X-ray tube, X-ray focus adjusting method and CT equipment

Abstract

The invention relates to an X-ray tube, an X-ray focus adjusting method and CT equipment. The X-ray tube comprises a flat cathode, a focusing electrode, a vacuum closed shell and a beam adjusting assembly. The flat cathode is used for emitting direct-current electron beams; the focusing electrode surrounds the periphery of the flat cathode, forms an angle with the plane where the flat cathode is located, and is used for focusing the direct current electron beam; the vacuum closed shell is provided with a beam channel arranged on one side of the beam outlet direction of the plate cathode, an inlet of the beam channel and the plate cathode are arranged at an interval, and the beam channel is used for direct current electron beams to pass through; the beam adjusting assembly comprises a solenoid arranged on the periphery of the beam channel, and the solenoid is used for focusing the direct current electron beam passing through the beam channel. When the plate cathode emits an electron beam, the focusing electrode focuses the electron beam for the first time. And the solenoid performs secondary focusing. The electron beam is focused twice, so that the focusing force in one focusing process can be smaller, and the uniformity of the electron beam in the transmission process is better.

Description

Technical Field

[0001] The present application relates to the field of X-ray technology, and in particular to an X-ray tube, an X-ray focus adjustment method and a CT device. Background Art

[0002] X-ray technology is widely used in life, such as industrial non-destructive testing, safety inspection, medical diagnosis and treatment, etc. However, after the cathode of the existing X-ray tube emits an electron beam, the uniformity of the electron beam is poor, which affects the treatment effect. Summary of the invention

[0003] Based on this, it is necessary to provide an X-ray tube to address the problem that the electron beam emitted by the existing X-ray tube has poor uniformity and affects the treatment effect.

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

[0005] A flat cathode, the flat cathode being used for emitting a DC electron beam;

[0006] A focusing electrode, which is arranged around the outer periphery of the flat cathode and is arranged at an angle to the plane where the flat cathode is located, and is used to focus the DC electron beam;

[0007] A vacuum sealed shell, wherein the vacuum sealed shell is configured with a beam channel, wherein the beam channel is arranged on one side of the beam emitting direction of the flat cathode, wherein an entrance of the beam channel is spaced from the flat cathode along the beam emitting direction of the flat cathode, and wherein the beam channel is used for the DC electron beam focused by the focusing electrode;

[0008] A beam adjustment component includes a solenoid, the solenoid is arranged on the periphery of the beam channel, and the solenoid is used to focus the DC electron beam passing through the beam channel.

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

[0010] 60°≤θ≤80°.

[0011] In one embodiment, the flat cathode is a circular flat cathode, the focusing electrode is in a circular ring shape, and the focusing electrode is arranged around the outer circumference of the circular flat cathode, and the circumference of the inner ring of the focusing electrode matches the circumference of the circular flat cathode.

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

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

[0014] In one embodiment, the beam adjustment assembly further includes a quadruple magnet, which is disposed at the periphery of the beam channel, is spaced apart from the solenoid, and is disposed on a 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 focal spot size of the DC electron beam on the anode.

[0016] In one embodiment, the beam adjustment assembly further includes a guide magnet, which is disposed on the periphery of the beam channel, is spaced apart from the solenoid, and is disposed on a 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 focal spot position of the DC electron beam on the anode.

[0018] In one of the embodiments, a beam adjustment assembly skeleton is further included, wherein the beam adjustment assembly skeleton is used to fix the beam adjustment assembly, the guide magnet and the quadrupole magnet are arranged on the same beam adjustment assembly skeleton, and the guide magnet is arranged on a side of the beam adjustment assembly skeleton close to the exit direction of the beam channel.

[0019] In one of the embodiments, the vacuum enclosure is further configured with a first vacuum accommodating chamber, the first accommodating chamber is communicated with the entrance of the beam channel, and the cathode and the focusing electrode are accommodated in the first accommodating chamber.

