X-ray tube, method for adjusting an x-ray focus and ct device

Abstract

This application relates to an X-ray tube, an X-ray focus adjustment method, and a CT device. The X-ray tube includes a flat cathode, a focusing electrode, a vacuum-sealed housing, and a beam-tuning assembly. The flat cathode emits a direct current (DC) electron beam. The focusing electrode is disposed around the outer periphery of the flat cathode and angled to the plane of the flat cathode, and is used to focus the DC electron beam. The vacuum-sealed housing has a beam channel disposed on the side of the flat cathode in the beam-emission direction. The inlet of the beam channel is spaced apart from the flat cathode, and the beam channel allows the DC electron beam to pass through. The beam-tuning assembly includes a solenoid disposed around the outer periphery of the beam channel, and the solenoid is used to focus the DC electron beam passing through the beam channel. After the flat cathode emits the electron beam, the focusing electrode performs a first focusing of the electron beam. The solenoid performs a second focusing. Because the electron beam undergoes two focusing processes, the focusing force during the first focusing process can be relatively small, resulting in better uniformity of the electron beam during transmission.

Description

Technical Field

[0001] This application relates to the field of X-ray technology, and in particular to X-ray tubes, X-ray focus adjustment methods and CT equipment. Background Technology

[0002] X-ray technology is widely used in daily life, such as in industrial non-destructive testing, security inspection, and medical diagnosis and treatment. However, existing X-ray tubes suffer from poor electron beam uniformity after the electron beam is emitted from the cathode, which affects the treatment effect. Summary of the Invention

[0003] Therefore, it is necessary to provide a new type of X-ray tube to address the problem that the electron beam emitted by existing X-ray tubes has poor uniformity, which affects the treatment effect.

[0004] An X-ray tube, characterized in that the X-ray tube comprises:

[0005] A flat cathode, which is used to emit a direct current electron beam;

[0006] A focusing electrode is disposed around the outer periphery of the plate cathode and at an angle to the plane of the plate cathode. The focusing electrode is used to focus the DC electron beam.

[0007] A vacuum-sealed housing is provided, wherein a beam channel is configured to pass through the beam channel on one side of the flat plate cathode in the beam exit direction. The inlet of the beam channel is spaced apart from the flat plate cathode along the beam exit direction of the flat plate cathode. The beam channel is used to pass through the DC electron beam focused by the focusing electrode.

[0008] A beam-tuning assembly, comprising a solenoid disposed on the outer periphery of the beam channel, the solenoid being used to focus the DC electron beam passing through the beam channel.

[0009] In one embodiment, the focusing electrode is disposed around the periphery of the flat plate cathode; and the focusing electrode has a focusing surface, the angle θ between the focusing surface and the central axis of the flat plate cathode satisfying the condition:

[0010] 60°≤θ≤80°.

[0011] In one embodiment, the plate cathode is a circular plate cathode, the focusing electrode is annular, and the focusing electrode is arranged around the outer periphery of the circular plate cathode, with the inner circumference of the focusing electrode matching the circumference of the circular plate cathode.

[0012] In one embodiment, the potential of the focusing electrode is less than or equal to the potential of the plate cathode.

[0013] In one embodiment, the focusing electrode and the flat cathode have the same axis, and the focusing electrode is symmetrically arranged along the axis.

[0014] In one embodiment, the beam tuning assembly further includes a quadruple magnet disposed on the outer periphery of the beam channel, the quadruple magnet being spaced apart from the solenoid and disposed on the side of the solenoid away from the flat cathode;

[0015] When the DC electron beam passes through the beam channel, the quadrupole magnet can adjust the size of the focal spot of the DC electron beam on the anode.

[0016] In one embodiment, the beam tuning assembly further includes a guide magnet disposed on the outer periphery of the beam channel, the guide magnet being spaced apart from the solenoid and disposed on the side of the solenoid away from the flat cathode;

[0017] When the DC electron beam passes through the beam channel, the guide magnet can adjust the position of the focal spot of the DC electron beam on the anode.

[0018] In one embodiment, the assembly further includes a beam tuning component frame for fixing the beam tuning component. The guide magnet and the quadrupole magnet are disposed on the same beam tuning component frame, and the guide magnet is disposed on the side of the beam tuning component frame near the exit direction of the beam channel.

[0019] In one embodiment, the vacuum-sealed housing is further configured with a first vacuum-containing cavity, which is connected to the inlet of the beam channel, and the cathode and the focusing electrode are housed within the first vacuum-containing cavity.

[0020] In one embodiment, the X-ray tube further includes an anode, which is disposed on the side of the beam tuning assembly away from the flat cathode along the beam exit direction of the flat cathode, and the anode is spaced apart from the beam tuning assembly;

[0021] The vacuum-sealed housing has a second vacuum-containing cavity, in which the anode is housed. The second cavity is connected to the outlet of the beam channel. The anode is used to generate an X-ray beam when bombarded by the DC electron beam.

