Flat X-ray source and manufacturing method thereof

Abstract

The invention provides a flat plate X-ray source and a manufacturing method thereof. The flat plate X-ray source comprises a flat plate cathode and a flat plate anode which are oppositely arranged, the flat plate cathode comprises a first substrate, a conductive layer and a cathode emission layer which are sequentially laminated, the conductive layer comprises a plurality of conductive strips which are arranged in parallel at intervals, the cathode emission layer is deposited on the conductive strips, and the conductive strips are mutually insulated; the flat anode comprises a second substrate and a target material layer which are laminated in sequence, the target material layer comprises a plurality of target material strips which are arranged in parallel at intervals, the target material strips are mutually insulated, the target material strips are perpendicular to the conductive strips, and the projections of the target material strips on the first substrate and the conductive strips have overlapped areas. Each point source of the flat plate X-ray source can be independently controlled, namely, the emission area of the flat plate X-ray source is selectable, and only the area of interest can be irradiated under control, so that the radiation dose of a patient is remarkably reduced, and high-quality and high-contrast X-ray images can be obtained at a low dose level.

Description

Technical Field

[0001] The present application belongs to the technical field of X-ray imaging, and in particular, to a flat-panel X-ray source and a method for manufacturing the same. Background Art

[0002] X-ray tubes are widely used in medical imaging, industrial inspection, security inspection, scientific instrument analysis and other fields. Conventional X-ray tubes are usually composed of a thermionic cathode and a metal anode target. Due to the intrinsic characteristics of the thermionic cathode, this type of X-ray tube has the disadvantages of long response time, high power consumption, short life and large size. Field emission X-ray tubes using field emitters (i.e., cold cathodes) are expected to overcome these problems. When a cold cathode made of nanomaterials (e.g., carbon nanotubes, graphene) is used to replace the thermionic cathode, the X-ray tube has the advantages of low operating temperature, instantaneous response time and easy miniaturization, providing many benefits in applications such as high-resolution imaging, dynamic radiography and portable radiation systems. In general, conventional X-ray tubes emit X-rays from a single focal spot, resulting in a wide divergence of the X-ray cone beam. This requires that a sufficient distance be maintained between the single-point X-ray source and the imaging object to completely cover the imaging object for X-ray imaging, which increases the size of the imaging system. In medical applications, patients and operators may be exposed to unnecessary radiation risks. In addition, due to the geometric magnification effect, the divergent X-ray cone beam can cause image distortion of the imaging object.

[0003] In summary, traditional single-point emission thermionic cathode X-ray tube imaging has problems such as low spatial and temporal resolution and high radiation dose. Summary of the invention

[0004] The technical problem solved by the present application is: how to provide a flat-panel X-ray source and a manufacturing method thereof that can improve the spatial and temporal resolution during imaging and reduce the radiation dose.

[0005] The present application provides a flat-panel X-ray source, which includes a flat-panel cathode and a flat-panel anode arranged opposite to each other, wherein:

[0006] The flat cathode comprises a first substrate, a conductive layer, and a cathode emission layer stacked in sequence, wherein the conductive layer comprises a plurality of conductive strips spaced apart and arranged in parallel, the cathode emission layer is deposited on each of the conductive strips, and each of the conductive strips is insulated from each other;

[0007] The flat anode includes a second substrate and a target material layer stacked in sequence, the target material layer includes a plurality of target material strips spaced apart and arranged in parallel, the target material strips are insulated from each other, the target material strips are perpendicular to the conductive strips, and the projection of the target material strips on the first substrate has an overlapping area with the conductive strips.

[0008] Optionally, a projection of each of the target material strips on the first substrate has an overlapping area with all the conductive strips.

[0009] Optionally, the cathode emission layer is located in the overlapping area.

[0010] Optionally, the planar cathode further includes a gate layer, the gate layer is disposed on the cathode emission layer, and the gate layer is provided with a first through hole, the first through hole exposes the overlapping area, and the gate layer and the cathode emission layer are insulated from each other.

[0011] Optionally, the planar cathode further includes a focusing electrode layer, which is disposed on the gate layer and has a second through hole formed therein, the second through hole being opposite to the first through hole, and the focusing electrode layer and the gate layer are insulated from each other.

[0012] Optionally, the gate layer and the cathode emission layer, and the focusing electrode layer and the gate layer are separated by insulating spacers respectively.

[0013] Optionally, the focusing electrode layer is separated from the planar anode by an insulating spacer.