[0020] In one embodiment, the X-ray tube further comprises an anode, the anode is arranged on a side of the beam modulating assembly away from the flat cathode along the beam emitting direction of the flat cathode, and the anode is spaced apart from the beam modulating assembly;

[0021] The vacuum enclosure is configured with a second vacuum accommodating chamber, the anode is accommodated in the second accommodating chamber, the second accommodating chamber is communicated with the outlet of the beam channel, and the anode is used to generate an X-ray beam when bombarded by the DC electron beam.

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

[0023] Applying current to the flat cathode so that the flat cathode emits a direct current electron beam;

[0024] The voltage applied to the focusing electrode is adjusted so that the DC electron beam enters the entrance of the beam channel after being focused by the focusing electrode; wherein the focusing electrode is arranged around the periphery of the flat cathode, and the focusing surface of the focusing electrode is arranged at an angle to the plane where the flat cathode is located; the beam channel is arranged on one side of the beam output direction of the flat cathode, the entrance of the beam channel is arranged at intervals from the flat cathode along the beam output direction of the flat cathode, and the beam channel is used for the DC electron beam focused by the focusing electrode;

[0025] The current applied to the solenoid in the beam adjustment assembly is adjusted so that the solenoid focuses the DC electron beam passing through the beam channel; wherein the solenoid is arranged on the 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 flat cathode so that the potential of the focusing electrode is less than or equal to the potential of the flat cathode.

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

[0029] adjusting the current applied to the quadrupole magnet in the beam adjustment assembly so that the quadrupole magnet adjusts the focal spot size of the DC electron beam passing through the beam channel on the anode;

[0030] The quadruple magnet is arranged at the periphery of the beam channel, the quadruple magnet is spaced apart from the solenoid, and is arranged at a side of the solenoid away from the flat cathode.

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

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

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

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

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

[0036] In the above-mentioned X-ray tube, X-ray focus adjustment method and CT equipment, after the flat cathode emits a DC electron beam, the focusing electrode arranged on the periphery of the flat cathode first focuses the DC electron beam. When the DC electron beam passes through the beam channel during the transmission process, the solenoid performs a second focusing on the DC electron beam. The focusing force of the DC electron beam during the first focusing process through the focusing electrode can be selected to be a smaller value, thereby making the DC electron beam more uniform during the process of being transmitted to the beam adjustment component. At the same time, since the DC electron beam will be focused twice by the solenoid after being focused once by the focusing electrode, no additional nonlinear force will be introduced, and thus the final focusing effect of the DC electron beam is also better. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of an X-ray tube provided in accordance with an embodiment of the present application.

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

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

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

[0041] Figure numerals: 100 - flat cathode; 110 - DC electron beam; 200 - focusing electrode; 300 - beam adjustment assembly; 310 - solenoid; 320 - quadrupole magnet; 330 - guide magnet; 340 - beam adjustment assembly skeleton; 400 - vacuum enclosure; 410 - beam channel; 420 - first accommodating cavity; 430 - second accommodating cavity; 500 - anode; 510 - target disk edge; 600 - X-ray beam. DETAILED DESCRIPTION

[0042] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0043] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0044] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0045] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0046] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0047] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, 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 implementation method.

