Linear scanning CT imaging system and method

Abstract

A linear scanning computed tomography (CT) imaging system, comprising: a conveying apparatus (3), used for enabling an object (30) under scan to move in a preset conveying direction (D3) in a scanning channel (4); ray sources (1), used for alternately emitting ray beams to form a scanning area; detectors (2), including first detectors (21) and a second detector (22), wherein the first detectors (21) are used for detecting first projection data formed by the ray beams passing through said object (30) in the process of said object (30) passing through the scanning area, and the second detector (22) is used for detecting second projection data formed by the ray beams passing through said object (30) in the process of said object (30) passing through the scanning area; and an imaging apparatus (5), used for generating a digital ray image of said object (30) on the basis of the second projection data, and obtaining a CT scanning image of said object (30) on the basis of the first projection data and the second projection data. Also provided is a linear scanning CT imaging method.

Description

Linear scanning CT imaging system and method

[0001] This application claims priority to Chinese patent application No. 202311490080.9 filed on November 9, 2023, the contents of which are incorporated herein by reference. 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] At present, security issues are receiving increasing attention, and various public places are equipped with a variety of security equipment.

[0004] For example, most large cargo and container X-ray inspection systems use DR imaging, which obtains single-energy or dual-energy perspective images at a single angle or multiple angles for manual image interpretation to determine whether there are prohibited items in the cargo.

[0005] For example, CT inspection systems based on linear scanning trajectories can also be used for cargo security inspection. This technology requires no rotating components; the X-ray source and detector are stationary on either side of the scanning path. Objects are scanned using translational motion. This technology can also obtain internal attenuation coefficient information for automated 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 provide perspective images from one or more angles. If the components of the inspected goods are complex and tightly arranged, the perspective images will be severely stacked and blocked, making it difficult to extract information from different items and identify contraband.

[0008] The linear CT scanning system solves the problem of occlusion of perspective images, but due to the incomplete scanning angle, the scanning geometry is difficult to accurately locate; in order to improve the efficiency of scanning and outputting images, the data processing process is not sufficient. Therefore, compared with the images provided by traditional DR systems, CT images have inevitable deterioration of spatial resolution, uneliminable reconstruction artifacts, and even distortion of object shapes.

[0009] The above information disclosed in this section is only for understanding the background of the disclosed concept of the present disclosure and therefore the above information may contain information that does not constitute prior art.

[0010] Summary of the Invention

[0011] The present disclosure provides a linear scanning CT imaging system and an imaging method thereof.

[0012] According to a first aspect of the present disclosure, a linear scanning CT imaging system is provided, wherein the system includes: a conveying device for moving a scanned object along a predetermined conveying direction in a scanning channel, wherein the conveying device includes a conveying surface for placing the scanned object; m radiation sources, wherein the m radiation sources are used to alternately emit 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, wherein the n detectors are used to detect projection data formed after the radiation beam passes through the scanned object during the process of the scanned object passing through the scanning area, wherein the n detectors are located on the other side of the scanning channel, and the n detectors are arranged in sequence along the conveying direction at intervals, and n is a positive integer greater than or equal to 2. A positive integer 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; the n1 first detectors are used to detect first projection data formed after the radiation beam passes through the scanning object during the scanning object passes through the scanning area; the n2 second detectors are used to detect second projection data formed after the radiation beam passes through the scanning object during the scanning object passes through the scanning area; and the system further includes an imaging device, the imaging device being used to: generate a digitized radiation image of the scanning object based on the second projection data; and generate a computed tomography image of the scanning object based on the first projection data and the second projection data.

[0013] According to an embodiment of the present disclosure, at least one second detector is different from each of the first detectors.

[0014] According to an embodiment of the present disclosure, the resolution of the at least one second detector is higher than the resolution of each first detector.

[0015] According to an embodiment of the present disclosure, the number of pixels of at least one second detector is greater than the number of pixels of each first detector; and / or the pixel size of at least one second detector is smaller than the pixel size of each first detector.