[0022] This application also provides an X-ray focus adjustment method, which can solve at least one of the above-mentioned technical problems. The X-ray focus adjustment method provided by this application includes:

[0023] A current is applied to the plate cathode to cause the plate cathode to emit a DC electron beam;

[0024] The voltage applied to the focusing electrode is adjusted so that the DC electron beam enters the inlet of the beam channel after being focused by the focusing electrode; wherein, the focusing electrode is disposed around the outer periphery of the plate cathode, and the focusing surface of the focusing electrode is set at an angle to the plane of the plate cathode; the beam channel is disposed on one side of the beam exit direction of the plate cathode, and the inlet of the beam channel is spaced apart from the plate cathode along the beam exit direction of the plate cathode, and the beam channel is used to pass the DC electron beam focused by the focusing electrode;

[0025] The current applied to the solenoid in the beam focusing assembly is adjusted so that the solenoid focuses the DC electron beam passing through the beam channel; wherein the solenoid is disposed on the outer periphery of the beam channel.

[0026] In one embodiment, the X-ray focus adjustment method further includes:

[0027] The voltage applied to the focusing electrode is adjusted according to the voltage of the plate cathode so that the potential of the focusing electrode is less than or equal to the potential of the plate cathode.

[0028] In one embodiment, the X-ray focus adjustment method further includes:

[0029] The current applied to the quadruple magnet in the beam tuning assembly is adjusted so that the quadruple magnet adjusts the size of the focal spot on the anode of the DC electron beam passing through the beam channel;

[0030] The quadruple magnet is disposed on the outer periphery of the beam channel, and is spaced apart from the solenoid, and is disposed on the side of the solenoid away from the flat cathode.

[0031] In one embodiment, the X-ray focus adjustment method further includes:

[0032] The current applied to the guide magnet in the beam tuning assembly is adjusted so that the guide magnet adjusts the position of the focal spot on the anode of the DC electron beam passing through the beam channel;

[0033] The guide magnet is disposed on the outer periphery of the beam channel, and is spaced apart from the solenoid, and is disposed on the side of the solenoid away from the flat cathode.

[0034] This application also provides a CT device that can solve at least one of the above-mentioned technical problems.

[0035] The CT device provided in this application includes the X-ray tube described in any of the embodiments.

[0036] In the aforementioned X-ray tube, X-ray focus adjustment method, and CT equipment, after the flat cathode emits a DC electron beam, a focusing electrode located on the outer periphery of the flat cathode first focuses the DC electron beam. As the DC electron beam passes through the beam channel during transmission, a solenoid performs a secondary focusing. The focusing force during the primary focusing process through the focusing electrode can be selected to be relatively small, resulting in better uniformity of the DC electron beam during transmission to the beam-tuning assembly. Furthermore, since the DC electron beam undergoes secondary focusing through the solenoid after the primary focusing by the focusing electrode, no additional nonlinear forces are introduced, thus resulting in a better final focusing effect. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of an X-ray tube provided in an embodiment of this application.

[0038] Figure 2 To pass Figure 1 The diagram shows the first experimental result of the simulation experiment using the X-ray tube shown.

[0039] Figure 3 To pass Figure 1 The diagram shows the second experimental result of the simulation experiment using the X-ray tube shown.

[0040] Figure 4 To pass Figure 1 The diagram shows the third experimental result of the simulation experiment using an X-ray tube.

[0041] Reference numerals: 100-Plate cathode; 110-DC electron beam; 200-Focusing electrode; 300-Beam tuning assembly; 310-Solenoid; 320-Quadrupole magnet; 330-Guiding magnet; 340-Beam tuning assembly frame; 400-Vacuum sealed housing; 410-Beam channel; 420-First receiving cavity; 430-Second receiving cavity; 500-Anode; 510-Target disk edge; 600-X-ray beam. Detailed Implementation

[0042] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0043] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0044] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0045] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0046] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0047] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0048] See Figure 1 , Figure 1 A schematic diagram of an X-ray tube provided in an embodiment of this application is shown. The X-ray tube provided in an embodiment of this application includes a flat cathode 100, a focusing electrode 200, a vacuum-sealed housing 400, and a beam modulation assembly 300. A flat cathode 100 is used to emit a DC electron beam 110; a focusing electrode 200 is disposed around the outer periphery of the flat cathode 100 and at an angle to the plane of the flat cathode 100, and the focusing electrode 200 is used to focus the DC electron beam 110; a vacuum-sealed housing 400 is constructed with a beam channel 410, which is disposed on one side of the beam exit direction of the flat cathode 100, and the inlet of the beam channel 410 is spaced apart from the flat cathode 100 along the beam exit direction of the flat cathode 100, and the beam channel 410 is used to pass the DC electron beam 110 focused by the focusing electrode 200; a beam tuning assembly 300 includes a solenoid 310, which is disposed around the outer periphery of the beam channel 410, and the solenoid 310 is used to focus the DC electron beam 110 passing through the beam channel 410.