[0048] See also Figure 1 , Figure 1 A schematic diagram of an X-ray tube provided in an embodiment of the present application is shown. The X-ray tube provided in an embodiment of the present application includes a flat cathode 100, a focusing electrode 200, a vacuum-sealed shell 400 and a beam-adjusting assembly 300. The flat cathode 100 is used to emit a DC electron beam 110; the focusing electrode 200 is arranged around the periphery of the flat cathode 100 and is arranged at an angle to the plane where the flat cathode 100 is located, and the focusing electrode 200 is used to focus the DC electron beam 110; the vacuum closed shell 400 is constructed with a beam channel 410, and the beam channel 410 is arranged on one side of the beam output direction of the flat cathode 100, and the entrance of the beam channel 410 is arranged at intervals from the flat cathode 100 along the beam output 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; the beam adjustment component 300 includes a solenoid 310, and the solenoid 310 is arranged on the 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 above X-ray tube, after the flat cathode 100 emits the DC electron beam 110, the focusing electrode 200 disposed on the periphery of the flat cathode 100 performs a primary focusing on the DC electron beam 110. Specifically, the DC electron beam 110 is an electron beam that is continuously emitted for a period of time. When the DC electron beam 110 passes through the beam channel 410 during the transmission process, the solenoid 310 performs a secondary focusing on 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 smaller value, thereby making the DC electron beam 110 more uniform during the process of being transmitted to the beam adjustment component 300. At the same time, since the DC electron beam 110 is focused once through the focusing electrode 200 and then focuses twice through the solenoid 310, no additional nonlinear force is introduced, and thus the final focusing effect of the DC electron beam 110 is also better.

[0050] In the present application, the entrance of the beam channel 410 is spaced apart from the flat cathode 100 along the beam emission direction of the flat cathode 100, so that 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 the DC electron beam 110 is focused by 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 with a weak control effect. The effect is to focus the electrons in all directions. Compared with the focusing device control of a quadrupole magnet or electric focusing, the solenoid 310 uses a second-order force to focus. To achieve the same focusing strength as a quadrupole magnet, the current applied by the solenoid 310 is one order of magnitude higher than that of the quadrupole magnet. The focusing effect depends to a certain extent on the electron energy, the beam pipeline, and the current applied to the solenoid 310. In the present application, it is through the coordinated cooperation of the focusing electrode 200 and the solenoid 310 that the DC electron beam 110 has better uniformity during transmission to the beam adjustment component 300, and no additional nonlinear force is introduced, so that the final focusing effect of the DC electron beam 110 is also better.

[0052] It should be noted that the focusing electrode 200 and the solenoid 310 are matched, and the focusing electrode 200 does not change the current passing through the solenoid 310 and the length of the beam channel 410, nor does it change the electron energy. Instead, through the adaptive combination of the focusing electrode 200 and the solenoid 310, the focusing electrode 200 can first perform some micro-focusing, and then achieve a better effect after the solenoid 310 focuses.

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

[0054] The shape of the flat cathode 100 can be circular, elliptical, rectangular or any other regular or irregular shape structure, and there is no special limitation on this. When the flat 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 ratio of the width to the length of the beam spot of the DC electron beam 110.

[0055] The structure of the X-ray tube is described in detail below.

[0056] See also Figure 1The focusing electrode 200 of the X-ray tube provided in one embodiment of the present application is arranged around the flat cathode 100; and the focusing electrode 200 has a focusing surface, and 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 quasi-Pierce structure, so that the laminarity and uniformity of the DC electron beam 110 are better.

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

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

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

[0060] In some embodiments, the angle θ between the focusing plane and the central axis of the flat cathode 100 satisfies the condition: 65°≤θ≤75°. By setting the angle θ between the focusing plane of the focusing electrode 200 and the central axis p of the flat cathode 100 to be greater than or equal to 65° and less than or equal to 75°, the focusing electrode 200 is more likely to form a quasi-Pierce structure, thereby making the laminarity and uniformity of the DC electron beam 110 better.

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

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

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

[0064] In one embodiment, the flat cathode 100 is a circular flat cathode 100, the focusing electrode 200 is in a ring shape, and the focusing electrode 200 is arranged around the outer circumference of the circular flat cathode 100, and the circumference of the inner ring of the focusing electrode 200 matches the circumference of the circular flat cathode 100. By setting the shape of the flat cathode 100 and the shape of the focusing electrode 200 to be respectively matched with a circle and a ring, and the circumference of the inner ring of the focusing electrode 200 matches the circumference of the circular flat cathode 100, the gap between the focusing electrode 200 and the flat cathode 100 is made smaller, and the DC electron beam 110 emitted by the flat cathode 100 can be better focused by the focusing electrode 200, thereby making the laminarity and uniformity of the DC electron beam 110 better.

