Multi-energy spectrum x-ray detector and detection system

Abstract

The present invention provides a multi-energy spectrum X-ray detector and a detection system. Along an X-ray incident direction, the multi-energy spectrum X-ray detector comprises an upper detector module, filter layers, and lower detector modules that are sequentially stacked from top to bottom; there are N filter layers and N lower detector modules, wherein N is an integer greater than or equal to 1; and the filter layers and the lower detector modules are alternately stacked; and each lower detector module comprises a CMOS sensor and a scintillator located above the CMOS sensor. In the present invention, the lower A-Si sensor is replaced with a CMOS sensor, thereby achieving a higher signal-to-noise ratio without sacrificing spatial resolution while maintaining a large energy difference; a plurality of lower detector modules are arranged to obtain a multi-energy spectrum image, thereby improving the overall performance of the detector; the filter layer is pixelated, and energy spectrum regions of different thicknesses are formed on the filter layer, thereby enabling the dual-layer detector to achieve a multi-energy spectrum effect, and significantly reducing the structural and electronic design complexity, assembly complexity, and costs of the detector.

Description

A multi-energy spectral X-ray detector and detection system Technical Field

[0001] This invention belongs to the field of digital X-ray flat panel detector technology, and in particular relates to a multi-energy spectrum X-ray detector and detection system. Background Technology

[0002] In the field of medical imaging, dual-energy X-ray systems have attracted considerable attention due to their ability to distinguish the differences in X-ray absorption by substances of different atomic weights. This system utilizes the different X-ray absorption characteristics of bone and soft tissue to more significantly reflect changes in the attenuation intensity of X-ray beams at different energies. Specifically, dual-energy X-ray subtraction technology obtains clear images of soft tissue, bone tissue, or specific substances by subtracting two images obtained from exposing the same area to two different energies of X-rays.

[0003] Currently, there are two main methods for achieving dual-energy X-ray silhouettes: double exposure and single exposure. Double exposure, as the primary subtraction technique used clinically, rapidly acquires low-energy and high-energy images by switching between different tube voltages (kVp). However, this method suffers from low radiation utilization, high dose, and susceptibility to motion artifacts. In contrast, single exposure is based on a dual-layer X-ray flat panel detector design. The upper flat panel detector acquires the low-energy image, while the X-rays, after passing through a filter layer, acquire the high-energy image through the lower flat panel detector. This effectively eliminates motion artifacts and reduces the radiation dose to the patient and the requirements for the X-ray system.

[0004] However, existing dual-layer planar detector technology has certain limitations. These detectors are mainly implemented by embedding a dual-layer amorphous silicon thin-film transistor (A-Si TFT) sensor, a scintillator, and a filter layer. The filter layer typically uses a homogeneous Cu sheet to absorb low-energy X-rays. Increasing the thickness of the Cu sheet can improve the absorption capacity, thereby improving the effect of dual-energy silhouette, but it also weakens the X-ray energy received by the lower sensor, reduces the signal output, and thus affects the image signal-to-noise ratio. To improve the signal output of the lower sensor, increasing the thickness of the scintillator becomes necessary, but this sacrifices spatial resolution. Conversely, if high spatial resolution is maintained, the signal value is small, resulting in a poor signal-to-noise ratio for the lower image.

[0005] For multi-spectral detectors, conventional solutions employ multi-layer planar detectors, which incorporate at least three layers of A-Si TFT sensors, scintillators, and filter layers. Each sensor layer has a corresponding driving circuit. This approach is structurally, electronically, and technologically complex, costly, and its performance is not ideal.

[0006] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a multi-energy spectral X-ray detector and detection system to solve at least one of the technical problems existing in the prior art.

[0008] To achieve the above and other related objectives, the present invention provides a multi-spectral X-ray detector, which includes an upper detector module, a filter layer and a lower detector module stacked from top to bottom along the X-ray incident direction.

[0009] The filter layers consist of N layers, where N ≥ 1 and is an integer.

[0010] The number of lower-level detector modules is N, where N ≥ 1 and is an integer;

[0011] The filter layer and the lower detector module are stacked alternately, and the lower detector module includes a complementary metal-oxide-semiconductor sensor and a scintillator located above the complementary metal-oxide-semiconductor sensor.

[0012] Preferably, the upper detector module includes an upper detector and a scintillator layer located directly above the upper detector, wherein the upper detector includes an amorphous silicon thin-film transistor sensor or a complementary metal-oxide-semiconductor sensor.

