Cold cathode flat plate X-ray source capable of coding light emission and coding light emission method

Abstract

The embodiment of the invention discloses a cold cathode flat plate X-ray source capable of coding light emitting and a coding light emitting method, the ray source comprises a vacuum sealing cavity, a cathode assembly and an anode assembly, the cathode assembly and the anode assembly are arranged in the vacuum sealing cavity in a sealing manner, and the cathode assembly and the anode assembly are oppositely arranged at an interval; a vacuum working space for electron acceleration and X-ray generation is formed; the cathode assembly comprises a cathode substrate and a nano cold cathode electron source array arranged on the cathode substrate; the anode assembly comprises an anode substrate and a transmission anode target arranged on the anode substrate; wherein at least one of the nanometer cold cathode electron source array and the transmission anode target is in a coding state: when the nanometer cold cathode electron source array is in the coding state, the nanometer cold cathode electron source array comprises a micro-unit electron source array capable of independently addressing, and a preset coding pattern is formed; and when the transmission anode target is in a coding state, a metal coating with a preset coding pattern is formed on the surface of the anode substrate through a micromachining process so as to integrate a coding function.

Description

Technical Field

[0001] This application relates to the field of X-ray imaging technology, and more specifically, to a cold cathode flat-panel X-ray source capable of encoding light emission and a method for encoding light emission. Background Technology

[0002] X-ray imaging technology is widely used in medical diagnosis, industrial non-destructive testing, and security inspection. Flat-panel X-ray sources, due to their ability to achieve large-area uniform light output and addressable light output, have potential in short-range imaging and static CT. However, traditional flat-panel X-ray sources suffer from image blurring due to multi-path aliasing during direct projection imaging, making it difficult to meet the requirements of high-precision imaging. While coded aperture imaging technology can improve imaging efficiency, reduce radiation dose, and improve signal-to-noise ratio, existing systems are limited by mask manufacturing precision and cost, and the coding method is imperfect, restricting its large-scale application in high-precision industrial inspection and low-dose medical scenarios. Therefore, there is an urgent need to develop flat-panel X-ray sources with integrated coding functions to solve the image blurring problem and meet the high-precision requirements of direct projection imaging and CT imaging. Summary of the Invention

[0003] The purpose of this application is to provide a cold cathode flat panel X-ray source capable of encoding light emission and a method for encoding light emission, so as to integrate encoding function and meet the high precision requirements of direct projection imaging and CT imaging.

[0004] This application provides a cold cathode flat-panel X-ray source capable of encoding light, with the following technical solution: It includes a vacuum-sealed cavity, a cathode assembly, and an anode assembly. The cathode assembly and anode assembly are sealed within the vacuum-sealed cavity and arranged relatively spaced apart to form a vacuum working space for electron acceleration and X-ray generation. The cathode assembly includes a cathode substrate and a nano-cold cathode electron source array disposed on the cathode substrate. The anode assembly includes an anode substrate and a transmission anode target disposed on the anode substrate. At least one of the nano-cold cathode electron source array and the transmission anode target is in an encoded state: when the nano-cold cathode electron source array is in an encoded state, it contains an independently addressable micro-unit electron source array forming a preset encoded pattern; when the transmission anode target is in an encoded state, it forms a metal coating with a preset encoded pattern on the surface of the anode substrate through microfabrication processes.

[0005] Furthermore, this application also proposes that the nanocold cathode electron source array is composed of at least one of a vertical array of carbon nanotubes, a graphene edge emitter, or a metal oxide nanowire cold cathode; and that the metal coating material of the transmission anode target is at least one of tungsten, gold, or molybdenum.

[0006] Furthermore, this application also proposes that the micro-unit electronic source array includes multiple micro-unit electronic sources, each with a minimum feature size of 5 to 2000 μm and a spacing of 10 to 500 μm between adjacent micro-unit electronic sources.

[0007] Furthermore, this application also proposes that the anode substrate is a transparent anode substrate, the thickness of the transmission anode target is 10 nm to 0.1 mm, and when the transmission anode target is in the coded state, the coded pattern of the transmission anode target includes multiple micro-unit target regions, the minimum feature size of each micro-unit target region is 5 to 2000 μm, and the spacing between adjacent micro-unit target regions is 10 to 500 μm.

[0008] Furthermore, this application also proposes that the metal coating of the micro-unit target area adopts a gradient thickness design, with the gradient thickness gradually changing from thin to thick along the electron beam incident direction to form a spatially modulated X-ray intensity distribution.

[0009] Furthermore, this application also proposes that the preset coding pattern is a MURA array or a Fresnel zone plate structure; the microfabrication process includes at least one of photolithography, electroplating or laser etching.

[0010] Furthermore, this application also proposes that a matrix gated electrode is provided on the surface of the cathode substrate, the matrix gated electrode including several independent control units corresponding to the coded pattern space of the transmission anode target.

[0011] Furthermore, this application also proposes that when both the nano-cold cathode electron source array and the transmission anode target are in an encoded state, the micro-unit electron source of the nano-cold cathode electron source array and the micro-unit target area of ​​the transmission anode target are in a spatial projection mapping relationship, and the mapping error of the spatial projection mapping relationship is <5μm.

[0012] Furthermore, this application also proposes that the anode substrate is any one of doped diamond film, alumina ceramic, aluminum nitride ceramic, or borosilicate glass, with a thickness of 100 to 5000 μm; the spacing between the cathode and anode components is 0.5 to 10 mm; and the working vacuum level of the vacuum working space is ≤10. -4 Pa, the anode operating voltage of the anode assembly is 20 to 150 kV.

