Linear scanning CT imaging system and method

Abstract

Provided are a linear scanning CT imaging system and method, the system comprising: a transfer device for moving a scanned object in a scanning channel along a predetermined transfer direction; the ray source is used for alternately emitting ray beams to form a scanning area; the detector comprises a first detector and a second detector; the first detector is used for detecting first projection data formed after the ray beam penetrates through the scanning object in the process that the scanning object penetrates through the scanning area; the second detector is used for detecting second projection data formed after the ray beam penetrates through the scanning object in the process that the scanning object penetrates through the scanning area; and the imaging device is used for generating a digital ray image of the scanned object according to the second projection data and obtaining a computed tomography image of the scanned object according to the first projection data and the second projection data.

Description

[0001] This application is a divisional application of a Chinese invention patent application with application number 202311490080.9 (filing date: November 9, 2023; invention title: Linear Scanning CT Imaging System and Method). Technical Field

[0002] The present disclosure relates to the field of radiation imaging, and in particular, to a linear scanning CT imaging system and method. Background Art

[0003] Currently, safety issues have been increasingly emphasized, and various security inspection devices are installed in public places.

[0004] For example, most of the existing large cargo and container X-ray inspection systems adopt the DR imaging mode, and artificial image interpretation is carried out by obtaining single-energy or dual-energy fluoroscopic images at a single angle or multiple angles to determine whether there are prohibited items in the cargo.

[0005] For another example, a CT inspection system based on a linear scanning trajectory can also be used for cargo security inspection. This technology does not require rotating components, and the radiation source and detector are stationary and fixed on both sides of the scanning channel. The object is scanned through translational motion. This technology can also obtain the attenuation coefficient information inside the object for automatic identification.

[0006] However, based on the current application situation, the above two technologies have at least the following related problems.

[0007] The DR imaging inspection system can only give fluoroscopic images at one or more angles. If the composition of the inspected cargo is complex and the arrangement is dense, there will be serious stacking and occlusion in the fluoroscopic images, making it difficult to extract information of different items and judge prohibited items.

[0008] The linear CT scanning system solves the problem of occlusion in fluoroscopic images. However, due to the incomplete scanning angles and the difficulty in accurately positioning the scanning geometry, and in order to improve the scanning and imaging efficiency, the data processing process is not sufficient. Therefore, compared with the images given by the traditional DR system, the CT images have inevitable deterioration of spatial resolution, irreducible reconstruction artifacts, and even distortion of the object shape.

[0009] The above information disclosed in this section is only for understanding the background of the disclosed concept of the present disclosure. Therefore, the above information may include information that does not constitute the prior art. Summary of the Invention

[0010] In view of at least one aspect of the above technical problems, the present disclosure provides a linear scanning CT imaging system and its imaging method.

[0011] According to a first aspect of the present disclosure, there is provided a linear scanning CT imaging system. The system includes: a conveying device for moving a scanning object along a predetermined conveying direction in a scanning channel, wherein the conveying device includes a conveying surface for placing the scanning object; m radiation sources for alternately emitting radiation beams to form a scanning area, wherein the m radiation sources are located on one side of the scanning channel, and m is a positive integer greater than or equal to 2; and n detectors for detecting projection data formed after the radiation beam passes through the scanning object during the process of the scanning object passing through the scanning area, wherein the n detectors are located on the other side of the scanning channel, the n detectors are arranged at intervals in sequence along the conveying direction, and n is a positive integer greater than or equal to 3. Among them, the n detectors include n1 first detectors and n2 second detectors, n1 is a positive integer greater than or equal to 2, and n2 is a positive integer greater than or equal to 1; the n1 first detectors are used for detecting first projection data formed after the radiation beam passes through the scanning object during the process of the scanning object passing through the scanning area; the n2 second detectors are used for detecting second projection data formed after the radiation beam passes through the scanning object during the process of the scanning object passing through the scanning area; and the system further includes an imaging device for: generating a digital radiographic image of the scanning object according to the second projection data; and generating a computed tomography image of the scanning object according to the first projection data and the second projection data.

[0012] According to an embodiment of the present disclosure, at least one second detector is different from each first detector.

[0013] According to an embodiment of the present disclosure, the resolution of at least one second detector is higher than that of each first detector.

[0014] According to an embodiment of the present disclosure, the number of pixels of at least one second detector is greater than that of each first detector; and / or, the pixel size of at least one second detector is smaller than that of each first detector.

[0015] According to an embodiment of the present disclosure, the crystal material of at least one second detector is different from that of each first detector; and / or, the thickness of at least one second detector along the radiation incident direction is different from that of each first detector.

[0016] According to an embodiment of the present disclosure, the crystal afterglow of at least one second detector is less than that of each first detector; and / or, the detection efficiency of at least one second detector is better than that of each first detector.

[0017] According to an embodiment of the present disclosure, the first detector includes a plurality of first detector modules, the second detector includes a plurality of second detector modules, and the arrangement of the plurality of first detector modules is different from the arrangement of the plurality of second detector modules.

[0018] According to an embodiment of the present disclosure, the n1 first detectors are respectively linear detector arrays; and / or, the n2 second detectors are respectively linear detector arrays.

[0019] According to an embodiment of the present disclosure, the n1 first detectors are respectively linear detector arrays; and / or, at least one second detector includes a vertical arm detector arranged along a first direction and a horizontal arm detector arranged along a second direction, wherein the second direction intersects both the conveying direction and the first direction.

[0020] According to an embodiment of the present disclosure, the n1 first detectors are respectively linear detector arrays; and / or, at least one second detector includes a vertical arm detector arranged along a first direction, a first horizontal arm detector arranged along a second direction, and a second horizontal arm detector arranged along the second direction, wherein the first horizontal arm detector and the second horizontal arm detector are respectively located on the upper side and the lower side of the vertical arm detector in the first direction, and the second direction intersects both the conveying direction and the first direction.

[0021] According to an embodiment of the present disclosure, the m ray sources are arranged at intervals in sequence along a first straight line, the first straight line is an imaginary straight line extending along a first direction, and the first direction is perpendicular to the conveying surface.

[0022] According to an embodiment of the present disclosure, the n detectors include only 1 second detector, and at least one first detector is respectively arranged on both sides of the 1 second detector along the conveying direction.

[0023] According to an embodiment of the present disclosure, the plane where the 1 second detector and the first straight line are located is perpendicular to the conveying direction.

[0024] According to an embodiment of the present disclosure, at least one second detector includes k sub-detectors, k is a positive integer greater than or equal to 2, and the k sub-detectors are arranged at intervals in sequence along the conveying direction; the arrangement interval along the conveying direction between any two adjacent sub-detectors among the k sub-detectors is less than the arrangement interval along the conveying direction between any two adjacent first detectors among the n1 first detectors.

[0025] According to an embodiment of the present disclosure, the imaging device is configured to: combine the second projection data of the k sub-detectors to generate a digital radiographic image of the scanned object.

[0026] According to an embodiment of the present disclosure, the horizontal arm detector includes a plurality of detector modules, and the plurality of detector modules are connected end to end in sequence.

[0027] According to an embodiment of the present disclosure, the cross-arm detector includes a plurality of detector modules, and the plurality of detector modules are arranged at intervals in the second direction.

[0028] According to an embodiment of the present disclosure, the light-receiving surface of each detector module is perpendicular to the second straight line, and the second straight line is a straight line connecting the i-th ray source and a predetermined point on the light-receiving surface, where the predetermined point is located on the boundary of the light-receiving surface or within the light-receiving surface, and i is a positive integer greater than or equal to 1 and less than or equal to m.

[0029] According to an embodiment of the present disclosure, the conveying device includes a plurality of conveying rollers, and in the conveying direction, the second cross-arm detector is located at the gap between two adjacent conveying rollers.

[0030] According to an embodiment of the present disclosure, the number n2 of the second detectors is greater than or equal to 2, and the n2 second detectors and the n1 first detectors are arranged alternately in the conveying direction.

[0031] According to an embodiment of the present disclosure, among the n2 second detectors, the plane where one second detector and the first straight line are located is perpendicular to the conveying direction, and the planes where the other second detectors and the first straight line are located form an angle greater than 90° or less than 90° with the conveying direction.

[0032] According to an embodiment of the present disclosure, among the n2 second detectors, each second detector includes a vertical-arm detector arranged in the first direction and a cross-arm detector arranged in the second direction, where the second direction intersects both the conveying direction and the first direction.