[0049] In the aforementioned X-ray tube, after the flat cathode 100 emits a DC electron beam 110, the focusing electrode 200 disposed on the outer periphery of the flat cathode 100 focuses the DC electron beam 110 once. Specifically, the DC electron beam 110 is an electron beam continuously emitted over a period of time. When the DC electron beam 110 passes through the beam channel 410 during transmission, the solenoid 310 performs a secondary focusing of the DC electron beam 110. The focusing force of the DC electron beam 110 during the primary focusing process through the focusing electrode 200 can be selected to be a relatively small value, thereby ensuring good uniformity of the DC electron beam 110 during transmission to the beam tuning assembly 300. Furthermore, since the DC electron beam 110 undergoes secondary focusing through the solenoid 310 after the primary focusing by the focusing electrode 200, no additional nonlinear forces are introduced, resulting in a better final focusing effect for the DC electron beam 110.

[0050] In this application, by setting the entrance of the beam channel 410 and the flat cathode 100 at intervals along the beam exit direction of the flat cathode 100, the DC electron beam 110 emitted by the flat cathode 100 is accelerated to a set energy and the electric field is lower than the breakdown threshold of the X-ray tube.

[0051] It should be noted that when focusing the DC electron beam 110 through the solenoid 310, the focusing principle of the solenoid 310 is to first rotate the electrons and then focus them, which is a second-order force. The control effect is weak, but the effect is to focus the electrons in all directions. Compared to the control of a quadrupole magnet or an electrically focused focusing device, because the solenoid 310 uses a second-order force for focusing, to achieve the same focusing intensity as a quadrupole magnet, the applied current must be an order of magnitude higher. Its focusing effect depends to some extent on the electron energy, the beam channel, and the current applied to the solenoid 310. In this application, it is through the synergistic action of the focusing electrode 200 and the solenoid 310 that the DC electron beam 110 exhibits better uniformity during transmission to the beam tuning assembly 300, and no additional nonlinear forces are introduced. Therefore, the final focusing effect of the DC electron beam 110 is also better.

[0052] It should be noted that the combination of the focusing electrode 200 and the solenoid 310 does not change the current flowing through the solenoid 310 or the length of the beam channel 410, nor does it alter the electron energy. Instead, through the adapted combination of the focusing electrode 200 and the solenoid 310, the focusing electrode 200 can perform some micro-focusing first, and then the solenoid 310 focuses the signal, achieving a better overall effect.

[0053] It should be noted that in some embodiments, the flat cathode 100 may include multiple independent cathode emitting portions, and the multiple independent cathode emitting portions may have a certain angle with the central axis of the flat cathode 100. In other embodiments, the flat cathode 100 is a single integral cathode plate.

[0054] The shape of the flat plate cathode 100 can be circular, elliptical, rectangular, or any other regular or irregular shape, without any special limitation. When the flat plate cathode 100 is elliptical, the ratio of the major axis to the minor axis of the elliptical cathode can also be used to adjust the width to length ratio of the beam spot of the DC electron beam 110.

[0055] The following is a detailed description of the structure of an X-ray tube.

[0056] Please see Figure 1In one embodiment of this application, the focusing electrode 200 of the X-ray tube is disposed around the flat cathode 100; and the focusing electrode 200 has a focusing surface, the angle θ between the focusing surface and the central axis of the flat cathode 100 satisfies the condition: 60°≤θ≤80°. By setting the angle θ between the focusing surface of the focusing electrode 200 and the central axis p of the flat cathode 100 to be greater than or equal to 60° and less than or equal to 80°, the focusing electrode 200 is formed into a Pierce-like structure, thereby resulting in better laminar flow and better uniformity of the DC electron beam 110.

[0057] In one specific embodiment, the angle θ between the focusing surface and the central axis of the flat cathode 100 is 60°.

[0058] In another specific embodiment, the angle θ between the focusing surface and the central axis of the flat cathode 100 is 80°.

[0059] In another specific embodiment, the angle θ between the focusing surface and the central axis of the flat cathode 100 is 70°.

[0060] In some embodiments, the angle θ between the focusing surface and the central axis of the flat cathode 100 satisfies the condition: 65°≤θ≤75°. By setting the angle θ between the focusing surface of the focusing electrode 200 and the central axis p of the flat cathode 100 to a range greater than or equal to 65° and less than or equal to 75°, the focusing electrode 200 is more easily formed into a Pierce-like structure, thereby resulting in better laminar flow and uniformity of the DC electron beam 110.

[0061] In one specific embodiment, the angle θ between the focusing surface and the central axis of the flat cathode 100 is 65°.

[0062] In another specific embodiment, the angle θ between the focusing surface and the central axis of the flat cathode 100 is 75°.