[0065] In one embodiment, the electric potential of the focusing electrode 200 is less than or equal to the electric potential of the flat cathode 100. By setting the electric potential of the focusing electrode 200 to be less than or equal to the electric potential of the flat cathode 100, the electric potential of the flat cathode 100 is made larger, and when the flat cathode 100 emits the DC electron beam 110, the DC electron beam 110 is not easy to hit the focusing electrode 200. In one specific embodiment, the electric potential of the focusing electrode 200 is -61kv, and the electric potential of the flat cathode 100 is -60kv. In another specific embodiment, the electric potential of the focusing electrode 200 is -60kv, and the electric potential of the flat cathode 100 is -60kv.

[0066] It should be noted that, since the focusing electrode 200 can perform micro-focusing on the DC electron beam 110 emitted by the flat cathode 100, when the potential difference between the focusing electrode 200 and the flat cathode 100 is too high, other electrodes on the X-ray tube, such as the grid used to adjust the size of the emitted DC electron beam 110, may be broken down, thereby causing 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 3kV.

[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. By such an arrangement, the focusing electrode 200 has a better focusing effect on the DC electron beam 110. It should be noted that when the flat cathode 100 is composed of multiple independent cathode emitting parts, the multiple independent cathode emitting parts need to be regarded as an integral structure, and the axis of the integral structure is the axis of the flat cathode 100.

[0068] See also Figure 1The beam adjustment assembly 300 of the X-ray tube provided in an embodiment of the present application further includes a quadrupole magnet 320, which is arranged at the periphery of the beam channel 410, and is arranged at intervals from the solenoid 310, and is arranged 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 focal spot size of the DC electron beam 110 on the anode 500. By setting the quadrupole magnet 320, the quadrupole magnet 320 can adjust the focal spot size of the DC electron beam 110 on the anode 500, thereby making the focal spot of the DC electron beam 110 adaptable to different size requirements, and the adaptability of the entire X-ray tube is stronger.

[0069] It should be noted that in the prior art, when the X-ray tube only has a solenoid 310, in order to enhance the electron focusing force of the solenoid 310, it is usually adopted to emit mega-energy-level electrons or increase the beam pipe length or apply a large current to the solenoid 310. Therefore, the emission energy requirement is high, the overall tube length is greatly increased, and the device is easily damaged by long-term large current, and the life is short. When the X-ray tube only has a quadrupole magnet 320, the quadrupole magnet directly applies 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 in another perpendicular direction. Therefore, two quadrupole magnets 320 are generally required, and 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 offset each other, and the effective force applied to the DC electron beam 110 becomes smaller, thereby making the electron beam uniform.

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

[0071] In the X-ray tube of the present application, due to the combination of the solenoid 310 and the quadrupole magnet 320, there is no force offset similar to that of two quadrupole magnets 320, and although the force of the solenoid 310 is one 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, so that most of the electric focusing effect of the X-ray tube is transferred to the magnetic focusing of the solenoid 310, so that the beam laminarity of the DC electron beam 110 remains basically unchanged, the electron uniformity is good, and the uniformity of the electron distribution can be guaranteed on the basis of increasing the focusing intensity. After the electron beam weakly electrically focused by the flat cathode 100 in the X-ray tube provided by the present application passes through the pipeline, the solenoid 310 will further compress 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 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 in the tube to achieve a relatively uniform beam spot distribution and controllable focal beam spot size.

[0073] See also Figure 1 The beam adjustment assembly 300 of the X-ray tube provided in an embodiment of the present application further includes a guide magnet 330, which is arranged at the periphery of the beam channel 410, and is arranged at a distance from the solenoid 310, and is arranged at 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 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 making the focal spot position of the DC electron beam 110 adaptable to different position requirements, and the adaptability of the entire X-ray tube is stronger.

