Cold-cathode x-ray tube and CT scanner

Abstract

Provided in the present invention are a cold-cathode X-ray tube and a CT scanner. The cold-cathode X-ray tube comprises a housing, and a Buckypaper cathode emitter and an anode target material that are located in the housing, wherein the interior of the housing is in a high-vacuum state, the Buckypaper cathode emitter is made of Buckypaper prepared on the basis of carbon nanotubes, and the Buckypaper cathode emitter performs field emission under the action of an extra electric field, so as to generate electrons and bombards the anode target material, so as to generate X-rays. The present invention can prolong the service life of an X-ray tube, improve the reliability and stability, and facilitate heat dissipation; and the cold-cathode X-ray tube can withstand a greater electric-field force to produce higher doses of X-rays.

Description

Cold cathode X-ray tube and CT scanner TECHNICAL FIELD

[0001] The present application relates to the technical field of X-ray tube, in particular to a cold cathode X-ray tube and CT scanner. BACKGROUND

[0002] X-ray tube is a vacuum diode working at high voltage, which contains two electrodes: one is a filament for emitting electrons as a cathode; the other is a target for accepting electron bombardment as an anode. Both electrodes are sealed in a high-vacuum glass or ceramic envelope. The X-ray tube power supply part contains at least one low-voltage power supply for heating the filament and a high-voltage generator for applying high voltage to both electrodes. When the filament generates an electron cloud by passing sufficient current, and there is enough voltage (kV level) between the anode and the cathode, the electron cloud is pulled to the anode. At this time, the electrons generated by the cathode hit the anode target at high speed, and the kinetic energy of the high-speed electrons is suddenly converted into radiant energy in the form of X-rays.

[0003] At present, the cathode of the X-ray tube is usually formed by carbon nanotubes in the following two ways: 1. growing carbon nanotubes directly on the substrate; 2. depositing carbon nanotubes on the substrate.

[0004] The above two ways have the following defects:

[0005] For way 1, when field emission occurs, it is easily pulled out and damaged by strong electric field force;

[0006] For way 2, when field emission occurs, the emission current is too large, which can cause the emitter to overheat and easily cause the fuse to blow. SUMMARY

[0007] The cold cathode X-ray tube and CT scanner provided by the present application can improve the service life of the X-ray tube, improve reliability and stability, and be easier to dissipate heat; and can withstand higher electric field force, thereby generating higher dose of X-rays.

[0008] In a first aspect, the present application provides a cold cathode X-ray tube, comprising: the cold cathode X-ray tube comprises: a shell, and a Bakelite cathode emitter and an anode target material located inside the shell, the inside of the shell is in a high vacuum state, and the Bakelite cathode emitter adopts Bakelite prepared based on carbon nanotubes as a material; the Bakelite cathode emitter generates electrons by field emission under the action of an external electric field and bombards the anode target material to generate X-rays.

[0009] Optionally, the Bakelite cathode emitter is cut from Bakelite according to a required shape.

[0010] Optionally, the carbon nanotubes in the Bakelite cathode material are filled with other materials having high thermal conductivity and high electrical conductivity.

[0011] Optionally, the materials having high thermal conductivity and high electrical conductivity are filled between the carbon nanotubes in the Bakelite cathode material by liquid deposition, vapor deposition or solid phase compounding.

[0012] Optionally, the materials having high thermal conductivity and high electrical conductivity include at least one of the following materials: graphite, graphene, boron nitride, copper, silver, diamond, silicon carbide, sapphire and aluminum nitride.

[0013] Optionally, the Bakelite is further added with a material having a low work function.

[0014] Optionally, the material having a low work function includes at least one of the following materials: barium oxide, cesium oxide, scandium oxide, yttrium oxide, lanthanum boride, hafnium carbide and tantalum carbide.

[0015] In a second aspect, the present application provides a CT scanner, which comprises the cold cathode X-ray tube as described above.

[0016] The cold cathode X-ray tube and the CT scanner provided by the embodiments of the present application adopt a cathode emitter made of Bakelite, the interaction between the carbon nanotubes is stronger, and the carbon nanotubes are not easy to be pulled out and damaged, the service life of the X-ray tube is longer, the reliability and stability are higher, and the X-ray tube is easier to dissipate heat; the X-ray tube can withstand a higher electric field force, thereby generating a higher dose of X-rays. BRIEF DESCRIPTION OF DRAWINGS

[0017] Fig. 1 is a structural schematic diagram of a cold cathode X-ray tube according to an embodiment of the present application;

[0018] Fig. 2 is a flow chart of a preparation method of the cold cathode X-ray tube according to an embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0020] The embodiment of the present application provides a cold cathode X-ray tube, as shown in Figure 1, which comprises: the cold cathode X-ray tube comprises a shell 11 and a Bucky paper cathode emitter 12 and an anode target material 13 inside the shell 11, the inside of the shell 11 is in a high vacuum state, and the Bucky paper cathode emitter 12 is made of Bucky paper prepared based on carbon nanotubes; the Bucky paper cathode emitter 12 generates electrons under the action of an applied electric field and bombards the anode target material 13 to generate X-rays.

[0021] The cold cathode X-ray tube provided by the embodiment of the present application adopts the Bucky paper cathode emitter, has high density, strong interaction force between carbon nanotubes, is not easy to be damaged by being pulled out, has a longer service life of the X-ray tube, is higher in reliability and stability, is easier to dissipate heat, can withstand a higher electric field force, and thus can generate a higher dose of X-rays.