[0014] The present application also discloses a manufacturing method for manufacturing the above flat-panel X-ray source, the manufacturing method comprising:

[0015] Preparing a flat cathode: preparing a conductive layer on a first substrate, and depositing a cathode emission layer on the conductive layer, wherein the conductive layer includes a plurality of conductive strips that are spaced apart and arranged in parallel, and each of the conductive strips is insulated from each other;

[0016] Preparing a flat anode: preparing a target material layer on a second substrate, the target material layer comprising a plurality of target material strips spaced apart and arranged in parallel, wherein the target material strips are insulated from each other;

[0017] The flat cathode and the flat anode are arranged opposite to each other, so that the target strip is perpendicular to the conductive strip, and the projection of the target strip on the first substrate has an overlapping area with the conductive strip.

[0018] The present application provides a flat-panel X-ray source and a manufacturing method thereof, which have the following technical effects:

[0019] Each point source of the flat-panel X-ray source can be controlled independently, that is, the emission area of ​​the flat-panel X-ray source is selectable, and can be controlled to irradiate only the area of ​​interest, so that the radiation dose to the patient is significantly reduced, and high-quality and high-contrast X-ray images can be obtained at a low dose level. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a side view of a flat panel X-ray source according to one or more embodiments;

[0021] Figure 2 is a top view of a conductive layer according to one or more embodiments;

[0022] Figure 3 is a top view of a target layer according to one or more embodiments. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0024] Before describing the various embodiments of the present application in detail, the technical concept of the present application is briefly described first: At present, the conventional X-ray tube emits X-rays from a single focal point, and there are problems such as low spatial and temporal resolution and large radiation dose during imaging. For this reason, the present application provides a flat X-ray source and a manufacturing method thereof, wherein a striped conductive layer is formed on a flat cathode and a striped target layer is formed on a flat anode, respectively, and the conductive layer and the target layer are perpendicularly crossed with each other. The conductive layer and the target layer are energized at different intersections, and electrons can be generated at the intersections and emitted and bombarded with the target material to generate X-rays, so that addressable emission of the flat X-ray source can be achieved. Each point source of this flat X-ray source can be independently controlled, and the emission area of ​​the flat X-ray source is selectable, and it can be controlled to irradiate only the area of ​​interest, so that the radiation dose to the patient is significantly reduced, and high-quality and high-contrast X-ray images can be obtained at a low dose level. At the same time, the flat X-ray source can significantly shorten the distance between the light source and the imaging object, reduce the volume, and realize a portable mobile X-ray imaging system. The specific principles of the flat X-ray source and the manufacturing method of the present application are described below in conjunction with more embodiments.

[0025] Specifically, Figure 1 , Figure 2 and Figure 3 As shown, the flat-panel X-ray source of the present embodiment includes a flat-panel cathode 10 and a flat-panel anode 20 which are arranged opposite to each other. The flat-panel cathode 10 includes a first substrate 11, a conductive layer 12, and a cathode emission layer 13 which are stacked in sequence. The conductive layer 12 includes a plurality of conductive strips 12a which are spaced apart and arranged in parallel. The cathode emission layer 13 is deposited on each conductive strip 12a, and each conductive strip 12a is insulated from each other. The flat-panel anode 20 includes a second substrate 21 and a target layer 22 which are stacked in sequence. The target layer 22 includes a plurality of target strips 22a which are spaced apart and arranged in parallel. Each target strip 22a is insulated from each other. The target strip 22a is perpendicular to the conductive strip 12a, and the projection of the target strip 22a on the first substrate 11 has an overlapping area with the conductive strip 12a.

[0026] In one or more embodiments, the projection of each target strip 22a on the first substrate 11 has an overlapping area with all the conductive strips 12a. For example, if there are M target strips 22a and N conductive strips 12a, a total of M*N overlapping areas are formed. Exemplarily, the cathode emission layer 13 is located in the overlapping area, and the cathode emission layer 13 is distributed in an array. The cathode emission layer 13 includes a plurality of field emission cathodes, and the field emission cathodes are located in the overlapping area. When a specific target strip 22a and conductive strip 12a are energized, the cathode emission layer 13 at the overlapping area formed by the two generates electrons, thereby realizing addressable emission of the flat-panel X-ray source, and electrons can be generated from M*N different overlapping areas.