[0016] According to an embodiment of the present disclosure, at least one second detector is made of a different crystal material from each first detector; and / or at least one second detector is made of a different thickness from each first detector along the ray incidence direction.

[0017] 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.

[0018] 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 an arrangement of the plurality of first detector modules is different from an arrangement of the plurality of second detector modules.

[0019] 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.

[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 and a horizontal arm detector arranged along a second direction, wherein the second direction intersects both the transmission direction and the first direction.

[0021] 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 the first direction, a first horizontal arm detector arranged along the 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 and lower sides of the vertical arm detector in the first direction, and the second direction intersects both the transmission direction and the first direction.

[0022] According to an embodiment of the present disclosure, the m ray sources are sequentially spaced apart 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 transmission surface.

[0023] According to an embodiment of the present disclosure, the n detectors include only one second detector, and at least one first detector is respectively arranged on both sides of the one second detector along the conveying direction.

[0024] According to an embodiment of the present disclosure, the plane where the second detector and the first straight line are located is perpendicular to the conveying direction.

[0025] According to an embodiment of the present disclosure, at least one second detector includes k sub-detectors, where k is a positive integer greater than or equal to 2, and the k sub-detectors are arranged in sequence along the transmission direction; the arrangement interval between any two adjacent sub-detectors among the k sub-detectors along the transmission direction is smaller than the arrangement interval between any two adjacent first detectors among the n1 first detectors along the transmission direction.

[0026] According to an embodiment of the present disclosure, the imaging apparatus is configured to combine the second projection data of k sub-detectors to generate a digitized radiographic image of a scanned object.

[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 sequentially connected end to end.

[0028] 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.

[0029] 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, and 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.

[0030] 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 a gap between two adjacent conveying rollers.

[0031] 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 alternately arranged along the conveying direction.

[0032] 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 transmission direction, and the angle between the plane where the other second detectors and the first straight line are located and the transmission direction is greater than 90° or less than 90°.

[0033] According to an embodiment of the present disclosure, 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 the second direction, wherein the second direction intersects both the transmission direction and the first direction.

[0034] According to an embodiment of the present disclosure, a 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.

[0035] According to an embodiment of the present disclosure, the scanning channel is a straight channel.

[0036] A second aspect of the present disclosure provides a linear scanning CT imaging method, wherein the method includes: causing a conveying device to drive a scanned object to move along a predetermined conveying direction in a scanning channel, wherein the conveying device includes a conveying surface for placing the scanned object; causing m radiation sources to alternately emit 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; causing the scanned object to pass through the scanning area; and during the process of the scanned object passing through the scanning area, causing n detectors to detect projection data formed after the radiation beam passes through the scanned object, wherein the n detectors are located on the other side of the scanning channel, and the n detectors are sequentially spaced along the conveying direction, and the n detectors are arranged in sequence. 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; the projection data formed after the n detectors detect the radiation beam passing through the scanned object includes: first projection data formed after the n1 first detectors detect the radiation beam passing through the scanned object; and second projection data formed after the n2 second detectors detect the radiation beam passing through the scanned object; and the method further includes: generating a digitized radiation image of the scanned object based on the second projection data; and generating a computed tomography image of the scanned object based on the first projection data and the second projection data.

[0037] 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 transmission direction and the first direction; generating a digitized X-ray image of the scanned object based on the second projection data includes: proportionally adjusting the second projection data detected by the vertical arm detector and the horizontal arm detector, and then combining them to generate a digitized X-ray image of the scanned object.

[0038] According to an embodiment of the present disclosure, at least one second detector includes k sub-detectors, where k is a positive integer greater than or equal to 2, and the k sub-detectors are arranged in sequence along the transmission direction; the arrangement interval between any two adjacent sub-detectors among the k sub-detectors along the transmission direction is smaller than the arrangement interval between any two adjacent first detectors among the n1 first detectors along the transmission direction; and generating a digitized radiographic image of the scanned object based on the second projection data includes: combining the second projection data of the k sub-detectors to generate a digitized radiographic image of the scanned object. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to better understand the present disclosure, the present disclosure will be described in detail according to the following drawings:

[0040] FIG1 schematically shows a structural diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure.

