A dual energy X-ray detector

Abstract

The present invention discloses a dual-energy X-ray detector, comprising: a low-energy sub-board, comprising a low-energy scintillator array and a first photodiode array sequentially arranged on a first PCB board along the ray incident direction; a high-energy sub-board, comprising a high-energy scintillator array and a second photodiode array sequentially arranged on a second PCB board along the ray incident direction; the low-energy sub-board and the high-energy sub-board are directly connected to a motherboard in sequence through straight pins along the ray incident direction, and the center point of each pixel of the first optical isolation device is aligned with the center point of each pixel of the corresponding high-energy scintillator array; wherein the first optical isolation device is the low-energy scintillator array or the first photodiode array. The detector sub-boards of the present invention are directly connected to the motherboard through straight pins respectively, realizing a compact basic framework of the detector, improving integration, realizing high-reliability connection of the detector and reliability of product operation, and greatly reducing product cost.

Description

Technical Field

[0001] The present invention relates to the field of radiation detection technology, and more specifically, to a dual-energy X-ray detector. Background Art

[0002] X-rays are electromagnetic waves with very short wavelengths and high penetrating power. When using X-rays for detection, after the X-rays penetrate the object to be inspected, their energy spectrum will harden, and the degree of hardening is related to the material composition of the object to be inspected and the thickness in the penetration direction. The traditional dual-energy X-ray detector is composed of two detectors, high and low energy, usually using a pluggable array and a discrete amplifier circuit, where each detector includes a scintillator array and a photodiode array. The low-energy array detector is arranged on the side close to the object to be inspected, mainly absorbing the low-energy part of the X-ray energy spectrum, and the high-energy array detector is arranged behind the low-energy array detector, mainly absorbing the high-energy part of the X-ray energy spectrum. Generally, a filter is also configured between the low-energy array detector and the high-energy array detector to further absorb the remaining low-energy part of the X-ray energy spectrum. Using the dual-energy X-ray detector to output the original image signal, the processing system compares the transmittance of the object at two different energies based on the above original image signal, calculates the relative difference between the low-energy part and the high-energy part of the X-ray energy spectrum that penetrates the object, and then provides a basis for material identification.

[0003] On the one hand, traditional dual-energy X-ray detectors have low integration, and usually use flexible cables to connect high and low energy signals to the digital motherboard; the cost of flexible cables is relatively high. Although there is a certain degree of flexibility in repairing and replacing arrays, it is difficult to meet the market's requirements for high integration, high reliability and low cost. In addition, the rays that are not absorbed by the scintillator are scattered on the motherboard, and the scattered rays will reduce the life of electronic components, especially the backscattered rays will enter the scintillators of other pixel channels, generate crosstalk signals, and thus reduce image quality.

[0004] On the other hand, this traditional dual-energy X-ray detector is assembled from several parts. The scintillator arrays corresponding to the high-energy and low-energy detectors are aligned according to the center point of the scintillator pixel. However, for the commonly used low-energy scintillator such as GOS film, there is no optical separation between its pixels. Instead, it relies on the semi-transparent properties of this material and the photodiodes coupled with it (there is a dead zone between two adjacent photodiodes) to achieve rough isolation of adjacent signals. However, it is not easy to align accurately, especially since the photodiode mainly absorbs the light generated by the scintillator about half a millimeter near its active area. Therefore, when coupled, when the geometric center point of the GOS film deviates greatly from the center point of the photodiode pixel, it will cause the high and low energy channels to be unable to sample at the same ray position.

[0005] In this case, the correct approach should be to align the center point of the first photodiode active area with the center point of the high-energy scintillator unit with a light isolation layer. Therefore, this traditional alignment method is not conducive to sampling the high and low energy channels in the dual-energy X-ray detector at the same ray position, which will affect the material recognition ability of the scanning system.

[0006] Therefore, it is necessary to provide a new type of dual-energy X-ray detector. Summary of the invention

[0007] In order to solve at least one of the above technical problems, the present invention provides a dual-energy X-ray detector. The dual-energy X-ray detector has a compact structure and low cost, can ensure that high and low energy channels are sampled at the same ray position, and by adding an X-ray shielding layer, unabsorbed X-rays are absorbed, thereby reducing damage to electronic components and extending the life of electronic components.

[0008] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0009] In one aspect, the present invention provides a dual-energy X-ray detector, comprising a low-energy sub-board and a high-energy sub-board arranged correspondingly, wherein:

[0010] The low-energy sub-board includes a low-energy scintillator array and a first photodiode array sequentially arranged on the first PCB board along the incident direction of the ray, and the first photodiode array is used to detect the light signal emitted by the low-energy scintillator array and convert it into an electrical signal of the low-energy sub-board;

[0011] The high-energy sub-board includes a high-energy scintillator array and a second photodiode array sequentially arranged on the second PCB board along the incident direction of the ray, and the second photodiode array is used to detect the light signal emitted by the high-energy scintillator array and convert it into an electrical signal of the high-energy sub-board;

[0012] The low-energy daughter board and the high-energy daughter board are directly connected to the mother board in sequence through straight pins along the incident direction of the rays, and the center points of each pixel of the first optical isolation device are aligned with the center points of each pixel of the corresponding high-energy scintillator array, wherein the first optical isolation device is the low-energy scintillator array or the first photodiode array.