[0033] According to an embodiment of the present disclosure, the plane formed by the intersection of the vertical-arm detector and the cross-arm detector of each second detector extends through the first straight line.

[0034] According to an embodiment of the present disclosure, the scanning channel is a straight channel.

[0035] The second aspect of the present disclosure provides a linear scanning CT imaging method, which includes: driving a scanning object by a conveying device to move in a scanning channel along a predetermined conveying direction, wherein the conveying device includes a conveying surface for placing the scanning object; causing m ray sources to alternately emit beamlets to form a scanning area, wherein the m ray sources are located on one side of the scanning channel, and m is a positive integer greater than or equal to 2; causing the scanning object to pass through the scanning area; during the process that the scanning object passes through the scanning area, causing n detectors to detect projection data formed after the beamlets pass through the scanning object, wherein the n detectors are located on the other side of the scanning channel, the n detectors are arranged at intervals in sequence along the conveying direction, and n is a positive integer greater than or equal to 3, wherein the n detectors include n1 first detectors and n2 second detectors, n1 is a positive integer greater than or equal to 2, and n2 is a positive integer greater than or equal to 1; causing the n detectors to detect the projection data formed after the beamlets pass through the scanning object includes: causing the n1 first detectors to detect first projection data formed after the beamlets pass through the scanning object; and causing the n2 second detectors to detect second projection data formed after the beamlets pass through the scanning object; and the method further includes: generating a digital radiographic image of the scanning object according to the second projection data; and generating a computed tomography image of the scanning object according to the first projection data and the second projection data.

[0036] According to an embodiment of the present disclosure, at least one second detector includes a vertical arm detector arranged along a first direction and a horizontal arm detector arranged along a second direction, wherein the second direction intersects both the conveying direction and the first direction; generating a digital radiographic image of the scanning object according to the second projection data includes: performing proportional adjustment on the second projection data detected by the vertical arm detector and the horizontal arm detector, and then combining them to generate a digital radiographic image of the scanning object.

[0037] According to an embodiment of the present disclosure, at least one second detector includes k sub-detectors, k is a positive integer greater than or equal to 2, and the k sub-detectors are arranged at intervals in sequence along the conveying direction; the arrangement interval along the conveying direction between any two adjacent sub-detectors among the k sub-detectors is less than the arrangement interval along the conveying direction between any two adjacent first detectors among the n1 first detectors; generating a digital radiographic image of the scanning object according to the second projection data includes: combining the second projection data of the k sub-detectors to generate a digital radiographic image of the scanning object.

[0038] In the linear scanning CT imaging system according to an embodiment of the present disclosure, through one scan, DR imaging and CT imaging can be performed simultaneously. Through CT imaging, problems such as stacking or occlusion can be avoided. Through DR imaging, the quality of the image can be improved, the detailed structure of the scanned object can be observed, and problems such as resolution deterioration and artifacts can be avoided. Description of the Drawings

[0039] To better understand the present disclosure, the present disclosure will be described in detail with reference to the following drawings:

[0040] Figure 1 Schematically shows a schematic structural diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure.

[0041] Figure 2A and Figure 2B Schematically show schematic structural diagrams of a first detector and a second detector provided by an embodiment of the present disclosure, respectively, in which the pixel distribution is schematically shown.

[0042] Figure 3A and Figure 3B Schematically show schematic structural diagrams of a first detector and a second detector provided by an embodiment of the present disclosure, respectively, in which the detector module distribution is schematically shown.

[0043] Figure 4 Schematically shows a schematic structural diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which it is schematically shown that the second detector includes an L-shaped detector.

[0044] Figure 5A and Figure 5B Schematically show side views of a linear scanning CT imaging system provided by an embodiment of the present disclosure as viewed along the conveying direction.

[0045] Figure 6 and Figure 7 Schematic structural diagrams of a linear scanning CT imaging system provided by an embodiment of the present disclosure, respectively, in which it is schematically shown that the second detector includes a plurality of sub-detectors.

[0046] Figure 8 Schematically shows a side view schematic diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which it is schematically shown that the second detector includes a U-shaped detector.

[0047] Figure 9 Schematically shows a top view schematic diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which the relative positional relationship between the second detector and the conveying device is schematically shown.

[0048] Figure 10 Schematically shows a side view schematic diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which an arrangement mode of a cross-arm detector of the second detector is schematically shown.

[0049] Figure 11 Schematically shows a side view schematic diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which another arrangement mode of a cross-arm detector of the second detector is schematically shown.

[0050] Figure 12 Schematically shows a schematic structural diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which a plurality of second detectors are schematically shown.

[0051] Figure 13 Schematically shows a schematic structural diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which a plurality of L-shaped second detectors are schematically shown.

[0052] Figure 14 Schematically shows a schematic structural diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which a rotating device is schematically shown.

[0053] Figure 15 Schematically shows a structural block diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure.

[0054] Figure 16 Schematically shows a schematic diagram of a trigger pulse sequence provided by an embodiment of the present disclosure.

[0055] Figure 17 Schematically shows a schematic diagram of another trigger pulse sequence provided by an embodiment of the present disclosure.

[0056] Figure 18 Schematically shows a schematic diagram of yet another trigger pulse sequence provided by an embodiment of the present disclosure.

[0057] Figure 19 Schematically shows a schematic flow diagram of a linear scanning CT imaging method provided by an embodiment of the present disclosure.

[0058] Figure 20 Schematically shows a schematic flow diagram of a projection data processing method provided by an embodiment of the present disclosure.

[0059] Figure 21A and Figure 21B Schematically shows a schematic diagram of a second projection data ratio processing method provided by an embodiment of the present disclosure.

[0060] Figure 22 Schematically shows a block diagram of an imaging device of a linear scanning CT imaging system provided by an embodiment of the present disclosure. Detailed implementation manners

[0061] Specific embodiments of the present disclosure will be described in detail below. It should be noted that the embodiments described herein are only for illustrative purposes and are not intended to limit the present disclosure. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to those of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known structures, materials, or methods have not been specifically described to avoid obscuring the present disclosure.

[0062] Throughout the specification, references to "one embodiment", "an embodiment", "an example", or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present disclosure. Thus, the phrases "in one embodiment", "in an embodiment", "an example", or "an example" appearing throughout the specification do not necessarily all refer to the same embodiment or example. Additionally, the particular features, structures, or characteristics may be combined in any suitable combination and / or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will understand that the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0063] The terms used herein are merely for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. as used herein indicate the presence of features, steps, operations, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.

[0064] All terms used herein (including technical and scientific terms) have the meaning commonly understood by those of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0065] In the specification of the present disclosure, digital radiography (also known as DR) imaging refers to a technology of directly performing digital radiography under computer control. For example, an amorphous silicon flat panel detector can be used to convert the ray information penetrating the detection object into digital signals, and the computer reconstructs the image and performs a series of post-image processing to generate a digital radiography image of the scanned object.

[0066] Computed tomography (also known as CT) imaging refers to a technology in which after using rays to perform tomographic scanning on a detection object, the analog signals received by the detector are converted into digital signals, and the attenuation coefficient of each pixel is calculated by an electronic computer, and then the image is reconstructed, so as to display the tomographic structure of each part of the detection object.

[0067] It should be noted that the linear scanning CT imaging system and method provided by the embodiments of the present disclosure are applicable to security inspections of items in various public places, can obtain the internal attenuation coefficient distribution map of an object and automatically identify dangerous goods, and have advantages in the security inspection of large items (such as containers).

[0068] Figure 1 It is a schematic structural diagram of the linear scanning CT imaging system provided by the embodiments of the present disclosure. Figure 1 The linear scanning CT imaging system in includes: a conveying device 3, m radiation sources 1, n detectors 2, and an imaging device 5. Exemplarily, m is a positive integer greater than or equal to 2, and n is a positive integer greater than or equal to 3.

[0069] Specifically, the conveying device 3 is used to move the scanning object 30 in the scanning channel 4 along a predetermined conveying direction D3 (such as Figure 1 the direction indicated by the arrow in ), where the conveying device 3 includes a conveying surface 3S for placing the scanning object 30. Exemplarily, the conveying device 3 can be implemented in the form of belt conveying, or chain conveying, gear conveying, or other transmission methods, which are not limited herein. For example, the scanning object 30 is placed on the conveying surface 3S of the conveying device 3. It should be noted that in some exemplary embodiments, the power mechanism of the conveying device 3 can support one-way conveying and can also support two-way conveying.