[0041] 2A and 2B schematically illustrate the structures of a first detector and a second detector provided by an embodiment of the present disclosure, respectively, in which pixel distribution is schematically shown.

[0042] 3A and 3B schematically illustrate the structures of a first detector and a second detector provided by an embodiment of the present disclosure, respectively, in which the distribution of detector modules is schematically shown.

[0043] FIG4 schematically shows a structural diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, wherein the second detector is schematically shown to include an L-shaped detector.

[0044] 5A and 5B schematically illustrate side views of a linear scanning CT imaging system for observing along a transmission direction provided by an embodiment of the present disclosure.

[0045] FIG6 and FIG7 are schematic structural diagrams of a linear scanning CT imaging system provided by an embodiment of the present disclosure, respectively, which schematically illustrate that the second detector includes a plurality of sub-detectors.

[0046] FIG8 schematically shows a side view of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which the second detector is schematically shown to include a U-shaped detector.

[0047] FIG9 schematically shows a top view of the linear scanning CT imaging system provided by an embodiment of the present disclosure, in which the relative position relationship between the second detector and the conveying device is schematically shown.

[0048] FIG10 schematically shows a side view of a linear scanning CT imaging system provided by an embodiment of the present disclosure, in which a layout of a cross-arm detector of the second detector is schematically shown.

[0049] FIG11 schematically shows a side view of a linear scanning CT imaging system provided by an embodiment of the present disclosure, wherein another arrangement of the cross-arm detector of the second detector is schematically shown.

[0050] FIG12 schematically shows a 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] FIG13 schematically shows a 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] FIG14 schematically shows a 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] FIG15 schematically shows a structural block diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure.

[0054] FIG16 schematically shows a schematic diagram of a trigger pulse sequence provided by an embodiment of the present disclosure.

[0055] FIG17 schematically shows a schematic diagram of another trigger pulse sequence provided by an embodiment of the present disclosure.

[0056] FIG18 schematically shows a diagram of another trigger pulse sequence provided by an embodiment of the present disclosure.

[0057] FIG19 schematically shows a flow chart of the linear scanning CT imaging method provided in an embodiment of the present disclosure.

[0058] FIG20 schematically shows a flowchart of a projection data processing method provided by an embodiment of the present disclosure.

[0059] 21A and 21B schematically illustrate a second projection data ratio processing method provided by an embodiment of the present disclosure.

[0060] FIG22 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 DESCRIPTION

[0061] Specific embodiments of the present disclosure will be described in detail below. It should be noted that the embodiments described herein are intended to be illustrative only and are not intended to limit the present disclosure. In the following description, a large number of specific details are set forth to provide a thorough understanding of the present disclosure. However, it will be apparent to those skilled in the art that these specific details are not necessarily required to practice the present disclosure. In other examples, known structures, materials, or methods are not specifically described to avoid obscuring the present disclosure.

[0062] Throughout this 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, appearances of the phrases "in one embodiment," "in an embodiment," "an example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combinations and / or subcombinations in one or more embodiments or examples. Furthermore, one 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 only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of features, steps, operations, and / or components, but do not exclude 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 meanings commonly understood by those skilled 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 this disclosure, digital radiography (also known as DR) imaging refers to a technology that directly performs digital radiography under computer control. For example, an amorphous silicon flat-panel detector can be used to convert the radiation information penetrating the detection object into a digital signal, and the computer can reconstruct the image and perform a series of image post-processing to generate a digital radiographic image of the scanned object.

[0066] Computed tomography (also known as CT) imaging refers to the use of radiation to perform cross-sectional scanning of the object being examined. The analog signal received by the detector is then converted into a digital signal. The attenuation coefficient of each pixel is calculated by an electronic computer, and the image is reconstructed to display the cross-sectional structure of each part of the object being examined.

