Multi-focal x-ray tube, and multi-focal x-ray source and human tomography apparatus

Abstract

A multifocal X-ray tube, a multifocal X-ray source, and a human body tomography device are provided. The multifocal X-ray tube includes a housing, a window, and multiple anodes. Multiple spaced-apart exit windows are provided on the front wall of the housing. The window covers the multiple exit windows to seal the housing. The anodes are located inside the housing and have multiple target point groups corresponding one-to-one with the multiple exit windows. Each target point group includes multiple target points, each target point receiving bombardment from a corresponding electron beam drawn from the cathode and generating an X-ray beam. The distance between two adjacent target points in each target point group is smaller than the distance between two adjacent target groups. The multiple X-ray beams generated by the multiple target points in each target point group are led out of the X-ray tube through the exit windows corresponding to the exit windows, and the radiation fields of all X-ray beams approximately overlap on a common plane outside the X-ray tube.

Description

Technical Field

[0001] Embodiments of the present invention relate to an X-ray tube, and more particularly, to a multifocal X-ray tube capable of emitting multiple beams of X-rays, a multifocal X-ray source including such a multifocal X-ray tube, and a human body tomography device. Background Technology

[0002] X-rays have wide applications in industrial non-destructive testing, security inspection, medical diagnosis and treatment, and other fields. The device that generates X-rays is called an X-ray source, which typically consists of an X-ray tube, a power supply and control system, and auxiliary devices such as cooling and shielding. An X-ray tube comprises three main parts: a cathode, an anode, and a housing. The cathode, when heated, generates an electron beam. This electron beam is accelerated by the high-voltage electric field between the cathode and anode and strikes the anode target, thereby producing X-rays.

[0003] Generally, the cathode and anode installed within the housing need to operate in an ultra-high vacuum environment. If the vacuum level within the housing is insufficient, the electron beam will frequently collide with gas molecules, causing the energy of the high-voltage electric field to be converted into ineffective heat energy, severely reducing the number of effective electrons bombarding the target point of the anode; simultaneously, gas ionization will contaminate the cathode and diffuse the electron beam spot, causing a sharp decrease in X-ray output efficiency; furthermore, the high ion concentration within the housing leads to a sharp increase in the arcing frequency under a high-voltage electric field, which can severely damage the X-ray tube housing. Therefore, it is necessary to ensure the airtightness of the housing.

[0004] The X-ray beam generated inside the X-ray tube's housing needs to exit the housing, enter the atmosphere, penetrate the target being inspected, and then be received by the detector to generate an image of the target. Therefore, the X-ray beam needs to be extracted from a specific location on the housing, usually called the extraction window. An extremely thin metal film is used to encapsulate the extraction window to maintain a vacuum inside the housing. Typically, the extraction window and the encapsulation film are collectively referred to as the X-ray window. This X-ray window must simultaneously meet the following conditions: the encapsulation film needs to be as thin as possible to ensure high transmittance of the X-ray beam at the X-ray window, avoiding excessive energy attenuation; the encapsulation film needs to maintain a high vacuum seal with the housing to prevent vacuum degradation leading to electron beam failure; and the encapsulation film needs to possess sufficient mechanical strength and positional accuracy at the X-ray window to ensure accurate beam exit angle and prevent deformation of the radiation field formed by the X-ray beam outside the X-ray tube.

[0005] In the invention patent application for a multifocal X-ray tube (publication number CN109216140B, hereinafter referred to as "related technology 1"), a narrow slit-like extraction window is arranged on the housing at a position aligned with multiple target points of the anode disposed inside the housing, so that multiple X-ray beams emitted from multiple target points of the anode can be extracted to the outside of the housing through a common extraction window. In implementing the technical solution of this invention, the inventors discovered that: the elongated slit-shaped exit window reduces the overall structural strength of the shell serving as the X-ray tube cavity; the X-ray window is prone to deformation, affecting the accuracy of the X-ray beam exit position and easily causing changes in the size of the radiation field, thus affecting the imaging range; the thin-film metal sealing window at the elongated slit-shaped exit window has a large area and high stress, making it prone to damage under high temperature and atmospheric pressure, increasing the risk of compromised sealing of the X-ray tube cavity; the large overall deformation of the X-ray tube cavity will affect the positional accuracy of components such as the cathode and anode inside the shell, easily leading to problems such as X-ray tube arcing; in addition, improving the structural strength of the exit window based on the above defects usually involves increasing the thickness of the shell in the region where the X-ray window is located, which will significantly increase the weight and volume of the entire X-ray tube cavity, thereby significantly increasing manufacturing costs.

[0006] In another invention patent application for a multifocal X-ray tube (publication number CN109935509A, hereinafter referred to as "related technology 2"), multiple extraction windows are arranged on the housing at positions aligned with multiple target points of the anode inside the housing. This allows multiple X-ray beams emitted from the multiple target points of the anode to be extracted to the outside of the housing through their respective aligned extraction windows. The number of extraction windows corresponds to the number of target points, and the extraction windows have little impact on the overall structural strength of the X-ray tube cavity. However, in implementing this invention, the inventors discovered that to ensure that the X-ray beam extracted from each target point can radiate to the same detector area (radiation field) and is not blocked by the gap between adjacent extraction windows, the distance between adjacent target points needs to be made sufficiently large. This reduces the density of target points and extraction windows, and consequently reduces the number of target points and extraction windows. The limited number of target points and extraction windows results in less information from different angles obtained by the X-ray imaging system using this multifocal X-ray tube, making it difficult to construct high-resolution three-dimensional images. On the other hand, if the number of target points and extraction windows is increased, since the thin-film windows need to form a vacuum seal with the front wall of the shell around the extraction window (e.g., through welding or press sealing), a certain sealing area needs to be maintained around each extraction window. This makes it difficult to arrange the extraction windows closely, and increasing the spacing between the extraction windows will increase the weight and volume of the entire X-ray tube cavity, thereby increasing manufacturing costs. Summary of the Invention

[0007] The technical problem to be solved by the embodiments of the present invention is to provide a multifocal X-ray tube, a multifocal X-ray source and a human body tomography device, which can improve the structural strength and sealing of the housing and the lead-out window, while ensuring the number of target points and constructing a clear three-dimensional image.