[0063] In another specific embodiment, the angle θ between the focusing surface and the central axis of the flat cathode 100 is 68°.

[0064] In one embodiment, the flat plate cathode 100 is circular, and the focusing electrode 200 is annular, arranged around the outer periphery of the circular flat plate cathode 100. The circumference of the inner ring of the focusing electrode 200 matches the circumference of the circular flat plate cathode 100. By setting the shapes of the flat plate cathode 100 and the focusing electrode 200 to be matched circular and annular respectively, and matching the circumference of the inner ring of the focusing electrode 200 with the circumference of the circular flat plate cathode 100, the gap between the focusing electrode 200 and the flat plate cathode 100 is smaller. This allows the DC electron beam 110 emitted by the flat plate cathode 100 to be better focused by the focusing electrode 200, resulting in better laminar flow and uniformity of the DC electron beam 110.

[0065] In one embodiment, the potential of the focusing electrode 200 is less than or equal to the potential of the plate cathode 100. By setting the potential of the focusing electrode 200 to be less than or equal to the potential of the plate cathode 100, the potential of the plate cathode 100 is made larger, making it less likely for the DC electron beam 110 to hit the focusing electrode 200 when it emits it. In one specific embodiment, the potential of the focusing electrode 200 is -61 kV, and the potential of the plate cathode 100 is -60 kV. In another specific embodiment, the potential of the focusing electrode 200 is -60 kV, and the potential of the plate cathode 100 is -60 kV.

[0066] It should be noted that, because the focusing electrode 200 can micro-focus the DC electron beam 110 emitted from the flat cathode 100, if the potential difference between the focusing electrode 200 and the flat cathode 100 is too high, it may damage other electrodes on the X-ray tube, such as the grid used to adjust the size of the emitted DC electron beam 110, leading to grid failure. Therefore, the potential of the focusing electrode 200 should not be too large, and the potential difference between the focusing electrode 200 and the flat cathode 100 should not exceed 3 kV.

[0067] In one embodiment, the focusing electrode 200 and the flat cathode 100 have the same axis, and the focusing electrode 200 is symmetrically arranged along the axis. This arrangement improves the focusing effect of the focusing electrode 200 on the DC electron beam 110. It should be noted that when the flat cathode 100 is composed of multiple independent cathode emitting sections, these multiple independent cathode emitting sections should be considered as a single integrated structure, and the axis of this integrated structure is the axis of the flat cathode 100.

[0068] Please see Figure 1The X-ray tube beam tuning assembly 300 provided in one embodiment of this application further includes a quadrupole magnet 320. The quadrupole magnet 320 is disposed on the outer periphery of the beam channel 410, spaced apart from the solenoid 310, and disposed on the side of the solenoid 310 opposite to the flat cathode 100. When the DC electron beam 110 passes through the beam channel 410, the quadrupole magnet 320 can adjust the size of the focal spot of the DC electron beam 110 on the anode 500. By setting the quadrupole magnet 320, the size of the focal spot of the DC electron beam 110 on the anode 500 can be adjusted, thereby enabling the focal spot of the DC electron beam 110 to adapt to different size requirements, making the entire X-ray tube more adaptable.

[0069] It should be noted that in existing technologies, when the X-ray tube only has a solenoid 310, in order to enhance the electron focusing power of the solenoid 310, it is usually necessary to emit mega-energy electrons, increase the length of the beam channel, or apply a large current to the solenoid 310. Therefore, the emission energy requirement is high, the overall tube length is significantly increased, and the device is prone to damage due to long-term high current, resulting in a short lifespan. However, when the X-ray tube only has a quadrupole magnet 320, the quadrupole magnet directly applies a force to the DC electron beam 110, which is a first-order force with a strong control effect. Its effect is to focus the DC electron beam 110 in one direction and diverge it in another perpendicular direction. Therefore, two quadrupole magnets 320 are generally required. The forces applied by the two quadrupole magnets 320 to the DC electron beam 110 are completely opposite, so that most of the forces generated by the two quadrupole magnets 320 cancel each other out, and the effective force applied to the DC electron beam 110 is reduced, thus resulting in better electron beam uniformity.

[0070] It should also be noted that since the first quadrupole magnet 320 causes the DC electron beam 110 to diverge in one direction, making the spot size of the DC electron beam 110 in that direction larger, it will increase the risk of electrons hitting the tube wall and reduce the life of the X-ray tube. Therefore, the X-ray tube of this application uses a solenoid 310 plus a quadrupole magnet 320 to reduce the possibility of electrons hitting the tube wall and improve the life of the X-ray tube.