[0013] Furthermore, this application also proposes a method for encoding light emission from a cold cathode flat-panel X-ray source. The method includes: generating a spatially modulated X-ray beam through a nano-cold cathode electron source array or a transmission anode target in an encoded state; rotating the cold cathode flat-panel X-ray source around the target object at multiple angles; and collecting encoded projection data in conjunction with an external detector; processing the encoded projection data through an iterative image restoration algorithm to reconstruct a three-dimensional image of the target object to achieve projection imaging or CT imaging.

[0014] As described above, this application provides a cold cathode flat-panel X-ray source capable of encoding light emission and its encoding light emission method, comprising a vacuum-sealed cavity, a cathode assembly, and an anode assembly. The cathode assembly and anode assembly are sealed within the vacuum-sealed cavity and arranged relatively spaced apart to form a vacuum working space for electron acceleration and X-ray generation. The cathode assembly includes a cathode substrate and a nano-cold cathode electron source array disposed on the cathode substrate. The anode assembly includes an anode substrate and a transmission anode target disposed on the anode substrate. This application designs the nano-cold cathode electron source array and the transmission anode target as at least one co-located architecture in an encoded state, retaining the advantage of large-area uniform light emission in a full-surface configuration while generating spatially encoded X-rays through the encoded electron source or anode target. It is understood that when the electron source is in an encoded state, electron emission can be precisely controlled through independently addressed micro-unit electron sources; when the anode is in an encoded state, X-ray emission can be modulated by a metal coating with a preset encoded pattern; and when both are in an encoded state, more precise spatial projection mapping can be achieved. This design reduces multi-path aliasing at the source, effectively solving the problem of blurred imaging in traditional flat-panel X-ray sources and significantly improving imaging accuracy. At the same time, it eliminates the need for external coding masks, reducing system complexity and cost, and broadening the application scenarios of cold cathode flat-panel X-ray sources in fields such as coding imaging and CT. Furthermore, the cold cathode structure has advantages over hot cathodes in terms of smaller size, longer lifespan, and lower operating temperature. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of the cold cathode flat plate X-ray source with a full-surface cathode and a coded anode provided in this application;

[0017] Figure 2 This is a schematic diagram of the structure of the cold cathode flat plate X-ray source with coded cathode and full-surface anode provided in this application;

[0018] Figure 3 This is a schematic diagram of the structure of the cold cathode flat plate X-ray source with coded cathode + coded anode provided in this application;

[0019] Figure 4 This is a schematic diagram of the coded imaging CT system using a cold cathode flat panel X-ray source according to this application;

[0020] Figure 5This is the MURA-coded anode structure of the cold cathode flat-panel X-ray source of Embodiment 1 of this application;

[0021] Figure 6 This is the Fresnel zone plate encoded anode structure of the cold cathode flat X-ray source of Embodiment 2 of this application;

[0022] Explanation of reference numerals in the attached figures:

[0023] Vacuum-sealed cavity 1, cathode assembly 2, anode assembly 3, cold cathode flat panel X-ray source 4, X-ray flat panel detector 5, CT system support 6, object under test 7, exhaust pipe 11, getter chamber 12, low melting point glass 13, isolator 14, cathode substrate 21, nano cold cathode electron source array 22, cathode conductive layer 23, transparent anode substrate 31, transmission anode target 32, anode conductive layer 33. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0025] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0026] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0027] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0028] In existing technologies, X-ray imaging technology is widely used in medical diagnosis, industrial non-destructive testing, and security inspection. Flat-panel X-ray sources, due to their ability to achieve large-area uniform light output and addressable light output, have potential in short-range imaging and static CT. However, when traditional flat-panel X-ray sources are used for direct projection imaging, the overlapping of multiple light paths causes imaging blurring, making it difficult to meet the requirements of high-precision imaging. Although coded aperture imaging technology can improve imaging efficiency, reduce radiation dose, and improve signal-to-noise ratio, existing systems rely on external mask structures. Limited by mask manufacturing precision and cost, its large-scale application in high-precision industrial inspection and low-dose medical scenarios is restricted.

[0029] To address the aforementioned issues, the structure of the flat-panel X-ray source needs to be redesigned, integrating the encoding function directly within the source. Traditional solutions separate the encoding mask from the X-ray source, increasing system complexity and making optical path alignment difficult. Analysis revealed that directly constructing the encoding structure at the electron emission end or anode target surface avoids errors introduced by external masks. Further considering the controllability of the cold cathode electron source, a proposed method is to form a pre-defined encoding pattern on the cathode or anode surface, enabling the X-ray beam to possess spatial modulation characteristics from the generation stage.

[0030] Therefore, this application proposes a cold cathode flat-panel X-ray source capable of encoding light, comprising a vacuum-sealed cavity, a cathode assembly, and an anode assembly. The cathode assembly and anode assembly are sealed within the vacuum-sealed cavity and arranged at relative intervals to form a vacuum working space for electron acceleration and X-ray generation. The cathode assembly includes a cathode substrate and a nano-cold cathode electron source array disposed thereon, and the anode assembly includes an anode substrate and a transmission anode target disposed thereon. At least one of the nano-cold cathode electron source array and the transmission anode target is in an encoded state: when the nano-cold cathode electron source array is in an encoded state, it includes an array of independently addressable micro-unit electron sources to form a preset encoded pattern; when the transmission anode target is in an encoded state, it forms a metal coating with a preset encoded pattern on the surface of the anode substrate through microfabrication processes.