[0008] According to one aspect of the present invention, a multifocal X-ray tube is provided, comprising: a housing having a plurality of spaced-apart exit windows on its front wall; a window covering the plurality of exit windows to seal the housing; and a plurality of anodes located within the housing and having a plurality of target groups corresponding one-to-one with the plurality of exit windows, each target group comprising a plurality of target points, each target point receiving bombardment from a corresponding electron beam drawn from a cathode and generating an X-ray beam. The distance between two adjacent target points in each target group is smaller than the distance between two adjacent target groups; the plurality of X-ray beams generated by the plurality of target points in each target group are led out of the X-ray tube through the exit windows corresponding to the target group, and the radiation fields of all X-ray beams substantially overlap on a common plane located outside the X-ray tube.

[0009] In some embodiments, the gap between adjacent lead-out windows is integrally formed with the front wall, and the width 'a' of the gap is not less than the thickness of the front wall.

[0010] In some embodiments, the distance between two adjacent target groups The following relationship must be satisfied:

[0011]

[0012] Among them, the geometric centers of multiple target points are located on the target point line parallel to the front wall, a is the distance between two adjacent lead-out windows, d is the distance between the target point line and the front wall, l is the distance between the plane where the radiation field is located and the target point line, and c is the length of the radiation field in the direction parallel to the target point line.

[0013] In some embodiments, the length s of each outgoing window satisfies the following relationship:

[0014]

[0015] Where n is the number of targets in each target group, f is the distance between two adjacent targets in each target group, and c is the length of the radiation field in the direction parallel to the target line.

[0016] In some embodiments, the width h of each outgoing window satisfies the following relationship:

[0017]

[0018] Where d is the distance between the target line and the front wall, l is the distance between the plane P containing the radiation field and the target line, and w is the length of the radiation field in the direction perpendicular to the target line.

[0019] In some embodiments, the length of each outgoing window is no more than 30 times its width.

[0020] In some embodiments, the length of each lead-out window is no more than 300 mm, such that the deformation of the lead-out window in the operating state is no more than 0.1 mm.

[0021] In some embodiments, the window is made of a thin film that allows X-ray beams to pass through, and all the lead-out windows share a single, integral thin film.

[0022] In some embodiments, the window is made of a thin film that allows X-ray beams to pass through, and the thin film disposed on each lead-out window is independent.

[0023] According to another embodiment of the present invention, a multifocal X-ray source is provided, comprising: a multifocal X-ray tube as described in any of the above embodiments; an anode controller connected to the anode and providing anode high voltage; and a cathode controller connected to the cathode and controlling the cathode to generate electron beams emitted toward various target locations.

[0024] According to another aspect of the present invention, a human body tomography imaging device is provided, comprising: a support frame; a multifocal X-ray source as described in the above embodiments, mounted on the support frame; a bed body adapted to hold a patient to be examined, wherein an X-ray beam from the multifocal X-ray source is irradiated onto the patient; a detector array disposed within the bed body, adapted to receive the X-ray beam after the patient; and an imaging device for generating a three-dimensional image based on the X-ray beam received by the detector array.

[0025] According to the multifocal X-ray tube and multifocal X-ray source of the above-described working embodiment of the present invention, the target points of the anode are divided into multiple target point groups. The distance between two adjacent target points in each target point group is smaller than the distance between two adjacent target point groups. This ensures the number and distribution density of target points within the housing without significantly increasing the external dimensions of the housing. As a result, the X-ray imaging system using this multifocal X-ray tube can obtain more information from different angles, thereby constructing a high-definition three-dimensional image. The X-ray beams generated by multiple target points in each target point group are led out of the X-ray tube through a common corresponding extraction window. The radiation fields of the multiple X-ray beams on a common plane outside the X-ray tube approximately overlap. This improves the structural strength and sealing of the housing and extraction window without increasing the thickness of the front wall of the housing. Attached Figure Description

[0026] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

[0027] Figure 1 This is a schematic diagram illustrating the principle of a multifocal X-ray tube according to an exemplary embodiment of the present invention;

[0028] Figure 2 This is a schematic cross-sectional view of a multifocal X-ray tube according to an exemplary embodiment of the present invention;

[0029] Figure 3 This is a simplified top view illustrating a multifocal X-ray tube according to an exemplary embodiment of the present invention;

[0030] Figure 4 It is shown Figure 3 The figure shows a front view of the housing of a multifocal X-ray tube, with windows not shown.

[0031] Figure 5 This is a front view showing a housing according to an exemplary embodiment of the present invention;

[0032] Figure 6 This is a front view showing a housing according to another exemplary embodiment of the present invention;

[0033] Figure 7 This is a cross-sectional view showing the front wall of the housing according to an exemplary embodiment of the present invention;

[0034] Figure 8 This is a cross-sectional view showing the front wall of the housing according to another exemplary embodiment of the present invention;

[0035] Figure 9 This is a simplified schematic diagram illustrating the principle of a multifocal X-ray source according to an exemplary embodiment of the present invention;

[0036] Figure 10 This is a schematic diagram illustrating the principle of a human body tomography imaging device according to an exemplary embodiment of the present invention;

[0037] Figure 11 This is a simplified top view illustrating a multifocal X-ray tube of a related technology;

[0038] Figure 12 It is shown Figure 11 The front view of the housing of the multifocal X-ray tube shown;

[0039] Figure 13 This is a simplified top view illustrating another related technology: a multifocal X-ray tube.

[0040] Figure 14 It is shown Figure 13 The front view of the housing of the multifocal X-ray tube is shown. Detailed Implementation

[0041] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In this specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall concept of the invention and should not be construed as a limitation thereof. Throughout the specification, similar reference numerals denote similar parts.