[0013] The dual-energy X-ray detector of the present invention uses straight pins instead of expensive flexible cables to connect the signals of the low-energy daughter board and the high-energy daughter board to the motherboard, thereby reducing costs; at the same time, it overcomes the defect of low integration when using pin components.

[0014] Preferably, when the first optical isolation device is a low-energy scintillator array, the low-energy scintillator array is provided with an optical isolation.

[0015] Preferably, a filter is provided between the low-energy sub-plate and the high-energy sub-plate, and the filter is used to absorb the low-energy part of the X-ray energy spectrum.

[0016] More preferably, the material of the filter is metallic copper, metallic silver or a copper-silver alloy.

[0017] Preferably, an X-ray shielding layer is further provided between the high-energy daughter board and the mother board.

[0018] The X-ray shielding layer is used to absorb X-rays that are not completely absorbed by the high-energy scintillator array, suppress X-ray scattering, and shield electronic components, reduce the damage to electronic components caused by X-ray scattering, and extend the life of electronic components. At the same time, it prevents the backscattered rays of this part of X-rays from entering the scintillators of other pixel channels, generating crosstalk signals and thus reducing image quality, effectively improving image quality.

[0019] More preferably, the X-ray shielding layer is arranged on a surface of the second PCB board on a side facing away from the second photodiode array.

[0020] In another preferred embodiment, the X-ray shielding layer is arranged on a surface of one side of the motherboard close to the second PCB board.

[0021] Further preferably, the material of the X-ray shielding layer is one or a combination of metal lead, tungsten, molybdenum, copper and an alloy containing lead, tungsten, molybdenum and copper.

[0022] Further preferably, the thickness of the X-ray shielding layer is 0.1-10 mm.

[0023] Preferably, the low energy scintillator material is: GOS film, GOS ceramic, CsI(T1), CdWO4 or ZnSe.

[0024] Preferably, the high energy scintillator material is: GOS ceramic, CsI(T1), CdWO4 or ZnSe.

[0025] Another aspect of the present invention provides a method for aligning a low-energy sub-panel and a high-energy sub-panel in a dual-energy X-ray detector, characterized in that when the low-energy scintillator array has a light barrier, the center point of each pixel of the low-energy scintillator array is aligned with the center point of each pixel of the corresponding high-energy scintillator array;

[0026] When the low-energy scintillator array has no light barrier, the center point of each pixel of the first photodiode array is aligned with the center point of each pixel of the corresponding high-energy scintillator array.

[0027] The beneficial effects of the present invention are as follows:

[0028] In the dual-energy X-ray detector of the present invention, a three-layer circuit board stacking structure is formed, and the detector sub-boards are directly connected to the motherboard through straight pins, realizing a compact basic structure of the detector, improving the integration, realizing high-reliability connection of the detector and reliability of product operation, and greatly reducing product costs; the X-ray shielding layer suppresses X-ray scattering and realizes shielding of electronic components. In addition, it is also realized that on the X-ray path, between the corresponding pixels of high and low energy, the center points of the first isolated device are aligned with each other; in particular, when the low-energy scintillator is not isolated, the center points of each pixel of the first photodiode array are aligned with the center points of the corresponding high-energy scintillator pixel; at the same time, since the low-energy detector array and the high-energy detector array are accurately aligned, it is beneficial to improve the ability to identify materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0030] Figure 1 A schematic diagram of the structure of a dual-energy X-ray detector in the prior art is shown.

[0031] Figure 2 A schematic structural diagram of a preferred embodiment of the dual-energy X-ray detector of the present invention is shown.

[0032] Figure 3 A schematic structural diagram of another preferred embodiment of the dual-energy X-ray detector of the present invention is shown. DETAILED DESCRIPTION

[0033] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0034] The terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods or devices.

[0035] Figure 1The schematic diagram of the dual-energy X-ray detector of the conventional technology is shown. The conventional linear array dual-energy X-ray detector is composed of two detectors, high and low energy, usually using a pluggable array and a discrete amplifier circuit, wherein each detector includes a scintillator array and a photodiode array. The low-energy array detector is arranged on the side close to the object to be inspected, and mainly absorbs the low-energy part of the X-ray energy spectrum. The high-energy array detector is arranged behind the low-energy array detector, and mainly absorbs the high-energy part of the X-ray energy spectrum. Generally, a filter is also arranged between the low-energy array detector and the high-energy array detector to further absorb the remaining low-energy part of the X-ray energy spectrum.