[0070] In Figure 1 the embodiment of, the scanning channel 4 is a linear scanning channel, that is, the movement trajectory of the scanning object 30 in the scanning area is a linear trajectory.

[0071] Continue to refer to Figure 1 , the m radiation sources 1 are used to alternately emit radiation beams to form a scanning area, where the m radiation sources 1 are located on one side of the scanning channel 4. In some exemplary embodiments of the present disclosure, the m radiation sources 1 are arranged at intervals along a first straight line L1, and the first straight line L1 is an imaginary straight line extending along a first direction D1, and the first direction D1 is perpendicular to the conveying surface 3S. That is, the multiple radiation sources 1 are distributed at different height positions on a vertical line, and the multiple radiation sources 1 alternately emit radiation beams to form a scanning area.

[0072] Exemplarily, the radiation source 1 can be an accelerator, the energy of the accelerator can be adjusted, and the penetration power is strong. It should be noted that the embodiments of the present disclosure do not make special restrictions on the type of the radiation source 1. In other embodiments, the radiation source 1 can adopt other types of radiation sources, for example, an X-ray machine.

[0073] Continue to refer to Figure 1, n detectors 2 are used to detect the projection data formed after the radiation beam passes through the scanned object 30 during the process of the scanned object 30 passing through the scanning area. Among them, the n detectors are located on the other side of the scanning channel 4, and the n detectors 2 are arranged at intervals in sequence along the conveying direction D3.

[0074] In an embodiment of the present disclosure, as Figure 1 shown, the n detectors 2 include n1 first detectors 21 ( Figure 1 schematically shown by solid lines in Figure 1 ) and n2 second detectors 22 (

[0075] schematically shown by dashed lines in

[0076] ). For example, n1 is a positive integer greater than or equal to 2, and n2 is a positive integer greater than or equal to 1. The n1 first detectors 21 are used to detect the first projection data formed after the radiation beam passes through the scanned object 30 during the process of the scanned object 30 passing through the scanning area. The n2 second detectors 22 are used to detect the second projection data formed after the radiation beam passes through the scanned object 30 during the process of the scanned object 30 passing through the scanning area.

[0077] It should be noted that in combination with reference to Figure 1, the scanning object 30 moves in the scanning channel 4 and passes through the scanning area. During the process of passing through the scanning area, multiple ray sources 1 alternately emit ray beams, and the first detector 21 and the second detector 22 respectively detect the first projection data and the second projection data simultaneously. In this way, DR imaging and CT imaging can be performed simultaneously through one scan. That is, in the embodiments of the present disclosure, it is not necessary for the scanning object 30 to first perform DR imaging and then perform CT imaging, that is, it is not necessary to separate the scanning segments for DR imaging and CT imaging. Therefore, from a spatial perspective, the occupied space of the linear scanning CT imaging system can be reduced, and a structurally compact linear scanning CT imaging system can be realized; from a temporal perspective, the imaging time for forming DR images and CT images can be shortened, which is beneficial to improving the detection efficiency.

[0078] It should also be noted that in the embodiments of the present disclosure, by arranging the first detector 21 and the second detector 22 simultaneously for multiple ray sources 1, DR imaging and CT imaging can be performed simultaneously through one scan, and it is not necessary for the scanning object 30 to pass through the scanning area multiple times. For example, it is not necessary for the conveying device 3 to drive the scanning object 30 to move bidirectionally to pass through the scanning area multiple times. Therefore, from a structural perspective, the structure of the conveying device 3 can be simplified; from a temporal perspective, the imaging time for forming DR images and CT images can be shortened, which is beneficial to improving the detection efficiency.

[0079] Particularly advantageously, since DR imaging and CT imaging can be performed simultaneously through one scan and it is not necessary for the scanning object 30 to pass through the scanning area multiple times, the linear scanning CT imaging system and method provided by the embodiments of the present disclosure are particularly suitable for the security inspection of large items (such as containers).

[0080] It should also be noted that in the embodiments of the present disclosure, the scanning channel 4 is a linear scanning channel, that is, the movement trajectory of the scanning object 30 in the scanning area is a linear trajectory. That is, the scanning object 30 moves along a single linear trajectory relative to the ray source and the detector, and there is no need to set complex rotating motion components such as slip rings, which is beneficial to simplifying the structural complexity of the linear scanning CT imaging system and improving the reliability of the linear scanning CT imaging system.

[0081] It should also be noted that in the embodiments of the present disclosure, multiple ray sources 1 are arranged along a first straight line, that is, a ray source distributed along a straight line is formed, and multiple ray sources are controlled to alternately emit beams, and in this way, the scanning object 30 is scanned and imaged from multiple angles. In this way, it is possible to avoid setting complex rotating motion components such as slip rings to drive the ray source to move, which is beneficial to simplifying the structural complexity of the linear scanning CT imaging system and improving the reliability of the linear scanning CT imaging system.

[0082] It should also be noted that in the embodiments of the present disclosure, the second detector for DR imaging and the first detector for other CT imaging are arranged along the conveying direction. By changing the arrangement manner of the detectors, DR and CT imaging can be achieved simultaneously, improving the quality of the imaging images without increasing the complexity of the system structure.

[0083] In the embodiments of the present disclosure, at least one second detector 22 is different from each first detector 21. Specifically, the second detector 22 can be used for DR imaging, and the first detector 21 can be used for CT imaging, that is, the resolution of the DR image formed by the second detector 22 is higher than the resolution of the CT image formed by the first detector 21. In other words, the resolution of at least one second detector 22 is higher than the resolution of each first detector 21.

[0084] Figure 2A and Figure 2B Schematically show the structural diagrams of the first detector and the second detector respectively.

[0085] For example, with reference to Figure 2A and Figure 2B , the first detector 21 can include a plurality of pixels 21P, the second detector 22 can include a plurality of pixels 22P, and the number of pixels of at least one second detector 22 is greater than the number of pixels of each first detector 21.

[0086] In some exemplary embodiments, with continued reference to Figure 3A and Figure 3B , the first detector 21 can include a plurality of first detector modules 21M, and the second detector 22 can include a plurality of second detector modules 22M. For example, the first detector module 21M can include at least one pixel 21P, and the second detector module 22M can include at least one pixel 22P. The arrangement manner of the plurality of first detector modules 21M is different from the arrangement manner of the plurality of second detector modules 22M. For example, the plurality of first detector modules 21M can be arranged in an array of r1 rows and c1 columns, and the plurality of second detector modules 22M can be arranged in an array of r2 rows and c2 columns, where r1, r2, c1, and c2 are positive integers greater than or equal to 2, r1 may not be equal to r2, and / or c1 may not be equal to c2.

[0087] For another example, with reference to Figure 2A and Figure 2B, the pixel size of at least one second detector 22 is smaller than that of each first detector 21. Exemplarily, a pixel 21P of the first detector 21 may have a substantially rectangular shape, and a pixel 22P of the second detector 22 may have a substantially rectangular shape. At least one dimension of the length and width of the pixel 21P is smaller than at least one dimension of the length and width of the pixel 22P. It should be noted that the shapes of the pixels of the first detector and the second detector are not limited to rectangular shapes, and may include any suitable shapes. The embodiments of the present disclosure do not impose special restrictions on this.

[0088] In the embodiments of the present disclosure, by setting the size of the pixels, the arrangement of the pixels, and / or the arrangement of the modules of the first detector and the second detector, the number of pixels per unit area of the first detector is smaller than the number of pixels per unit area of the second detector. In this way, the resolution of the image formed by the second detector is higher than the resolution of the image formed by the first detector.

[0089] In some exemplary embodiments, at least one second detector 22 is made of a different crystal material from each first detector 21. The crystal afterglow of at least one second detector 22 is less than that of each first detector 21.

[0090] It should be noted that the "crystal afterglow" here refers to the afterglow effect of the crystal. When the ray beam emitted by the ray source 1 passes through the light receiving surface and enters each crystal, and after being absorbed by the crystal to generate a projected image after attenuation, it will still remain for a period of time.

[0091] In some exemplary embodiments, at least one second detector 22 has a different thickness from each first detector 21 along the ray incident direction.

[0092] In some exemplary embodiments, the detection efficiency of at least one of the second detectors 22 is better than that of each of the first detectors 21.

[0093] In some exemplary embodiments, as Figure 1 shown, n1 first detectors 21 are respectively linear detector arrays; and / or, n2 second detectors 22 are respectively linear detector arrays. Compared with the area array detector, the linear detector array is more flexible and has lower cost.