[0042] Furthermore, in the following detailed description, numerous specific details are set forth for ease of explanation to provide a thorough understanding of the embodiments disclosed herein. However, it will be apparent that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and apparatuses are illustrated to simplify the figures.

[0043] According to the general inventive concept of the present invention, a multifocal X-ray tube (hereinafter referred to as "X-ray tube") is provided, comprising: a housing, a window, and a plurality of anodes. A plurality of spaced-apart exit windows are provided on the front wall of the housing. The window covers the plurality of exit windows to seal the housing. The anodes are located within the housing and have a plurality of target point groups corresponding one-to-one with the plurality of exit windows. Each target point group includes a plurality of target points, each target point receiving bombardment from a corresponding electron beam drawn from the cathode and generating an X-ray beam. The distance between two adjacent target points in each target point group is smaller than the distance between two adjacent target groups. The plurality of X-ray beams generated by the plurality of target points in each target point group are led out of the X-ray tube through the exit windows corresponding to that target point group, and the radiation fields of all X-ray beams substantially overlap on a common plane located outside the X-ray tube.

[0044] Figure 1 This is a schematic diagram illustrating the principle of a multifocal X-ray tube according to an exemplary embodiment of the present invention; Figure 2 This is a schematic cross-sectional view of a multifocal X-ray tube according to an exemplary embodiment of the present invention; Figure 3 This is a simplified top view illustrating a multifocal X-ray tube according to an exemplary embodiment of the present invention; Figure 4 It is shown Figure 3 The figure shows a front view of the housing of a multifocal X-ray tube, with the windows not shown.

[0045] like Figures 1-4As shown, a multifocal X-ray tube 100 according to an embodiment of the present invention includes: a housing 1, a cathode 2, a window 5, and a plurality of anodes 3. A plurality of spaced-apart exit windows 4 are provided on the front wall 11 of the housing 1; the window 5 covers the plurality of exit windows 4 to seal the housing 1, allowing a vacuum to be formed inside the housing 1. The exit windows 4 and the window 5 are collectively referred to as X-ray windows. The cathode 2 is located within the housing 1 and is configured to extract electron beams E from multiple locations. The plurality of anodes 3 are located within the housing and have a plurality of target groups 31 corresponding one-to-one with the plurality of exit windows. Each target group 31 includes a plurality of target points (foci) 311, all target points are arranged in a straight line, and each target point 311 receives bombardment from the corresponding electron beam E extracted from the cathode 2 and generates an X-ray beam X. The distance between two adjacent target points (foci) 311 in each target point group 31 is smaller than the distance between two adjacent target point groups 31; multiple X-ray beams X generated by multiple target points 311 in each target point group 31 are led out of the X-ray tube through the extraction window 4 corresponding to that target point group, and the radiation fields of all X-ray beams on the common plane P outside the X-ray tube roughly overlap. That is, the number of target point groups 31 and the number of extraction windows 4 correspond one-to-one, and the X-ray beams X generated by multiple target points 311 belonging to the same target point group 31 can be led out through the same extraction window 4; the X-ray beams generated by all target points 311 can be led out from the same sidewall 11 of the multifocal X-ray tube, and their radiation fields on the common plane P outside the same sidewall 11 of the multifocal X-ray tube roughly overlap.

[0046] Specifically, a single cathode can be used, or multiple cathodes corresponding to the number of target points (foci) can be used. Under the control of the cathode controller, cathode 2 generates an electron beam E. Under the control of the anode controller, a high voltage is generated on anode 3, causing the electron beam E drawn from cathode 2 to be accelerated and energized by the high-voltage electric field located between the cathode and anode 3, impacting multiple target points (or focal points) 311 on multiple focal planes on anode 3, thereby controllably generating multiple X-ray beams X. An external controller is electrically connected to cathode 2 and anode 3 through an external power interface to control the operation of cathode 2 and anode 3. In this paper, the radiation field refers to the area of ​​the common irradiation region (detection region of the X-ray detector) of all X-ray beams pointing out of the X-ray tube on plane P, where the intensity of the X-rays irradiating the radiation field exceeds a specific or prescribed level.

[0047] In the multifocal X-ray tube of this embodiment, the target point 311 of the anode 3 is divided into multiple target point groups 31, and the distance between two adjacent target points 311 in each target point group 31 is smaller than the distance between two adjacent target point groups 31. In this way, without significantly increasing the external dimensions of the housing 1, the number and distribution density of target points within the housing 1 are ensured, thereby enabling the X-ray imaging system using this multifocal X-ray tube to obtain more information from different angles, and thus construct a high-definition three-dimensional image. On the other hand, the X-ray beams generated by the multiple target points 311 in each target point group 31 are led out of the X-ray tube through a common corresponding extraction window 4, and the radiation fields of the multiple X-ray beams on a common plane P outside the X-ray tube approximately overlap. This can improve the structural strength and sealing of the housing 1 and the extraction window 4 without increasing the thickness of the front wall 11 of the housing 1, reduce the shrinkage deformation of the extraction window during operation when the housing is in a vacuum state, and reduce the manufacturing cost of the X-ray tube.

[0048] Furthermore, in radiation imaging systems incorporating such multifocal X-ray tubes, the X-ray beam emanating from the tube penetrates the object being inspected. Multiple X-ray detectors mounted in the plane of the radiation field detect the intensity of the X-ray beam illuminating the field, thereby detecting the physical properties of the object. Since all X-ray beams converge in a common radiation field, X-ray detectors can be placed only within the area of ​​the radiation field, reducing the number of detectors and lowering the complexity and manufacturing cost of the radiation imaging system.

[0049] It can be understood that the common region (radiation field) outside the shell 1 refers to a plane with a finite area located in front of the extraction window 4 and intersecting with the X-ray beams extracted from each extraction window. For example, the plane containing this radiation field is approximately parallel to the side wall plane of the shell where the extraction window 4 is located.

