WO2014209158A1

WO2014209158A1 - Multibeam x-ray tube

Info

Publication number: WO2014209158A1
Application number: PCT/RU2013/000558
Authority: WO
Inventors: Олег Юрьевич МАСЛЕННИКОВ; Игорь Анатольевич ГУЗИЛОВ
Original assignee: ДЕМИДОВА, Елена Викторовна
Priority date: 2013-06-28
Filing date: 2013-06-28
Publication date: 2014-12-31
Also published as: RU2578675C1

Abstract

A multibeam x-ray tube (1) for scanning a stationary object (13) in intersecting directions while in a static position, containing, positioned in a grounded housing (2): a rotating anode (3) having a flat annular target (4) positioned on the flat side thereof; a system (5) of electron sources, positioned above the surface of the target (4) and containing N sources (10) of electrons for supplying N streams (17) of electrons, said streams having a circular cross section, a control electrode (22) for converting the N streams (17) of electrons into N configured streams (23) of electrons which create, on the working surface (4a) of the target (4), N sources (12) of x-ray radiation in the form of narrow figures similar to a rectangle, which extend in the direction of an output window (6) and which converge to a single point beyond the output window; stationary collimators (27) for selecting radiation from the entire area of a source (12) of x-ray radiation in the direction of the output window (6), and for forming a pyramidally-shaped x-ray beam (30) which encompasses the region of x-ray radiation, having the highest energy density in a beam which adjoins the upper (6a) and lower (6c) sides of the rectangular output window (6), and having a rectangular base (30a) which encompasses the region (13) of the object to be scanned.

Description

Multipath X-ray Tube

The invention relates to the field of electronic technology, in particular, to multi-beam X-ray tubes, providing the ability to obtain a tomographic image of various objects, including for medical purposes for mammography, using multi-beam multi-source electron emission sources to obtain a series of images of the object from different angles for computer tomography and tomosynthesis.

State of the art

It is known that to obtain a variety of x-rays, allowing you to get a series of images of the object at different angles, in the x-ray tube, an embodiment of x-ray tubes with many cathodes is mainly used. In this case, the movement of a multi-cathode X-ray tube in space, as in traditional tomosynthesis systems using a single-beam X-ray emitter, is not required. Replacing the mechanical movement of the emitter by electric switching of the cathodes leads to a significant improvement in the quality of image reconstruction due to the exact positioning of the focal spots of electron emission in space, the complete immobility of the focal spot during exposure of the target, which reduces the total duration of the examination time to several seconds.

The specificity of multi-cathode multi-beam X-ray tubes for computed tomography for medical purposes, in particular for mammographs, is the need for tomographic analysis with scanning the object in intersecting directions at different angles with the possibility of creating a three-dimensional image of the scanned object, and much attention is paid to ensuring safe thermal regime of the functioning of x-ray tubes and the safety of working with medical devices.

A known X-ray tube for generating a variety of X-rays of various intensities (US, 4,823,371, B1), including many cathodes of various sizes with devices for controlling the focal length, providing quick switching between discrete values of the working currents, and the anode located at a distance from the cathodes. However, the focal spots of individual electron beams are located on the anode in one place, which leads to the formation of a single directed x-ray beam and to the impossibility of conducting tomographic analysis with scanning the object in different directions.

A device for x-ray computed tomography (US, 5,195,1 12, B1), containing many stationary electronic sources, including devices for emitting and accelerating the movement of electrons to the stationary ring anode, means for applying an electric potential between each of the many electronic sources and the anode for acceleration the movement of electrons to the anode so that the electrons collide with the anode and generate radiation and that the focal spots are scanned by the installed sections of the anode before As any significant acceleration of electrons takes place, and a detector for generating an image signal and an image forming apparatus. However, the power of x-ray radiation is limited due to the need to limit thermal loads on the anode, which leads to insufficiently high definition of the recorded signal, weakened by the passage of radiation through various tissues, during the formation of three-dimensional images.

A device for generating multiple x-rays and a device for generating an x-ray image for performing non-destructive radiography (RU, 2399907, C1), the device for generating multiple x-rays contains a plurality of electron sources that are two-dimensional and provide electron emission during selective activation of electron sources in accordance with the attached activation signals from the activation means, and a plurality of targets located opposite to the plural source in electrons, and wherein the target generating X-rays with different radiation quality in accordance with a place generating X-rays, and X-ray imaging device comprises a two-dimensional X-ray detector. However, the device for generating multiple X-rays has a low X-ray power due to the need to limit the thermal load on the stationary targets. Known technical solutions of multi-beam multi-cathode x-ray tubes, in which to reduce the thermal load on the target, the anode is made rotating.

Known x-ray tube for circular scanning in tomosynthesis mode (US, 2011002442, A), containing in the casing an anode in the form of a rotating disk with a target on its conical lateral surface and a plurality of cathodes mounted in the casing around the anode in the plane of its rotation, providing many focal spots on the surface of the target, uniformly distributed, for example, on the circular line of the target, and creating x-ray sources when exposed to electrons emerging from the cathodes. The object of examination can be located on the axis of rotation of the anode at a certain distance from the radiation source and subjected to x-ray irradiation performed sequentially in all radiation sources, while the x-ray tube maintains a static position relative to the object, providing the creation of three-dimensional images.