[0031] This application designs a collaborative architecture where the nano-cold cathode electron source array and the transmission anode target are in at least one encoded state. This retains the advantage of large-area uniform light emission in a full-surface configuration while generating spatially encoded X-rays through the encoded electron source or anode target. Understandably, when the electron source is in encoded state, electron emission can be precisely controlled through independently addressed micro-unit electron sources; when the anode is in encoded state, X-ray emission can be modulated by a metal coating with a preset encoded pattern; and when both are in encoded state, more precise spatial projection mapping can be achieved. This design reduces multi-path aliasing at the source, effectively solving the problem of blurred imaging in traditional flat-panel X-ray sources and significantly improving imaging accuracy. Simultaneously, it eliminates the need for external encoded masks, reducing system complexity and cost, and broadening the application scenarios of cold cathode flat-panel X-ray sources in fields such as encoded imaging and CT. Furthermore, the cold cathode structure offers advantages over hot cathodes in terms of smaller size, longer lifespan, and lower operating temperature.

[0032] refer to Figures 1 to 3 , Figure 1 This is a schematic diagram of the structure of the flat X-ray source with a full-surface cathode and a coded anode provided in this application; Figure 2 This is a schematic diagram of the structure of the flat X-ray source with coded cathode and full-surface anode provided in this application; Figure 3 This is a schematic diagram of the structure of the coded cathode + coded anode flat X-ray source provided in this application; wherein, this application uses a whole-surface or coded cold cathode electron source as the cathode and a whole-surface or coded transmission target as the anode, which can realize the coded uniform emission of X-rays, and control the emission position by using cathodes and transmission anodes of different shapes.

[0033] refer to Figure 4 , Figure 4 This is a schematic diagram of the coded imaging CT system using a cold cathode flat-panel X-ray source according to this application. This application uses a cold cathode flat-panel X-ray source 4 capable of encoding light as the light source, combined with an X-ray flat-panel detector 5 to project an image onto the object under test 7. The optical path is fixed by a CT system bracket 6. The object under test 7 is the target object. The optical path rotates relative to the object under test 7 at multiple angles and projects an image, thereby achieving coded CT imaging.

[0034] refer to Figure 5 and Figure 6 , Figure 5 This is the MURA-coded anode structure of the cold cathode flat X-ray source 4 in Embodiment 1 of this application; Figure 6 This is the Fresnel zone plate encoded anode structure of the cold cathode flat X-ray source 4 in Embodiment 2 of this application; wherein, the encoded cathode and encoded anode used in this application adopt MURA encoding or Fresnel zone encoding, so the following specific embodiments exist:

[0035] Example 1:

[0036] Example 1 provides a MURA-coded anode structure for a cold cathode flat-panel X-ray source 4. The cathode substrate 21 is made of borosilicate glass. Figure 1 As shown, the nano-cold cathode electron source array 22 is a full-surface ZnO nanowire. The transparent anode substrate 31 is made of borosilicate glass, and the transparent anode target 32 ​​is a tungsten target with a thickness of 2 μm. Figure 5 As shown, the transmission anode target 32 ​​employs a modified uniformly redundant arrays (MURA) encoded anode structure. MURA encoding originates from the quadratic residual array of cyclic difference, and the encoded aperture arrangement follows the principle that the vectors between any two apertures have the same number of repetitions. The distance between the surface of the cathode substrate 21 and the inner surface of the transmission anode substrate 31 is 6 mm. In Example 1, spatially encoded X-rays can be emitted under operating conditions of 60 kV / 1 mA. The cold cathode flat plate X-ray source 4 uses the Richardson-Lucy image restoration method to obtain a reconstructed image of the target object with low signal-to-noise ratio and high resolution.

[0037] Example 2:

[0038] Example 2 provides a MURA-coded cathode structure for a cold cathode flat-panel X-ray source 4. The cathode substrate 21 uses an alumina ceramic material. Figure 2 As shown, the nano-cold cathode electron source array 22 is as follows Figure 5 The graphene film with a MURA-coded structure is shown. The transparent anode substrate 31 is made of alumina ceramic, and the transmission anode target 32 ​​is a full-surface gold target with a thickness of 2 μm. The distance between the surface of the cathode substrate 21 and the inner surface of the transparent anode substrate 31 is 8 mm. In Example 2, spatially coded X-rays can be emitted under the operating conditions of 80 kV / 1 mA.

[0039] Example 3:

[0040] Example 3 provides a MURA-coded cathode and coded anode combination structure for a cold cathode flat-panel X-ray source 4. The cathode substrate 21 is made of aluminum nitride ceramic material. Figure 3 As shown, the nano-cold cathode electron source array 22 is as follows Figure 5 The MURA-encoded structure of ZnO nanowires is shown. The transparent anode substrate 31 is made of aluminum nitride ceramic material, and the transparent anode target 32 ​​is as follows: Figure 5 The MURA-coded tungsten target shown has a thickness of 3 μm. The distance between the surface of the cathode substrate 21 and the inner surface of the transparent anode substrate 31 is 10 mm. Example 3 can emit space-coded X-rays under 100 kV / 1 mA operating conditions.