[0074] The X-ray tube of the present application has strong inclusiveness, because the X-ray tube of the present application can integrate the focusing of the adjustable voltage focusing electrode 200 and the combination of the multiple cathode emission parts constituting the flat cathode 100, so as to realize a more powerful focus tuning function. Compared with the X-ray tube of the present application focusing the beam spot by the voltage adjustable focusing electrode 200, the focusing of the electrons by the solenoid 310 will not change the laminar flow of the electron beam, and a more uniform beam spot distribution can be obtained. At the same time, the present invention can also retain the electron flying focus function by the guide magnet 330.

[0075] See also Figure 1The X-ray tube provided in an embodiment of the present application further includes a beam adjustment component skeleton, which is used to fix the beam adjustment component 300. The guide magnet 330 and the quadrupole magnet are arranged on the same beam adjustment component skeleton, and the guide magnet 330 is arranged on the side of the beam adjustment component skeleton close to the exit direction of the beam channel 410. By setting the beam adjustment component skeleton, the guide magnet 330 and the quadrupole magnet 320 are arranged on the same skeleton structure, and the assembly of the entire X-ray tube is simpler. At the same time, the guide magnet 330 is arranged on the side closer to the exit direction of the beam channel 410, so that the DC electron beam 110 is adjusted by the secondary focusing of the solenoid 310 and the focal spot size of the quadrupole magnet 320, and then the focal spot position of the DC electron beam 110 on the anode 500 is adjusted by the guide magnet 330, so that the position accuracy and focal spot size accuracy of the DC electron beam 110 on the anode 500 are finally high, and the treatment effect is better.

[0076] See also Figure 1 The vacuum enclosure 400 of the X-ray tube provided in one embodiment of the present application is further configured with a vacuum first accommodating chamber 420, the first accommodating chamber 420 is communicated with the entrance of the beam channel 410, and the cathode and the focusing electrode 200 are accommodated in the first accommodating chamber 420. By accommodating the cathode and the focusing electrode 200 in the first accommodating chamber 420, the DC electron beam 110 emitted by the flat cathode 100 is transmitted in a vacuum environment and finally hits the anode 500. The entire transmission process is carried out in a high vacuum environment, and relatively stable X-rays can be generated.

[0077] See also Figure 1 The X-ray tube provided in an embodiment of the present application further includes an anode 500, which is arranged on a side of the beam adjustment component 300 away from the flat cathode 100 along the beam emission direction of the flat cathode 100, and the anode 500 is arranged at a distance from the beam adjustment component 300; the vacuum sealed shell 400 is configured with a vacuum second accommodating chamber 430, and the anode 500 is accommodated in the second accommodating chamber 430, and the second accommodating chamber 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. When the flat cathode 100 emits the DC electron beam 110, the DC electron beam 110 passes through the first accommodating chamber 420, the beam channel 410 and the second accommodating chamber 430 and then hits the anode 500. The DC electron beam 110 is always carried out in a high vacuum environment during the entire transmission process, and can generate relatively stable X-rays, so that the anode 500 finally generates an X-ray beam 600 when bombarded by the DC electron beam 110, and then performs irradiation treatment operations on the preset part of the patient.

[0078] See also Figure 1The anode 500 of the X-ray tube provided in one embodiment of the present application further includes a target disk edge 510, which has a certain inclination angle for linear focusing of the DC electron beam 110. After the DC electron beam 110 bombards the target disk edge 510, X-rays are generated for medical imaging.

[0079] The present application also provides an X-ray focus adjustment method, which includes: applying current to the flat cathode 100 so that the flat cathode 100 emits a DC electron beam 110; adjusting the voltage applied to the focusing electrode 200 so that the DC electron beam 110 enters the entrance of the beam channel 410 after being focused by the focusing electrode 200; wherein the focusing electrode 200 is arranged around the periphery of the flat cathode 100, and the focusing surface of the focusing electrode 200 is arranged at an angle to the plane where the flat cathode 100 is located; the beam channel 410 is arranged on one side of the beam output direction of the flat cathode 100, and the entrance of the beam channel 410 is arranged at intervals from the flat cathode 100 along the beam output direction of the flat cathode 100, and the beam channel 410 is used for the DC electron beam 110 focused by the focusing electrode 200; adjusting the current applied to the solenoid 310 in the beam adjustment component 300 so that the solenoid 310 focuses the DC electron beam 110 passing through the beam channel 410; wherein the solenoid 310 is arranged on the periphery of the beam channel 410.