However, the narrow zone of location of focal spots on the target and, as a result, the high density of thermal energy released in the region of the x-ray source on the surface of the anode and the large number of spatially separated x-ray output windows make it impossible to scan large objects with dimensions comparable to the diameter of the tube anode .

Known technical solutions to ensure a specific location of the focal spot on the target to prevent overheating of the target.

For example, an X-ray tube is known with many focal spots of different sizes (US, 5.51-1.105, A), comprising: an anode in the form of a plate with a means of rotation, having a target divided into many regions consisting of different materials, and electron emission sources to generate at least one focal spot in each indicated area of the target and a plurality of focal spots of respectively different sizes in at least one of the areas, and emission sources generate focal spots in different areas and focal spots and of different sizes in the same region adjacent to them, at different radii of the indicated plate of the anode in its peripheral part along a straight line intersecting the specified peripheral part, or along a straight line directed radially on the plate of the anode and crossing the specified peripheral part, to obtain the focus position, which will be the same for all indicated focal spots. Wherein emission sources contain means for generating at least one large focal spot and at least one small focal spot in two regions, and for generating large local spots immediately adjacent to each other, and the anode is divided into two parts made of different materials. The tube has a common output window for all focal spots.

A technical solution is known for a circular multi-beam X-ray device using a multi-beam X-ray tube having the shape of a circle (US, 8,031,832, B), consisting of at least two segments and several diaphragms, while the focal spots of the tube are located around the circumference. The object of study and the detector are located in the center of the circle. The handset control unit sets the sequence for switching on the rays. Images of tomosynthesis can be obtained without mechanical movements of the emitter.

A multipath x-ray emitter is known (US, 7,970,099, B), in which the multipath x-ray tube is made in the form of a polygon, in which focal spots are located along the sides of the polygon. The control unit of the x-ray tube includes alternately separate radiation sources. The device is equipped with several diaphragms that can move along the sides of the polygon and form the direction and angle of the radiation beam. A layered image of the object of study can be obtained without moving the x-ray tube.

Closest to the present invention is a general-purpose x-ray tube for stereography (US, 4,596,028, B) containing in the cylindrical body an anode in the form of a rotating disk with a target on its lateral conical surface and N identical independent cathodes forming focal spots of the same size on the target surface, located on the surface of the target in such a way as to obtain on the target of the anode N discrete sources of x-rays at a distance from each other, while any two of these sources zlucheniya form a working pair, so that X-ray radiation which they generate during rotation of the anode are sequentially outputted to the output window located in the end of the tube body in a plane parallel to the plane of rotation of the anode that allows the irradiation of the object to obtain object stereographic pattern in the radiation detector. 13 000558

5

However, in the aforementioned x-ray tubes, the narrow area of the focal spot on the target, as well as the shape of the focal spot of the electron beam in the form of a circle on the target, that is, the concentration of the energy flux in a small limited area, leads to a high density of thermal energy in the focal spot released on the surface target / anode, and a large number of spatially separated windows for X-ray output and the geometric arrangement of X-ray sources along an arc of a circle in a plane that does not intersect the scan object, d barks it impossible to conduct a comprehensive analysis of the tomographic scanning.

Thus, the problem of creating a multi-cathode x-ray emitter, providing a high density of x-ray irradiation in combination with the possibility of spatial scanning of an object with a static location of the emitter relative to this object, is very relevant.

Disclosure of invention

The present invention is directed to solving the technical problem of creating an x-ray tube, which provides spatial scanning of a stationary object in intersecting directions at different angles by discrete x-rays having a high x-ray density, with a static arrangement of the x-ray tube relative to this object.

When creating the present invention, the task was to provide in a stationary multipath x-ray tube the formation and output from the tube in the intersecting directions of discrete X-rays, covering the stationary object of scanning and having a high energy density necessary for tomographic analysis of the scanned object, by:

- the use of electron sources supplying an electron beam in the form of an electron stream with a cross-sectional configuration that provides in their focal spot on the target a configuration of an x-ray source in the form of a narrow figure extended toward the x-ray output window and providing the highest energy density in the electron stream in a direction perpendicular to the direction of output of x-rays;

- subsequent selection of x-rays in the direction of the output window from the entire area of the x-ray source and the formation of discrete scanning x-ray, covering the area of the object to be scanned;

placing the x-ray sources on the target, ensuring the direction of the generated scanning x-rays with their crossing in the area to be scanned, with the cross-sectional area of the beam covering the scanning area,

and at the same time it would be provided:

- placement of electron sources among themselves at the shortest distance necessary to ensure the discreteness of electron beams and, accordingly, the discreteness of x-ray sources generated on a target in the region of focal spots of electron beams;

- reducing the temperature loads on the target at the points of formation of the x-ray sources and creating the best conditions for cooling the target between the pulsed effects of electron fluxes on the target points.