[0050] In embodiments of the present invention, such as Figure 1 As shown, the focal plane of each target point 311 is configured such that the central axis of the X-ray beam generated from the target point 311 is parallel to the incident electron beam E (see [reference]). Figure 9The X-ray beam (described below) is perpendicular to the central axis of the incident electron beam, and the plane formed by the two is perpendicular to the focal plane. Thus, the X-ray beam with optimal application value travels in a direction where the central axis of the incident electron beam is perpendicular to the central axis of the incident electron beam, and the plane formed by the two is perpendicular to the focal plane. To converge the X-ray radiation beam with optimal application value to the same area outside the X-ray tube, different focal planes need to be installed for each target location. For example, the focal plane located on the central line of the multifocal X-ray tube is parallel to the plane of the radiation field, while the focal planes on either side of the central line form an angle with the plane of the radiation field, with the angle increasing the further away from the central line. Thus, by setting the orientation of the focal plane on the anode (the angle relative to the plane of the radiation field), the most valuable portion of the X-rays generated at each target point passes through the corresponding X-ray window and / or collimator, and the X-ray beam (application radiation beam) drawn from the X-ray tube can be converged into a common radiation field.

[0051] In one exemplary embodiment, such as Figure 3 and Figure 4 As shown, the spacer 41 between adjacent outlet windows 4 is integrally formed with the front wall 11, and the width 'a' of the spacer 41 is not less than the thickness of the front wall. The spacer 41 serves as a structural support between the two outlet windows 4. In an exemplary embodiment, the housing 1 is made of a metal material such as stainless steel. Finite element simulation analysis using SolidWorks Simulation software (described in detail below) shows that if the width of the spacer 41 is less than the thickness of the front wall 11, the local stress at the spacer 41 will be too large. Calculations show that the stress concentration at the spacer is significant and far exceeds the yield strength of stainless steel. Furthermore, problems such as large deformation and failure to meet design requirements exist during processing.

[0052] In one exemplary embodiment, such as Figure 3 and Figure 4 As shown, the distance b between two adjacent target point groups 31 satisfies the following relationship (1):

[0053] (1);

[0054] Among them, the geometric centers of multiple target points are located on the target point line parallel to the front wall, a is the distance between two adjacent lead-out windows 4 (the length of the interval), d is the distance between the target point line and the front wall, l is the distance between the plane P where the radiation field is located and the target point line, and c is the length of the radiation field in the direction parallel to the target point line.

[0055] In one exemplary embodiment, such as Figure 3 and Figure 4As shown, the length s of each outgoing window satisfies the following relationship:

[0056] (2);

[0057] Where n is the number of targets in each target group, f is the distance between two adjacent targets in each target group, and c is the length of the radiation field in the direction parallel to the target line. In this way, f can be reduced to 4 mm, and as many target points as possible can be set on the anode 3 to form a high-resolution three-dimensional image.

[0058] According to embodiments of the present invention, the multifocal X-ray tube, by concentrating multiple target points 311 into a target point group 31, can reduce the distribution length of all target points. The overall volume of the X-ray tube can be made smaller, the spacing between adjacent target points is smaller, and the target point density is greater, thereby increasing the number of viewing angles of the X-ray beam and resulting in richer three-dimensional image information and better reconstruction effect based on the X-ray beam.

[0059] In some embodiments, 4 mm ≤ f ≤ 5 mm, and b is 4-5 times f. For example, f is 4 mm, 4.05 mm, 4.1 mm, 4.15 mm, 4.2 mm, 4.25 mm, 4.3 mm, 4.35 mm, 4.4 mm, 4.45 mm, 4.5 mm, 4.55 mm, 4.6 mm, 4.65 mm, 4.7 mm, 4.75 mm, 4.8 mm, 4.85 mm, 4.9 mm, 4.95 mm, or 5 mm.

[0060] In an exemplary embodiment, a = 5 mm, d = 50 mm, l = 1550 mm, and c = 430 mm are taken. Then, according to the relation (1), the distance b between two adjacent target point groups 31 is not less than 17.4 mm.

[0061] Based on the above, in one example, assuming the shell length is 1000 mm, 7 target point groups are set, and b is 17.4 mm and f is 4 mm, then based on the following relationship (3):

[0062] (3);

[0063] We obtain n = 32.9. Rounding 32.9 to the nearest integer, we get n = 32 targets in each target group. Thus, the total number of targets is 224 (32 × 7). Furthermore, based on the above, and using the above relationship (2), we can obtain that the length s of each extraction window is not less than 133.8 mm.

[0064] Based on the above, in another example, assuming the shell length is 1000 mm, 7 target point groups are set, and b is 17.4 mm and f is 12 mm, then the following relationship (3) can be used:

[0065] (3);

[0066] We get n = 11.6. Rounding 11.6 to the nearest integer, we get n = 11 targets in each target group. Thus, the total number of targets is 77 (11 × 7).

[0067] In one exemplary embodiment, such as Figure 3 and Figure 4 As shown, to ensure that the X-ray beam covers the detector array located in the radiation field, the width h of each extraction window satisfies the following relationship (4):

[0068] (4);

[0069] Where d is the distance between the target line and the front wall, l is the distance between the plane P containing the radiation field and the target line, and w is the length of the radiation field in the direction perpendicular to the target line.

[0070] In one exemplary embodiment, such as Figure 3 and Figure 4 As shown, the total length Ly of all outgoing windows satisfies the following relationship (5):

[0071] (5);

[0072] Where d is the distance between the target line and the front wall, l is the distance between the plane P where the radiation field is located and the target line, c is the length of the radiation field in the direction parallel to the target line, and Ls is the minimum distribution length of all focal points.