[0041] Example 4:

[0042] Example 4 provides a Fresnel zone-coded anode structure for a cold cathode flat-panel X-ray source 4. The cathode substrate 21 is made of diamond thin film material, the nano-cold cathode electron source array 22 is a carbon nanotube array, and the matrix-type gated electrode 23 is AZO; the transparent anode substrate 31 is made of diamond thin film material, and the transmission anode target 32 ​​is a molybdenum target with a thickness of 3 μm. Figure 6 As shown, the transmission anode target 32 ​​adopts a Fresnel zone plate encoded anode structure, and the distance between the surface of the cathode substrate 21 and the inner surface of the transmission anode substrate 31 is 10 mm. Example 4 can emit spatially encoded X-rays under a 100 kV / 1 mA operating condition. Combined with... Figure 4 The coded imaging CT system of the cold cathode flat panel X-ray source 4 shown can realize high-resolution CT imaging of the object under test 7.

[0043] Based on the above embodiments 1 to 4, further explanations and interpretations of this application are as follows:

[0044] The vacuum-sealed cavity 1 refers to a sealed structure that maintains the vacuum environment required for electron emission and acceleration. It can be constructed using metal or ceramic welding and serves to provide a gas-free transmission path for the electron beam. The cathode assembly 2 is a structural unit that incorporates electron emission functionality. Field-induced electron emission is achieved through nano-cold cathode materials, reducing operating voltage and improving response speed. The anode assembly 3 is a functional unit that receives the electron beam and generates X-rays. The transmission anode target 32 ​​allows X-rays to penetrate and exit, avoiding the geometric obstruction problems of traditional reflective targets. The encoded state refers to a physical structure with spatial modulation capabilities. A specific pattern is formed through microfabrication technology, and its function is to directly assign spatial encoded information during the X-ray generation stage.

[0045] Specifically, when the nano-cold cathode electron source array 22 is in the encoded state, its micro-unit electron source array can be independently controlled to turn on or off. By selectively activating electron sources at specific locations, electron bombardment regions with corresponding encoded patterns are formed on the anode target surface, thereby generating an X-ray beam with spatial modulation characteristics. When the transmission anode target 32 ​​is in the encoded state, the encoded pattern of the metal coating changes the X-ray transmittance of different regions, allowing the X-ray beam passing through the target surface to carry encoded information. These two encoding methods can be used individually or in combination, directly achieving spatial modulation of X-rays within a vacuum working space without relying on external mask devices.

[0046] Compared to existing technologies, traditional coded imaging systems require a physical mask between the X-ray source and the detector, resulting in increased system size and difficulties in optical path alignment. This solution integrates the coding function within the X-ray source, directly modulating the emitted X-ray beam through the coding structure of the cathode or anode. This integrated design eliminates installation errors from external masks and reduces imaging blurring caused by multi-path aliasing. Furthermore, the controllability of the cold cathode electron source allows for dynamic adjustment of the coding pattern, overcoming the lack of flexibility inherent in fixed masks.

[0047] In this application, the anode substrate is a light-transmitting anode substrate 31, and the thickness of the transmission anode target 32 ​​is from 10 nm to 0.1 mm. When the transmission anode target 32 ​​is in the encoding state, the encoding pattern of the transmission anode target 32 ​​includes multiple micro-unit target regions. The minimum feature size of each micro-unit target region is from 5 to 2000 μm, and the spacing between adjacent micro-unit target regions is from 10 to 500 μm.

[0048] The transparent anode substrate 31 refers to the substrate material that allows X-rays to pass through. Specifically, it can be made of doped diamond film or borosilicate glass, whose light-transmitting properties reduce imaging noise caused by X-ray scattering. The thickness range of the transmissive anode target 32 ​​is determined by balancing X-ray generation efficiency and penetration performance. For example, a thickness below 10 nm may not effectively block the electron beam, while a thickness exceeding 0.1 mm will lead to excessive X-ray attenuation. The minimum feature size and spacing of the micro-unit target area are set by matching the electron beam focusing accuracy with the encoding pattern resolution requirements. For example, photolithography can achieve pattern accuracy on the order of 5 μm, thus meeting the high-resolution encoding requirements.

[0049] Specifically, the synergistic design of the transparent anode substrate 31 and the transmission anode target 32 ​​reduces scattering interference when X-rays penetrate the anode. Simultaneously, the micro-unit target areas within the coded pattern generate spatially modulated X-ray beams through selective electron bombardment. When the electron beam bombards the coded anode target, only the micro-unit target areas covered by the metal coating are able to generate X-rays, while the uncovered areas produce almost no X-rays due to the transmission characteristics of the substrate material. Thus, the coded pattern can be directly converted into an X-ray intensity distribution, for example, forming a spatially modulated signal corresponding to the coded pattern in projection imaging.

[0050] In this application, the nanocold cathode electron source array 22 is composed of at least one of a vertical array of carbon nanotubes, a graphene edge emitter, or a metal oxide nanowire cold cathode; the metal coating material of the transmission anode target 32 ​​is at least one of tungsten, gold, or molybdenum.

[0051] Among them, the vertical array of carbon nanotubes refers to a field emission structure composed of oriented carbon nanotubes, which can be grown on the surface of the cathode substrate 21 by chemical vapor deposition. It has high aspect ratio and low work function characteristics, enabling stable electron emission under low voltage drive. The graphene edge emitter refers to the use of atomic dangling bonds at the edge of graphene sheets as electron emission sites. It can be prepared by plasma etching to expose the edges of the graphene film. It has excellent conductivity and thermal stability, which can reduce the operating temperature of the cathode. The metal oxide nanowire cold cathode refers to an electron emitter composed of zinc oxide, copper oxide, or tungsten oxide nanowires. It can be prepared on the surface of the cathode substrate 21 by hydrothermal synthesis. It has controllable morphology and chemical stability and can adapt to different vacuum environments. The metal coating material of the transmission anode target 32 ​​is at least one of tungsten, gold, or molybdenum. It can be deposited on the surface of the anode substrate by magnetron sputtering or electron beam evaporation. Its high atomic number and high melting point characteristics can improve X-ray conversion efficiency and suppress anode thermal damage.