[0071] In the X-ray tube of this application, due to the combination of the solenoid 310 and the quadrupole magnet 320, there is no force counteracting similar to that of two quadrupole magnets 320. Although the force of the solenoid 310 is an order of magnitude smaller than that of the quadrupole magnet 320, the effective force applied to the DC electron beam 110 is not much smaller. Thus, most of the electrical focusing effect of this X-ray tube is transferred to the magnetic focusing of the solenoid 310, thereby keeping the laminar flow of the DC electron beam 110 basically unchanged and ensuring good electron uniformity. This allows the electron distribution to remain uniform even with increased focusing intensity. In the X-ray tube provided by this application, the electron beam weakly focused by the flat cathode 100 passes through the tube, and the solenoid 310 further compresses the size of the electrons in all directions, effectively reducing the risk of the DC electron beam 110 bombarding the tube wall and improving the life of the X-ray tube.

[0072] In one specific embodiment, the flat cathode 100 is a circular cathode. By combining the circular cathode, the solenoid 310, and the quadrupole magnet 320, another technical means is provided for achieving a more uniform beam distribution and controllable focal spot size in the X-ray tube.

[0073] Please see Figure 1 The X-ray tube beam tuning assembly 300 provided in one embodiment of this application further includes a guide magnet 330. The guide magnet 330 is disposed on the outer periphery of the beam channel 410, spaced apart from the solenoid 310, and disposed on the side of the solenoid 310 opposite to the flat cathode 100. When the DC electron beam 110 passes through the beam channel 410, the guide magnet 330 can adjust the focal spot position of the DC electron beam 110 on the anode 500. By setting the guide magnet 330, the guide magnet 330 can adjust the focal spot position of the DC electron beam 110 on the anode 500, thereby enabling the focal spot position of the DC electron beam 110 to adapt to different positional requirements, making the entire X-ray tube more adaptable.

[0074] The X-ray tube of this application has strong inclusiveness because it can integrate the focusing of the adjustable voltage focusing electrode 200 and the multiple cathode emitting sections constituting the flat cathode 100, thereby achieving a more powerful focus tuning function. Compared with the X-ray tube of this application which focuses the beam spot through the adjustable voltage focusing electrode 200, the focusing of electrons by the solenoid 310 does not change the laminar flow of the electron beam, and a more uniform beam spot distribution can be obtained. At the same time, this invention can also retain the electron fly-focusing function through the guide magnet 330.

[0075] Please see Figure 1The X-ray tube provided in one embodiment of this application also includes a beam modulation assembly frame, which is used to fix the beam modulation assembly 300. The guide magnet 330 and the quadrupole magnet are disposed on the same beam modulation assembly frame, and the guide magnet 330 is disposed on the side of the beam modulation assembly frame closer to the exit direction of the beam channel 410. By setting the beam modulation assembly frame, the guide magnet 330 and the quadrupole magnet 320 are disposed on the same frame structure, which simplifies the assembly of the entire X-ray tube. At the same time, by placing the guide magnet 330 closer to the exit direction of the beam channel 410, the DC electron beam 110, after being adjusted by the solenoid 310 for secondary focusing and the quadrupole magnet 320 for focal spot size adjustment, is further adjusted by the guide magnet 330 for focal spot position on the anode 500. This results in higher accuracy in the position and focal spot size of the DC electron beam 110 on the anode 500, leading to better treatment effect.

[0076] Please see Figure 1 In one embodiment of this application, the vacuum-sealed housing 400 of the X-ray tube further comprises a first vacuum-containing cavity 420, which is connected to the inlet of the beam channel 410. The cathode and focusing electrode 200 are housed within the first cavity 420. By housing the cathode and focusing electrode 200 within the first cavity 420, the DC electron beam 110 emitted by the flat cathode 100 is transmitted in a vacuum environment and ultimately strikes the anode 500. The entire transmission process is carried out in a high-vacuum environment, which can generate relatively stable X-rays.

[0077] Please see Figure 1 An embodiment of this application provides an X-ray tube that also includes an anode 500. The anode 500 is disposed on the side of the beam-tuning assembly 300 away from the flat cathode 100 along the beam-out direction of the flat cathode 100, and the anode 500 and the beam-tuning assembly 300 are spaced apart. The vacuum-sealed housing 400 is constructed with a second vacuum-containing cavity 430, in which the anode 500 is housed. The second cavity 430 is connected to the outlet of the beam channel 410. The anode 500 is used to generate an X-ray beam 600 when bombarded by a DC electron beam 110. When the flat cathode 100 emits a DC electron beam 110, the DC electron beam 110 passes through the first cavity 420, the beam channel 410, and the second cavity 430 before striking the anode 500. The DC electron beam 110 is always in a high vacuum environment throughout the transmission process, which can generate relatively stable X-rays. Ultimately, the anode 500 generates an X-ray beam 600 when bombarded by the DC electron beam 110, thereby performing irradiation treatment on a predetermined part of the patient.

[0078] Please see Figure 1In one embodiment of this application, the anode 500 of the X-ray tube further includes a target disk edge 510, which has a certain tilt angle for linear focusing of the DC electron beam 110. After the DC electron beam 110 bombards the target disk edge 510, it generates X-rays for medical imaging.