[0094] In some exemplary embodiments, the number of ray sources 1 is m, and the number of detectors is n. m is a positive integer greater than or equal to 2, and n is a positive integer greater than or equal to 3. Each detector can collect the attenuation signal of the ray beam emitted by each ray source 1 at a certain angle, that is, a set of projection data. Then, m×n sets of projection data can be obtained in one scanning process.

[0095] Figure 4 A schematic structural diagram of the linear scanning CT imaging system provided by an embodiment of the present disclosure, in which it is schematically shown that the second detector includes an L-shaped detector. Figure 4 The linear scanning CT imaging system in [reference] includes: a conveying device 3, m radiation sources 1, n detectors 2, and an imaging device 5. Exemplarily, m is a positive integer greater than or equal to 2, and n is a positive integer greater than or equal to 3.

[0096] In an embodiment of the present disclosure, as Figure 4 shown, the n detectors 2 include n1 first detectors 21 ( Figure 4 schematically shown by solid lines in [reference]) and n2 second detectors 22 ( Figure 4 schematically shown by dashed lines in [reference]). For example, n1 is a positive integer greater than or equal to 2, and n2 is a positive integer greater than or equal to 1. The n1 first detectors 21 are used to detect first projection data formed after the radiation beam passes through the scanning object 30 during the process of the scanning object 30 passing through the scanning area. The n2 second detectors 22 are used to detect second projection data formed after the radiation beam passes through the scanning object 30 during the process of the scanning object 30 passing through the scanning area.

[0097] As Figure 4 shown, the n1 first detectors 21 are respectively linear detector arrays; and / or, at least one second detector 22 includes a vertical arm detector 221 arranged along a first direction D1 and a horizontal arm detector 222 arranged along a second direction D2, where the second direction D2 intersects both the conveying direction D3 and the first direction D1.

[0098] By adding a horizontal arm detector, the second detector can scan and image the scanning object at a larger scanning angle, which is beneficial to improving the quality of DR images.

[0099] Continuing to refer to Figure 4 , for the added horizontal arm detector, it can mainly target the lowermost radiation source 1, that is, during the scanning process, the horizontal arm detector 222 mainly receives the signal of the radiation beam emitted by the lowermost radiation source 1 after being attenuated by the scanning object.

[0100] Figure 5A and Figure 5B are respectively side views of the linear scanning CT imaging system observed along the conveying direction. Referring to Figure 5A and Figure 5B, the cone angle φ1 of the ray source 1 located at the lowermost side is greater than the cone angle φ2 of other ray sources 1. In this way, during the scanning process, the cone angle of the ray beam emitted by the ray source 1 located at the lowermost side is larger, enabling the vertical arm detector 221 and the horizontal arm detector 222 to detect the signal after attenuation of the ray beam emitted by the ray source 1 located at the lowermost side by the scanning object; the cone angles of the ray beams emitted by other ray sources 1 are smaller, so that the ray beams emitted by other ray sources 1 will not have a negative impact on DR imaging due to scattering or other reasons.

[0101] Figure 6 and Figure 7 are respectively the structural schematic diagrams of the linear scanning CT imaging system provided by the embodiments of the present disclosure, in which it is schematically shown that the second detector includes a plurality of sub-detectors.

[0102] As Figure 6 and Figure 7 shown, at least one second detector 22 includes k sub-detectors, where k is a positive integer greater than or equal to 2, and the k sub-detectors are arranged at intervals in sequence along the conveying direction.

[0103] The arrangement interval along the conveying direction between any two adjacent sub-detectors among the k sub-detectors is less than the arrangement interval along the conveying direction between any two adjacent first detectors 21 among the n1 first detectors 21.

[0104] As Figure 6 shown, each sub-detector is a linear detector array. As Figure 7 shown, each sub-detector is an L-shaped detector, that is, each sub-detector may include a vertical arm detector and a horizontal arm detector.

[0105] In this embodiment, the imaging device is used to combine the second projection data of the k sub-detectors to generate a digital ray image of the scanning object. By arranging a plurality of densely arranged sub-detectors to form the second detector, the DR imaging quality of the scanning object can be further improved.

[0106] It should be noted that the "combination" here includes various data processing methods such as recombination, combination, and resampling. For example, if the second detector 22 includes 2 sub-detectors, and each sub-detector collects 1000 data during one scan, then the 1000 columns of data collected by each of the 2 sub-detectors can be arranged alternately, so that an image of 2000 columns can be obtained, which is equivalent to doubling the spatial sampling rate in the motion direction.

[0107] It should be noted that in Figure 6 and Figure 7In the illustrated embodiment, a layout is schematically shown in which the second detector has two rows (i.e., k = 2) with a relatively small row pitch. However, the embodiments of the present disclosure are not limited thereto. In other embodiments, the second detector may have more rows with a relatively small row pitch.

[0108] Figure 8 FIG. 4 is a side view schematic diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which it is schematically shown that the second detector includes a U-shaped detector.

[0109] As Figure 8 described, the n1 first detectors 21 are respectively linear detector arrays. At least one second detector 22 includes a vertical arm detector 221 arranged along a first direction D1, a first horizontal arm detector 222 arranged along a second direction D2, and a second horizontal arm detector 223 arranged along the second direction D2. Among them, the first horizontal arm detector 222 and the second horizontal arm detector 223 are respectively located above and below the vertical arm detector 221 in the first direction D1.

[0110] Continuing to refer to Figure 8 , for the two additional horizontal arm detectors, it can be for all the radiation sources 1. That is, during the scanning process, the first horizontal arm detector 222 and the second horizontal arm detector 223 receive the signals after the radiation beams emitted by all the radiation sources 1 are attenuated by the scanned object. Correspondingly, in the Figure 8 illustrated embodiment, the cone angles φ of the radiation beams emitted by the three radiation sources 1 are all relatively large.

[0111] By adding two horizontal arm detectors, the second detector can scan and image the scanned object at a larger scanning angle, which is beneficial to improving the quality of the DR image.

[0112] Figure 9 FIG. 5 is a top view schematic diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which the relative positional relationship between the second detector and the conveying device is schematically shown.

[0113] Referring to Figure 9 , the conveying device 3 may include a plurality of conveying rollers 31. In the conveying direction D3, the second horizontal arm detector 223 is located at the gap between two adjacent conveying rollers 31.

[0114] Combined with reference to Figure 8 and Figure 9When the linear track transmission adopts the roller way, there are rail vehicles and turntables at both ends of the linear motion to realize operations such as goods entry, exit and rotation. A cross-arm detector 223 can be laid at the gap between two rollers. At this time, the ray beams emitted by all the ray sources 1 can be used for DR imaging, that is, DR imaging from multiple perspectives can be carried out, and the conveyor roller 31 will not block the signals received by the cross-arm detector 223, which is beneficial to further improving the quality of DR imaging.

[0115] Figure 10 FIG. is a side view schematic diagram of the linear scanning CT imaging system provided by the embodiment of the present disclosure, in which a layout mode of the cross-arm detector of the second detector is schematically shown. Referring jointly to Figure 3B and Figure 10 , the cross-arm detector 222 may include a plurality of detector modules 22M, and the plurality of detector modules 22M may be connected end to end in sequence.

[0116] In this embodiment, for the cross-arm detector, all the ray sources 1 can be targeted, that is, during the scanning process, the cross-arm detector 222 receives the signals attenuated by the scanning object from the ray beams emitted by all the ray sources 1. Correspondingly, in Figure 10 the embodiment shown, the cone angles φ of the ray beams emitted by the 3 ray sources 1 are all relatively large. In this way, the DR images formed by the ray beams emitted by all the ray sources 1 are all continuous and untruncated images.

[0117] Figure 11 FIG. is a side view schematic diagram of the linear scanning CT imaging system provided by the embodiment of the present disclosure, in which another layout mode of the cross-arm detector of the second detector is schematically shown. Referring jointly to Figure 3B and Figure 11 , the cross-arm detector 222 may include a plurality of detector modules 22M, and the plurality of detector modules 22M are arranged at intervals in the second direction D2.

[0118] In this embodiment, the light-receiving surface 22MS of each detector module 22M is perpendicular to the second straight line L2, and the second straight line L2 is a straight line connecting the i-th ray source 1 and a predetermined point P on the light-receiving surface 22MS, where i is a positive integer greater than or equal to 1 and less than or equal to m.