The problem was solved by creating a multi-beam x-ray tube for scanning a stationary object in intersecting directions with its static position, containing:

- an anode having a disk shape, equipped with a target located on its surface, and a built-in mechanism for the rotation of the anode around its axis of rotation, coinciding with the axis of its symmetry;

- a system of electron sources containing N electron sources and generating N discrete electron streams to be supplied to the target surface to form N discrete X-ray sources on the target in the locations of N focal spots of said discrete electron streams;

- window output x-ray radiation,

characterized in that:

- the anode has the shape of a disk facing a flat surface to the specified system of electron sources, and is isolated from the housing by a high-voltage insulator;

- the target is located on the indicated flat surface of the anode and has the form of a flat ring centered on the axis of rotation of the anode;

- the X-ray output window is common for the X-ray output of all N X-ray sources, located in the side wall of the casing is higher than the level of the target plane and is made flat in the form of a rectangle perpendicular to the plane of the target and having the upper side of the rectangle at a level of no more than 35 ° to the plane of the target and the lower side of the rectangle at least 10 ° to the plane of the target;

- the system of electron sources is adapted for generating and projecting N discrete electron fluxes having a cross-sectional configuration on the target in a periodic pulsed mode, which ensures the formation of N focal spots on the surface of the target, respectively, having the highest electron energy density in the focal spot in the direction perpendicular to outputting x-ray radiation generated by the x-ray source generated in the specified focal spot through the window in output;

- additionally contains N stationary collimators having the potential of the anode, placed by an input each close to the corresponding x-ray source having the configuration of the focal spot indicated above the target surface in the region between each one x-ray source and the output window, and each collimator provides radiation selection from the surface of the corresponding single source of x-ray radiation in the direction of the output window and the formation of the specified x-ray radiation in de beam of a pyramidal shape, covering the region of the highest energy density in the beam, conjugated in the middle part with the upper and lower sides of the rectangle of the output window and having a rectangular base covering the area of the object to be scanned.

Moreover, according to the invention, it is advisable that the system of electron sources be made in the form of an electron-optical system that provides, in a periodic pulsed mode, a sequential supply of discrete electron flows to the target, which ensure the formation of focal spots on the target surface in the form of narrow figures extended to the side output windows and oriented along the length in the direction of the same common point for them.

Moreover, according to the invention, it is advisable that the system of electron sources be made in the form of an electron-optical system that provides, in a periodic pulsed mode, a sequential supply of discrete electron flows to the target, which ensure the formation on the target surface focal spots having the shape of ovals close to a rectangle, with a ratio of the lengths of the major axis of the oval and the minor axis of the oval not less than 5: 1, with large axes converging outside the output window in the area of the object to be scanned, with the centers of the indicated ovals N focal spots on the target on one line spaced from the axis of rotation of the anode in the direction of the output window.

Moreover, according to the invention, it is advisable that these centers of the ovals of N focal spots were located on the target on the same line, which is a segment of the chord parallel to the plane of the output window.

Moreover, according to the invention, it is advisable that these centers of the ovals N focal spots were located on the target on the same line, which is a segment of the chord located at an angle of 1-2 ° to the plane of the output window.

Moreover, according to the invention, it is advisable that the tube contains a system of electron sources, made in the form of an electron-optical system, in which:

- these pulsed N electron sources are placed in the tube body along one straight line at an equal distance from each other above the surface of the target portion closest to the indicated output window, and are adapted to generate and output in the direction of the target plane sequentially in the periodic pulse mode of each one of N electron flows having a circular cross-section;

- between the terminals of the indicated N electron sources and the target there is a grounded control electrode adapted for converting each of these N electron streams having a circular cross-section into one of the N configured electron streams, which, when projected onto the target, will form on the target, respectively, one of the N focal spots, having the shape of an oval close to a rectangle, with a ratio of the lengths of the major axis of the oval and the minor axis of the oval not less than 5: 1, with the direction of the major axes converging in about a point common to them outside the exit window, with the centers of the indicated ovals N of the focal spots on the target located on a segment of its chord, spaced from the axis of rotation of the anode in the direction to the exit window.

Moreover, according to the invention, it is advisable that the specified control electrode was placed parallel to the plane of the target and provided with N cascades of through holes located near the indicated outputs of N electron sources and having round inlet openings in the cascade for introducing one of the indicated N electron flows and oval shaped exit openings with large axes oriented towards the output window and converging outside the output window in common point for them, for the output of each one of the indicated N configured, electron flows.

Moreover, according to the invention, it is advisable that these N electron sources were made in the form of N cathode nodes containing, respectively:

- N cathodes electrically isolated from the tube body;

- N cathode heaters, electrically isolated from said cathodes and electrically connected in parallel to each other;

- N focusing electrodes electrically connected to these cathodes and having round-shaped exit holes,

and while these N cathodes are configured to control the cross-sectional area of each of these N electron flows by changing the potential of the corresponding cathode.

Brief List of Drawings

Further, the multi-beam x-ray tube according to the invention is illustrated by an example of its implementation and the accompanying drawings, in which: Figure 1 - multi-beam x-ray tube according to the invention, a longitudinal section aa in figure 2;

Figure 2 - multi-beam x-ray tube according to the invention, section bb in figure 1;

FIG. 3 is a system of electron sources according to the invention, fragment I in FIG. 1; Figure 4 is a system of electron sources according to the invention, a section D-D in Figure 2; 5 is an electrical diagram of a multipath x-ray tube according to the invention;

Fig.6 - the location of the focal spots on the surface of the target, fragment III in Fig.2; 7 is a system of electron sources according to the invention, view F in FIG. 4, fragment;

FIG. 8.9 are diagrams of the formation of a configured electron stream into a system of electron sources according to the invention, transverse and longitudinal sections; Figure 10 is a diagram of the projection of x-ray radiation on the plane of the output window, in the plane of the major axis of the focal spot;

11,12 is a diagram of the selection and formation of an x-ray pyramidal shape, a side view of the target - 11, fragment II in figure 1, and a top view of the target - Fig;

Fig. 13 is a diagram showing the output of scanning x-rays formed in the shape of a pyramid using fixed collimators, with the arrangement of focal spots on a chord parallel to the plane of the output window;

Fig. 14 is a diagram showing the output of scanning x-rays formed in the shape of a pyramid using fixed collimators, with focal spots being arranged on a chord located at an angle β to the plane of the output window.