[0052] Specifically, a vertical array of carbon nanotubes generates a high-density electron beam under a low electric field through the tip field emission effect. Graphene edge emitters utilize edge defect sites to reduce the electron work function, and metal oxide nanowire cold cathodes enhance the electron tunneling probability through a localized surface electric field. All three can achieve cold cathode electron emission, avoiding the energy consumption and lifespan issues caused by high temperatures in traditional hot cathodes. The transmission anode target 32 ​​is coated with tungsten, gold, or molybdenum, utilizing its high atomic number to enhance the X-ray yield under electron bombardment. Simultaneously, the transmission design allows X-rays to directly penetrate the anode substrate, reducing imaging noise caused by scattering. Optimization of the cathode and anode materials combination improves the modulation accuracy and radiation efficiency of the X-ray source, providing a high signal-to-noise ratio X-ray source for coded imaging.

[0053] In this application, the cold cathode flat X-ray source also includes: an exhaust pipe 11 for the vacuum pumping process of the vacuum-sealed cavity, a getter chamber 12 for continuously adsorbing residual gases in the cavity, a low-melting-point glass 13 as a sealing component of the vacuum-sealed cavity, an isolator 14 for the supporting structure that physically separates the cathode assembly and the anode assembly, a cathode conductive layer 23 that provides electrical connection and driving support for the nano-cold cathode electron source array, and an anode conductive layer 33 that provides high-voltage power supply and current output for the transmission anode target.

[0054] In this application, the micro-unit electronic source array includes multiple micro-unit electronic sources, each with a minimum feature size of 5 to 2000 μm and a spacing of 10 to 500 μm between adjacent micro-unit electronic sources.

[0055] The micro-unit electron source refers to an independent, controllable electron emission unit formed through microfabrication processes. Specifically, it can be fabricated using a combination of photolithography and thin-film deposition, for example, by forming a conductive microstructure with a specific geometry on the surface of the cathode substrate 21. This feature size range balances fabrication precision and electron beam focusing capability; for example, a 5μm feature size enables high-resolution encoding, while a 2000μm feature size is suitable for scenarios with large-scale uniform light emission. Setting the adjacent spacing to 10 to 500μm avoids spatial crosstalk in the electron beam; for example, a 10μm spacing allows for dense array arrangement, while a 500μm spacing is suitable for low-density encoding requirements.

[0056] Specifically, by limiting the minimum feature size of the micro-unit electronic source to 5 to 2000 μm, the unit size can be flexibly selected for different application scenarios. For example, a 50 μm feature size is used in medical CT imaging to ensure a clear boundary of the electron beam on the anode target surface; an 800 μm feature size is used in industrial inspection to achieve large-area coverage. When the adjacent spacing is set to 10 to 500 μm, both the insulation performance between units can be guaranteed, and the spatial frequency requirements of different coding patterns can be matched by adjusting the spacing. In practical implementation, micro-unit structures with rectangular or circular cross-sections can be fabricated using photolithography mask technology, and the feature size can be precisely controlled by controlling the exposure accuracy.

[0057] Through the above technical solution, this application can precisely control the spatial distribution of the electron beam according to imaging requirements, and directly form coded patterns during the X-ray generation stage. For example, in a security inspection scenario, using an array arrangement with a feature size of 100μm and a spacing of 200μm can ensure that the X-ray beam maintains the integrity of the coded information when penetrating the object under test 7. Compared with the traditional uniform light output method, the signal-to-noise ratio received by the detector is improved by about 40%, while avoiding the problem of decoding error accumulation in subsequent image processing.

[0058] In this application, the metal coating of the micro-unit target area adopts a gradient thickness design, with the gradient thickness gradually changing from thin to thick along the electron beam incident direction to form a spatially modulated X-ray intensity distribution.

[0059] Gradient thickness design refers to the continuous or stepwise variation of the metal coating thickness along the electron beam incident direction. This can be achieved using physical vapor deposition combined with masking, adjusting the thickness by controlling the deposition time or mask opening size in different regions. Spatially modulated X-ray intensity distribution refers to the variation in X-ray intensity corresponding to the thickness gradient in the emission direction due to the differential absorption of electron beam energy by metal layers of different thicknesses, thus encoding the X-ray energy distribution in the spatial dimension.

[0060] Specifically, when the electron beam is incident on the transmission anode target 32, the thinner areas of the metal coating have a weaker blocking effect on the electron beam, resulting in higher X-ray intensity. As the coating thickness gradually increases along the incident direction of the electron beam, the penetration depth of the electron beam decreases, and the X-ray intensity decreases accordingly. This intensity gradient distribution, combined with the coded pattern, can form a modulated signal with spatial resolution during projection imaging. After being received by the detector and combined with the decoding algorithm, the internal structure of the object can be reconstructed.

[0061] Through the above technical solution, this application solves the projection aliasing problem caused by uniform light emission in traditional flat-panel X-ray sources. By realizing spatial encoding of X-ray intensity through the structure of the anode target itself, the imaging signal-to-noise ratio and resolution are effectively improved, which is especially suitable for detecting the internal structure of objects with complex density distribution.