[0036] During detection, the X-ray 100 first enters the low-energy scintillator 101 and deposits energy therein to release visible light, and the photodetector 102 converts the visible light signal into an electrical signal. The X-rays that do not interact with the low-energy scintillator pass through the filter 111 to further reduce the low-energy part and low-energy scattered rays in the X-ray energy spectrum, and then the X-rays are almost completely absorbed inside the high-energy scintillator 121, and the released visible light is converted into an electrical signal in the photodetector 122. Here, the low-energy scintillator 101 and the photodetector 102 form a low-energy detector, which is plugged into the circuit board through the pin 104 and connected to the signal amplification and data conversion circuit thereon; the high-energy scintillator 121 and the photodetector 122 form a high-energy detector, which is plugged into the circuit board through the pin 124 and connected to the signal amplification and data conversion circuit thereon. This type of detector has a low integration because it uses components with pins. In addition, in the prior art, a flexible flat cable can be used to connect the high-energy and low-energy detectors to the circuit board respectively, but the cost of the flexible flat cable is relatively high. Existing detectors have low integration and high costs. Although they have a certain flexibility in maintenance and array replacement, they are difficult to meet the market's requirements for high integration, high reliability and low cost. There are also problems such as crosstalk of scattered rays and alignment of high and low energy corresponding channels.

[0037] The present invention provides a dual-energy X-ray detector, such as Figure 2In a preferred embodiment shown, the dual-energy X-ray detector includes a low-energy sub-board and a high-energy sub-board arranged accordingly, wherein: the low-energy sub-board includes a low-energy scintillator array 201 and a first photodiode array 202 arranged in sequence on a first PCB board 204 along the ray incidence 200 direction, the first photodiode array 202 is used to detect the light signal emitted by the low-energy scintillator array 201 and convert it into an electrical signal of a low-energy detection unit; X-rays that do not interact with the low-energy scintillator pass through the filter 211 to further reduce the low-energy part and low-energy scattered rays in the X-ray energy spectrum; the high-energy sub-board includes a high-energy scintillator array 221 and a second photodiode array 222 arranged in sequence on a second PCB board 224 along the ray incidence 200 direction, the second photodiode array 222 is used to detect the light signal emitted by the high-energy scintillator array 221 and convert it into an electrical signal of a high-energy detection unit.

[0038] In the present invention, the low-energy daughter board and the high-energy daughter board are directly connected to the motherboard 241 through the straight pins 203 and 223 along the ray incidence direction 200. The dual-energy X-ray detector of the present invention uses straight pins instead of expensive soft cables to connect the signals of the low-energy daughter board and the high-energy daughter board to the motherboard, which reduces the cost and improves the integration compared with the dual-energy X-ray detector connected by pins.

[0039] In the dual-energy X-ray detector of the present invention, the center point of each pixel of the first optical spacer device is aligned with the center point of each pixel of the corresponding high-energy scintillator array, wherein the first optical spacer device is the low-energy scintillator array or the first photodiode array. When the first optical spacer device is the low-energy scintillator array, the low-energy scintillator array is provided with an optical spacer.

[0040] The present invention provides a method for aligning a low-energy sub-plate and a high-energy sub-plate in a dual-energy X-ray detector. When a low-energy scintillator array has a light barrier, the center point of each pixel of the low-energy scintillator array is aligned with the center point of each pixel of the corresponding high-energy scintillator array; when the low-energy scintillator array has no light barrier, the center point of each pixel of the first photodiode array is aligned with the center point of each pixel of the corresponding high-energy scintillator array.

[0041] Since the traditional dual-energy X-ray detector is assembled from several parts, the scintillator arrays corresponding to the high- and low-energy detectors are aligned according to the center point of the scintillator pixel. However, for the commonly used low-energy scintillator such as GOS film, there is no optical separation between its pixels. Instead, it relies on the semi-transparent properties of this material and the photodiodes coupled with it (there is a dead zone between two adjacent photodiodes) to achieve rough isolation of adjacent signals. However, it is not easy to align accurately, especially since the photodiode mainly absorbs the light generated by the scintillator about half a millimeter near its active area. Therefore, when coupled, when the geometric center point of the GOS film deviates greatly from the center point of the photodiode pixel, it will cause the high and low energy channels to be unable to sample at the same ray position.

[0042] In the present invention, whether the low-energy scintillator array or the center point of each pixel of the first photodiode array is aligned with the center point of each pixel of the corresponding high-energy scintillator array is determined according to whether there is a light barrier in the low-energy scintillator, thereby overcoming the technical defect of inaccurate alignment in the prior art, achieving sampling of high and low energy channels at the same ray position, and improving the material recognition capability of the ray scanning baggage detection system.