Moreover, the described embodiment of the multi-beam X-ray tube according to the invention is not exhaustive, does not limit the invention and does not go beyond the scope of the claims.

Best Mode for Carrying Out the Invention

A multi-beam x-ray tube according to the invention for scanning a stationary object in intersecting directions with its static position can be performed in the embodiment shown in Fig.1-14.

As shown in FIG. 1, the multi-beam X-ray tube 1 according to the invention comprises an electron 3 placed in a grounded housing 2: an anode 3 with a flat target 4, an electron source system 5 placed above the surface of the target 4 and generating discrete and generating onto the target surface 4 electron flows causing the formation of 4 discrete X-ray sources on the target, and an X-ray output window 6.

According to the invention, as shown in Fig. 1.2, the anode 3 is made in the form of a flat disk, with a flat end face 7 facing the indicated system 5 of electron sources, equipped with an integrated mechanism 8 for rotating the anode 3 around its axis of rotation, coinciding with its axis of symmetry , and is isolated from the casing 2 by a high-voltage insulator 9. At the same time, the built-in mechanism 8 for rotating the anode 3 around its axis For rotation can be made in the form of an electric motor, the rotor 8a of which is located in the casing 2 of the tube 1, in its vacuum part, and the stator 8c is placed outside the housing 2 (Fig. 1). Moreover, according to the invention, the target 4 (Fig. 1, 2) is made in the form of a flat ring centered on the axis of rotation of the anode 3, and is fixed on the flat end surface 7 of the disk of the anode 3 so that the working surface 4a of the target 4 is facing the system 5 sources of electrons.

According to the invention, the system of 5 sources of electrons (Fig. 1,2) is made in the form of an electron-optical system containing N sources of 10 electrons and providing, in a periodic pulsed mode, the generation and projection of 4 N discrete streams of electrons onto the target surface, which ensure the formation on the target surface 4, respectively, N focal spots 11 (FIG. 2) having the highest electron energy density in a direction perpendicular to the direction of output of X-ray radiation generated by the X-ray source 12 ovskogo radiation (Fig.1,2) formed in the location of said focal spot 11 through output window 6 (Fig.1,2).

According to the invention, the electron source system 5 can be made in the form of an electron-optical system that provides, in a periodic pulsed mode, a sequential supply of 4 discrete electron streams to the target, providing formation of focal spots 1 1 having the shape of narrow figures on the target surface (FIG. 2 ), extended to the side of the output window 6 and each oriented in length in the direction of one point P, the same for all focal spots 1 1, in the region 13 of the object to be scanned (Fig. 1.2.).

In this case, according to the invention, the electron source system 5 can be made in the form of an electron-optical system that provides, in a periodic pulsed mode, a sequential supply of 4 discrete electron streams to the target 4, which ensure the formation of 4 focal spots And having the shape of ovals on the surface of the target (FIG. 2,6), close to a rectangle, having the length L _{\ of the} major axis 14 of the oval and the length Li of the minor axis 15 of the oval with the ratio L _\ l Li> 5, with large axes 14 converging outside the output window 6 at the point P of the area 13 of the object, subject to ska ation, with the location of the centers of said ovals CN N focal spots 11 on the target 4 on a straight line 16 (Figure 2, 6), spaced apart from the axis of rotation behind the anode 3 towards the output window 6.

Moreover, according to the invention, these centers CN of the ovals N of the focal spots 1 1 can be located on the target 4 on one straight line 16a, which is a segment of a chord parallel to the plane of the output window 6 (Fig.13), and in this case, two centers of the N centers of CN focal spots 11 are located on the same circle of the target ring 4.

According to the invention, these centers CN of ovals N of focal spots 1 1 can be located on target 4 on one straight line 16c, which is a segment of a chord located at an angle β = 1-2 ° to the plane of the output window 6 (Fig. 14), and each center of the Ν centers C of focal spots 1 1 is located on its circumference of the target ring 4, which improves the thermal regime of the target 4 and the anode 3.

Since the density / thermal load on the anode 3 of the tube 1 is inversely proportional to the area S of the focal spot 1 1 of the electron beam, according to the invention, in a shape close to a rectangle, and S = Lj -L ^ and

J = - -—, where / is the current of the cathode 18 of the source of 10 electrons,

I, L ₂

then by increasing the ratio L \ ILi in the range of more than 5: 1, a decrease in the density / thermal load on the target 4 and the anode 3 of the tube 1 is achieved.

Thus, the location and shape of the discrete focal spots 1 1 with centers C on a certain circumference of the target ring 4 according to the invention in combination with the rotation of the anode 3 with a certain speed reduces the thermal load on the anode 3 and allows it to cool in the intervals between the successive pulses of discrete streams electrons to the same point on the target 4.