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

[0068] Figure 1 is a schematic diagram of the structure of a linear scanning CT imaging system provided by an embodiment of the present disclosure. The linear scanning CT imaging system in Figure 1 includes a transmission device 3, m radiation sources 1, n detectors 2, and an imaging device 5. For example, 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 conveyor 3 is used to move the scanned object 30 along a predetermined conveying direction D3 (as indicated by the arrow in FIG. 1 ) within the scanning channel 4 . The conveyor 3 includes a conveying surface 3S on which the scanned object 30 is placed. By way of example, the conveyor 3 can be implemented as a belt conveyor, a chain conveyor, a gear conveyor, or other transmission method, which is not limited herein. For example, the scanned object 30 is placed on the conveying surface 3S of the conveyor 3 . It should be noted that, in some exemplary embodiments, the power mechanism of the conveyor 3 can support both unidirectional and bidirectional conveying.

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

[0071] Continuing with FIG1 , m radiation sources 1 are configured to alternately emit radiation beams to form a scanning area. 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 sequentially spaced apart along a first straight line L1, which is an imaginary straight line extending along a first direction D1 perpendicular to the transmission surface 3S. Specifically, the multiple radiation sources 1 are distributed at different heights along a vertical line and alternately emit radiation beams to form a scanning area.

[0072] For example, the radiation source 1 may be an accelerator, the energy of which can be adjusted and which has strong penetrating power. It should be noted that the embodiments of the present disclosure do not impose any particular limitation on the type of radiation source 1. In other embodiments, the radiation source 1 may be other types of radiation sources, such as an X-ray machine.

[0073] 1 , the n detectors 2 are used to detect projection data formed after the beam passes through the scanned object 30 as the scanned object 30 passes through the scanning area. The n detectors are located on the other side of the scanning channel 4 and are arranged in sequence along the transmission direction D3.

[0074] In an embodiment of the present disclosure, as shown in FIG1 , the n detectors 2 include n1 first detectors 21 (schematically shown by solid lines in FIG1 ) and n2 second detectors 22 (schematically shown by dashed lines in FIG1 ), where, 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 when a beam of radiation passes through the scanned object 30 as the scanned object 30 passes through a scanning region. The n2 second detectors 22 are used to detect second projection data formed when a beam of radiation passes through the scanned object 30 as the scanned object 30 passes through the scanning region.

[0075] The imaging device 5 is used to generate a digitized radiographic image (ie, a DR image) of the scanned object 30 based on the second projection data; and to generate a computed tomography image (ie, a CT image) of the scanned object 30 based on the first projection data and the second projection data.

[0076] In the linear scanning CT imaging system according to an embodiment of the present disclosure, when performing a security inspection on a scanned object, a conveyor device 3 can move the scanned object along a conveying direction within a scanning channel and through a scanning area formed by the alternating radiation beams emitted by multiple radiation sources 1. Multiple first and second detectors then detect first and second projection data formed by the radiation beams emitted by the multiple radiation sources 1 passing through the scanned object as the scanned object passes through the scanning area. The imaging device then generates a computed tomography (CT) image of the scanned object based on the first and second projection data from the multiple radiation sources 1, and generates a digitized radiographic image of the scanned object based on the second projection data from the multiple radiation sources 1. Based on this, image recognition can be performed simultaneously based on both the digitized radiographic image and the CT image to identify the presence of prohibited items. In other words, in the linear scanning CT imaging system according to an embodiment of the present disclosure, both DR imaging and CT imaging can be performed simultaneously in a single scan. CT imaging can avoid issues such as overlap or occlusion, while DR imaging can improve image quality, avoiding issues such as resolution degradation and artifacts.

[0077] It should be noted that, with reference to FIG1 , the scanned object 30 moves in the scanning channel 4 and passes through the scanning area. During the process of passing through the scanning area, the multiple radiation sources 1 alternately emit radiation beams, and the first detector 21 and the second detector 22 simultaneously detect the first projection data and the second projection data, respectively. In this way, DR imaging and CT imaging can be performed simultaneously in a single scan. That is, in the embodiment of the present disclosure, it is not necessary to perform DR imaging on the scanned object 30 first 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, realizing a compact linear scanning CT imaging system. From a temporal perspective, the imaging time for forming DR images and CT images can be shortened, which is conducive to improving detection efficiency.