[0119] It should be noted that the "predetermined point P on the light-receiving surface 22MS" may be an end point, a center point or other suitable points of the light-receiving surface 22MS of the detector module, that is, the predetermined point P on the light-receiving surface 22MS is located on the boundary of the light-receiving surface 22MS or within the light-receiving surface 22MS, and the embodiments of the present disclosure do not make special limitations on this.

[0120] Through such a setting method, each detector module of the cross-arm detector can be oriented towards a certain ray source 1. For example, inFigure 11 In the illustrated embodiment, each detector module of the cross-arm detector faces the radiation source 1 located at the lowermost side. On this basis, a clearer DR image can be obtained through the second detector.

[0121] In this embodiment, the radiation beam emitted by the radiation source 1 is perpendicularly incident on the crystal of the cross-arm detector. When the radiation beam is perpendicularly incident on the crystal, the thickness of the crystal penetrated is equal to the crystal thickness, and the equivalent area of the crystal is equal to the actual area of the light receiving surface of the crystal. Therefore, in the embodiments of the present disclosure, by the way of perpendicularly incident on the crystal, on the one hand, it can increase the thickness of the crystal effectively penetrated, thereby improving the penetration power of the radiation beam, and further making the projection data carried by the detected projection image more comprehensive; on the other hand, it can make the equivalent crystal area equal to the actual area of the light receiving surface, thereby improving the spatial resolution of the radiation beam, and further making the resolution of the projection data carried by the detected projection image higher.

[0122] In some exemplary embodiments of the present disclosure, the n detectors may include only 1 second detector 22, and at least one first detector 21 is arranged on both sides of the 1 second detector 22 along the conveying direction D3. In this embodiment, only one column of detectors needs to be replaced, and a clearer and more complete DR image can be obtained at low cost, and the CT image will not deteriorate.

[0123] Exemplarily, referring to Figure 1 , the plane P1 where the 1 second detector 22 and the first straight line L1 are located is perpendicular to the conveying direction D3. When the radiation beam emitted by the radiation source 1 is a cone beam, through such a setting method, the central beam plane of the cone beam can be made to face the second detector 22 directly, which is beneficial to obtaining a clearer and more complete DR image.

[0124] In some other exemplary embodiments of the present disclosure, the n detectors may include multiple second detectors, that is, the number n2 of the second detectors 22 is greater than or equal to 2.

[0125] It should be noted that, in some exemplary embodiments of the present disclosure, the sum of the numbers of the first detector 21 and the second detector 22 is odd, and the odd-numbered detectors are arranged at intervals along the conveying direction, and the detector at the middle position is the second detector 22. For example, the plane P1 where the second detector 22 at the middle position and the first straight line L1 are located is perpendicular to the conveying direction D3. For another example, the other even-numbered detectors are symmetrically arranged with respect to the second detector 22 at the middle position. Through such a setting method, the central beam plane of the cone beam can be made to face the second detector 22 directly, which is beneficial to obtaining a clearer and more complete DR image.

[0126] It should also be noted that in some other exemplary embodiments of the present disclosure, the sum of the number of the first detectors 21 and the second detectors 22 is an even number, and the even number of detectors are arranged at intervals along the conveying direction. At least one of the two detectors in the middle position is the second detector 22. For example, the plane P1 where one of the second detectors 22 in the middle position and the first straight line L1 are located is not perpendicular to the conveying direction D3.

[0127] Figure 12 FIG. is a schematic structural diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which a plurality of second detectors are schematically shown.

[0128] Referring to Figure 12 , the number n2 of the second detectors 22 is greater than or equal to 2, and the n2 second detectors 22 and the n1 first detectors 21 are alternately arranged along the conveying direction D3.

[0129] It should be noted that the "alternate arrangement" here may mean that along the conveying direction D3, at least one first detector 21 is arranged on both sides of at least one second detector 22, and / or at least one first detector 21 is arranged on both sides of at least two second detectors 22. As Figure 12 shown, along the conveying direction D3, for some of the second detectors 22, one first detector 21 is arranged on both sides of each second detector 22; for another part of the second detectors 22, one first detector 21 is arranged on both sides of two second detectors 22.

[0130] In this embodiment, by increasing the number of the second detectors 22, DR images of multiple viewpoints can be obtained, which is beneficial to improving the quality of DR imaging.

[0131] Continuing to refer to Figure 12 , in the n2 second detectors 22, the plane where one second detector 22 and the first straight line L1 are located is perpendicular to the conveying direction D3, and the planes where the other second detectors 22 and the first straight line L1 are located form an angle greater than 90° or less than 90° with the conveying direction D3.

[0132] For example, as Figure 12 shown, the angle between the plane where the second detector 22 counted from left to right and the first straight line L1 are located and the conveying direction D3 is about 90°, and the angle between the plane where the second detector 22 counted from left to right and the first straight line L1 are located and the conveying direction D3 is greater than 90°, and the angles between the planes where the 3rd and 4th second detectors 22 counted from left to right and the first straight line L1 are located and the conveying direction D3 、 are both less than 90°. Exemplarily, That is, the angles between the planes where each second detector arranged along the conveying direction and the first straight line L1 and the conveying direction D3 decrease in sequence.

[0133] By reasonably arranging the angles between each second detector and the central beam plane of the ray source, each view angle for obtaining a DR image can be reasonably designed, which is beneficial to further improving the quality of DR imaging.

[0134] Figure 13 FIG. is a schematic structural diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which a plurality of L-shaped second detectors are schematically shown.

[0135] Referring to Figure 13 , the number n2 of the second detectors 22 is greater than or equal to 2, and the n2 second detectors 22 and the n1 first detectors 21 are alternately arranged along the conveying direction D3. Among the n2 second detectors, each second detector 22 includes a vertical arm detector 221 arranged along the first direction D1 and a horizontal arm detector 222 arranged along the second direction D2.

[0136] Continuing to refer to Figure 13 , the plane formed by the intersection of the vertical arm detector 221 and the horizontal arm detector 222 of each second detector extends through the first straight line L1.

[0137] Through such a setting method, the placement angle of the horizontal arm detector is matched with the optical path of the ray beam emitted by the ray source, so that DR image data without distortion can be generated.

[0138] In some exemplary embodiments of the present disclosure, referring to Figure 14 , the linear scanning CT imaging system may further include a rotating device 6 located at one end or both ends of the conveying device 3. The rotating device 6 is used to rotate the scanned object by a preset angle when the scanned object passes through the scanning area and moves to the end side of the conveying device 3.

[0139] For example, the conveying device 3 may also be used to make the rotated scanned object pass through the scanning area again; the detector 2 may also be used to detect the first projection data and the second projection data formed after the ray beams emitted by the plurality of ray sources 1 pass through the rotated scanned object during the process that the rotated scanned object passes through the scanning area again; the imaging device 5 may also be used to generate a digital ray image of the scanned object according to the second projection data, and obtain a three-dimensional reconstruction image of the scanned object according to the first projection data and the second projection data.

[0140] It should be noted that the step of rotating the scanning object by a preset angle and passing through the scanning area can be performed multiple times. Those skilled in the art should understand that the more times the scanning object passes through the scanning area in one inspection, the more comprehensive the angles at which the scanning object is irradiated, and thus the higher the quality of the reconstructed image obtained.

[0141] The working process of the linear scanning CT imaging system according to the embodiments of the present disclosure will be described in detail below. Exemplarily, the working process of the linear scanning CT imaging system may include the following steps.

[0142] First, the scanning object 30 is fixed on the conveying device 3, and the scanning object 30 is moved in the scanning channel 4 along the conveying direction D3 of the conveying device 3.

[0143] Next, a plurality of radiation sources 1 distributed in the vertical direction alternately emit beams to form a scanning area.

[0144] Then, the first detector 21 and the second detector 22 respectively detect the first projection data and the second projection data formed after the radiation beams emitted by the plurality of radiation sources 1 pass through the scanning object during the process of the scanning object passing through the scanning area.

[0145] Then, the imaging device 4 generates a digital radiographic image of the scanning object according to the second projection data, and obtains a computed tomography image of the scanning object according to the first projection data and the second projection data.

[0146] According to the embodiments of the present disclosure, with reference to Figure 15 , the linear scanning CT imaging system may further include a pulse generator 7 for generating a trigger pulse sequence for controlling the plurality of radiation sources 1 to alternately emit radiation beams. Among them, the pulse trigger sequence may specifically include the following situations.

[0147] In the first case, a trigger pulse sequence includes trigger pulse signals corresponding one-to-one to the plurality of radiation sources 1, and the trigger pulse signals are used to control the corresponding radiation sources 1 to emit radiation beams with the same energy.