[0013] Preferably, the pixel size of the amorphous silicon thin-film transistor sensor is not less than 100μm.

[0014] Preferably, the pixel size of the complementary metal-oxide-semiconductor sensor is no greater than 1000nm.

[0015] Preferably, the filter layer includes at least two pixel units arranged in an array, each pixel unit corresponding to an energy spectrum region of different thickness, and each energy spectrum region having different absorption energies for X-rays.

[0016] Preferably, the filter layer is made of copper, and the thickness of each energy spectrum region ranges from 0 to 3 mm.

[0017] Preferably, when N≥2 and is an integer, the filter layer is a homogeneous filter layer, the material of the homogeneous filter layer is copper, and the homogeneous filter layer corresponds to an energy spectrum region of the same thickness.

[0018] The present invention also provides a detection system comprising the above-described multi-energy spectral X-ray detector.

[0019] As described above, the multi-energy spectral X-ray detector and detection system of the present invention have the following beneficial effects:

[0020] To improve the image quality of dual-energy X-ray spectroscopy (DEX) imaging, this invention addresses the issue that when the average energy difference is large, the energy of the X-rays passing through the filter layer is relatively weak. To acquire images with a high signal-to-noise ratio while maintaining a certain spatial resolution, the amorphous silicon thin-film transistor sensor in the lower layer is replaced with a complementary metal-oxide-semiconductor (CMOS) sensor. Because the CMOS sensor has high sensitivity and low noise, the DEX detector can achieve a high signal-to-noise ratio even with a large energy difference without sacrificing spatial resolution. Furthermore, using an amorphous silicon thin-film transistor sensor in the upper layer and a CMOS sensor in the lower layer reduces overall cost and the complexity of the manufacturing process.

[0021] This invention improves the overall performance of a multi-energy spectrum X-ray detector by setting up multiple lower-layer detector modules to obtain multi-energy spectrum images. The filter layer is pixelated. Since the pixels of the lower-layer complementary metal-oxide-semiconductor sensor are much smaller than those of the upper-layer amorphous silicon thin-film transistor sensor, energy spectrum regions of different thicknesses are made on the filter layer corresponding to multiple pixels of the lower layer, corresponding to a single pixel of the upper layer. Different thicknesses of energy spectrum regions correspond to different energy spectrum information, thereby enabling the dual-layer detector to achieve a multi-energy spectrum effect. Compared with multi-layer sensors and multi-layer filter layers, this invention can significantly reduce the structural and electronic design complexity, assembly complexity, and cost of the multi-energy spectrum X-ray detector. Attached Figure Description

[0022] Figure 1 shows a schematic diagram of the structure of one type of multi-spectral X-ray detector in a specific embodiment of the present invention.

[0023] Figure 2 shows a schematic diagram of another multi-energy spectrum X-ray detector in a specific embodiment of the present invention.

[0024] Figure 3 shows a schematic diagram of another multi-energy spectrum X-ray detector in a specific embodiment of the present invention.

[0025] Figure 4 shows a schematic diagram of another multi-energy spectrum X-ray detector in a specific embodiment of the present invention.

[0026] Figure 5 shows a schematic diagram of the structure of a filter layer with two energy spectrum regions in a specific embodiment of the present invention.

[0027] Figure 6 shows a schematic diagram of the structure of a filter layer with three energy spectrum regions in a specific embodiment of the present invention.

[0028] Figure 7 shows a schematic diagram of the structure of a filter layer with four energy spectrum regions in a specific embodiment of the present invention.

[0029] Component Labeling Explanation: 10 Multi-spectral X-ray Detector; 100, 400 Scintillator Layer; 200 Amorphous Silicon Thin Film Transistor Sensor or A-Si Sensor; 300 Filter Layer; 301 Pixel Unit; 3011 First Energy Spectrum Region; 3012 Second Energy Spectrum Region; 3013 Third Energy Spectrum Region; 3014 Fourth Energy Spectrum Region; 500 Complementary Metal-Oxide-Semiconductor Sensor or CMOS Sensor. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0031] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0032] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0033] Please refer to Figures 1 to 7. It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the figures only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0034] Please refer to Figures 1 to 7. It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the figures only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0035] The present invention provides a multi-spectral X-ray detector 10, which includes an upper detector module, a filter layer 300 and a lower detector module stacked from top to bottom along the X-ray incident direction.