[0079] This application also provides an X-ray focus adjustment method, which includes: applying a current to a flat plate cathode 100 to cause the flat plate cathode 100 to emit a DC electron beam 110; adjusting the voltage applied to a focusing electrode 200 so that the DC electron beam 110 enters the entrance of a beam channel 410 after being focused by the focusing electrode 200; wherein the focusing electrode 200 is disposed around the outer periphery of the flat plate cathode 100, and the focusing surface of the focusing electrode 200 is angled to the plane of the flat plate cathode 100; the beam channel 410 is disposed on one side of the beam exit direction of the flat plate cathode 100, and the entrance of the beam channel 410 and the flat plate cathode 100 are spaced apart along the beam exit direction of the flat plate cathode 100, and the beam channel 410 is used to pass the DC electron beam 110 focused by the focusing electrode 200; adjusting the current applied to a solenoid 310 in a beam adjustment assembly 300 so that the solenoid 310 focuses the DC electron beam 110 passing through the beam channel 410; wherein the solenoid 310 is disposed around the outer periphery of the beam channel 410.

[0080] This X-ray focus adjustment method applies a voltage to the focusing electrode 200, enabling the DC electron beam 110 to be focused initially under the action of the focusing electrode 200. When the DC electron beam 110 passes through the beam channel 410 during transmission, the solenoid 310 performs secondary focusing on the DC electron beam 110. Since focusing the DC electron beam 110 is achieved through two focusing operations, the focusing force during the initial focusing process through the focusing electrode 200 can be selected to be smaller. This results in better uniformity of the DC electron beam 110 during transmission to the beam-tuning assembly 300, and the DC electron beam 110 is less likely to hit the outer wall of the X-ray tube during transmission, thus reducing the risk of damage to the X-ray tube wall and extending the service life of the X-ray tube and the entire X-ray tube. Furthermore, because the DC electron beam 110 undergoes secondary focusing through the solenoid 310 after the initial focusing by the focusing electrode 200, the final focusing effect of the DC electron beam 110 is also better.

[0081] In one embodiment, the X-ray focus adjustment method further includes: adjusting the voltage applied to the focusing electrode 200 according to the voltage of the plate cathode 100, so that the potential of the focusing electrode 200 is less than or equal to the potential of the plate cathode 100. By setting the potential of the focusing electrode 200 to be less than or equal to the potential of the plate cathode 100, the potential of the plate cathode 100 is made larger, and when the plate cathode 100 emits a DC electron beam 110, the DC electron beam 110 is less likely to hit the focusing electrode 200. In one specific embodiment, the potential of the focusing electrode 200 is -61 kV, and the potential of the plate cathode 100 is -60 kV. In another specific embodiment, the potential of the focusing electrode 200 is -60 kV, and the potential of the plate cathode 100 is -60 kV.

[0082] In one embodiment, the X-ray focus adjustment method further includes: adjusting the current applied to the quadrupole magnet 320 in the beam modulation assembly 300, so that the quadrupole magnet 320 adjusts the focal spot size of the DC electron beam 110 passing through the beam channel 410 on the anode 500; wherein, the quadrupole magnet 320 is disposed on the outer periphery of the beam channel 410, the quadrupole magnet 320 is spaced apart from the solenoid 310, and is disposed on the side of the solenoid 310 opposite to the flat cathode 100. By setting the quadrupole magnet 320, the quadrupole magnet 320 adjusts the focal spot size of the DC electron beam 110 on the anode 500, thereby enabling the focal spot of the DC electron beam 110 to adapt to different size requirements, and making the entire X-ray tube more adaptable.

[0083] In one embodiment, the X-ray focus adjustment method further includes: adjusting the current applied to the guide magnet 330 in the beam modulation assembly 300, so that the guide magnet 330 adjusts the focal spot position of the DC electron beam 110 passing through the beam channel 410 on the anode 500; wherein, the guide magnet 330 is disposed on the outer periphery of the beam channel 410, the guide magnet 330 is spaced apart from the solenoid 310, and is disposed on the side of the solenoid 310 opposite to the flat cathode 100. By setting the guide magnet 330, the guide magnet 330 adjusts the focal spot position of the DC electron beam 110 on the anode 500, thereby enabling the focal spot position of the DC electron beam 110 to adapt to different positional requirements, and making the entire X-ray tube more adaptable.