[0073] In an exemplary embodiment, d is 50 mm, l is 1550 mm, the radiation field is square, i.e., w=c and w is 430 mm, Ls is 744 mm. Based on relation (4), we get h≥13.9 mm. Based on relation (5), we get Ly≥733.5 mm. Considering the processing and assembly errors, as well as the influence of the thickness of the front wall of the housing on the beam angle, the initial setting of the ray window width h is 15 mm, and the sum of the distribution lengths of all focal points is 740 mm. Thus, the size of all lead-out windows 4 is 15 mm × 740 mm, which is an ultra-large area. Sampling stainless steel film is used as window 5 to ensure the reliability of welding and high-temperature baking exhaust processes. When designing the housing 1, the material of window 5 is considered flexible.

[0074] In one exemplary embodiment, see Figure 4If h is the width (height) of each lead-out window, the length s of each lead-out window 4 is no greater than 30 times the width h. In some embodiments, the length s of each lead-out window 4 does not exceed 300 mm, for example, it can be 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, or 300 mm. In an exemplary embodiment, all lead-out windows 4 are 15 mm × 740 mm in size. If 7 lead-out windows 4 are provided (with 6 spacers 41), and the distance (length of the spacer) a between two adjacent lead-out windows 4 is 5 mm, then the length of each lead-out window is 101.4 mm ((740 - (7-1) × 5) / 7). In this way, when the housing 1 is in a vacuum working state, the dimensional deformation of the lead-out windows 4 can be very small, such as deformation ≤ 0.1 mm.

[0075] In one exemplary embodiment, the length s of each lead-out window 4 is no greater than 300 mm, such that the deformation of the lead-out window in the operating state is no greater than 0.1 mm. For example, when seven lead-out windows are provided, the length of each lead-out window is 101.4 mm.

[0076] Figure 5 This is a front view showing a housing according to an exemplary embodiment of the present invention.

[0077] In one exemplary embodiment, see Figure 5 The window 5 is made of a thin film that allows X-ray beams to pass through, and the exit windows 4 share a single, integral film. That is, multiple exit windows 4 share a large-area window 5, which is vacuum-sealed with a complete rectangular annular ring on the front wall 11 that surrounds all exit windows 4. In this way, the width 'a' of the gap 41 between adjacent exit windows 4 is not affected by the sealing area of ​​the window 5, and can be made as small as possible, which is beneficial for further reducing the distribution density of the exit windows and the arrangement density of the focal group.

[0078] Figure 6 This is a front view showing a housing according to another exemplary embodiment of the present invention.

[0079] In one exemplary embodiment, see Figure 6The window 5 is made of a thin film that allows X-ray beams to pass through, and the film on each lead-out window 4 is independent. That is, the window 5 for each lead-out window 4 forms a vacuum seal with the front wall 11 surrounding that lead-out window 4. This construction reduces the area of ​​each window, making it easier to ensure the structural strength of the housing and to seal individual lead-out windows. Furthermore, damage to one lead-out window will not affect the function and sealing of other lead-out windows.

[0080] Figure 7 This is a cross-sectional view showing the front wall of the housing according to an exemplary embodiment of the present invention; Figure 8 This is a cross-sectional view showing the front wall of the housing according to another exemplary embodiment of the present invention.

[0081] Those skilled in the art will understand that the extraction window is suitable for extracting X-rays generated under vacuum conditions inside the housing 1 of a multifocal X-ray tube to the external atmospheric environment for applications such as X-ray fluoroscopy imaging. On one hand, the extraction window 4 must isolate the vacuum from the atmospheric environment; therefore, it must possess sufficient strength and form an integral sealed structure with the housing 1 to prevent air from entering the housing. This allows the cathode 2 and anode 3 to remain in a high vacuum environment for extended periods, ensuring that the anode 3 is under a relatively high voltage relative to the cathode 2 without easily causing breakdown or arcing. On the other hand, it must extract the X-ray beam to the outside of the housing while minimizing obstruction of the X-ray beam. Therefore, a window 5, typically very thin, is installed on the extraction window 4. Because the material forming the window 5 is very thin, the X-ray transmittance is significantly improved, effectively suppressing X-ray energy loss. For example, as... Figure 7 As shown, the thickness D1 of the window 5 is less than 1 mm, preferably 0.02-0.5 mm. In a further embodiment, the ratio of the window thickness D1 to the thickness D of the housing 1 is less than 1:5, preferably less than 1:10. The window 5 can be disposed on the inner side, outer side, or between the inner and outer sides of the lead-out window 4. Figure 8 As shown, window 5 is positioned outside the lead-out window 4. Window 5 and housing 1 may be made of the same or different materials.

[0082] Figure 9 This is a simplified schematic diagram illustrating the principle of a multifocal X-ray source according to an exemplary embodiment of the present invention.

[0083] According to another embodiment of the invention, see Figure 9 A multifocal X-ray source 400 is provided, comprising: a multifocal X-ray tube as described in any of the above embodiments; an anode controller 7 connected to the anode 3 and providing anode high voltage; and a cathode controller 8 connected to the cathode 2 and controlling the cathode to generate an electron beam E emitted to each focal position.

[0084] In a further embodiment, the multifocal X-ray tube of this invention further includes an anode cooling device 9 configured to control the anode temperature and a shielding device 10 configured to shield X-rays from directions other than the radiation beam. Thus, in a radiation imaging system including such a multifocal X-ray source, the X-ray beam emitting the X-ray source penetrates the object being inspected, and the intensity of the X-ray beam irradiating the radiation field is detected by multiple X-ray detectors mounted in the plane of the radiation field, thereby detecting the physical properties of the object being inspected. Since all X-ray beams converge in a common radiation field, X-ray detectors can be placed only within the area of ​​the radiation field, reducing the number of detectors, lowering the complexity and manufacturing cost of the radiation imaging system, while enabling rapid multi-view imaging.

[0085] Figure 10 This is a schematic diagram illustrating the principle of a human body tomography device according to an exemplary embodiment of the present invention.