[0022] Further, the Bucky paper is additionally provided with barium oxide, cesium oxide, scandium oxide, yttrium oxide, lanthanum boride, hafnium carbide, tantalum carbide and other materials with low work function, so as to reduce the work function of the Bucky paper cathode emitter.

[0023] Further, the Bucky paper cathode material is filled with other materials with high thermal conductivity and high electrical conductivity between the carbon nanotubes, so as to further improve the interaction force between the carbon nanotubes and be easier to dissipate heat. Optionally, the material with high thermal conductivity and high electrical conductivity is filled between the carbon nanotubes of the Bucky paper cathode material by means of liquid deposition, gas deposition or solid-phase compounding.

[0024] The liquid deposition can adopt some high-molecular systems, the gas deposition can adopt the gas phase form of alkynyl hydrocarbon or alcohol ketone ether and the like, or can adopt high-carbon-content quasi-solid-state materials such as pitch to be compounded with the Bucky paper.

[0025] Optionally, the material with high thermal conductivity and high electrical conductivity comprises at least one of the following materials: graphite, graphene, boron nitride, copper, silver, diamond, silicon carbide, sapphire and aluminum nitride.

[0026] The cathode is cut from the Bucky paper with optimized performance according to a required shape.

[0027] The embodiment of the present application further provides a CT scanner comprising the cold cathode X-ray tube as described above.

[0028] The CT scanner can be applied to the fields of medical treatment, security check, industrial product detection and the like, but is not limited thereto.

[0029] The embodiment of the present application further provides a preparation method of a cold cathode X-ray tube, as shown in Figure 2, which comprises the following steps:

[0030] Step S11, cutting the performance-optimized bucky paper into a structure with a specific shape as required.

[0031] Since the performance of the carbon nanotubes in the directly prepared bucky paper is poor, the carbon nanotubes need to be chemically or mechanically treated, resulting in more defects or functional groups in the carbon nanotubes, which will cause poor emission stability and reliability when used as an electron emission source. Therefore, some measures need to be taken to optimize the performance of the carbon nanotubes to improve the quality of the carbon nanotubes. In this embodiment, a high-temperature treatment method is used for performance optimization, so that the defects existing in the carbon nanotubes can be better removed or repaired at high temperature, and the functional groups can be completely removed, thereby obtaining a bucky paper emitter with excellent performance.

[0032] The high-temperature treatment method can be a direct heating method or an indirect heating method, such as laser, high temperature, electric furnace, induction heating, etc.

[0033] Specifically, the performance-optimized bucky paper can be cut into a structure with a specific shape as required by mechanical cutting or laser cutting, etc.

[0034] The specific shape can be a comb shape, a sawtooth shape, a strip shape, a corrugated shape, etc.

[0035] Step S12, reliably connecting the bucky paper cut into a structure with a specific shape with a substrate composed of a metal or an alloy, and forming a cathode assembly by fixing and assembling.

[0036] Step S13, assembling the cathode assembly according to the requirements of the X-ray tube for electron emission to form a cathode emitter.

[0037] Step S14, assembling the assembled cathode emitter to a cathode slot and sealing it together with an anode target in a shell to form a cold cathode X-ray tube.

[0038] Further, barium oxide, cesium oxide, scandium oxide, yttrium oxide, lanthanum boride, hafnium carbide, and tantalum carbide, etc. with low work function can also be added to the bucky paper to reduce the work function of the bucky paper cathode emitter. Specifically, the above-mentioned materials can be formed into a good composite with the bucky paper by in-situ reaction of plating film or direct physical deposition and / or chemical deposition.

[0039] The preparation method of the cold cathode X-ray tube provided by the embodiment of the present application uses the cathode made of the bucky paper by the above-mentioned method, the interaction between the carbon nanotubes is stronger, and the carbon nanotubes are not easy to pull out and damage, the service life of the X-ray tube is longer, the reliability and stability are higher, and the heat dissipation is easier; it can withstand higher electric field force, thereby generating higher dose of X-rays.

[0040] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A cold cathode X-ray tube, comprising: A shell, and a Bakal paper cathode emitter and an anode located inside the shell, the inside of the shell being in a high vacuum state, characterized in that the Bakal paper cathode emitter adopts a Bakal paper prepared based on carbon nanotubes as a material; the Bakal paper cathode emitter generates electrons under the action of an applied electric field and bombards the anode target to generate X rays.

2. The cold cathode X-ray tube according to claim 1, characterized in that The Bakal paper cathode emitter is cut according to a required shape.

3. The cold cathode X-ray tube according to claim 1 or 2, characterized in that In the Bakal paper cathode material, other materials with high thermal conductivity and high electrical conductivity are filled between the carbon nanotubes.

4. The cold cathode X-ray tube according to claim 3, characterized in that The material with high thermal conductivity and high electrical conductivity is filled between the carbon nanotubes of the Bakal paper cathode material by means of liquid deposition, gas deposition or solid-phase compounding.

5. The cold cathode X-ray tube according to claim 3, characterized in that The material with high thermal conductivity and high electrical conductivity includes at least one of the following materials: graphite, graphene, boron nitride, copper, silver, diamond, silicon carbide, sapphire and aluminum nitride.

6. The cold cathode X-ray tube according to claim 1 or 2, characterized in that The Bakal paper further adds a material with a low work function.

7. The cold cathode X-ray tube of claim 1, wherein, The material with a low work function includes at least one of the following materials: barium oxide, cesium oxide, scandium oxide, yttrium oxide, lanthanum boride, hafnium carbide and tantalum carbide.

8. A CT scanner characterized by, The CT scanner includes the cold cathode X-ray tube according to any one of claims 1 to 7.

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