaning, after which they are installed on the cooling plate with a gap of 0.4 mm relative to each other. In this case, holes 27 in the plate are used to attach the target blocks to the cooling plate, which allow positioning the target blocks with the specified gap. W-shaped sensors 17 can also be installed on the target segments. The manufactured target system in accordance with the claimed invention is used in a device for generating X-ray radiation and an electron beam scanner. The device for generating X-ray radiation includes a vacuum chamber 33 mounted on a supporting frame 32, on the front end of which this target system 1 is installed, and on the rear part of the chamber - two electron sources 34 (electron guns) powered by a high-voltage voltage source, each of which creates an electron beam with a given kinetic energy and the necessary configuration. The device also includes a magnetic system for rotating, focusing and deflecting electron beams 35, directing the beams along trajectories in the direction of active (generating) arc-shaped ring targets, and X-ray exit windows 36, limiting the propagation of X-ray radiation (ensuring the propagation of X-ray radiation only to the object under study). The magnetic system includes one focusing coil and several deflection coils for each electron source, which are placed on the vacuum chamber and fed from a controlled current source. The vacuum chamber is a welded supporting structure made of stainless steel, which is shielded from X-ray radiation and provides an ultra-high vacuum of 10' ⁵ to 10' ⁹ Pa, which is necessary for the formation of an electron beam. The X-ray exit window is made of a thin X-ray-transparent metal (e.g., beryllium, thin stainless steel) and is part of the vacuum chamber in the X-ray exit area. The X-ray window area is located opposite the targets and allows the beam of generated X-ray radiation to move in the area under study. The angle between the targets provides continuous coverage of the object under study with X-ray radiation.

The electron beam scanner (scanning system) includes the above-described device for generating X-ray radiation, a detector system 37 and a collimator 38 mounted on a supporting frame 32, located between the target system and the detector system. The detector system is formed by a set of scintillation matrices fixed on a ring-shaped frame 39, which is provided with a gap 40 dividing the detector system 37 into two ring-shaped sectors. In this case, the frame 39 is made with side walls 41, one of which is removable, and is provided with a mechanism 42 for fastening and adjusting the detector system, as well as fixing the frame to the supporting frame, while in the fixed position the side walls of the frame are located on opposite sides from the supporting frame. The target system 1 is fixed on the supporting frame by means of fastening the annular plate 18 to the frame. The frame 39 is arranged concentrically relative to the target system with the gap 40 arranged opposite the output window 36 of the device for generating X-ray radiation, wherein one sector of the detector system is arranged with the possibility of detecting radiation from the internal target 19, and the other - from the external 20, where the internal and external targets are arranged with the provision of passage of the generated radiation into the gap 40. In the preferred embodiment of the invention, the internal diameter of the frame of the detector system is not less than 1040 mm, wherein the diameter of the annular sector is not less than 1175 mm and its width is not less than 235 mm. Each sector of the detector system includes a set of scintillation matrices of not less than 16x32 in size with a pixel size of not more than 1.06 mm by 1.12 mm, with a total detection area of not less than 16 cm ² . The gap 40 in the annular frame can be made with a width of 16.5 to 17 mm and removed from the lower boundary of the internal target at a distance of no more than 50 mm.