[0148] Exemplarily, Figure 16 shows the trigger pulse signals corresponding one-to-one to 3 radiation sources 1. Among them, the abscissa indicates time, and the trigger pulse signals corresponding one-to-one to the 3 radiation sources 1 are alternately arranged along the direction of the time axis. The ordinate indicates energy, and the energy indicated by all trigger pulse signals is E1. The projection image data obtained in this way is complete data that can be used for monoenergetic CT reconstruction.

[0149] In the second case, a period of the trigger pulse sequence includes a group of trigger pulse signals corresponding one by one to a plurality of radiation sources 1. The group of trigger pulse signals includes a first trigger pulse signal and a second trigger pulse signal. The first trigger pulse signal and the second trigger pulse signal are used to control the corresponding radiation source 1 to sequentially emit a first sub-ray beam with a first energy and a second sub-ray beam with a second energy. Wherein, the radiation source 1 can be a dual-energy accelerator with adjustable energy.

[0150] Exemplarily, Figure 17 shows a group of trigger pulse signals corresponding one by one to 3 radiation sources 1, that is, each radiation source 1 emits a beam twice. Wherein, the abscissa indicates time, and the groups of trigger pulse signals corresponding one by one to the 3 radiation sources 1 are arranged alternately along the direction of the time axis. The ordinate indicates energy. The energy indicated by the first trigger pulse signal in each group of trigger pulse signals is all E2, and the energy indicated by the second trigger pulse signal in each group of trigger pulse signals is all E3. The projection image data obtained in this way is complete data that can be used for dual-energy CT reconstruction.

[0151] The principle of dual-energy CT reconstructed images will be described in detail below.

[0152] First, use dual-energy rays to scan the scanned object to obtain dual-energy projection data;

[0153] Then, according to a pre-created look-up table or by solving a system of equations, calculate the projection values of the basis material coefficients corresponding to the dual-energy projection data. Wherein, the method of creating the look-up table is to select two basis materials, calculate the projection values of the dual-energy rays passing through different thicknesses of these two materials, and obtain the look-up table according to the relationship between the high- and low-energy projection values and different thickness combinations. The method of analytically solving the system of equations is to use the actually obtained high- and low-energy projection values, and obtain the corresponding thickness combination by solving the high- and low-energy projection equations under basis material decomposition.

[0154] Then, from the projection values of the basis materials, the distribution images of the basis material coefficients can be obtained. From the basis material coefficient distribution, the atomic number, characteristic density image of the scanned object, and the attenuation coefficient image of the scanned object at any energy can be obtained, so as to perform material classification and automatic identification of the scanned object.

[0155] It should be noted that, in order to perform dual-energy CT reconstruction on the projection image data obtained in the second case, the linear scan CT imaging system further includes a decomposition unit. The decomposition unit decomposes the first sub-projection data and the second sub-projection data corresponding to the first sub-ray beam and the second sub-ray beam from the first projection data and the second projection data respectively. The imaging device obtains the reconstructed image of the scanned object according to the first sub-projection data and the second sub-projection data of the first projection data, and the first sub-projection data and the second sub-projection data of the second projection data.

[0156] In the third case, the radiation source 1 can be a mono-energetic accelerator with adjustable energy. One period of the trigger pulse sequence includes trigger pulse signals corresponding one-to-one to a plurality of radiation sources 1. During the first scan of the scanned object 30, the trigger pulse signals are used to control the corresponding radiation sources 1 to emit radiation beams with the first same energy; during the second scan of the scanned object 30, the trigger pulse signals are used to control the corresponding radiation sources 1 to emit radiation beams with the second same energy.

[0157] Exemplarily, the energy indicated by all trigger pulse signals during the first scan is E1 (see Figure 16 ); the energy indicated by all trigger pulse signals during the second scan is E4 (see Figure 18 ). The projection image data obtained in this way can also be used for dual-energy CT reconstruction. The image information of the scanned object 30 obtained includes high-energy attenuation coefficient, low-energy attenuation coefficient, atomic number, electron density and other information, so as to classify and automatically identify the scanned object by material.

[0158] Figure 19 FIG. is a schematic flow chart of the linear scan CT imaging method provided by an embodiment of the present disclosure, which is applied to the linear scan CT imaging system as described above. Figure 19 The linear scan CT imaging method in

[0159] In step S131, the conveying device 3 is used to drive the scanned object to move along a predetermined conveying direction in the scan channel, where the conveying device 3 includes a conveying surface for placing the scanned object.

[0160] In step S132, m radiation sources 1 alternately emit radiation beams to form a scan area, where the m radiation sources 1 are located on one side of the scan channel, and m is a positive integer greater than or equal to 2.

[0161] In step S133, the scanned object is made to pass through the scan area.

[0162] In step S134, during the process that the scanned object passes through the scan area, n detectors are used to detect the projection data formed after the radiation beams pass through the scanned object, where the n detectors are located on the other side of the scan channel, the n detectors are arranged at intervals in sequence along the conveying direction, n is a positive integer greater than or equal to 3, the n detectors include n1 first detectors 21 and n2 second detectors 22, n1 is a positive integer greater than or equal to 2, and n2 is a positive integer greater than or equal to 1.

[0163] Figure 20 FIG. is a schematic flow chart of the projection data processing method according to an embodiment of the present disclosure. The above step S134 can further include operation steps S1341 to S1343.

[0164] In step S1341, n1 first detectors 21 detect first projection data formed after a radiation beam passes through a scanned object.

[0165] In step S1342, n2 second detectors 22 detect second projection data formed after a radiation beam passes through a scanned object.

[0166] In step S1343, a digital radiography image of the scanned object is generated according to the second projection data; and a computed tomography image of the scanned object is generated according to the first projection data and the second projection data.

[0167] Exemplarily, the data obtained by the second detector 22 and the first detector 21 are used together for CT reconstruction to obtain a three-dimensional reconstructed image of the object to be examined and display it.

[0168] For example, the data of the second detector 22 can be directly used for reconstruction, or the data of the second detector 22 can be equivalent to the data of the first detector 21 at the same position, and then conventional linear CT reconstruction is performed.

[0169] In some exemplary embodiments, at least one second detector 22 includes a vertical arm detector arranged along a first direction and a horizontal arm detector arranged along a second direction, where the second direction intersects both the conveying direction and the first direction.

[0170] Figure 21A and Figure 21B is a schematic diagram of a method for processing the proportion of second projection data according to an embodiment of the present disclosure.

[0171] In some exemplary embodiments, generating a digital radiography image of the scanned object according to the second projection data includes: performing proportion adjustment on the second projection data detected by the vertical arm detector and the horizontal arm detector, and then combining them to generate a digital radiography image of the scanned object, so as to eliminate visual inconsistency at the junction.

[0172] For example, with reference to Figure 7 , at least one second detector 22 includes k sub-detectors, k is a positive integer greater than or equal to 2, and the k sub-detectors are arranged at intervals along the conveying direction in sequence; the arrangement interval along the conveying direction between any two adjacent sub-detectors among the k sub-detectors is less than the arrangement interval along the conveying direction between any two adjacent first detectors 21 among the n1 first detectors 21. Generating a digital radiography image of the scanned object according to the second projection data includes: combining the second projection data of the k sub-detectors to generate a digital radiography image of the scanned object.

[0173] If the second detector 22 adopts a layout with two or more rows and a relatively small row pitch, in data processing, the data of multiple rows can be combined and equivalent to a row of DR images for display.

[0174] In some exemplary embodiments, the linear scanning CT imaging system further includes a pulse trigger. Before the step of causing multiple radiation sources 1 to alternately emit radiation beams to form a scanning area, the linear scanning CT imaging method further includes: generating, by the pulse trigger, a trigger pulse sequence for controlling the multiple radiation sources 1 to alternately emit radiation beams.

[0175] Wherein, within one period of the trigger pulse sequence, there may be trigger pulse signals corresponding one-to-one to the multiple radiation sources 1, and the trigger pulse signals are used to control the corresponding radiation sources 1 to emit radiation beams with the same energy.

[0176] Within one period of the trigger pulse sequence, there may also be groups of trigger pulse signals corresponding one-to-one to the multiple radiation sources 1. The group of trigger pulse signals includes a first trigger pulse signal and a second trigger pulse signal. The first trigger pulse signal and the second trigger pulse signal are used to control the corresponding radiation source 1 to sequentially emit a first sub-radiation beam with a first energy and a second sub-radiation beam with a second energy.