[0078] It should also be noted that in the embodiments of the present disclosure, by simultaneously arranging first detectors 21 and second detectors 22 for multiple radiation sources 1, DR imaging and CT imaging can be performed simultaneously in a single scan, eliminating the need for the scanned object 30 to pass through the scanning area multiple times. For example, there is no need for the conveyor 3 to move the scanned object 30 in both directions to pass through the scanning area multiple times. Therefore, structurally, the structure of the conveyor 3 can be simplified; and from a time perspective, the imaging time required to form DR and CT images can be shortened, thereby improving detection efficiency.

[0079] Particularly advantageously, since DR imaging and CT imaging can be performed simultaneously in one scan, there is no need to scan the object through the scanning area more than 30 times. Therefore, the linear scanning CT imaging system and method provided by the embodiments of the present disclosure are particularly suitable for security inspections of large items (such as containers).

[0080] It should also be noted that in the embodiment of the present disclosure, scanning channel 4 is a linear scanning channel. That is, the motion trajectory of the scanned object 30 within the scanning area is a linear trajectory. Specifically, the scanned object 30 moves along a single linear trajectory relative to the radiation source and detector, eliminating the need for complex rotating components such as slip rings. This simplifies the structural complexity of the linear scanning CT imaging system and improves its reliability.

[0081] It should also be noted that in the embodiment of the present disclosure, multiple radiation sources 1 are arranged along a first straight line, i.e., forming a linearly distributed radiation source. The multiple radiation sources are controlled to alternately emit beams, thereby scanning and imaging the scan object 30 from multiple angles. This avoids the need for complex rotating components such as slip rings to drive the radiation sources, thereby simplifying the structural complexity of the linear scanning CT imaging system and improving its reliability.

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

[0083] In an embodiment 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 the at least one second detector 22 is higher than the resolution of each first detector 21.

[0084] 2A and 2B schematically illustrate the structures of a first detector and a second detector, respectively.

[0085] For example, referring to FIG. 2A and FIG. 2B , the first detector 21 may include a plurality of pixels 21P, the second detector 22 may 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 FIG3A and FIG3B , the first detector 21 may include a plurality of first detector modules 21M, and the second detector 22 may include a plurality of second detector modules 22M. For example, the first detector module 21M may include at least one pixel 21P, and the second detector module 22M may include at least one pixel 22P. The arrangement of the plurality of first detector modules 21M is different from the arrangement of the plurality of second detector modules 22M. For example, the plurality of first detector modules 21M may be arranged in an array of r1 rows and c1 columns, and the plurality of second detector modules 22M may be arranged in an array of r2 rows and c2 columns, where r1, r2, c1, and c2 are each 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, referring to FIG2A and FIG2B , the pixel size of at least one second detector 22 is smaller than the pixel size of each first detector 21. For example, a pixel 21P of the first detector 21 can have a substantially rectangular shape, and a pixel 22P of the second detector 22 can have a substantially rectangular shape, with at least one of the length and width of pixel 21P being smaller than at least one of the length and width of pixel 22P. It should be noted that the shape of the pixels of the first and second detectors is not limited to a rectangular shape; they can include any suitable shape, and the embodiments of the present disclosure are not particularly limited in this regard.

[0088] In an embodiment of the present disclosure, the pixel sizes, pixel arrangements, and / or module arrangements of the first and second detectors are set so that 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, the at least one second detector 22 is made of a different crystal material than each of the first detectors 21. The at least one second detector 22 has a crystal afterglow that is less than the crystal afterglow of each of the first detectors 21.

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

[0091] In some exemplary embodiments, the thickness of the at least one second detector 22 is different from that of each first detector 21 along the radiation incident direction.