[0036] There are N filter layers (300), where N ≥ 1 and is an integer;

[0037] There are N lower-level detector modules, where N ≥ 1 and is an integer;

[0038] The filter layer 300 is alternately stacked with the lower detector module, which includes a complementary metal-oxide-semiconductor (CMOS) sensor and a scintillator located above the complementary metal-oxide-semiconductor sensor 500.

[0039] Specifically, when N=1, the multi-energy spectral X-ray detector 10 is a dual-energy spectral X-ray detector. To improve the image effect of dual-energy subtraction, when the average energy difference is large, the energy of the rays passing through the filter layer 300 is weaker. To acquire images with a high signal-to-noise ratio while maintaining a certain spatial resolution, the sensor in the lower detector module is replaced with a CMOS sensor 500. Because the CMOS sensor 500 has high sensitivity and low noise, a high signal-to-noise ratio is obtained even with a large energy difference without sacrificing spatial resolution. Of course, in other embodiments, N can also be 2, 3, 4, etc., that is, to obtain more energy levels and acquire images with more energy spectra, multiple sensors are stacked.

[0040] As an example, the upper detector module includes an upper detector and a scintillator layer 100 located directly above the upper detector, wherein the upper detector includes an amorphous silicon thin-film transistor sensor 200 or a complementary metal-oxide-semiconductor sensor 500.

[0041] Specifically, scintillator layers 100 and 400 are responsible for absorbing X-rays and converting them into visible light. When X-rays enter scintillator layers 100 and 400, they cause scintillator atoms to ionize or be excited. When the excited atoms are de-excited, they emit fluorescence with a wavelength in the visible light band. In a specific embodiment of the present invention, both the upper detector module and the lower detector module include scintillator layers 100 and 400. The thickness and material of the scintillator layers 100 and 400 are not overly restricted here, as long as they can meet the actual use requirements.

[0042] In one embodiment of the present invention, referring to FIG1, the sensor in the upper detector module is an amorphous silicon thin-film transistor (A-Si) sensor, N=1, and there is one lower detector module, i.e., along the X-ray incident direction. The structure of this multi-energy spectral X-ray detector 10 includes a scintillator layer 100, an A-Si sensor, a filter layer 300, a scintillator layer 400, and a CMOS sensor 500. Since the large-area CMOS sensor 500 has relatively high cost and complex process, the overall cost and implementation difficulty can be reduced by using an A-Si sensor in the upper layer and a CMOS sensor 500 in the lower layer. At the same time, a high signal-to-noise ratio can be obtained without sacrificing spatial resolution.

[0043] In another specific embodiment of the present invention, referring to FIG2, the sensor in the upper detector module is a CMOS sensor 500, N=1, and the lower detector module is one, that is, along the X-ray incident direction, the structure of the multi-energy spectrum X-ray detector 10 includes a scintillator layer 100, a CMOS sensor 500, a filter layer 300, a scintillator layer 400, and a CMOS sensor 500.

[0044] In another specific embodiment of the present invention, in order to obtain more energy levels and acquire more energy spectrum images, it can also be a stacked configuration of multiple scintillator layers 100 and 400 and sensors. Referring to Figure 3, the sensor in the upper detector module is an A-Si sensor, and the sensor in the lower detector module is a CMOS sensor 500, and N=2; that is, along the X-ray incident direction, the structure of the multi-energy spectrum X-ray detector 10 includes a scintillator layer 100, an A-Si sensor, a filter layer 300, a scintillator layer 400, a CMOS sensor 500, a filter layer 300, a scintillator layer 400, and a CMOS sensor 500.

[0045] In another specific embodiment of the present invention, referring to FIG4, the sensor in the upper detector module is a CMOS sensor 500, the sensor in the lower detector module is a CMOS sensor 500, and N=2; that is, along the X-ray incident direction, the structure of the multi-energy spectral X-ray detector 10 includes a scintillator layer 100, a CMOS sensor 500, a filter layer 300, a scintillator layer 400, a CMOS sensor 500, a filter layer 300, a scintillator layer 400, and a CMOS sensor 500. Of course, when N=3, it includes 3 filter layers 300 and 3 lower sensor modules; N can also be other integers, which will not be elaborated here.

[0046] As an example, the pixel size of the amorphous silicon thin-film transistor sensor 200 is not less than 100μm.

[0047] Specifically, pixel size usually refers to the physical size of a pixel, that is, the actual size of a single pixel unit 301 on the sensor surface. For amorphous silicon thin-film transistor sensors 200, the pixels are typically in the hundreds of micrometers range, greater than or equal to 100μm. The pixel size of commercially available amorphous silicon thin-film transistor sensors 200 is 100μm.