[0080] The X-ray focus adjustment method applies a voltage to the focusing electrode 200 so that the DC electron beam 110 can be focused once under the action of the focusing electrode 200. When the DC electron beam 110 passes through the beam channel 410 during the transmission process, the solenoid 310 performs a secondary focusing on the DC electron beam 110. Since the DC electron beam 110 is focused twice, 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 smaller value, thereby making the DC electron beam 110 more uniform during the transmission to the beam adjustment component 300, and the DC electron beam 110 is not easy to hit the tube wall arranged on its periphery during the transmission process, so that the tube wall is not easy to be damaged, and the service life of the tube and the entire X-ray tube is longer. At the same time, since the DC electron beam 110 is focused once through the focusing electrode 200, it will be focused twice through the solenoid 310, so 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 flat cathode 100, so that the potential of the focusing electrode 200 is less than or equal to the potential of the flat cathode 100. By setting the potential of the focusing electrode 200 to be less than or equal to the potential of the flat cathode 100, the potential of the flat cathode 100 is made larger, and when the flat cathode 100 emits the DC electron beam 110, the DC electron beam 110 is not easy to hit the focusing electrode 200. In one specific embodiment, the potential of the focusing electrode 200 is -61kv, and the potential of the flat cathode 100 is -60kv. In another specific embodiment, the potential of the focusing electrode 200 is -60kv, and the potential of the flat cathode 100 is -60kv.

[0082] In one embodiment, the X-ray focus adjustment method further includes: adjusting the current applied to the quadrupole magnet 320 in the beam adjustment 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 arranged at the periphery of the beam channel 410, the quadrupole magnet 320 is arranged at intervals from the solenoid 310, and is arranged on the side of the solenoid 310 away from the flat cathode 100. By arranging 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 the adaptability of the entire X-ray tube is stronger.

[0083] In one embodiment, the X-ray focus adjustment method further includes: adjusting the current applied to the guide magnet 330 in the beam adjustment 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 arranged at the periphery of the beam channel 410, the guide magnet 330 is arranged at a distance from the solenoid 310, and is arranged on the side of the solenoid 310 away from the flat cathode 100. By arranging 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 position requirements, and the adaptability of the entire X-ray tube is stronger.

[0084] See also Figure 2 , Figure 2 Shown by Figure 1 The first experimental result schematic diagram of the simulation experiment of the X-ray tube shown is shown. Figure 2Line e in the figure is the change of the beam spot size of the DC electron beam 110 with the electron position when the tube voltage is 140kv, that is, the potential of the flat cathode 100 is -140kv. Line f is the change of the beam spot size of the DC electron beam 110 with the electron position when the tube voltage is 60kv, that is, the potential of the flat cathode 100 is -60kv. Since the potential of the focusing electrode 200 is consistent with that of the flat cathode 100, and the focusing of the focusing electrode 200 on the DC electron beam 110 is weak, the difference in the electric focusing effect of the electrons under different tube voltages is not much. Here Figure 2 In Figures (a)-(d), line e is used as an example to analyze the change in the beam spot size of the DC electron beam 110 with the electron position when the tube voltage is 140 kV, that is, the potential of the flat cathode 100 is -140 kV. Figure 2 (a) in the figure shows the beam spot distribution on the emitting surface of the flat electrode, which is a uniform circle. Figure 2 (b) in the figure shows the beam spot at the position of the solenoid 310. After the electrical focusing of the Pierce-like electrode formed by the focusing electrode 200, the beam spot becomes smaller, but the distribution is still relatively uniform. Figure 2 (c) in the figure shows the beam spot distribution at the quadrupole magnet 320 . Figure 2 (d) in FIG. 5 is the beam spot distribution at the target disk of the anode 500. Figure 2 From the changes in Figures (a)-(d) in FIG. 1 , the X-ray tube provided in the present application can transmit the DC electron beam 110 in a micro-focusing effect from the solenoid 310 to the anode 500 .