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

[0093] In some exemplary embodiments, as shown in FIG1 , the n1 first detectors 21 are each a linear detector array; and / or the n2 second detectors 22 are each a linear detector array. Compared to area array detectors, linear detector arrays are more flexible and less expensive to set up.

[0094] In some exemplary embodiments, the number of ray sources 1 is m, and the number of detectors is n, where 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 an attenuation signal of a ray beam emitted by each ray source 1 at a certain angle, that is, a piece of projection data, and m×n pieces of projection data can be obtained during one scan.

[0095] Figure 4 is a schematic diagram of the structure of a linear scanning CT imaging system provided by an embodiment of the present disclosure, schematically illustrating that the second detector comprises an L-shaped detector. The linear scanning CT imaging system in Figure 4 includes a transmission device 3, m radiation sources 1, n detectors 2, and an imaging device 5. For example, 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 shown in FIG4 , the n detectors 2 include n1 first detectors 21 (schematically shown by solid lines in FIG4 ) and n2 second detectors 22 (schematically shown by dashed lines in FIG4 ), where, 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 when a radiation beam passes through the scanned object 30 as the scanned object 30 passes through the scanned region. The n2 second detectors 22 are used to detect second projection data formed when a radiation beam passes through the scanned object 30 as the scanned object 30 passes through the scanned region.

[0097] As shown in Figure 4, 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 the first direction D1 and a horizontal arm detector 222 arranged along the second direction D2, wherein the second direction D2 intersects with both the transmission direction D3 and the first direction D1.

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

[0099] Continuing to refer to FIG4 , the additional cross arm detector can be mainly used for the ray source 1 located at the bottom. That is, during the scanning process, the cross arm detector 222 mainly receives the signal of the ray beam emitted by the ray source 1 located at the bottom after attenuation by the scanned object.

[0100] FIG5A and FIG5B are side views of the linear scanning CT imaging system viewed along the transmission direction. Referring to FIG5A and FIG5B, the cone angle of the ray source 1 located at the bottom is Greater than the cone angle 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 bottom is larger, so that the vertical arm detector 221 and the horizontal arm detector 222 can detect the signal of the ray beam emitted by the ray source 1 located at the bottom after attenuation by the scanned 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 and other reasons.

[0101] FIG6 and FIG7 are schematic structural diagrams of a linear scanning CT imaging system provided by an embodiment of the present disclosure, respectively, which schematically illustrate that the second detector includes a plurality of sub-detectors.

[0102] As shown in FIG6 and FIG7 , the 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 sequentially spaced apart along the conveying direction.

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

[0104] As shown in Figure 6 , each sub-detector is a linear detector array. As shown in Figure 7 , 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 k sub-detectors to generate a digitized radiographic image of the scanned object. By providing a plurality of densely arranged sub-detectors to form the second detector, the DR imaging quality of the scanned object can be further improved.

[0106] It should be noted that the term "combination" herein includes various data processing methods such as reorganization, combination, and resampling. For example, if the second detector 22 includes two sub-detectors, and each sub-detector collects data 1000 times in one scan, then the 1000 columns of data collected by the two sub-detectors can be interleaved to obtain a 2000-column image, which is equivalent to doubling the spatial sampling rate in the motion direction.

[0107] It should be noted that, in the embodiments shown in FIG6 and FIG7, the second detectors are schematically shown to be arranged in double rows (i.e., k=2) with a smaller row spacing. However, the embodiments of the present disclosure are not limited to this. In other embodiments, the second detectors may be arranged in more rows with a smaller row spacing.

[0108] FIG8 is a side schematic diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, which schematically shows that the second detector includes a U-shaped detector.

[0109] As shown in FIG8 , the n1 first detectors 21 are each a linear detector array. The 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. 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 with FIG8 , the two additional cross-arm detectors can be used for all the ray sources 1. That is, during the scanning process, the first cross-arm detector 222 and the second cross-arm detector 223 receive the signals of the ray beams emitted by all the ray sources 1 after attenuation by the scanned object. Accordingly, in the embodiment shown in FIG8 , the cone angles of the ray beams emitted by the three ray sources 1 are Both are larger.