[0027] In one or more embodiments, the flat cathode 10 further includes a gate layer 14, the gate layer 14 is disposed on the cathode emission layer 13, and the gate layer 14 is provided with a first through hole 14a, the first through hole 14a exposes the overlapping area, and the gate layer 14 and the cathode emission layer 13 are insulated from each other. When the flat X-ray source is working, the gate layer 14 is grounded, a certain cathode voltage is applied to the cathode emission layer 13, a potential difference is formed between the gate layer 14 and the cathode emission layer 13, an electric field is generated, and the cathode emission layer 13 emits an electron beam under the action of the voltage, and the electron beam passes through the first through hole 14a and moves toward the target layer 22.

[0028] In one or more embodiments, the flat cathode 10 further includes a focusing electrode layer 15, which is disposed on the gate layer 14, and the focusing electrode layer 15 is provided with a second through hole 15a, the second through hole 15a is opposite to the first through hole 14a, and the focusing electrode layer 15 is insulated from the gate layer 14. When the flat X-ray source is working, the generated electron beam is accelerated by the focusing electrode layer 15 and bombards the target layer 22, generating X-rays, which are emitted after passing through the second substrate 21.

[0029] Exemplarily, the gate layer 14 and the cathode emission layer 13 are separated by insulating spacers, the focusing electrode layer 15 and the gate layer 14 are separated by insulating spacers, and the focusing electrode layer 15 and the planar anode 20 are separated by insulating spacers.

[0030] In one or more embodiments, a method for manufacturing a flat panel X-ray source comprises the following steps:

[0031] The steps of preparing the flat cathode 10 are as follows: preparing a conductive layer 12 on a first substrate 11, and depositing a cathode emission layer 13 on the conductive layer 12, wherein the conductive layer 12 includes a plurality of conductive strips 12a spaced apart and arranged in parallel, and each conductive strip 12a is insulated from each other.

[0032] Exemplarily, the first substrate 11 may be an insulating substrate such as glass, ceramic or insulating silicon wafer. The conductive layer 12 may be a conductive material such as gold, silver, titanium, copper, nickel, cobalt, molybdenum, tungsten, platinum, tantalum, etc., with a thickness of 1-10 microns, and the conductive layer 12 may be prepared by magnetron sputtering, electron beam evaporation, screen printing, etc. The material of the cathode emission layer 13 may be one-dimensional nanomaterials such as carbon nanotubes, boron nitride nanotubes, titanium dioxide nanotubes, zinc oxide nanowires, and mixtures thereof, or two-dimensional nanomaterials such as graphene, tungsten disulfide nanosheets, molybdenum disulfide nanosheets, titanium alloy nanosheets, and mixtures thereof, or a mixture of one-dimensional and two-dimensional nanomaterials. The field emission cathode material is deposited above the conductive layer, at the intersection of the conductive strip 12a and the target strip 22a.

[0033] Furthermore, the cathode emission layer 13 may be deposited by screen printing or chemical vapor deposition. For the screen printing method, the field emission material is mixed with the conductive particles, the adhesive particles and the organic solvent by ball milling to form a uniform slurry, and then the slurry is printed on the specified position of the first substrate 11 through a screen printing screen, and after drying, annealing, and mechanical post-treatment, the cathode emission layer 13 is formed. For the chemical vapor deposition method, the catalyst material is deposited on the specified position of the first substrate 11 through a mask to form a catalyst array, and then the first substrate 11 is placed in a reaction furnace, and the field emission material growth precursor is introduced. Under the action of the catalyst, the precursor undergoes a high-temperature reaction to grow the desired field emission material array at the specified position.

[0034] The steps of preparing the flat anode 20 are as follows: preparing a target material layer 22 on the second substrate 21 , wherein the target material layer 22 comprises a plurality of target material strips 22 a which are spaced apart and arranged in parallel, and each target material strip 22 a is insulated from each other.

[0035] Exemplarily, the second substrate 21 is quartz glass or an insulating silicon wafer with a thickness of 0.5-1 mm. The target layer material can be high-purity tungsten, high-purity molybdenum or high-purity rhodium with a purity of 99.99%. The optimal thickness of the target layer 22 (i.e., the highest X-ray output efficiency) is related to the anode operating voltage. The higher the anode operating voltage, the greater the optimal thickness of the target layer. The anode operating voltage is 20-120 kilovolts. For tungsten targets, the optimal thickness is 0.5-5 microns. For molybdenum targets, the optimal thickness is 1-10 microns. For rhodium targets, the optimal thickness is 0.8-8 microns. The target layer 22 can be prepared by magnetron sputtering or electron beam evaporation deposition. During preparation, a striped target layer 22 is obtained through a striped mask, that is, a plurality of target strips 22a are formed.

[0036] Furthermore, the gate layer 14 and the focusing electrode layer 15 can be prepared in sequence, and the gate layer 14 and the focusing electrode layer 15 are made of stainless steel conductive material.