In accordance with the claimed invention, a target system was manufactured consisting of 12 segments fixed on a ring-shaped plate with a gap of 0.4 mm between adjacent segments. The overall dimensions of the segment base were: Ы=278 mm, L2=139 mm, L3=129 mm (Fig. 5). The width of the inner and outer plates fixed to the base was 14.5 mm, the width of the tuning plate was 29.5 mm. The height Ы of the protrusion was 0.9 mm. The thickness of the plates was 0.8 mm, with the outer plate fixed at an angle of α= 17° relative to the plane of the tuning plate, and the inner plate at an angle of θ=13° to this plane. The radius of curvature of the inner longitudinal surface of the segment Rl= 621 mm; the radius of curvature of the outer surface of the inner plate R2=644 mm; the radius of curvature of the outer surface of the tuning plate R3=714 mm, the radius of curvature of the outer surface of the outer plate R4=675 mm, the radius of curvature of the inner surface of the inner plate R5=629.7 mm, the radius of curvature of the inner surface of the outer plate R6=661.1 mm, the radius of curvature of the inner surface of the tuning plate R7=714.2 mm (Fig. 5). The lower boundary of the outer plate is located at a height of hl = 3.5 mm from the lower boundary of the tuning plate, the upper boundary of the inner plate is located at a height of h2 = 21.1 mm from the lower boundary of the tuning plate, and the lower boundary of the inner plate is located at a height of h3 = 23.6 mm from the lower boundary of the tuning plate, wherein the lower boundary of the outer plate is removed from the lower boundary of the inner plate by a distance of 31.4 mm in projection onto the plane of the tuning target; The lower boundary of the outer plate is removed from the tuning plate by a distance of 53.1 mm. The segments are equipped with tungsten W-shaped sensors for tracking the position of the electron beam on the tuning plate. The rods had a diameter of 0.76 mm, the length of the outer rods was 59 mm, the central rod - 43 mm. The rods were fixed on a heat-conducting base with a gap relative to the tuning plate of 10 mm. The plate on which the segments were installed had overall dimensions L4 = 1491 mm, L5 = 1636.6, the internal radius of curvature of the cooling plate R8 = 587.5. The thickness of the cooling plate was L6 = 22 mm. The plate was divided into two sections, each of which was formed by seven channels for cooling liquid, having a rectangular cross-sectional profile, with the distance between adjacent channels L7 = 14 mm, the channel width L8 = 4 mm and the channel height Ы 1 = 8 mm. The gap (cavity) between the lower boundary of the cover and the upper boundary of the rectangular channel was L9 = 8 mm, the thickness of the cooling plate from the lower boundary of the channel to the lower boundary of the cooling plate was L10 = 4 mm. The target system was fixed on a supporting frame with a vacuum chamber, on which a frame with a detector system including 1161 scintillation matrices measuring 16x32 with a pixel size of 1.06 mm by 1.12 mm and a collimator were also installed, while the inner diameter of the detector system frame was 1040 mm. The frame had a 16.5 mm wide gap dividing the detector system into two 235 mm wide annular sectors located 50 mm from the lower boundary of the internal target. The diameter of the annular sector was 1175 mm. The X-ray exit window was a 0.38 mm thick stainless steel strip.

Typical scanning parameters provided by the manufactured scanner: anode voltage from -70 kV to -140 kV; beam current determined by the perveance of the electron source is 1.5 A at a cathode voltage of -140 kV; vacuum in the electron source is 10' ⁸ -10' ⁷ Torr, in the scanning tube in the target area - 10' ⁶ - 10' ⁵ Torr; beam travel time across the target (duration of one scan) is 25 ms; the size of the beam spot ellipse axes on the target is about 1 mm by 7 mm. The length of the scanning area is 16 cm. The scanner aperture (gantry diameter) was 100 cm.

Fig. 14 shows a general view of an electron-beam computer tomograph, implemented using the claimed group of inventions, with additional equipment, and which includes an electron-beam scanner with a gantry 43, and an electronic control unit connected to the scanner, designed with the possibility of regulating the voltage supply to the device for generating X-ray radiation of the electron beam scanner and data retrieval from the detector, power distribution system 45, power supply and energy storage system 46, high-voltage power source 47, chiller 51. In this case, the electronic control unit includes beam scanning control electronics (BSCE) 48, computer control system 49, block 50, including a data acquisition system and a data reconstruction system. The tomograph also includes a patient table 44, an electrocardiograph 52 and a control panel (not shown). The BSCE is located in a standard rack and is connected by means of connecting cables to the power distribution system, magnetic deflection system, computer control system, data acquisition system, patient table, high-voltage power source, electrocardiograph.

Upon exiting the source, the electron beam enters the electron beam scanner through a flange with a built-in ion removal electrode, which “intercepts” ions moving from the target area to the cathode area in order to minimize the impact of such ions on the cathode surface and the effect on the inhomogeneity of the beam space charge. The electron beam is controlled by a magnetic deflection system, which consists of a focusing solenoid (creates primary beam focusing), two pairs of dipole coils (create magnetic deflection fields transverse to the beam axis, as well as a quadrupole moment to create an elliptical beam cross-section), and angular quadrupole coils to “rotate” the beam ellipse. The currents in the coils are controlled by beam sweep control electronics. The electron beam exiting the source is focused on an X-ray target under vacuum and scans it. The X-ray source moves along an arc of a circle, the X-rays pass through the object under study in the gantry area and are detected by the matrix of receiving elements. The signals from the detectors are converted into data that are used to create three-dimensional images of the volume of the object under study. In this case, the data acquisition system, which is part of the electron beam computed tomograph, provides reading and transmission of data from the detector system to the data acquisition server and records the collected data in the server memory. The resulting data set is processed by the data reconstruction system using reconstruction algorithms that allow obtaining an image of the volume of the object under study. The properties of the electron beam and the beam spot on the target must remain within the specified values during the entire scan. The magnetic system ensures alternate movement of electron beams along arc-shaped sections of the target system, located at different angles, to expand the scanning area of the object under study within the framework of one scan. The use of two electron sources ensures a proportional reduction in the length of the electron beam trajectory and, accordingly, a reduction in the linear dimensions of the electron beam scanner along the scanning axis. In this case, the reduction in the time of one scan is determined by the corresponding reduction in the scan trajectory (arc-shaped target), which falls on one source.