[0111] By adding two cross-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 DR images.

[0112] FIG9 is a schematic top view of the linear scanning CT imaging system provided by an embodiment of the present disclosure, which schematically shows the relative position relationship between the second detector and the conveying device.

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

[0114] With reference to Figures 8 and 9 , when linear rail transport utilizes roller conveyors, railcars and turntables are located at both ends of the linear motion to facilitate operations such as cargo entry, exit, and rotation. A crossbar detector 223 can be positioned in the gap between the two roller conveyors. In this case, all radiation beams emitted by the radiation source 1 can be used for DR imaging, enabling DR imaging from multiple perspectives. Furthermore, the conveyor rollers 31 do not obstruct the signals received by the crossbar detector 223, further improving the quality of DR imaging.

[0115] FIG10 is a side view schematic diagram of a linear scanning CT imaging system according to an embodiment of the present disclosure, which schematically illustrates one arrangement of a cross-arm detector of the second detector. Referring to FIG3B and FIG10 , the cross-arm detector 222 may include multiple detector modules 22M, which may be sequentially connected end-to-end.

[0116] In this embodiment, the cross-arm detector can be used for all the ray sources 1. That is, during the scanning process, the cross-arm detector 222 receives the signals of the ray beams emitted by all the ray sources 1 after being attenuated by the scanned object. Accordingly, in the embodiment shown in FIG10 , the cone angles of the ray beams emitted by the three ray sources 1 are In this way, the DR images formed by the ray beams emitted by all the ray sources 1 are continuous and uninterrupted images.

[0117] FIG11 is a side view schematic diagram of a linear scanning CT imaging system according to an embodiment of the present disclosure, illustrating another arrangement of a second detector cross-arm detector. Referring to FIG3B and FIG11 , the cross-arm detector 222 may include a plurality of detector modules 22M spaced apart in a 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, which 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" can be an end point, a center point or other suitable point on 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. The embodiments of the present disclosure do not impose any special restrictions on this.

[0120] Through such a setting, each detector module of the cross-arm detector can be directed toward a certain ray source 1. For example, in the embodiment shown in Figure 11, each detector module of the cross-arm detector is directed toward the ray source 1 located at the bottom. On this basis, a clearer DR image can be obtained through the second detector.

[0121] In this embodiment, the beam of light emitted by the radiation source 1 is perpendicularly incident on the crystal of the cross-arm detector. When the beam of light is perpendicularly incident on the crystal, the thickness of the crystal it passes through 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 disclosed embodiment, by perpendicularly incident on the crystal, on the one hand, the thickness of the crystal that the beam of light effectively passes through is increased, thereby improving the penetration of the beam of light, thereby making the projection data carried by the detected projection image more comprehensive; on the other hand, the equivalent crystal area is equal to the actual area of ​​the light-receiving surface, thereby improving the spatial resolution of the beam of light, thereby 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 one second detector 22, with at least one first detector 21 disposed on either side of the second detector 22 along the transmission direction D3. In this embodiment, only one row of detectors needs to be replaced, resulting in a clearer and more complete DR image while ensuring low cost and without degrading the CT image.

[0123] For example, referring to FIG1 , a plane P1 containing a second detector 22 and first line L1 is perpendicular to the transmission direction D3. When the radiation source 1 emits a cone beam, this arrangement allows the central beam plane of the cone beam to face the second detector 22, facilitating the acquisition of a clearer and more complete DR image.

[0124] In some other exemplary embodiments of the present disclosure, the n detectors may include a plurality of 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 number of first detectors 21 and second detectors 22 is an odd number. These odd-numbered detectors are arranged at intervals along the transmission direction, with the detector in the middle being the second detector 22. For example, the plane P1 on which the second detector 22 in the middle and the first line L1 lie is perpendicular to the transmission direction D3. For another example, the other even-numbered detectors are arranged symmetrically relative to the second detector 22 in the middle. This arrangement allows the central beam plane of the cone beam to face the second detector 22, facilitating the acquisition of clearer and more complete DR images.