[0086] According to another aspect of the present invention, see Figure 10 A human body tomography imaging device is provided, comprising: a support frame 12; a multifocal X-ray source 400 as described in any of the above embodiments, mounted on the support frame 12; a bed 14 adapted to carry a patient being examined, wherein an X-ray beam from the multifocal X-ray source 400 irradiates the patient 300; a detector array 15 disposed within the bed 14, adapted to receive the X-ray beam after the patient 300; and an imaging device 13, which generates a three-dimensional image based on the X-ray beam received by the detector array.

[0087] In a further exemplary embodiment, the human body tomography apparatus also includes a beam limiter 16 configured to shape the X-ray beam drawn from the multifocal X-ray source 400. By setting the beam limiter 16, the shape and irradiation position of the applied radiation beam can be limited, so that the multiple X-ray beams from the X-ray tubes are well converged on the detector array.

[0088] The human tomographic imaging device provided in the embodiments of the present invention can be used for rapid three-dimensional imaging of a mobile human thoracic cavity. It achieves fluoroscopic imaging from different angles by sequentially emitting X-ray beams from multiple focal points at different locations inside the X-ray tube. Then, a tomographic image of the thoracic cavity is reconstructed using a tomographic imaging algorithm, assisting doctors in making more accurate diagnoses. The distributed multifocal X-ray tube is suspended at the upper end of the support frame 12. The design targets are an anode high voltage of 120kV, an anode current of 15mA, an anode length not exceeding 1 meter, and a weight not exceeding 40 kilograms.

[0089] In a distributed multifocal X-ray tube of an exemplary embodiment, at least 60 X-ray beams at different angles can be output through an internally arrayed array of carbon nanotube (CNT) cold cathodes and arrayed anode targets. The X-ray beam generated by each target point is collimated by a collimator (or beam limiter) and passes through the chest cavity of the patient being examined, covering the detector array below the patient's body. Therefore, the X-ray tube cavity formed within the housing 11 of the distributed multifocal X-ray tube is designed as a long rectangle according to the array arrangement of the cathode 2, anode 3, and target 311, with a long linear X-ray window on the front wall 11.

[0090] In one exemplary embodiment, the CNT cold cathodes within the X-ray tube cavity can be arranged in a close-packed configuration with a minimum spacing of 12 mm. A design of 63 cathodes generates 63 focal points (targets) on the anode. The minimum distribution length of all focal points (excluding the distance between target groups) is 744 mm. The anode operates at a high voltage of 120 kV. Considering the insulation distance from the anode, the length of the housing will be close to 1 m. The sum of the opening lengths of all the lead-out windows 4 on the front wall 11 is similar to the sum of the focal point distribution lengths.

[0091] In one exemplary embodiment, the X-ray window of the X-ray tube is made of a lightweight, thin sheet of metal, which allows for a high proportion of X-ray beam passage while achieving a high-vacuum seal inside the housing. The size and structure of the exit window opening can be designed according to the irradiation area of ​​the X-ray beam. For example, in a thoracic DR imaging device including the multifocal X-ray tube of this embodiment, the detector array size is 43 cm × 43 cm, and the distance between the detector array and the X-ray tube is 150 cm. Figure 3 As shown, the dimensions of the X-ray tube's ray window in the cone angle (width) and fan angle (length) directions can be calculated separately.

[0092] Performance comparison of X-ray tubes according to embodiments of the present invention, and X-ray tubes based on related technology 1 (CN109216140B) and related technology 2 (CN109935509A).

[0093] For the X-ray tube of the present invention and the X-ray tube based on related technology 1 and related technology 2, finite element simulation and physical measurement were performed using SolidWorks Simulation software to analyze the structural stress and deformation under the two design schemes.

[0094] Figure 11 This is a simplified top view illustrating a multifocal X-ray tube of a related technology; Figure 12 It is shown Figure 11 The front view of the housing of the multifocal X-ray tube is shown.

[0095] In a multifocal X-ray tube based on prior art 1, see Figure 11 and Figure 12 A narrow, elongated slit-like extraction window 104 is arranged on the housing 101 at a position aligned with the multiple target points 1031 of the anode 103 disposed inside the housing 101. A window body 105 is disposed on the extraction window 104. Multiple X-ray beams X emitted from the multiple target points 1031 of the anode 103 are extracted to the outside of the housing 101 through the common extraction window 104.

[0096] Figure 13 This is a simplified top view illustrating another related technology: a multifocal X-ray tube. Figure 14 It is shown Figure 13 The front view of the housing of the multifocal X-ray tube is shown.

[0097] In a multifocal X-ray tube based on prior art 2, see Figure 13 and Figure 14 Multiple exit windows 204 are arranged on the housing 201 at positions aligned with the multiple target points 2031 of the anode 203 inside the housing 201. Window bodies 205 are set on the exit windows 204. Multiple X-ray beams X emitted from the multiple target points 2031 of the anode are led out to the outside of the housing 201 through their respective aligned exit windows 204. The number of exit windows 204 is consistent with the number of target points 2031 and corresponds one-to-one.

[0098] Comparative Analysis Example 1

[0099] A comparison between the X-ray tube of this invention and the X-ray tube based on related technology 1.

[0100] For the X-ray tube of this embodiment of the invention and an example of an X-ray tube based on related technology 1 (shell cross-section 136mm×141mm×1000mm, window height 5mm, cavity stainless steel thickness 3mm), calculations were performed, and the following results were obtained under the condition of equal thickness:

[0101] (1) In the embodiment of the present invention, the maximum deformation at the exit window of the X-ray tube under vacuum (at atmospheric pressure) is sharply reduced from 3.28 mm with a single exit window in related technology 1 to 0.055 mm with 7 windows in the embodiment of the present invention, a reduction of 98.5%; the inward deformation of the front wall 11 of the housing 1 is reduced from 1.258 mm to 0.367 mm, which is lower than the requirement that the inward deformation should not exceed 0.4 mm. It can be seen that the interval between the exit windows in the embodiment of the present invention has a supporting function, effectively reducing the deformation of the X-ray window and effectively ensuring the positional accuracy of the X-ray window.