[0062] In this application, the preset coding pattern is a MURA array or a Fresnel zone plate structure; the microfabrication process includes at least one of photolithography, electroplating or laser etching.

[0063] Among them, MURA array refers to a non-redundant pseudo-random coding pattern, which can be implemented using two-dimensional orthogonally arranged transparent and shielding units. Its autocorrelation function has sharp peak characteristics, which can improve the signal-to-noise ratio of the coding imaging system. Fresnel zone plate structure refers to a diffractive optical element composed of alternating transparent and shielding rings, which can be implemented in the form of concentric rings or spirals. It can achieve focusing or coding modulation through the diffraction effect of X-rays. Photolithography refers to the formation of micron-scale patterns on the substrate surface through exposure and development. It can be implemented using ultraviolet lithography or electron beam lithography and is suitable for high-precision metal coating patterning. Electroplating refers to the formation of metal layers in specific areas through electrolytic deposition. It can be implemented using mask-guided selective electroplating and is suitable for the preparation of metal target areas with complex three-dimensional structures. Laser etching refers to the removal of material to form microstructures using a high-energy laser beam. It can be implemented using femtosecond laser micromachining and is suitable for high-resolution patterning of hard and brittle material surfaces.

[0064] Specifically, within the vacuum-sealed cavity 1, the coded pattern is spatially modulated using a pre-defined MURA array or a Fresnel zone plate structure. When using a MURA array, its pseudo-randomly arranged transmission and blocking regions can eliminate the aliasing effect of traditional periodic encoding, improving the decodeability of the projection data. When using a Fresnel zone plate, its diffraction characteristics enable the X-ray beam to generate both intensity and phase modulation, enhancing the spatial resolution of the imaging system. In microfabrication processes, photolithography can precisely control the boundary accuracy of metal coatings to the sub-micron level, electroplating can achieve continuous deposition of gradient thickness metal layers, and laser etching can directly etch complex three-dimensional target structures on the surface of the anode substrate.

[0065] Through the above technical solutions, this application achieves deep matching between the coded pattern and the physical properties of X-rays, solving the aliasing and blurring problem in direct imaging with traditional flat-panel X-ray sources. The pseudo-random characteristics of the MURA array reduce the redundancy of the projection data, and the diffraction modulation of the Fresnel zone plate enhances the spatial resolution of the imaging system. The combined process of photolithography, electroplating, and laser etching significantly reduces the fabrication cost of complex coded structures while ensuring pattern accuracy, providing a feasible technical path for high-precision, low-dose X-ray imaging.

[0066] In this application, a matrix gated electrode is provided on the surface of the cathode substrate 21. The matrix gated electrode includes several independent control units corresponding to the coded pattern space of the transmission anode target 32.

[0067] Among them, the matrix-type gated electrode refers to an electrode network composed of row-column intersecting wiring. Specifically, a metal wire mesh can be fabricated on the surface of the cathode substrate 21 using photolithography, and different control units are isolated by an insulating layer for regional electric field modulation of the nano-cold cathode electron source array 22. The independent control unit refers to the independent electrode region formed by each intersection node. Specifically, it can be individually powered and controlled by a semiconductor switching circuit, so that the electron emission state of each micro-unit electron source can be independently adjusted, thereby forming a spatial correspondence with the coded pattern of the transmission anode target 32.

[0068] Specifically, when the surface of the transmission anode target 32 ​​has a preset coded pattern, each independent control unit of the matrix-type grid-controlled electrode controls whether the micro-unit electron source at the corresponding position emits an electron beam via a voltage signal. For example, when the coded pattern of the anode target is a MURA array, the control unit in the grid-controlled electrode corresponding to the light-transmitting unit of the target area is activated, driving the electron source in that area to emit an electron beam to bombard the target material, while the electron source corresponding to the blocking unit remains in the off state. This spatially selective excitation can avoid electron beam scattering in ineffective areas, directly generate an X-ray beam matching the coded pattern, and eliminate the multi-path aliasing problem in projection imaging.

[0069] Through the above technical solution, this application achieves precise spatial matching between the electron emission region of the X-ray source and the coded pattern of the anode target, avoiding the manufacturing errors and cost limitations caused by traditional physical masks. By selectively adjusting the electron beam emission state through an independent control unit, a high-contrast coded X-ray beam can be directly generated, improving the clarity and signal-to-noise ratio of the projection image. At the same time, it supports rapid switching between different coding modes to meet the needs of dynamic imaging scenarios.

[0070] In this application, when both the nano-cold cathode electron source array 22 and the transmission anode target 32 ​​are in the encoded state, the micro-unit electron source of the nano-cold cathode electron source array 22 and the micro-unit target area of ​​the transmission anode target 32 ​​are in a spatial projection mapping relationship, and the mapping error of the spatial projection mapping relationship is <5μm.

[0071] The spatial projection mapping relationship refers to the precise correspondence between the geometric position of the projection area formed by the electron beam emitted by the micro-unit electron source on the surface of the transmission anode target 32 ​​and the micro-unit target area. This can be achieved using a precision alignment system combined with optical calibration marks to ensure the electron beam path matches the target area position. A mapping error of <5μm refers to the range of positional deviation between the center point of the projection area and the center point of the target area. This can be achieved through high-precision microfabrication processes and a real-time electron beam trajectory monitoring system, used to eliminate the influence of electron beam scattering or mechanical assembly errors on imaging accuracy.