[0084] Please see Figure 2 , Figure 2 It shows the way Figure 1 The diagram shows the first experimental result of the simulation experiment using the X-ray tube shown. Figure 2Line e represents the change in beam size of the DC electron beam 110 with electron position when the tube voltage is 140 kV, or the potential of the plate cathode 100 is -140 kV. Line f represents the change in beam size of the DC electron beam 110 with electron position when the tube voltage is 60 kV, or the potential of the plate cathode 100 is -60 kV. Since the potential of the focusing electrode 200 is the same as that of the plate cathode 100, and the focusing electrode 200 provides weak focusing for the DC electron beam 110, the difference in electron focusing effect under different tube voltages is not significant. Figure 2 Figures (a)-(d) take the change in beam spot size of DC electron beam 110 with electron position as an example when the tube voltage is 140kV, that is, the potential of plate cathode 100 is -140kV. Figure 2 In the diagram, (a) shows the beam distribution on the emitting surface of the planar electrode, which is a uniform circle. Figure 2 In (b), the beam spot at the position of solenoid 310 is smaller after being focused by the Pierce-like electrode formed by focusing electrode 200, but the distribution is still relatively uniform. Figure 2 (c) in the figure represents the beam spot distribution at 320° of the quadrupole magnet. Figure 2 In the diagram, (d) represents the beam spot distribution at the target disk of the 500 anode. (Through...) Figure 2 As can be seen from the changes in (a)-(d) in the figure, the X-ray tube provided in this application enables the DC electron beam 110 to be transmitted with a micro-focusing effect in the section from solenoid 310 to anode 500.

[0085] Please see Figure 3 and Figure 4 , Figure 3 It shows the way Figure 1 The diagram shows the second experimental result of the simulation experiment using the X-ray tube shown. Figure 4 It shows the way Figure 1 The diagram shows the third experimental result of the simulation experiment using an X-ray tube.

[0086] After initial weak focusing by focusing electrode 200, the DC electron beam 110 is refocused using solenoid 310. The focusing intensity of solenoid 310 can be adjusted by applying different currents. The magnetic field provided by quadrupole magnet 320 compresses the beam spot size in the width direction of the DC electron beam 110 and stretches the beam spot in the length direction. Guide magnet 330 then achieves different distances of fly-focusing in the width and length directions as required. Applying a relatively strong current to solenoid 310 allows the DC electron beam 110 to be focused smaller. Simultaneously, applying a relatively small current to quadrupole magnet 320 keeps the beam spot small in the width direction without increasing its length direction, ultimately achieving a small focal spot. Conversely, applying a relatively weak current to solenoid 310 reduces the focusing force, while applying a relatively large current to quadrupole magnet 320 increases both the width and length of the beam spot, thus achieving a large focal spot. Figure 3 Figure (a) shows the beam spot at the target point when the focal point is large, obtained using the method described above. Figure 3 Figures (b) and (c) show the width and length envelopes of the beam spot when the focal spot is large, respectively, which are approximately 1.5 mm (IEC60336-2005). Figure 4 Figure (a) shows the beam spot at the target point when the focal point is small, obtained using the method described above. Figure 4 Figures (b) and (c) show the width and length envelopes of the beam spot when the focal spot is small, respectively, which are approximately 1.0 mm (IEC60336-2005).

[0087] It should be noted that the uniformity of the DC electron beam 110 can be achieved by adjusting the focusing intensity of the focusing electrode 200 and the solenoid 310. However, to achieve a more uniform beam distribution, the focusing intensity of the focusing electrode 200 needs to be reduced, allowing the solenoid 310 to share more of the focusing force.

[0088] This X-ray tube and X-ray focus adjustment method can achieve switching between multiple focus sizes while ensuring a certain uniformity of the DC electron beam 110.

[0089] This application also provides a CT device that includes the X-ray tube described in any of the above embodiments, and is capable of achieving at least one of the above-described technical effects.

[0090] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An X-ray tube, characterized in that, The X-ray tube includes: A flat cathode (100) is used to emit a DC electron beam (110). A focusing electrode (200) is disposed around the outer periphery of the flat cathode (100) and at an angle to the plane of the flat cathode (100). The focusing electrode (200) is used to focus the DC electron beam (110). A vacuum-sealed housing (400) is provided with a beam channel (410). The beam channel (410) is located on the side of the flat cathode (100) in the beam exit direction. The inlet of the beam channel (410) is spaced apart from the flat cathode (100) in the beam exit direction. The beam channel (410) is used to pass through the DC electron beam (110) focused by the focusing electrode (200). A beam modulation assembly (300) comprising: A solenoid (310) is disposed on the outer periphery of the beam channel (410) and is used to focus the DC electron beam (110) passing through the beam channel (410); A quadrupole magnet (320) is disposed on the outer periphery of the beam channel (410). The quadrupole magnet (320) is disposed at a distance from the solenoid (310) and is disposed on the side of the solenoid (310) away from the flat cathode (100). When the DC electron beam (110) passes through the beam channel (410), the quadrupole magnet (320) can adjust the size of the focal spot of the DC electron beam (110) on the anode (500).

2. The X-ray tube according to claim 1, characterized in that, The focusing electrode (200) is disposed around the flat plate cathode (100); and the focusing electrode (200) has a focusing surface, the angle θ between the focusing surface and the central axis of the flat plate cathode (100) satisfies the following condition: 60°≤θ≤80°.