According to the invention, said system of electron sources 5 can be made in the form of an electron-optical system in which these pulsed N electron sources 10 (Fig. 3.4) are placed in the housing 2 of tube 1 along one line, for example, a straight line corresponding to a location line centers C of the focal spots 11, at the same distance from each other above the surface of the part of the target 4, closest to the specified window 6 output (Fig A), and are adapted to generate and output in the direction of the plane of the target 4 sequentially in a periodic pulsed mode of each one of the N streams of electrons 17 (Figure 4) having a flow cross-section 17 in the shape of circle.

Moreover, according to the invention, these N electron sources 10 can be made in the form of N cathode nodes (Fig.3,4), containing, respectively: - N cathodes 18, configured to control the cross-sectional area of each of these N electron streams 17 by changing the potential of the corresponding cathode 18;

- N heaters 19 cathodes 18;

- N focusing electrodes 20 having round-shaped outlet openings 21.

According to the invention, between the terminals of these N electron sources 10 and the target 4 is placed a grounded control electrode 22.

An electrical diagram of a multi-cathode multi-beam X-ray tube 1 according to the invention is shown in FIG. 5.

According to the invention, N cathodes 18 are electrically isolated relative to the ground and from the casing 2 of the tube 1, N heaters 19 are electrically isolated from these cathodes 18 and have two leads 19a and 196, the conclusions 19a being grounded to the casing 2 of the tube 1, and the conclusions 196 are electrically connected between a common bus 19c, to which the filament voltage UH is applied, and N focusing electrodes 20 are electrically connected in parallel to each other, have the same potential and are electrically connected to. cathodes 18. Focusing electrodes 20 are not shown in the diagram, since they have the same potential with cathodes 18

According to the invention, the control electrode 22 (FIGS. 3,4,6) is adapted to convert each of these N electron streams 17 (FIG. 4) having a cross section of a circle-shaped stream 17 into one of the N configured electron streams 23 (FIG. .7,8,9), providing, upon contact with the target 4, the formation on the target 4, respectively, of one of these N focal spots 11 (Fig. 8,9), having the shape of an oval close to a rectangle, having a length Li of major axis 14 oval and length Lz of the minor axis 15 of the oval with a ratio of L2> 5, with large axes 14 converging outside the window 6 of the output at point P (Fig. 2,13.14), the same for all major axes of the focal spots 11, in the region 13 of the object to be scanned, with the centers C of the indicated ovals N of the focal spots 11 on the target 4 on the same line 16 (Fig. 2), spaced from the axis of rotation of the anode 3 in the direction of the output window 6, for example, on a line 16a parallel to the plane of the output window (FIG. 13) or on a line 16c located at an angle β = 1-2 ° to the plane of the window 6 output (Fig).

Moreover, according to the invention, the specified control electrode 22 is placed parallel to the plane of the target 4 (Figure 4) and is equipped with Ν cascades 24 through holes (Figs. 3,7,8,9) located near the exits 10a of the indicated N electron sources 10 and having inlet 24 round-shaped inlets 25 (Figs. 7,8,9) for introducing one of these N discrete streams 17 electrons and oval-shaped exit openings 26 (Figs. 7, 8, 9), in which the large axes 26a are oriented towards the output window 6 (Fig. 7) and converge behind the output window 6, for output of each one of these N configured streams of 23 electrons in the direction of the plane of the target 4 (Fig.8.9). In this case, the axis of symmetry of the through holes of the cascades 24 of the control electrode 22 coincide with the axis of the openings of the outputs 10a of the indicated N electron sources 10.

The choice of the size, shape and orientation of the outlet openings 26 of the control electrode 22 provides a configured electron stream 23 having the corresponding desired shape and orientation of its cross section, which allows focusing in the cascade 24 of through holes of the control electrode 22 to obtain a focal spot 11 on the target surface 4 given shape and area, with a specific orientation on the target 4.

As known to specialists in the field of x-ray, the x-ray image is the sum of the shadows of the investigated object on the table 13A of the x-ray detectors (Fig.1,2), obtained from each point of the source 12 of the x-ray radiation. With a large size of the source of X-ray radiation, the shadows formed by the radiation of individual points of the source 12 are shifted relative to each other: penumbra appear at the image boundary, and the clarity of the image decreases, the images of small inclusions inside the scan objects are blurred.

In a plane perpendicular to the direction of the output of x-ray radiation and passing through the major axis 14 of the focal spot And, the value L of the x-ray height projected onto the output window 6 (Figure 10) is determined by the expression L = tga, where is the angle of inclination of the x-ray height to the plane target 4.

The projection of the X-ray image depends on the projection size of this value L on the plane of the output window 6 and on the projection size of the width L2 of the radiation source 12 (Fig. 12): with a decrease in the sizes L2 and L, the image clarity increases. Since the location and configuration of N X-ray sources 12 is due to the location and configuration of the corresponding N focal spots 11 on the target 4, which are formed upon the contact of the corresponding N configured electron flows 23 with the target 4, the formation of N focal spots 1 1 in the form of narrow figures in the contact area with the highest concentration of electron energy in their narrow part, for example, elongated ovals facing the major axis towards the output window 6, with the direction of their major axes in one, the same point P in of the region to be scanned (Fig. 2), it is possible to obtain on the target 4 N sources 12 of X-ray radiation having the highest density of X-ray radiation in a narrow part of the ovals, perpendicular to the direction of output of X-ray radiation from the tube 1 (Fig.12,13,14).