[0072] Specifically, when the electron source array and the anode target are simultaneously in the coded state, each micro-unit electron source is independently controlled to emit an electron beam, and its corresponding micro-unit target region receives the electron bombardment and generates X-rays. By establishing a spatial projection mapping relationship, the path of the electron beam corresponds strictly to the spatial distribution of the target region. For example, a micro-unit at a specific position in the electron source array only excites the target region at the corresponding position on the anode target. The mapping error is controlled by optimizing the alignment structure inside the vacuum cavity. For example, optical positioning marks are set at the edges of the cathode substrate 21 and the anode substrate, and assembly calibration is performed using a laser interferometer to ensure that the relative positional deviation between the electron source and the target region is always within a threshold range.

[0073] Through the above technical solution, this application can achieve high-precision spatial projection imaging, reduce the positional shift of X-ray signals during transmission, reduce geometric distortion during image reconstruction, and is suitable for micro-focus CT imaging scenarios with strict requirements for spatial resolution.

[0074] In this application, the anode substrate is any one of doped diamond film, alumina ceramic, aluminum nitride ceramic, or borosilicate glass, with a thickness of 100 to 5000 μm; the spacing between the cathode component 2 and the anode component 3 is 0.5 to 10 mm; and the working vacuum level of the vacuum working space is ≤10. -4 Pa, the anode operating voltage of anode assembly 3 is 20 to 150 kV.

[0075] The anode substrate material refers to the base material used to support the transmission anode target 32. Specifically, it can be a diamond-doped thin film to achieve high thermal conductivity and radiation stability, alumina ceramic or aluminum nitride ceramic for low-cost processing, or borosilicate glass for high light transmittance. These materials allow X-rays to penetrate efficiently while maintaining structural strength. The anode substrate thickness range refers to the balance between material thickness and X-ray transmission efficiency while ensuring mechanical support performance. Too thin a substrate will result in insufficient structural strength, while too thick a substrate will reduce X-ray output efficiency. The cathode-anode spacing is a parameter for controlling the electron beam acceleration path. This spacing is adjusted to match the electron beam focusing requirements under different anode voltages. Too small a spacing will lead to excessively high electric field strength, causing a breakdown risk; too large a spacing will reduce electron beam energy conversion efficiency. The working vacuum level refers to the vacuum environment conditions that maintain the electron free path and suppress gas discharge, achieved through the vacuum-sealed cavity 1 and the pumping system. The anode working voltage range refers to the acceleration voltage range required to excite X-rays. This range is adjusted according to the target X-ray energy and application scenario. Too low a voltage will not excite sufficiently intense X-rays, while too high a voltage will increase system power consumption and radiation shielding requirements.

[0076] Specifically, the selection of the anode substrate material balances mechanical support, heat dissipation performance, and X-ray transmission efficiency. For example, doped diamond films maintain high transmittance while possessing excellent thermal conductivity, effectively preventing heat accumulation on the anode target due to electron bombardment. The optimized cathode-anode spacing, combined with the anode voltage range, allows the electron beam to be accelerated to the required energy within the vacuum working space, generating X-rays upon impacting the transmission anode target 32. The working vacuum is controlled by the vacuum-sealed cavity 1 and an external pumping system, ensuring that the electron beam is not interfered with by gas molecule scattering during transmission. The adjustable range of the anode voltage covers various needs, from low-dose medical imaging to high-penetration industrial inspection; for example, 20-50kV is suitable for soft tissue imaging, while 80-150kV is suitable for non-destructive testing of metal components.

[0077] In some specific embodiments, the anode substrate can be made of alumina ceramic with a thickness of 200 μm, the distance between the cathode and the anode is set to 2 mm, the working vacuum is maintained in the range of 10 to 5 Pa, and the anode voltage is dynamically adjusted in the range of 30-120 kV according to the imaging requirements.

[0078] Through the above technical solutions, this application, while maintaining the compact structure of the flat-panel X-ray source, achieves precise control of X-ray intensity and energy spectrum through material optimization and synergistic parameter design, thereby improving imaging resolution and reducing radiation dose, while extending the equipment's service life. The selection of a high thermal conductivity anode substrate effectively suppresses target performance degradation caused by thermal effects; the synergistic control of vacuum level and spacing ensures efficient electron beam transmission; and the dynamic adjustment of the anode voltage meets the imaging needs of various scenarios.

[0079] In this application, the method for encoding light emission from a cold cathode flat-panel X-ray source includes: generating a spatially modulated X-ray beam through a nano-cold cathode electron source array or a transmission anode target in an encoded state, causing the cold cathode flat-panel X-ray source to rotate around the target object at multiple angles, and collecting encoded projection data in conjunction with an external detector; processing the encoded projection data through an iterative image restoration algorithm to reconstruct a three-dimensional image of the target object to achieve projection imaging or CT imaging.

[0080] Spatially modulated X-ray beams refer to non-uniform intensity distributions formed by spatially modulating the electron emission or X-ray generation process through a pre-defined coded pattern. This can be achieved using independently addressable micro-unit electron source arrays or transmission anode targets with coded metal coatings. Encoding is achieved by selectively activating the electron source or adjusting the target material distribution. Multi-angle rotation refers to the circular or arc-shaped trajectory movement of a cold cathode flat-plate X-ray source around the target object. This can be achieved using a mechanical rotating platform or an array-type light source layout. Multi-view projection data is obtained by changing the X-ray incident angle. Iterative image restoration algorithms are mathematical reconstruction methods that perform inverse solving based on coded projection data. This can be implemented using compressed sensing algorithms or maximum likelihood estimation algorithms, eliminating multi-path aliasing and improving image resolution through iterative optimization.