[0177] The imaging device decomposes first sub-projection data and second sub-projection data corresponding to the first sub-radiation beam and the second sub-radiation beam from the first projection data and the second projection data respectively. The imaging device obtains a reconstructed image of the scanned object based on the first sub-projection data and the second sub-projection data of the first projection data, and the first sub-projection data and the second sub-projection data of the second projection data.

[0178] In some exemplary embodiments, if the radiation source 1 adopts a dual-energy beam output mode and the second detector 22 adopts a detector with energy resolution ability, then spectral DR with more spectral measurements can be achieved, which is more accurate in image color and can classify more substances.

[0179] Figure 22 Schematically shows a block diagram of an imaging device of a linear scanning CT imaging system according to an embodiment of the present disclosure.

[0180] As Figure 22As shown, the imaging device 4 of the linear scanning CT imaging system according to an embodiment of the present disclosure may include a processor 401, which may perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 402 or a program loaded from a storage section 408 into a random access memory (RAM) 403. The processor 401 may include, for example, a general-purpose microprocessor (e.g., CPU), an instruction set processor, and / or a related chipset, and / or a dedicated microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 401 may also include on-board memory for caching purposes. The processor 401 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present disclosure.

[0181] In the RAM 403, various programs and data required for the operation of the electronic device 400 are stored. The processor 401, the ROM 402, and the RAM 403 are connected to each other via a bus 404. The processor 401 performs various operations of the method flow according to an embodiment of the present disclosure by executing the programs in the ROM 402 and / or the RAM 403. It should be noted that the programs may also be stored in one or more memories other than the ROM 402 and the RAM 403. The processor 401 may also perform various operations of the method flow according to an embodiment of the present disclosure by executing the programs stored in the one or more memories.

[0182] According to an embodiment of the present invention, the electronic device 400 may further include an input / output (I / O) interface 405, and the input / output (I / O) interface 405 is also connected to the bus 404. The electronic device 400 may further include one or more of the following components connected to the I / O interface 405: an input section 406 including a keyboard, a mouse, etc.; an output section 407 including, for example, a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 408 including a hard disk, etc.; and a communication section 409 including a network interface card such as a LAN card, a modem, etc. The communication section 409 performs communication processing via a network such as the Internet. A drive 410 is also connected to the I / O interface 405 as needed. A removable medium 411, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 410 as needed so that a computer program read from it can be installed into the storage section 408 as needed.

[0183] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagram may represent a module, a segment of a program, or a part of code, which contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than that marked in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram or flowchart, as well as combinations of blocks in the block diagram or flowchart, can be implemented by a dedicated hardware-based system that performs the specified functions or operations, or can be implemented by a combination of dedicated hardware and computer instructions.

[0184] In an embodiment of the present disclosure, a linear scan CT imaging system and a corresponding linear scan CT imaging method are provided. In this linear scan CT imaging system, a system design of DR based on linear CT is realized, which has no impact on the original scanning mode of linear CT and does not increase the linear CT scanning steps; by simply replacing one or several columns of detectors, a clearer and more complete DR image can be obtained, and the three-dimensional reconstruction image will not deteriorate; when the radiation source adopts a dual-energy beam output mode, the color of the DR image will also be more accurate; when the radiation source adopts a dual-energy beam output mode and the second detector adopts a detector with energy resolution ability, energy spectrum DR with more energy spectrum measurements can be realized, which is more accurate in image color and can also realize the classification of more substances.

[0185] The embodiments of the present disclosure have been described above. However, these embodiments are only for illustrative purposes and do not limit the scope of the present disclosure. Although the embodiments have been described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should all fall within the scope of the present disclosure.

Claims

1. A linear scanning CT imaging system, wherein, The system includes: a conveying device configured to move a scanning object along a predetermined conveying direction in a scanning channel, wherein the conveying device includes a conveying surface for placing the scanning object; m radiation sources, where the m radiation sources are configured to alternately emit radiation beams to form a scanning region, wherein the m radiation sources are located on one side of the scanning channel, and m is a positive integer greater than or equal to 2; and n detectors, where the n detectors are configured to detect projection data formed after the radiation beams pass through the scanning object during the process that the scanning object passes through the scanning region, wherein the n detectors are located on the other side of the scanning channel, and the n detectors are arranged at intervals in sequence along the conveying direction, and n is a positive integer greater than or equal to 3, wherein the n detectors include n1 first detectors and n2 second detectors, n1 is a positive integer greater than or equal to 2, n2 is a positive integer greater than or equal to 1, and at least one of the second detectors is different from each of the first detectors; the n1 first detectors are configured to detect first projection data formed after the radiation beams pass through the scanning object during the process that the scanning object passes through the scanning region; the n2 second detectors are configured to detect second projection data formed after the radiation beams pass through the scanning object during the process that the scanning object passes through the scanning region; and the system further includes an imaging device, where the imaging device is configured to: generate a digital radiographic image of the scanning object according to the second projection data; and generate a computed tomography image of the scanning object according to the first projection data and the second projection data, so that the imaging system can perform digital radiographic imaging and computed tomography imaging simultaneously through one scan.

2. The system according to claim 1, wherein, The resolution of at least one of the second detectors is higher than that of each of the first detectors.

3. The system according to claim 2, wherein The number of pixels of at least one of the second detectors is greater than that of each of the first detectors; and / or, The pixel size of at least one of the second detectors is smaller than that of each of the first detectors.

4. The system according to any one of claims 1-3, wherein, The crystal material of at least one of the second detectors is different from that of each of the first detectors; and / or, the thickness of at least one of the second detectors along the radiation incident direction is different from that of each of the first detectors.

5. The system according to claim 4, wherein The crystal afterglow of at least one of the second detectors is less than that of each of the first detectors; and / or, the detection efficiency of at least one of the second detectors is better than that of each of the first detectors.

6. The system according to any one of claims 1-3 and 5, wherein, The first detector includes a plurality of first detector modules, the second detector includes a plurality of second detector modules, and the arrangement manner of the plurality of first detector modules is different from the arrangement manner of the plurality of second detector modules.

7. The system according to claim 4, wherein The first detector includes a plurality of first detector modules, the second detector includes a plurality of second detector modules, and the arrangement manner of the plurality of first detector modules is different from the arrangement manner of the plurality of second detector modules.

8. The system according to any one of claims 1-3, 5, and 7, wherein The n1 first detectors are respectively linear detector arrays; and / or, the n2 second detectors are respectively linear detector arrays.

9. The system according to claim 4, wherein The n1 first detectors are respectively linear detector arrays; and / or, the n2 second detectors are respectively linear detector arrays.

10. The system according to any one of claims 1-3, 5, and 7, wherein, The n1 first detectors are respectively linear detector arrays; and / or, At least one of the second detectors includes a vertical arm detector arranged along a first direction and a horizontal arm detector arranged along a second direction, wherein the second direction intersects both the conveying direction and the first direction.

11. The system according to claim 4, wherein, The n1 first detectors are respectively linear detector arrays; and / or, At least one of the second detectors includes a vertical arm detector arranged along a first direction and a horizontal arm detector arranged along a second direction, wherein the second direction intersects both the conveying direction and the first direction.

12. The system according to any one of claims 1-3, 5, and 7, wherein, The n1 first detectors are respectively linear detector arrays; and / or, At least one of the second detectors includes a vertical arm detector arranged along a first direction, a first horizontal arm detector arranged along a second direction, and a second horizontal arm detector arranged along the second direction, wherein the first horizontal arm detector and the second horizontal arm detector are respectively located on the upper side and the lower side of the vertical arm detector in the first direction, and the second direction intersects both the conveying direction and the first direction.

13. The system according to claim 4, wherein, The n1 first detectors are respectively linear detector arrays; and / or, At least one of the second detectors includes a vertical arm detector arranged along a first direction, a first horizontal arm detector arranged along a second direction, and a second horizontal arm detector arranged along the second direction, wherein the first horizontal arm detector and the second horizontal arm detector are respectively located on the upper side and the lower side of the vertical arm detector in the first direction, and the second direction intersects both the conveying direction and the first direction.

14. The system according to any one of claims 1-3, 5, 7, 9, 11, and 13, wherein, The m ray sources are arranged at intervals in sequence along a first straight line, the first straight line is an imaginary straight line extending along a first direction, and the first direction is perpendicular to the conveying surface.

15. The system according to claim 4, wherein, The m ray sources are arranged at intervals in sequence along a first straight line, the first straight line is an imaginary straight line extending along a first direction, and the first direction is perpendicular to the conveying surface.