[0102] (2) The maximum stress at the exit window of the X-ray tube in this embodiment of the invention is 1.692 × 10⁻⁶. 8 N / m 2Compared to the maximum stress of 3.565 × 10 at the lead-out window in related technology 1. 8 N / m 2 The strength was reduced by 52%, and fell within the yield strength range of stainless steel. Therefore, the X-ray tube of this embodiment effectively ensures the overall structural strength of the housing.

[0103] (3) According to the above example of the shell, in order to achieve the same amount of deformation, the weight of the shell of related technology 1 needs to be increased to about 249 kg, which is 24.6 times the weight of the shell of the X-ray tube in the embodiment of the present invention.

[0104] Comparative Analysis Example 2

[0105] A comparison between the X-ray tube of this invention and the X-ray tube based on related technology 2.

[0106] Examples of X-ray tubes according to embodiments of the present invention and X-ray tubes based on related technology 2, such as Figure 3 , Figure 4 and Figure 13 As shown, the shell is 1000 mm long, and f = 4 mm, d = 50 mm, l = 1550 mm, and c = 430 mm.

[0107] For the X-ray tube based on related technology 2, since the lead-out window is independently sealed and welded, a = 5 mm. According to the relationship (1), the distance b between two adjacent target points 2031 is not less than 19.5 mm. Then the number of all target points m can be calculated by the following relationship:

[0108] .

[0109] That is, the total number of target points m of the X-ray tube based on related technology 2 is 52.

[0110] For an X-ray tube according to one embodiment of the present invention, 7 target groups are set. Since the lead-out window is sealed and welded by a common window body, a=3 mm. According to the relationship (1), the distance b between two adjacent target groups 31 is not less than 17.4 mm. Therefore, it can be based on the following relationship (3):

[0111] (3);

[0112] The number of target points n in each target point group is 32.9. Rounding 32.9 to the nearest integer, the number of target points n in each target point group is 32. Thus, in this embodiment of the invention, when the X-ray tube is integrally sealed and welded by a common window, the total number of target points m1 is 224 (32 × 7).

[0113] For the X-ray tube of another embodiment of the present invention, 7 target point groups are set. Since the lead-out windows are independently sealed and welded by different window bodies, in order to ensure the sealing strength, a=5 mm. According to the relationship (1), the distance b between two adjacent target point groups 31 is not less than 19.5 mm. Then, based on the following relationship (3):

[0114] (3);

[0115] The number of target points n in each target point group is 32.5. Rounding 32.5 to the nearest integer, the number of target points n in each target point group is 32. Thus, in this embodiment of the invention, when the X-ray tube is independently sealed and welded by different windows, the total number of target points m2 is 224 (32 × 7).

[0116] Thus, in this embodiment of the invention, the X-ray tube has a maximum of 224 target points within a 1-meter radius of the housing, while in related technology 2, the maximum number of target points is 52. This represents a 330% increase in target point density while maintaining the overall strength and deformation of the X-ray tube. Therefore, without significantly increasing the external dimensions of the housing 1, the number and distribution density of target points within the housing 1 can be ensured. This allows the X-ray imaging system using this multifocal X-ray tube to obtain information from more different angles, thereby constructing high-resolution three-dimensional images. Furthermore, finite element simulation analysis shows that the deformation and overall strength of the housing are also guaranteed due to the local support reinforcement of the spacing between adjacent lead-out windows.

[0117] Comparative Analysis Example 3

[0118] A comparison of the X-ray tube of the present invention with X-ray tubes based on related technology 1 and prior art 2.

[0119] The X-ray tubes provided in the embodiments of the present invention, as well as those based on related technology 1 and prior art 2, are all X-ray tubes used in human body tomography equipment for three-dimensional imaging of the human thoracic cavity. In these X-ray tubes, the distance l between the plane P containing the radiation field and the target line is 1550 mm, the distance d between the target line and the front wall is 50 mm, the length c of the radiation field in the direction parallel to the target line is 430 mm, the width h of the lead-out window is 15 mm, and the thickness of the sidewall of the shell made of 304 stainless steel plate is 3.0 mm.

[0120] Meanwhile, in order to ensure the reliability of the vacuum devices inside the housing, the deformation and structural stress are controlled as follows: (1) The width of the lead-out window does not exceed 0.1 mm, reducing the radiation field of the emitted X-ray beam, and at the same time reducing the deformation and pulling amount of the X-ray window frame on the vacuum sealing film (window) to ensure the reliable sealing effect; (2) The structural stress at each position inside the housing is less than the yield strength of the material.

[0121] For X-ray tubes based on related technology 1, such as Figure 11 and Figure 12 As shown, a slender slit-type extraction window 104 is used, with a minimum distribution length of all focal points Ls = 744 mm and a total length Ly of all extraction windows of 740 mm. When the cavity structure (inside the shell) is subjected to one atmosphere of pressure in a high-vacuum environment, it will undergo certain deformation. Finite element simulation analysis shows that the maximum deformation at the central position of the X-ray window extraction window is 1.494 hm, far exceeding the design requirement of 0.1 mm. The maximum stress at the corner of the extraction window reaches 8.134 × 10⁻⁶. 8 N / m 2 This far exceeds the yield strength of 304 stainless steel (2.068 × 10⁻⁶). 8 N / m 2 With 63 target points, the target point distribution density of this X-ray tube can reach up to 85 targets / meter (63 / 0.744).

[0122] For X-ray tubes based on related technology 2, such as Figure 13 and Figure 14 As shown, the number of extraction windows 204 is consistent with the number of target points 1031, and they correspond one-to-one. Each target point emits a beam through a separate X-ray window. The deformation and stress distribution under atmospheric pressure in the high-vacuum cavity structure (inside the shell) meet the design requirements. The distance (length of the spacer) a between two adjacent extraction windows 204 is 5 mm, and the minimum distance f' between two adjacent target points is 19.5 mm. Therefore, 52 target points are arranged in the equivalent length of 1 meter for the total length Ly of all extraction windows (1000 / (19.5+5)). Thus, the target point distribution density of the X-ray tube based on background technology 2 is 52 / meter, and the total number of target points is reduced by 38.8% ((85-52) / 85) compared to background technology 1.