[0085] See also Figure 3 and Figure 4 , Figure 3 Shown by Figure 1 The schematic diagram of the second experimental result of the simulation experiment on the X-ray tube shown is shown. Figure 4 Shown by Figure 1 The third experimental result schematic diagram of the simulation experiment of the X-ray tube shown.

[0086] After the weak focusing of the focusing electrode 200, the solenoid 310 is used to complete the secondary focusing of the DC electron beam 110. The solenoid 310 can adjust the focusing strength by applying currents of different sizes. The magnetic field provided by the 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 of the DC electron beam 110. The guide magnet 330 then realizes flying focus in the width and length directions at different distances as required. Applying a relatively strong current to the solenoid 310 can make the DC electron beam 110 focus smaller. At the same time, applying a relatively small current to the quadrupole magnet 320 can keep the beam spot in the width direction of the DC electron beam 110 small, and the beam spot in the length direction will not become very large, and finally a small focus beam spot can be achieved. Applying a relatively weak current to the solenoid 310 can reduce the focusing force of the beam spot, and at the same time, applying a relatively large current to the quadrupole magnet 320 can make the beam spot larger in the width direction, and the beam spot in the length direction also becomes larger, thereby achieving a large focus beam spot. Figure 3 Figure (a) shows the beam spot of the target at a large focus obtained using the above method. Figure 3 Figures (b) and (c) are the width and length envelopes of the beam spot at large focus, which are approximately 1.5 mm (IEC60336-2005). Figure 4 Figure (a) shows the beam spot of the target point at a small focus obtained by the above method. Figure 4 Figures (b) and (c) are the width and length envelopes of the beam spot when the focus is small, which are about 1.0 mm (IEC60336-2005).

[0087] It should be noted that the uniformity of the beam spot of the DC electron beam 110 can be achieved by adjusting the focusing strength of the focusing electrode 200 and the solenoid 310. If a more uniform beam spot distribution is required, the focusing strength of the focusing electrode 200 needs to be reduced so that the solenoid 310 can share more focusing force.

[0088] The X-ray tube and X-ray focus adjustment method can realize the switching of various focus sizes and ensure a certain uniformity of the beam spot of the DC electron beam 110 at the same time.

[0089] The present application also provides a CT device, which includes the X-ray tube described in any one of the above embodiments and can achieve at least one of the above technical effects.

[0090] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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 above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. An X-ray tube, characterized in that: The X-ray tube comprises: A flat cathode (100), the flat cathode (100) being used to emit a direct current electron beam (110); A focusing electrode (200), the focusing electrode (200) being arranged around the periphery of the flat cathode (100) and being arranged at an angle to the plane where the flat cathode (100) is located, the focusing electrode (200) being used to focus the DC electron beam (110); A vacuum sealed shell (400), wherein the vacuum sealed shell (400) is configured with a beam channel (410), wherein the beam channel (410) is arranged on one side of the beam emitting direction of the flat cathode (100), wherein an entrance of the beam channel (410) and the flat cathode (100) are arranged at intervals along the beam emitting direction of the flat cathode (100), and wherein the beam channel (410) is used for the DC electron beam (110) focused by the focusing electrode (200); A beam adjustment component (300) comprises a solenoid (310), wherein the solenoid (310) is arranged on the 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).