[0048] As an example, the pixel size of the complementary metal-oxide-semiconductor sensor 500 is no greater than 1000nm.

[0049] Specifically, the pixel size of the complementary metal-oxide-semiconductor (CMOS) sensor 500 can be achieved at the nanometer level, typically between tens and hundreds of nanometers. The pixel size is relatively flexible and not fixed, and can be adjusted according to design requirements. No further restrictions are imposed here.

[0050] As an example, the filter layer 300 includes at least two pixel units 301 arranged in an array, each pixel unit 301 corresponding to an energy spectrum region of different thickness, and each energy spectrum region having different absorption energies for X-rays.

[0051] Specifically, the filter layer 300 includes at least two pixel units 301 arranged in an array, that is, the original homogeneous filter layer 300 is pixelated. The pixelated filter layer 300 changes the traditional continuous and uniform filter layer 300 into a structure composed of many pixel units 301. Each pixel unit 301 can independently filter the passing X-rays, thereby enabling more precise control over the filtering of X-rays and improving the performance of the detector and the imaging quality.

[0052] Referring to Figure 1, the structure of the multi-spectral X-ray detector 10 includes a scintillator layer 100, an A-Si sensor, a filter layer 300, a scintillator layer 400, and a CMOS sensor 500. The filter layer 300 is configured as an array of pixel units 301, each pixel unit 301 corresponding to a different thickness of the energy spectrum region. Different filter layer thicknesses correspond to different energy spectrum regions, and these different energy spectrum regions absorb X-rays with different energies. This causes X-rays passing through the filter layer 300 to be divided into X-rays with different energy spectra, thus achieving a multi-spectral design. Compared to multi-layer sensors and multi-layer filter layers 300, this dual-spectral X-ray detector significantly reduces the complexity of the structure and electronic design, assembly complexity, and cost. As an example, the filter layer 300 is made of copper, and the thickness of each energy spectrum region ranges from 0 to 3 mm.

[0053] Specifically, the materials in each spectral region are the same, but the thicknesses are different. By utilizing the different absorption capacities of different thicknesses for X-rays (thickness is directly proportional to the absorption capacity of X-rays), each spectral region has different absorption energies for X-rays. The thickness of each spectral region can be any value within the range of 0, 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc., and can be adjusted according to the actual application.

[0054] In the first example of the present invention, referring to FIG5, a schematic diagram of the structure of a filter layer 300 having two energy spectrum regions is shown. The filter layer 300 includes two pixel units 301 arranged in an array. The two pixel units 301 correspond to energy spectrum regions of different thicknesses, namely, a first energy spectrum region 3011 and a second energy spectrum region 3012. If the first energy spectrum region 3011 is defined to have low absorption energy for X-rays and the second energy spectrum region 3012 is defined to have high absorption energy for X-rays, then the X-rays passing through the filter layer 300 will be divided into two X-rays with different low and high energy spectra. The pixel unit 301 is rectangular in shape, and each energy spectrum region is rectangular in shape. Each energy spectrum region can be divided equally left and right or vertically. Of course, each energy spectrum region can also be of different sizes.

[0055] Referring to Figure 5, if the filter layer 300 of the dual-energy X-ray detector in Figure 1 is designed to have a first energy spectral region 3011 and a second energy spectral region 3012, the detector is equivalent to a three-energy X-ray detector.

[0056] In another example of the present invention, referring to FIG6, a schematic diagram of a filter layer 300 having three energy spectrum regions is provided. The filter layer 300 includes three pixel units 301 arranged in an array. The three pixel units 301 correspond to energy spectrum regions of different thicknesses, namely the first energy spectrum region 3011, the second energy spectrum region 3012, and the third energy spectrum region 3013. X-rays passing through the filter layer 300 are divided into three X-rays with different energy spectra.

[0057] In another example of the present invention, referring to FIG7, a schematic diagram of a filter layer 300 having four energy spectrum regions is provided. The filter layer 300 includes four pixel units 301 arranged in an array. The four pixel units 301 correspond to energy spectrum regions of different thicknesses, namely a first energy spectrum region 3011, a second energy spectrum region 3012, a third energy spectrum region 3013, and a fourth energy spectrum region 3014. X-rays passing through the filter layer 300 are divided into four X-rays with different energy spectra.

[0058] Of course, the filter layer 300 may also include five or more energy spectrum regions with different absorption energies for X-rays, which will not be elaborated further here. As an example, when N≥2 and is an integer, the filter layer 300 is a homogeneous filter layer 300, the material of the homogeneous filter layer 300 is copper, and the homogeneous filter layer 300 corresponds to energy spectrum regions of the same thickness.