[0043] The X-ray shielding layer 231 can be installed on the detector sub-board or the digital circuit motherboard to suppress X-ray scattering and shield electronic components. The material of the X-ray shielding layer is metal lead, tungsten, molybdenum, copper or an alloy containing lead, tungsten, molybdenum, copper or a combination of one or more of them. These materials with higher atomic numbers strongly absorb rays, can effectively suppress scattering, and play a shielding role.

[0044] In this preferred embodiment, the dual-energy X-ray detector further includes an X-ray shielding layer disposed between the high-energy daughter board and the mother board. The X-ray shielding layer is disposed on a surface of the second PCB board facing away from the second photodiode array (e.g. Figure 2 As shown in FIG. 1 ). It is easy to understand for those skilled in the art that the X-ray shielding layer can also be disposed on a side surface of the motherboard close to the second PCB board (as shown in FIG. 1 ). Figure 3 ).

[0045] The X-ray shielding layer is used to absorb X-rays that are not completely absorbed by the high-energy scintillator array, suppress X-ray scattering, and shield electronic components, reduce the damage to electronic components caused by X-ray scattering, and extend the life of electronic components. At the same time, it prevents the backscattered rays of this part of X-rays from entering the scintillators of other pixel channels, generating crosstalk signals and thus reducing image quality, effectively improving image quality.

[0046] In various embodiments of the present invention, the material of the X-ray shielding layer is one or a combination of metal lead, tungsten, molybdenum, copper and alloys containing lead, tungsten, molybdenum and copper; the thickness is 0.1-10 mm. The material of the filter is metal copper, metal silver or copper-silver alloy. The low-energy scintillator material is: GOS film, GOS ceramic, CsI (T1), CdWO4 or ZnSe. The high-energy scintillator material is: GOS ceramic, CsI (T1), CdWO4 or ZnSe.

[0047] The "multiple" mentioned in the embodiments of the present invention refers to two or more. "And / or" describes the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0048] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A dual energy X-ray detector, characterized in that: It includes correspondingly set low-energy sub-board and high-energy sub-board, where: The low-energy sub-board includes a low-energy scintillator array and a first photodiode array sequentially arranged on the first PCB board along the incident direction of the ray, and the first photodiode array is used to detect the light signal emitted by the low-energy scintillator array and convert it into an electrical signal of the low-energy sub-board; The high-energy sub-board includes a high-energy scintillator array and a second photodiode array sequentially arranged on the second PCB board along the incident direction of the ray, and the second photodiode array is used to detect the light signal emitted by the high-energy scintillator array and convert it into an electrical signal of the high-energy sub-board; An X-ray shielding layer is also provided between the high-energy daughter board and the mother board. The low-energy daughter board and the high-energy daughter board are directly connected to the mother board in sequence through straight pins along the incident direction of the rays, and the center points of each pixel of the first optical isolation device are aligned with the center points of each pixel of the corresponding high-energy scintillator array, wherein the first optical isolation device is a first photodiode array, A filter is also arranged between the low-energy sub-plate and the high-energy sub-plate, and the filter is used to absorb the low-energy part of the X-ray energy spectrum.

2. The dual energy X-ray detector according to claim 1, characterized in that: The material of the filter is metal copper, metal silver or copper-silver alloy.

3. The dual energy X-ray detector according to claim 1, characterized in that: The X-ray shielding layer is arranged on a surface of a side of the second PCB board facing away from the second photodiode array.

4. The dual energy X-ray detector according to claim 1, characterized in that: The X-ray shielding layer is arranged on a surface of one side of the motherboard close to the second PCB board.

5. The dual energy X-ray detector according to claim 1, characterized in that: The material of the X-ray shielding layer is one or a combination of metal lead, tungsten, molybdenum, copper and alloys containing lead, tungsten, molybdenum and copper.

6. The dual energy X-ray detector according to claim 1, characterized in that: The thickness of the X-ray shielding layer is 0.1-10 mm.

7. A method for aligning a low-energy sub-plate and a high-energy sub-plate in a dual-energy X-ray detector, wherein the dual-energy X-ray detector comprises a low-energy sub-plate and a high-energy sub-plate arranged in sequence, wherein the low-energy sub-plate comprises a low-energy scintillator array and a first photodiode array arranged in sequence along a ray incident direction, and the high-energy sub-plate comprises a high-energy scintillator array and a second photodiode array arranged in sequence along a ray incident direction, wherein: When the low-energy scintillator array has a light barrier, the center point of each pixel of the low-energy scintillator array is aligned with the center point of each pixel of the corresponding high-energy scintillator array; When the low-energy scintillator array has no light barrier, the first photodiode array serves as a light barrier device, and the center point of each pixel of the first photodiode array is aligned with the center point of each pixel of the corresponding high-energy scintillator array.

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