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

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

4. The X-ray tube according to claim 1, characterized in that The electric potential of the focusing electrode (200) is less than or equal to the electric potential of the flat 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 any one of claims 1 to 5, characterized in that The beam adjustment assembly (300) further comprises a quadrupole magnet (320), wherein the quadrupole magnet (320) is arranged at the periphery of the beam channel (410), the quadrupole magnet (320) is spaced apart from the solenoid (310), and is arranged at a 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 focal spot size of the DC electron beam (110) on the anode (500).

7. The X-ray tube according to claim 6, characterized in that The beam adjustment assembly (300) further comprises a guide magnet (330), wherein the guide magnet (330) is arranged at the periphery of the beam channel (410), the guide magnet (330) is arranged at a distance from the solenoid (310), and is arranged at a 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 focal spot position of the DC electron beam (110) on the anode (500).

8. The X-ray tube according to claim 7, characterized in that The invention also comprises a beam adjustment component (300) frame, wherein the beam adjustment component (300) frame is used to fix the beam adjustment component (300), the guide magnet (330) and the quadrupole magnet are arranged on the same beam adjustment component (300) frame, and the guide magnet (330) is arranged on one side of the beam adjustment component (300) frame close to the exit direction of the beam channel (410).

9. The X-ray tube according to any one of claims 1 to 5 or claims 7 to 8, characterized in that: The vacuum enclosure (400) is also configured with a first vacuum accommodating chamber (420), the first accommodating chamber (420) being in communication with the entrance of the beam channel (410), and the cathode and the focusing electrode (200) being accommodated in the first accommodating chamber (420).

10. The X-ray tube according to claim 9, characterized in that The X-ray tube further comprises an anode (500), the anode (500) being arranged on a side of the beam modulation component (300) away from the flat cathode (100) along the beam output direction of the flat cathode (100), and the anode (500) and the beam modulation component (300) being arranged at a distance; The vacuum enclosure (400) is configured with a second vacuum accommodating chamber (430), the anode (500) being accommodated in the second accommodating chamber (430), the second accommodating chamber (430) being connected to an outlet of the beam channel (410), and the anode (500) being used to generate an X-ray beam (600) when bombarded by the DC electron beam (110).

11. An X-ray focus adjustment method, characterized in that: The X-ray focus adjustment method comprises: Applying current to the flat cathode (100) so that the flat cathode (100) emits a direct current electron beam (110); The voltage applied to the focusing electrode (200) is adjusted so that the DC electron beam (110) enters the entrance of the beam channel (410) after being focused by the focusing electrode (200); wherein the focusing electrode (200) is arranged around the periphery of the flat cathode (100), and the focusing surface of the focusing electrode (200) is arranged at an angle with the plane where the flat cathode (100) is located; the beam channel (410) is arranged on one side of the beam output direction of the flat cathode (100), the entrance of the beam channel (410) and the flat cathode (100) are arranged at intervals along the beam output direction of the flat cathode (100), and the beam channel (410) is used for the DC electron beam (110) focused by the focusing electrode (200); The current applied to the solenoid (310) in the beam adjustment component (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 arranged on the periphery of the beam channel (410).

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

13. The X-ray focus adjustment method according to any one of claims 11 to 12, characterized in that: The X-ray focus adjustment method further comprises: adjusting the current applied to the quadrupole magnet (320) in the beam adjustment 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); The quadrupole magnet (320) is arranged on the periphery of the beam channel (410), the quadrupole magnet (320) is spaced apart from the solenoid (310), and is arranged on a side of the solenoid (310) away from the flat cathode (100).

14. The X-ray focus adjustment method according to any one of claims 11 to 12, characterized in that: The X-ray focus adjustment method further comprises: adjusting the current applied to the guide magnet (330) in the beam adjustment component (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); The guide magnet (330) is arranged on the periphery of the beam channel (410), the guide magnet (330) is spaced apart from the solenoid (310), and is arranged on a side of the solenoid (310) away from the flat cathode (100).

15. A CT device, characterized in that: The X-ray tube comprises the X-ray tube according to any one of claims 1 to 10.

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