According to the invention, the X-ray output window 6 (FIG. 1.2) is common for X-ray output of all N X-ray sources 12 generated on the target 4 in the region of said focal spots 11 N configured electron streams 23, while the output window 6 is located in the side the wall 2a of the housing 2 of the tube 1 is higher than the level of the target plane 4 (FIG. 1) and is made flat in the form of a rectangle perpendicular to the plane of the target 4 and having a rectangle at the level of the angle a? not more than 35 ° to the plane of the target 4 and the lower side 6c of the rectangle at the level of the angle not less than 10 ° to the plane of the target 4 (Fig. And).

Thus, the implementation of the output window 6 according to the invention provides the output of a discrete scanning x-ray in a certain range of angles ccj and CC2 along the height of the output window 6, corresponding to the most efficient projection of x-rays of the smallest height L and smallest width Ztf Ha the output window 6 from the entire area of the source 12 x-ray along the length Lj.

Moreover, according to the invention, the tube 1 contains N stationary collimators 27 (Fig. 1, 2) having the potential of the anode 3, each placed with its input 28 close to the corresponding X-ray source 12 having the configuration of the focal spot And, above the surface of the target 4 in the region between each one x-ray source 12 and window b output (Figure 1.2). In this case, each collimator 27 provides the selection of x-ray radiation from the entire surface of the corresponding one x-ray source 12 in the direction of the output window 6 (Fig. 11) and the formation at the output 29 of each of the N x-ray collimators 27 in the form of a pyramidal stream 30 conjugated to the middle part with the upper 6a and lower 6c sides of the rectangle of the output window 6 and having a rectangular base 30a (Fig.11), covering the area 13 of the object to be scanned.

Thus, according to the invention, the output through the window 6 of the output of x-ray radiation with the highest energy density over the entire height L and the entire width bg of the x-ray beam is provided, and its cross-sectional dimensions are provided that allow the beam to cover the entire scanning area at the highest x-ray energy density inside the specified stream in a pyramidal shape.

Thus, the implementation of the multi-beam x-ray tube 1 according to the invention provides:

- placement of sources of 10 electrons among themselves at the shortest distance necessary to ensure the discreteness of the electron beams and, accordingly, the discreteness of the sources of X-ray radiation while reducing the heat load on the target 4 and the anode 3;

- the formation of a stream of 23 electrons with the configuration of their cross section, providing in their focal spot 11 on the target the configuration of the x-ray source 12 in the form of a narrow figure, extended towards the window 6 of the output of the x-ray beam 30 and providing the highest energy density in the electron stream in the direction perpendicular the direction of the output of x-rays;

- the location of the sources of X-ray radiation 12 on the target, providing the direction of the generated scanning x-rays 30 with their crossing at one point of the region 13 to be scanned, with a minimum cross-sectional area of the scanning beam 30, covering the scanning region,

- the formation of sources of X-ray radiation 12 in the best cooling conditions of the target 4 and the anode 3 between the pulsed action of the fluxes of 23 electrons on the same points of the target 4; - withdrawal from the fixed tube 1 in the intersecting directions of discrete x-rays 30, covering the stationary object of scanning and having a high energy density necessary for tomographic analysis of the scanned object;

- selection of x-ray radiation in the direction of the output window 6 from the entire area of the x-ray source 12 with the formation of an x-ray beam 30 having a pyramidal shape, characterized by the smallest height L and the smallest width bj of the projection of this beam onto the plane of the output window 6.

Multipath x-ray tube 1 according to the invention operates as follows.

Initially, all cathodes 18 are supplied with a positive bias potential U cm _{> the} currents of the cathodes 18 are absent.

The anode 3 is at a positive potential U _A and rotates at a certain linear speed sufficient to ensure that the heat load of the configured electron stream 23 on the target 4 of the anode 3 does not lead to evaporation of the target material 4 and overheating of the anode 3.

During operation of the multipath X-ray tube 1, negative polarity pulses with amplitude Uu are alternately fed to cathodes 18, with Uu <2UC _M , which leads to the appearance of an emission current. In this state, the potential of the cathode 18 is negative with respect to earth: i / * = UM - UU.

When a negative polarity pulse Uu arrives at the cathode 18, the electrons of the cathode 18 under the influence of an electric field in the space between the cathode 18 and the anode 3 begin to move towards the anode 3.

When this occurs, the formation of one of the N discrete streams of 17 electrons generated in a pulsed mode by a source of 10 electrons, respectively, in the direction of one corresponding to it, a point on the target 4 and having a cross section of the stream 17 in the form of a circle.

Then, when the electron stream 17 passes through the cascade 24 of through holes of the control electrode 22, a configured electron stream 23 is formed, having, after the cascade 24 is removed from the opening 26, a cross section of predetermined dimensions in the form of a narrow oval with a given ratio of the lengths of its major and minor axes, with a large an axis directed to a certain common point for them outside the output window 6. The thus configured stream 23 electrons upon its contact with the surface of the target 4 provides the formation in a specific area of the target 4, corresponding to the specified source 10 of electrons, a focal spot 11 having a given shape, size and orientation on the target 4, with the center C / focal spot 11 at a certain point on a given line 16 the location of the centers of all N focal spots 11, for example, at a given point on a segment of the chord 16a parallel to the plane of the output window 6, or on a segment of the chord 16a having an angle β = 1-2 ° with the plane of the output window 6. The calculation of the trajectories of the configured electron flows 23 is shown in FIG. 7.