[0123] For the X-ray tube of this embodiment of the invention, such as Figure 3 and Figure 4As shown, seven target point groups 31 are set, and each target point group 31 has nine target points 311. A gap of about 5 mm is reserved between adjacent lead-out windows 4 as a reinforcing rib structure. The total length of all lead-out windows (including the length a of the gap) Ly is 802 mm. The deformation and maximum stress of the X-ray window are within the normal range. Thus, the target point distribution density of the X-ray tube in this embodiment of the invention is 78 targets / meter (63 / 0.802), which is only 8.2% lower than that of the X-ray tube based on related technology 1 ((85-78) / 85).

[0124] In other words, compared with the X-ray tube based on related technology 1, with the same 63 target points, the X-ray tube of the present invention has a gap of about 5 mm between adjacent target point groups 31, the total length Ly (802 mm) of all lead-out windows is increased, the target point distribution density is slightly reduced, but the structural strength is significantly enhanced.

[0125] The comparative values ​​of the three X-ray tubes are shown in the table below after analysis:

[0126]

[0127] Comparative analysis reveals that in prior art 1, the use of a narrow, elongated slit-type extraction window leads to structural instability of the X-ray tube due to the lack of a support area (extraction window shrinkage deformation > 0.1 mm); in prior art 2, the dense spacing between multiple independent extraction windows, acting as a support structure, results in a significant decrease in target density (38.8%). Neither prior art 1 nor prior art 2 can simultaneously meet the requirements of vacuum sealing strength, high-density imaging, and compactness.

[0128] In contrast, the X-ray tube of this invention adopts the inventive concept of target point grouping and target points sharing an extraction window in each target point group. This overcomes the defect of reduced strength caused by the lack of support structure for a single independent extraction window in related technology 1, and also eliminates the defect of significantly reduced target point density in related technology 2. Under the premise of ensuring structural strength and positional accuracy, it effectively improves target point density and completely resolves the contradiction triangle of "strength-density-size".

[0129] Although the invention has been described in detail with reference to embodiments currently considered to be the most practical and preferred for illustrative purposes, those skilled in the art will understand that the embodiments described above are exemplary and can be modified thereto. The structures described in the various embodiments can be freely combined without causing structural or principle conflicts, thereby achieving a wider variety of multifocal X-ray tubes and multifocal X-ray sources while solving the technical problems of the present invention.

[0130] After a detailed description of the preferred embodiments of the present invention, those skilled in the art will clearly understand that various changes and modifications can be made without departing from the scope and spirit of the appended claims, and that the present invention is not limited to the embodiments described in the specification.

Claims

1. A multifocal X-ray tube, comprising: The housing has multiple spaced-out windows on its front wall; A form, covering multiple outgoing windows, to seal the housing; as well as Multiple anodes are located within the housing and have multiple target groups corresponding to multiple extraction windows. Each target group includes multiple target points, and each target point receives bombardment from a corresponding electron beam extracted from the cathode, generating an X-ray beam. The distance between two adjacent target points in each target group is less than the distance between two adjacent target groups; multiple X-ray beams generated by multiple target points in each target group are led out of the X-ray tube through the extraction window corresponding to the target group, and the radiation fields of all X-ray beams on a common plane outside the X-ray tube roughly overlap. The gap between adjacent lead-out windows is integrally formed with the front wall, and the width 'a' of the gap is not less than the thickness of the front wall. Distance between two adjacent target groups The following relationship must be satisfied: Among them, the geometric centers of multiple target points are located on the target point line parallel to the front wall, a is the distance between two adjacent lead-out windows, d is the distance between the target point line and the front wall, l is the distance between the plane where the radiation field is located and the target point line, and c is the length of the radiation field in the direction parallel to the target point line.

2. The multifocal X-ray tube according to claim 1, wherein, The length s of each outgoing window satisfies the following relationship: Where n is the number of targets in each target group, f is the distance between two adjacent targets in each target group, and c is the length of the radiation field in the direction parallel to the target line.

3. The multifocal X-ray tube according to claim 1 or 2, wherein, The width h of each outgoing window satisfies the following relationship: Where d is the distance between the target line and the front wall, l is the distance between the plane P containing the radiation field and the target line, and w is the length of the radiation field in the direction perpendicular to the target line.

4. The multifocal X-ray tube according to claim 3, wherein, The length of each outgoing window shall not exceed 30 times its width.

5. The multifocal X-ray tube according to claim 4, wherein, The length of each lead-out window is no more than 300 mm, so that the deformation of the lead-out window in the operating state is no more than 0.1 mm.

6. The multifocal X-ray tube according to claim 1 or 2, wherein, The window is made of a thin film that allows X-ray beams to pass through, and all the lead-out windows share a single, integral thin film.

7. The multifocal X-ray tube according to claim 1 or 2, wherein, The window is made of a thin film that allows X-ray beams to pass through, and the thin film set on each lead-out window is independent.

8. A multifocal X-ray source, comprising: The multifocal X-ray tube according to any one of claims 1-7; An anode controller is connected to the anode and provides high voltage to the anode. as well as A cathode controller is connected to the cathode and controls the cathode to generate an electron beam that is emitted toward each target location.

9. A human body tomographic imaging device, comprising: Support frame; The multifocal X-ray source as described in claim 8 is mounted on the support frame; A bed, suitable for accommodating the patient being examined, on which an X-ray beam from the multifocal X-ray source irradiates; A detector array, disposed within the bed, is adapted to receive X-ray beams after the patient. as well as An imaging device that generates a three-dimensional image based on the X-ray beam received by the detector array.

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