3. The X-ray tube according to claim 1, characterized in that, The plate cathode (100) is a circular plate cathode (100), the focusing electrode (200) is annular, and the focusing electrode (200) is arranged around the outer periphery of the circular plate cathode (100). The inner circumference of the focusing electrode (200) matches the circumference of the circular plate cathode (100).

4. The X-ray tube according to claim 1, characterized in that, The potential of the focusing electrode (200) is less than or equal to the potential of the plate cathode (100).

5. The X-ray tube according to claim 1, characterized in that, The focusing electrode (200) and the flat cathode (100) have the same axis, and the focusing electrode (200) is symmetrically arranged along the axis.

6. The X-ray tube according to claim 1, characterized in that, The beam tuning assembly (300) further includes a guide magnet (330), which is disposed on the outer periphery of the beam channel (410). The guide magnet (330) is spaced apart from the solenoid (310) and is disposed on the side of the solenoid (310) away from the flat cathode (100). When the DC electron beam (110) passes through the beam channel (410), the guide magnet (330) can adjust the position of the DC electron beam (110) on the anode (500).

7. The X-ray tube according to claim 6, characterized in that, It also includes a beam tuning component frame (340) for fixing the beam tuning component (300), the guide magnet (330) and the quadrupole magnet are disposed on the same beam tuning component frame (340), and the guide magnet (330) is disposed on the side of the beam tuning component frame (340) near the exit direction of the beam channel (410).

8. The X-ray tube according to any one of claims 1-7, characterized in that, The vacuum-sealed housing (400) is also configured with a first vacuum-containing cavity (420), which is connected to the inlet of the beam channel (410), and the cathode and the focusing electrode (200) are housed in the first vacuum-containing cavity (420).

9. The X-ray tube according to claim 8, characterized in that, The X-ray tube also includes an anode (500), which is disposed on the side of the beam tuning assembly (300) away from the flat cathode (100) along the beam exit direction of the flat cathode (100), and the anode (500) and the beam tuning assembly (300) are spaced apart. The vacuum-sealed housing (400) is configured with a second vacuum-containing cavity (430), the anode (500) is housed in the second cavity (430), the second cavity (430) is connected to the outlet of the beam channel (410), and the anode (500) is used to generate an X-ray beam (600) when bombarded by the DC electron beam (110).

10. A method for adjusting the focus of an X-ray beam, characterized in that, The X-ray focus adjustment method includes: A current is applied to the plate cathode (100) to cause the plate cathode (100) to emit a DC electron beam (110). The voltage applied to the focusing electrode (200) is adjusted so that the DC electron beam (110) enters the inlet of the beam channel (410) after being focused by the focusing electrode (200); wherein, the focusing electrode (200) is disposed around the outer periphery of the plate cathode (100), and the focusing surface of the focusing electrode (200) is set at an angle to the plane of the plate cathode (100); the beam channel (410) is disposed on one side of the beam exit direction of the plate cathode (100), and the inlet of the beam channel (410) is spaced apart from the plate cathode (100) along the beam exit direction of the plate cathode (100), and the beam channel (410) is used to pass the DC electron beam (110) focused by the focusing electrode (200). The current applied to the solenoid (310) in the beam tuning assembly (300) is adjusted so that the solenoid (310) focuses the DC electron beam (110) passing through the beam channel (410); wherein the solenoid (310) is disposed on the outer periphery of the beam channel (410); The current applied to the quadrupole magnet (320) in the beam tuning assembly (300) is adjusted so that the quadrupole magnet (320) adjusts the size of the focal spot of the DC electron beam (110) passing through the beam channel (410) on the anode (500); wherein the quadrupole magnet (320) is disposed on the outer periphery of the beam channel (410), the quadrupole magnet (320) is spaced apart from the solenoid (310), and is disposed on the side of the solenoid (310) away from the flat cathode (100).

11. The X-ray focus adjustment method according to claim 10, characterized in that, The X-ray focus adjustment method further includes: Based on the voltage of the plate cathode (100), the voltage applied to the focusing electrode (200) is adjusted so that the potential of the focusing electrode (200) is less than or equal to the potential of the plate cathode (100).

12. The X-ray focus adjustment method according to any one of claims 10-11, characterized in that, The X-ray focus adjustment method further includes: The current applied to the guide magnet (330) in the beam tuning assembly (300) is adjusted so that the guide magnet (330) adjusts the position of the focal spot of the DC electron beam (110) passing through the beam channel (410) on the anode (500); The guide magnet (330) is disposed on the outer periphery of the beam channel (410), and the guide magnet (330) is disposed at a distance from the solenoid (310), and is disposed on the side of the solenoid (310) away from the flat cathode (100).

13. A CT scanner, characterized in that, The X-ray tube included in any one of claims 1-9.

Images