16. The system according to any one of claims 1-3, 5, 7, 9, 11, 13, and 15, wherein The n detectors include only 1 second detector, and at least one of the first detectors is arranged on each side of the 1 second detector along the conveying direction.

17. The system according to claim 16, wherein, The m ray sources are arranged at intervals in sequence along a first straight line, the first straight line is an imaginary straight line extending along a first direction, and the first direction is perpendicular to the conveying surface; The plane where the 1 second detector and the first straight line are located is perpendicular to the conveying direction.

18. The system according to any one of claims 1-3, 5, 7, 9, 11, 13, and 15, wherein, At least one of the second detectors includes k sub-detectors, k is a positive integer greater than or equal to 2, and the k sub-detectors are arranged at intervals in sequence along the conveying direction; The arrangement interval along the conveying direction between any two adjacent sub-detectors among the k sub-detectors is smaller than the arrangement interval along the conveying direction between any two adjacent first detectors among the n1 first detectors.

19. The system according to claim 18, wherein, The imaging device is configured to: combine the second projection data of the k sub-detectors to generate a digital radiograph of the scanned object.

20. The system according to claim 10, wherein, The cross-arm detector includes a plurality of detector modules, and the plurality of detector modules are connected end to end in sequence.

21. The system according to claim 11, wherein, The cross-arm detector includes a plurality of detector modules, and the plurality of detector modules are connected end to end in sequence.

22. The system according to claim 12, wherein, The cross-arm detector includes a plurality of detector modules, and the plurality of detector modules are connected end to end in sequence.

23. The system according to claim 13, wherein The cross-arm detector includes a plurality of detector modules, and the plurality of detector modules are connected end to end in sequence.

24. The system according to claim 10, wherein The cross-arm detector includes a plurality of detector modules, and the plurality of detector modules are arranged at intervals in the second direction.

25. The system according to claim 11, wherein, The cross-arm detector includes a plurality of detector modules, and the plurality of detector modules are arranged at intervals in the second direction.

26. The system according to claim 12, wherein, The cross-arm detector includes a plurality of detector modules, and the plurality of detector modules are arranged at intervals in the second direction.

27. The system according to claim 13, wherein, The cross-arm detector includes a plurality of detector modules, and the plurality of detector modules are arranged at intervals in the second direction.

28. The system according to any one of claims 20-23, wherein, The light-receiving surface of each detector module is perpendicular to a second straight line, which is a straight line connecting the i-th radiation source and a predetermined point on the light-receiving surface, and the predetermined point is located on the boundary of the light-receiving surface or within the light-receiving surface, where i is a positive integer greater than or equal to 1 and less than or equal to m.

29. The system according to claim 12, wherein, The conveying device includes a plurality of conveying rollers, and in the conveying direction, the second cross-arm detector is located at the gap between two adjacent conveying rollers.

30. The system according to claim 13, wherein The conveying device includes a plurality of conveying rollers, and in the conveying direction, the second cross-arm detector is located at the gap between two adjacent conveying rollers.

31. The system according to any one of claims 1 - 3, 5, 7, 9, 11, 13, 15, 17, 19 - 27, 29 and 30, wherein, The number n2 of the second detectors is greater than or equal to 2, and the n2 second detectors and the n1 first detectors are arranged alternately in the conveying direction.

32. The system according to claim 31, wherein, The m radiation sources are arranged at intervals in sequence along a first straight line, which is an imaginary straight line extending in a first direction, and the first direction is perpendicular to the conveying surface; Among the n2 second detectors, the plane where one second detector and the first straight line are located is perpendicular to the conveying direction, and the planes where the other second detectors and the first straight line are located form an angle greater than 90° or less than 90° with the conveying direction.

33. The system according to claim 4, wherein, The number n2 of the second detectors is greater than or equal to 2, and the n2 second detectors and the n1 first detectors are arranged alternately in the conveying direction.

34. The system according to claim 33, wherein, The m radiation sources are arranged at intervals in sequence along a first straight line, which is an imaginary straight line extending in a first direction, and the first direction is perpendicular to the conveying surface; Among the n2 second detectors, the plane where one second detector and the first straight line are located is perpendicular to the conveying direction, and the planes where the other second detectors and the first straight line are located form an angle greater than 90° or less than 90° with the conveying direction.

35. The system according to claim 28, wherein, The number n2 of the second detectors is greater than or equal to 2, and the n2 second detectors and the n1 first detectors are arranged alternately in the conveying direction.

36. The system according to claim 35, wherein, The m radiation sources are arranged at intervals in sequence along a first straight line, where the first straight line is an imaginary straight line extending along a first direction, and the first direction is perpendicular to the conveying surface; Among the n2 second detectors, the plane where one second detector and the first straight line are located is perpendicular to the conveying direction, and the planes where the other second detectors and the first straight line are located form an angle greater than 90° or less than 90° with the conveying direction.

37. The system according to claim 31, wherein, Among the n2 second detectors, each second detector includes a vertical arm detector arranged along the first direction and a horizontal arm detector arranged along a second direction, where the second direction intersects both the conveying direction and the first direction.

38. The system according to claim 32, wherein, Among the n2 second detectors, each second detector includes a vertical arm detector arranged along the first direction and a horizontal arm detector arranged along a second direction, where the second direction intersects both the conveying direction and the first direction.

39. The system according to any one of claims 33-36, wherein, Among the n2 second detectors, each second detector includes a vertical arm detector arranged along the first direction and a horizontal arm detector arranged along a second direction, where the second direction intersects both the conveying direction and the first direction.

40. The system according to claim 37 or 38, wherein The plane formed by the intersection of the vertical arm detector and the horizontal arm detector of each second detector extends through the first straight line.

41. The system according to claim 39, wherein, The plane formed by the intersection of the vertical arm detector and the horizontal arm detector of each second detector extends through the first straight line.

42. The system according to any one of claims 1-3, 5, 7, 9, 11, 13, 15, 17, 19-27, 29, 30, 32-38, and 41, wherein The scanning channel is a straight channel.

43. The system according to claim 4, wherein The scanning channel is a straight channel.

44. A linear scanning CT imaging method, wherein, The method includes: Making a conveying device drive a scanning object to move in a scanning channel along a predetermined conveying direction, where the conveying device includes a conveying surface for placing the scanning object; Making m radiation sources alternately emit radiation beams to form a scanning area, where the m radiation sources are located on one side of the scanning channel, and m is a positive integer greater than or equal to 2; Making the scanning object pass through the scanning area; During the process of the scanning object passing through the scanning area, making n detectors detect the projection data formed after the radiation beams pass through the scanning object, where the n detectors are located on the other side of the scanning channel, the n detectors are arranged at intervals in sequence along the conveying direction, and n is a positive integer greater than or equal to 3, where the n detectors include n1 first detectors and n2 second detectors, n1 is a positive integer greater than or equal to 2, n2 is a positive integer greater than or equal to 1, and at least one of the second detectors is different from each of the first detectors; The step of making the n detectors detect the projection data formed after the radiation beams pass through the scanning object includes: making the n1 first detectors detect the first projection data formed after the radiation beams pass through the scanning object; and making the n2 second detectors detect the second projection data formed after the radiation beams pass through the scanning object; and The method further includes: generating a digital radiographic image of the scanned object according to the second projection data; and generating a computed tomography image of the scanned object according to the first projection data and the second projection data, so that the imaging system can perform digital radiographic imaging and computed tomography imaging simultaneously through one scan.

45. The method according to claim 44, wherein, At least one of the second detectors includes a vertical arm detector arranged in a first direction and a horizontal arm detector arranged in a second direction, wherein the second direction intersects both the conveying direction and the first direction. The generating a digital radiographic image of the scanned object according to the second projection data includes: performing ratio adjustment on the second projection data detected by the vertical arm detector and the horizontal arm detector, and then combining them to generate the digital radiographic image of the scanned object.

46. The method according to claim 44 or 45, wherein At least one of the second detectors includes k sub-detectors, where k is a positive integer greater than or equal to 2, and the k sub-detectors are arranged at intervals in sequence along the conveying direction; the arrangement interval along the conveying direction between any two adjacent sub-detectors among the k sub-detectors is smaller than the arrangement interval along the conveying direction between any two adjacent first detectors among the n1 first detectors. The generating a digital radiographic image of the scanned object according to the second projection data includes: combining the second projection data of the k sub-detectors to generate the digital radiographic image of the scanned object.

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