[0037] Finally, the flat cathode 10 and the flat anode 20 are arranged opposite to each other, so that the target strip 22a is perpendicular to the conductive strip 12a, and the projection of the target strip 22a on the first substrate 11 has an overlapping area with the conductive strip 12a. When the flat X-ray source is working, the gate is grounded, a certain cathode voltage is applied to the cathode, and the cathode emission layer 13 emits an electron beam under the action of the voltage. After the electron beam is focused by the focusing electrode, it is accelerated by the anode voltage and bombards the target layer 22 to generate X-rays. The X-rays are emitted through the second substrate 21. When a specific target strip 22a and a specific conductive strip 12a are energized at the same time, the cathode emission layer 13 at the intersection position emits electrons and bombards the target material to generate X-rays, so that the addressable emission of the flat X-ray source can be realized.

[0038] Compared with the traditional single-point emission thermionic cathode X-ray tube, the flat-panel X-ray source of this embodiment has a low operating temperature, low power consumption, and extremely fast response time, which can significantly improve the temporal resolution of X-ray imaging. In addition, due to the large area of ​​the flat-panel anode and excellent heat dissipation performance of the anode, the working reliability of the X-ray source is significantly improved. Compared with the single-point emission cone beam X-ray, the divergence of the X-ray beam of the flat-panel X-ray source is greatly reduced, which reduces the geometric magnification effect and significantly improves the spatial resolution of X-ray imaging. In addition, the emission area of ​​the flat-panel X-ray source is selectable, and it can be controlled to irradiate only the imaging area of ​​interest, significantly reducing the radiation dose of the patient.

[0039] The specific implementation methods of the present application are described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that these embodiments can be modified and improved without departing from the principles and spirit of the present application whose scope is defined by the claims and their equivalents. These modifications and improvements should also be within the scope of protection of the present application.

Claims

1. A flat-panel X-ray source, characterized in that: The flat-panel X-ray source comprises a flat-panel cathode and a flat-panel anode arranged opposite to each other, wherein: The flat cathode comprises a first substrate, a conductive layer, and a cathode emission layer stacked in sequence, wherein the conductive layer comprises a plurality of conductive strips spaced apart and arranged in parallel, the cathode emission layer is deposited on each of the conductive strips, and each of the conductive strips is insulated from each other; The flat anode includes a second substrate and a target material layer stacked in sequence, the target material layer includes a plurality of target material strips spaced apart and arranged in parallel, the target material strips are insulated from each other, the target material strips are perpendicular to the conductive strips, and the projection of the target material strips on the first substrate has an overlapping area with the conductive strips.

2. The flat panel X-ray source according to claim 1, characterized in that: The projection of each of the target material strips on the first substrate has an overlapping area with all the conductive strips.

3. The flat panel X-ray source according to claim 2, characterized in that: The cathode emission layer is located in the overlapping area.

4. The flat panel X-ray source according to claim 1, characterized in that: The planar cathode further comprises a gate layer, which is disposed on the cathode emission layer and has a first through hole formed therein, wherein the first through hole exposes the overlapping region, and the gate layer and the cathode emission layer are insulated from each other.

5. The flat panel X-ray source according to claim 4, characterized in that: The flat cathode further comprises a focusing electrode layer, which is arranged on the grid layer and has a second through hole formed therein, the second through hole is opposite to the first through hole, and the focusing electrode layer and the grid layer are insulated from each other.

6. The flat panel X-ray source according to claim 5, characterized in that: The gate layer and the cathode emission layer, and the focusing electrode layer and the gate layer are separated by insulating spacers respectively.

7. The flat panel X-ray source according to claim 5, characterized in that: The focusing electrode layer is separated from the flat anode by an insulating gasket.

8. A method for manufacturing the flat-panel X-ray source according to any one of claims 1 to 7, characterized in that: The manufacturing method comprises: Preparing a flat cathode: preparing a conductive layer on a first substrate, and depositing a cathode emission layer on the conductive layer, wherein the conductive layer includes a plurality of conductive strips that are spaced apart and arranged in parallel, and each of the conductive strips is insulated from each other; Preparing a flat anode: preparing a target material layer on a second substrate, the target material layer comprising a plurality of target material strips spaced apart and arranged in parallel, wherein the target material strips are insulated from each other; The flat cathode and the flat anode are arranged opposite to each other, so that the target strip is perpendicular to the conductive strip, and the projection of the target strip on the first substrate has an overlapping area with the conductive strip.

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