The impact of each configured electron stream 23 in the area of the focal spot 11 of its electron beam on the rotating target 4 causes the formation of the corresponding X-ray source 12 having an area, configuration and orientation on the target 4 corresponding to the focal spot 11. Moreover, in accordance with the most dense the distribution of electron energy in a narrow part of the oval of the focal spot 11, the x-ray radiation generated by the source 12 has the highest energy density of the x-ray zlucheniya with the surface of the source 12 in a narrow part of an oval, a width equal to the length of the minor axis of the oval focal spot 15 January 1st.

One of the Ν fixed collimators 27, having the potential of the anode 3 and each placed with its input 28 close to the corresponding x-ray source 12 above the surface of the target 4 in the region between the x-ray source 12 and the output window 6 (Fig. 11, 12), provides through the input 28 the selection of x-ray radiation from the entire surface of the corresponding one source 12 of x-ray radiation having the configuration of the focal spot 11, in the direction of the output window 6 and the formation at the output 29 of each of the ли collimator 27 x-ray radiation in the form of a pyramidal stream 30, covering the region of the highest energy density in the beam, conjugated in the middle part with the upper (6a) and lower (6c) sides of the rectangle of the output window (6) and having a rectangular base (30a) covering the region ( 13) the object to be scanned.

mated in the middle part with the upper 6a and lower 6c sides of the rectangle of the output window 6 and having a rectangular base 30a (Figure 1), covering the area 13 of the object to be scanned. Thus, the x-ray radiation of the source 12 is a pyramidal x-ray in which the region of the high energy density of the beam is limited in height and width by the planes of the pyramid conjugated with the upper 6a and lower 6c sides of the rectangle of the output window 6, which allows for a high energy density in the beam and, accordingly, high image clarity when scanning an object, and the rectangular base of the pyramid has predetermined dimensions and covers the scanned object, ensuring the safety of the use of a multipath x-ray tube 1 according to the invention.

When using the multi-beam multi-cathode tube 1 according to the invention for tomographic study of the internal structure of an object by scanning, sequential multiple exposing of this object by x-rays 30 in intersecting directions, caused by the direction of sequential output of x-ray radiation from the surface N of x-ray sources 12 having a narrow shape oriented length in the direction of the output window 6, at one point P of the scanning area 13 (Figure 1.2).

In this case, the electron sources 10 are switched on in turn by successively supplying negative potentials U _K to the cathode 18 corresponding to this source 10.

Then, computer processing of the obtained N x-ray images is performed in order to create a 3-dimensional image of the scanning object.

When comparing the experimental data on the creation of tomographic images obtained using the multi-beam X-ray tube 1 according to the invention, and images obtained previously in mutually intersecting directions using single-beam tubes moving around the object of scanning, the following was established:

1) Existing methods of computer image processing allow you to get both 3D and cross-sectional image of the scan object using a moving x-ray source. In this case, when the X-ray source moves during the image around the scanning object, the size L of the X-ray source increases to the size LQ: LB = VX T, where V is the linear velocity of the x-ray source, T is the exposure time of the object, which, accordingly, leads to a decrease sharpness of the image. 2) To increase the clarity of the image when using a single-beam tube, it is necessary to reduce either the speed of the x-ray source or the exposure time. Reducing the first increases the time it takes to take a tomogram; decreasing the second affects the image clarity negatively.

3) In the multi-beam x-ray tube 1 according to the invention, the x-ray sources 12 are stationary, their size L projected onto the output window 6 is determined only by the linear dimensions of the focal spot 11. Therefore, the exposure time and, accordingly, the image clarity can be increased many times over compared to traditional single-beam x-ray a tube moving around the scan object.

The multi-beam X-ray tube 1 according to the invention allows to create a computer tomograph for mammography examination, which has important advantages:

1) when constructing 3D images, all N sources of X-ray radiation are used in a given sequence, each of which ensures the creation of a corresponding X-ray image of the object in one of the intersecting directions, which allows you to get a number of consecutive images of the scan object and, after processing these images using computer, get a 3D image or a mid-section image of this object;

2) under the same current and the electron source cathode size L x-ray use narrow focal spot shape close to a rectangle that extends towards the withdrawal box, and variation magnitudes and _angles? allows you to increase the length of the target

X-ray source and, accordingly, increase the surface area that receives the heat of the electron flow, reduce the heat load on the rotating anode while ensuring constant image clarity of the X-ray image and increase the durability of the X-ray tube;

3) the X-ray output window, made in common, together with the collimators, allows you to limit the x-ray irradiation zone to the region in which the scan object is located, and at the same time use only one soldered assembly - one output window, which greatly simplifies the design of the tube.

Specialists in the field of radiography should be clear that in the multipath x-ray tube according to the invention can be introduced various modifications and improvements, not beyond the scope of the claims.

Industrial applicability

The multi-beam x-ray tube according to the invention can be manufactured using known materials, equipment and technologies, and can be widely used to obtain a tomographic image of various objects, including for medical purposes for mammography, to obtain a series of images of an object from different angles for computed tomography and tomosynthesis.