[0081] Specifically, a coded nano-cold cathode electron source array or transmission anode target spatially modulates the intensity of the electron beam or X-rays using a pre-defined coded pattern, forming an X-ray beam with a specific distribution. When the cold cathode flat-plate X-ray source rotates around the target object, coded X-rays at different angles penetrate the object and are projected by an external detector. Due to the spatial modulation effect of the coded pattern, the projection data contains multi-angle structural information of the target object. Subsequently, an iterative image restoration algorithm decouples and optimizes the coded projection data, using prior information from the coded pattern to eliminate aliasing noise, ultimately reconstructing a high-resolution three-dimensional image.

[0082] Through the above technical solution, this application solves the problem of multi-path aliasing in direct projection imaging of traditional flat panel X-ray sources, improves imaging clarity by using coding modulation and iterative reconstruction technology, and realizes low-radiation-dose three-dimensional imaging through multi-angle data acquisition. It is suitable for low-dose CT scanning in medical diagnosis and high-precision defect identification in industrial inspection.

[0083] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A cold cathode flat-panel X-ray source capable of encoding light, characterized in that, include: A vacuum-sealed cavity, a cathode assembly, and an anode assembly are provided, wherein the cathode assembly and the anode assembly are sealed within the vacuum-sealed cavity and are arranged relative to each other at intervals to form a vacuum working space for electron acceleration and X-ray generation. The cathode assembly includes a cathode substrate and a nano-cold cathode electron source array disposed on the cathode substrate; The anode assembly includes an anode substrate and a transmission anode target disposed on the anode substrate; Wherein, at least one of the nano-cold cathode electron source array and the transmission anode target is in an encoded state: When the nano-cold cathode electron source array is in an encoded state, it contains an independently addressable micro-unit electron source array, forming a preset encoded pattern; When the transmission anode target is in an encoded state, it forms a metal coating with a preset encoded pattern on the surface of the anode substrate through a micromachining process.

2. The cold cathode flat-panel X-ray source capable of encoding light according to claim 1, characterized in that, The nano-cold cathode electron source array is composed of at least one of a vertical array of carbon nanotubes, a graphene edge emitter, or a metal oxide nanowire cold cathode; the metal coating material of the transmission anode target is at least one of tungsten, gold, or molybdenum.

3. The cold cathode flat-panel X-ray source capable of encoding light according to claim 1, characterized in that, The micro-unit electronic source array includes multiple micro-unit electronic sources, each with a minimum feature size of 5 to 2000 μm and a spacing of 10 to 500 μm between adjacent micro-unit electronic sources.

4. The cold cathode flat-panel X-ray source capable of encoding light according to claim 3, characterized in that, The anode substrate is a transparent anode substrate, and the thickness of the transmissive anode target is from 10 nm to 0.1 mm. When the transmissive anode target is in an encoded state, the encoded pattern of the transmissive anode target includes multiple micro-unit target regions, the minimum feature size of each micro-unit target region is from 5 to 2000 μm, and the spacing between adjacent micro-unit target regions is from 10 to 500 μm.

5. The cold cathode flat-panel X-ray source capable of encoding light according to claim 4, characterized in that, The metal coating of the micro-unit target area adopts a gradient thickness design, which gradually changes from thin to thick along the electron beam incident direction to form a spatially modulated X-ray intensity distribution.

6. The cold cathode flat-panel X-ray source capable of encoding light according to claim 1, characterized in that, The preset coding pattern is a MURA array or a Fresnel zone plate structure; the microfabrication process includes at least one of photolithography, electroplating or laser etching.

7. The cold cathode flat-panel X-ray source capable of encoding light according to claim 1, characterized in that, The cathode substrate surface is provided with a matrix gated electrode, which includes several independent control units corresponding to the coded pattern space of the transmission anode target.

8. The light-encoding cold cathode flat-panel X-ray source according to claim 5, characterized in that, When both the nano-cold cathode electron source array and the transmission anode target are in an encoded state, the micro-unit electron source of the nano-cold cathode electron source array and the micro-unit target area of ​​the transmission anode target have a spatial projection mapping relationship, and the mapping error of the spatial projection mapping relationship is <5μm.

9. The light-encoding cold cathode flat-panel X-ray source according to any one of claims 1 to 8, characterized in that, The anode substrate is any one of doped diamond film, alumina ceramic, aluminum nitride ceramic, or borosilicate glass, with a thickness of 100 to 5000 μm. The spacing between the cathode assembly and the anode assembly is 0.5 to 10 mm. The working vacuum level of the vacuum working space is ≤10. -4 Pa, the anode operating voltage of the anode assembly is 20 to 150 kV.

10. A method for encoding light emission from a cold cathode flat-panel X-ray source, characterized in that, The method is applied to the light-encoding cold cathode flat-panel X-ray source according to any one of claims 1 to 9, and the method includes: The nano-cold cathode electron source array or the transmission anode target in the coded state generate a spatially modulated X-ray beam, causing the cold cathode flat plate X-ray source to rotate around the target object at multiple angles, and cooperate with an external detector to collect coded projection data. The encoded projection data is processed by an iterative image restoration algorithm to reconstruct a three-dimensional image of the target object, thereby achieving projection imaging or CT imaging.

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