The declared electron beam scanner is characterized by a reliable and simple design, provides improved quality of X-ray images, reduced scanning time, and is also characterized by a scanning area length of at least 16 cm.

It should be clear to those skilled in the art that various modifications and improvements can be made to the electron beam scanner according to the invention without going beyond the scope of the claims. The electron beam scanner can be manufactured using known materials, equipment and technologies, and can find wide application for obtaining tomographic images of various objects for medicine (cardiological research) and industrial non-destructive testing.

Claims

CLAUSE OF INVENTION 1. A segment of a target system of a device for generating X-ray radiation, made in the form of a three-dimensional part containing a base made of a heat-conducting material, having external and internal longitudinal surfaces, mating end surfaces, external and internal mounting surfaces, wherein the base has a stepped cross-sectional profile and is provided on the side of the internal mounting surface with at least two steps with internal and external arc-shaped plates for generating X-ray radiation fixed thereto, and a platform located parallel to the external mounting surface, with a tuning plate fixed thereto, where the first step of the base with the fixed internal plate is located at an angle a with respect to the plane of the tuning plate, and the second step with the fixed external plate is located at an angle 0 with respect to the plane of the tuning plate, where 0<a; the base is provided with at least four mounting holes, two of which are located between the inner and outer plates, and the other two are located between the adjustment plate and the outer longitudinal surface of the base. 2. A segment of the target system according to item 1, characterized in that the base steps are provided with stop projections for the plates on the side of the inner longitudinal surface of the base. 3. A segment of the target system according to item 1, characterized in that the platform for placing the tuning plate is provided with a stop protrusion. 4. A segment of the target system according to item 1, characterized in that angle a is made equal to 17°, angle 0 is made equal to 13°. 5. A segment of the target system according to item 1, characterized in that the base is made of oxygen-free copper. 6. A segment of the target system according to item 1, characterized in that tungsten-rhenium plates are used as plates. 7. A segment of the target system according to claim 1, characterized in that it contains at least two tungsten W-shaped sensors for tracking the position of the electron beam on the tuning plate, fixed on a heat-conducting base with a gap relative to the tuning plate. 8. A target system of a device for generating X-ray radiation, containing a set of segments made according to any of paragraphs 1-7, fixed on a ring-shaped plate with the formation of at least two arc-shaped targets - internal and external, and one tuning target, wherein the segments are fixed on the plate with a gap relative to each other, ensuring the exclusion of damage to the segments during their thermal expansion during operation of the device, the plate is provided with channels for cooling the segments of the target system, located with the formation of at least two cooling sections, as well as input and output openings for the cooling medium. 9. The target system according to item 8, characterized in that it includes 12 segments. 10. The target system according to I.8, characterized in that the channels for cooling the segments of the target system are made with a rectangular cross-sectional profile. 11. The target system according to I.8, characterized by the fact that the channels are located parallel to the arcuate targets at an equal distance from each other. 12. The target system according to item 8, characterized in that the channels are arranged to form two cooling sections, symmetrical relative to a vertical axis passing through the center of the annular plate. 13. The target system according to I.8, characterized by the fact that the number of channels in each section is selected to be no less than 7, while the width and height of the channels is no less than 4 mm, and the distance between adjacent channels is no less than 14 mm. 14. The target system according to item 8, characterized in that the gap between adjacent segments is 0.4 mm. 15. A device for generating X-rays, comprising a vacuum chamber; at least two electron sources located on the rear side of the vacuum chamber; a magnetic system for rotating, focusing and deflecting electron beams; a target system according to any of paragraphs 8-14, for generating X-rays, located in the front part of the vacuum chamber; X-ray exit windows. 16. An electron beam scanner, including a device for generating X-ray radiation according to I.15, a detector system, a collimator located between the target system and the detector system, mounted on a supporting frame, wherein the detector system is formed by a set of scintillation matrices fixed on a frame provided with a gap separating the detector a system into two annular sectors, wherein the frame is made with side walls, one of which is removable, and is provided with a mechanism for fastening and adjusting the detector system, which also ensures the fixation of the frame to the supporting frame with the side walls located on opposite sides from the supporting frame, and the target system is secured to the supporting frame with an annular plate with cooling channels placed on it, wherein the frame is located concentrically relative to the target system with a gap located opposite the output window of the device for generating X-ray radiation, wherein one sector of the detector system is located with the possibility of detecting radiation from the internal target, and the other - from the external one, where the internal and external targets are located with the provision of passage of the generated radiation into the gap of the frame. 17. An electron beam scanner according to item 16, characterized in that the internal diameter of the frame of the detector system is at least 1040 mm. 18. An electron beam scanner according to claim 16, characterized in that the detector system includes scintillation matrices of at least 16x32 in size with a pixel size of no more than 1.06 mm by 1.12 mm.