[0059] Specifically, when N≥2 and is an integer, the multi-energy spectrum X-ray detector 10 includes an upper detector module, at least two filter layers 300 and at least two lower detector modules. That is, the multi-energy spectrum X-ray detector 10 is at least a three-energy spectrum X-ray detector and can acquire multi-energy spectrum images. Its structural schematic diagram is shown in Figures 3 and 4.

[0060] The present invention also provides a detection system comprising the multi-energy spectral X-ray detector 10 described above.

[0061] Specifically, the detection system includes an X-ray source; the aforementioned multi-spectral X-ray detector 10, which is positioned opposite to the X-ray source to receive X-rays and convert them into electrical signals; and a drive circuit and a readout circuit connected to the multi-spectral X-ray detector 10.

[0062] In summary, to improve the image quality of dual-energy X-ray spectroscopy (DEX) silhouettes, this invention addresses the issue that, when the average energy difference is large, the energy of the X-rays passing through the filter layer is relatively weak. To acquire images with a high signal-to-noise ratio while maintaining a certain spatial resolution, the lower-layer amorphous silicon thin-film transistor sensor is replaced with a complementary metal-oxide-semiconductor (CMOS) sensor. Because the CMOS sensor has high sensitivity and low noise, the DEX detector can achieve a high signal-to-noise ratio even with a large energy difference without sacrificing spatial resolution. Furthermore, using an amorphous silicon thin-film transistor sensor in the upper layer and a CMOS sensor in the lower layer reduces overall cost and processing complexity. The present invention overcomes the complexity of existing technologies by setting up multiple lower-layer detector modules to obtain multi-energy spectrum images, thereby improving the overall performance of the multi-energy spectrum X-ray detector. The filter layer is pixelated; since the pixels of the lower-layer complementary metal-oxide-semiconductor sensor are much smaller than those of the upper-layer amorphous silicon thin-film transistor sensor, different thicknesses of energy spectrum regions are created on the filter layer corresponding to multiple pixels in the lower layer, corresponding to a single pixel in the upper layer. These different thicknesses of energy spectrum regions correspond to different energy spectrum information, thus enabling the dual-layer detector to achieve a multi-energy spectrum effect. Compared to multi-layer sensors and multi-layer filters, this significantly reduces the structural and electronic design complexity, assembly complexity, and cost of the multi-energy spectrum X-ray detector. Therefore, the present invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.

[0063] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A multi-spectral X-ray detector, characterized by, The multi-spectrum X-ray detector comprises, from top to bottom, an upper detector module, a filtering layer and a lower detector module stacked in sequence along the X-ray incident direction; The filtering layer is N in number, wherein N is an integer greater than or equal to 1; The lower detector module is N in number, wherein N is an integer greater than or equal to 1; The filtering layer and the lower detector module are alternately stacked, and the lower detector module comprises a complementary metal oxide semiconductor sensor and a scintillator located above the complementary metal oxide semiconductor sensor.

2. The multi-spectral x-ray detector of claim 1, wherein: The upper detector module comprises an upper detector and a scintillator layer located directly above the upper detector, wherein the upper detector comprises an amorphous silicon thin film transistor sensor or a complementary metal oxide semiconductor sensor.

3. The multi-spectral x-ray detector of claim 2, wherein: The pixel size of the amorphous silicon thin film transistor sensor is not less than 100 μm.

4. The multi-spectral x-ray detector of claim 2, wherein: The pixel size of the complementary metal oxide semiconductor sensor is not greater than 1000 nm.

5. The multi-spectral x-ray detector of claim 1, wherein: The filtering layer comprises at least two pixel units arranged in an array, each of the pixel units corresponds to a different thickness of a spectrum region, and each of the spectrum regions has different absorption energy for X-rays.

6. The multi-spectral x-ray detector of claim 5, wherein: The material of the filtering layer is copper, and the thickness of each of the spectrum regions ranges from 0 to 3 mm.

7. The multi-spectral x-ray detector of claim 1, wherein: When N is an integer greater than or equal to 2, the filtering layer is a homogeneous filtering layer, the material of the homogeneous filtering layer is copper, and the homogeneous filtering layer corresponds to a spectrum region of the same thickness.

8. A detection system characterized by: The detection system comprises the multi-spectrum X-ray detector of any one of claims 1 to 7.

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