Claims

Claim

1. A multi-beam x-ray tube for scanning a stationary object in intersecting directions with its static position, comprising:

- window output x-ray radiation,

characterized in that:

- the anode (3) has the shape of a disk facing a flat surface (7) to the indicated system (5) of electron sources, and is isolated from the housing (2) by a high-voltage insulator;

- the target (4) is located on the indicated flat surface of the anode (3) and has the shape of a flat ring centered on the axis (3) of rotation of the anode (3);

- the X-ray output window (6) is common for the X-ray output (30) of all N X-ray sources (12), is located in the side wall of the housing (2) above the level of the target plane (4) and is made flat in the shape of a rectangle perpendicular to the plane target (4) and having a rectangle upper side (6a) at an angle level of no more than 35 ° to the target plane (4) and a rectangle having a top side (6a) at a corner level of at least 10 ° to the target plane (4);

- the system (5) of electron sources is adapted to generate and project N discrete streams of electrons having a cross-sectional configuration on the target in a periodic pulsed mode, which ensures the formation of N focal spots (11) on the target surface (4), respectively, having a focal spot (11) the highest electron energy density in the direction perpendicular to the direction of output of x-ray radiation (30), 23

generated by the x-ray source (12) generated in said focal spot (1 1) through the output window (6);

- additionally contains N fixed collimators (27) having the potential of the anode (3) placed by the input each near the corresponding source (12) of X-ray radiation having the configuration of the focal spot (11) indicated above the target surface (4) in the region between each one an X-ray source (12) and an output window (6), and each collimator (27) selects radiation from the surface of the corresponding one X-ray source (12) in the direction of the output window (6) and generates the specified X-ray Yenov radiation (30) in the form of a pyramidal beam, covering the region of the highest energy density in the beam, conjugated in the middle part with the upper (6a) and lower (6c) sides of the rectangle of the output window (6) and having a rectangular base (30a) covering the region (13) the object to be scanned.

2. The tube according to claim 1, characterized in that the system (5) of electron sources is made in the form of an electron-optical system that provides, in a periodic pulsed mode, the discrete streams (23) of electrons that provide formation on the surface (4a) to the target (4); ) targets (4) of focal spots (11), having the shape of narrow figures, extended towards the output window (6) and oriented along the length in the direction of the same common point for them outside the output window (6).

3. The tube according to claim 2, characterized in that the system (5) of electron sources is made in the form of an electron-optical system that provides, in a periodic pulsed mode, a discrete stream (23) of electrons, which form on the surface of the target, is supplied to the target (4) ( 4) focal spots (11) having the shape of ovals close to a rectangle, with the ratio of the lengths of the major axis (14) of the oval and the minor axis (15) of the oval not less than 5: 1, with large axes (14) converging outside the window (6) output in the area of the object (13) to be scanned, with the location of the centers (C) these ovals N focal spots (11) on the target (4) on one straight line (16), spaced from the axis of rotation of the anode (3) in the direction of the output window (6).

4. A tube according to claim 3, characterized in that the said centers (C) of the ovals N of the focal spots (11) are located on the target (4) on one straight line (16a), which is a segment of the chord parallel to the plane of the output window (6) .

5. A tube according to claim 3, characterized in that the said centers (C) of the ovals N of the focal spots (11) are located on the target (4) in one straight line (16c), which is a piece of the chord located at an angle of 1-2 ° to the plane of the window (6) output.

6. The tube according to claim 3, characterized in that it contains a system (5) of electron sources, made in the form of an electron-optical system, in which:

- these pulsed N sources (10) of electrons are placed in the body (2) of the tube (1) in one straight line at the same distance from each other above the surface of the target part (4) closest to the specified output window (6), and are adapted to generate and outputting in the direction of the plane (4a) of the target (4) sequentially in a periodic pulsed mode of each one of the N electron flows (17) having a circular cross-section;

- between the terminals of the indicated N sources (10) of electrons and the target there is a grounded control electrode (22) adapted to convert each of these N flows (17) of electrons having a circular cross-section into one of N configured flows (23_ electrons, providing, when projected onto the target (4), the formation on the target (4), respectively, of one of the N focal spots (11), having the shape of an oval close to a rectangle, with the ratio of the lengths of the major axis (14) of the oval and the minor axis (15) of the oval no less than 5: 1, with a direction of pain of their axes (14) converging at one point common to them outside the exit window (6), with the location of the centers (C) of the indicated ovals N focal spots (11) on the target (4) on a segment of its chord that is separated from the axis of rotation (3a) anode (3) in the direction of the output window (6).

7. The tube according to claim 6, characterized in that said control electrode (22) is placed parallel to the plane (4a) of the target (4) and is equipped with N cascades (24) of through holes located near the indicated outputs of N sources (1-) of electrons and having circular inlet openings (25) in the cascade (24) for inputting one of said N electron flows (17) and oval shaped outlets (26) having large axes (26a) oriented towards the output window (6) and converging outside the output window (6) at a point common to them, for outputting each one of the indicated ^ configured electron flows (23).

8. The tube according to claim 4, characterized in that the said N sources (10) of electrons are made in the form of N cathode nodes containing, respectively:

- N cathodes (18) electrically isolated from the body (2) of the tube (1);

- N heaters (19) of cathodes (18), electrically isolated from these cathodes (18) and electrically connected in parallel to each other;

- N focusing electrodes (20), electrically connected to these cathodes (18) and having round-shaped exit holes (21),

and while these N cathodes (18) are configured to control the cross-sectional area of each of these N electron streams (17) by changing the potential of the corresponding cathode (18).