[0126] It should also be noted that, in some other exemplary embodiments of the present disclosure, the sum of the number of first detectors 21 and second detectors 22 is an even number, the even number of detectors are arranged at intervals along the conveying direction, and 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] FIG12 is a schematic structural diagram of a linear scanning CT imaging system provided in an embodiment of the present disclosure, in which a plurality of second detectors are schematically shown.

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

[0129] It should be noted that the term "alternating arrangement" herein may mean that, along the conveying direction D3, at least one first detector 21 is disposed on both sides of at least one second detector 22, and / or at least one first detector 21 is disposed on both sides of at least two second detectors 22. As shown in FIG12 , along the conveying direction D3, for some second detectors 22, a first detector 21 is disposed on both sides of each second detector 22; for another portion of second detectors 22, a first detector 21 is disposed on both sides of two second detectors 22.

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

[0131] 12 , among the n2 second detectors 22 , the plane where one second detector 22 and the first straight line L1 are located is perpendicular to the transmission direction D3 , and the angle between the plane where the other second detectors 22 and the first straight line L1 are located and the transmission direction D3 is greater than 90° or less than 90°.

[0132] For example, as shown in Figure 12, the angle α0 between the plane containing the second second detector 22 and the first straight line L1, counted from left to right, and the conveying direction D3 is approximately 90°. The angle α1 between the plane containing the second second detector 22 and the first straight line L1, counted from left to right, and the conveying direction D3 is greater than 90°. The angles α2 and α3 between the plane containing the third and fourth second detectors 22 and the first straight line L1, counted from left to right, and the conveying direction D3 are both less than 90°. For example, α1>α0>α2>α3, that is, the angles between the plane containing the second detectors and the first straight line L1 arranged along the conveying direction and the conveying direction D3 decrease in sequence.

[0133] By rationally arranging the angles between each second detector and the central beam plane of the ray source, various viewing angles for obtaining DR images can be rationally designed, which is beneficial to further improve the quality of DR imaging.

[0134] FIG13 is a schematic structural diagram of a linear scanning CT imaging system provided in an embodiment of the present disclosure, in which a plurality of L-shaped second detectors are schematically shown.

[0135] 13 , the number n2 of 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. Each of the n2 second detectors 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 FIG. 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] By setting it in this way, the placement angle of the cross-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 or both ends of the conveying device 3, and the rotating device 6 is used to rotate the scanning object by a preset angle when the scanning object passes through the scanning area and moves to the end side of the conveying device 3.

[0139] For example, the conveying device 3 can also be used to make the rotated scanning object pass through the scanning area again; the detector 2 can also be used to detect the first projection data and the second projection data formed after the radiation beams emitted by the multiple radiation sources 1 pass through the rotated scanning object during the process of the scanning object passing through the scanning area again; the imaging device 5 can also be used to generate a digitized radiation image of the scanning object based on the second projection data, and obtain a three-dimensional reconstructed image of the scanning object based on the first projection data and the second projection data.

[0140] It should be noted that the steps of rotating the scanned object by a preset angle and passing through the scanning area may be performed multiple times. Those skilled in the art will understand that the more times the scanned object passes through the scanning area during a single examination, the more comprehensive the angles at which the scanned object is illuminated, thereby improving the quality of the reconstructed image.

[0141] The working process of the linear scanning CT imaging system according to the embodiment of the present disclosure is described in detail below. By way of example, 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 ray sources 1 distributed along the vertical direction emit beams alternately to form a scanning area.

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

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

[0146] According to an embodiment of the present disclosure, referring 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 multiple ray sources 1 to alternately emit ray beams. Specifically, the pulse trigger sequence may include the following situations.

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

[0148] For example, Figure 16 shows trigger pulse signals corresponding to three radiation sources 1. The horizontal axis indicates time, with the trigger pulse signals corresponding to the three radiation sources 1 arranged alternately along the time axis. The vertical axis indicates energy, with all trigger pulse signals indicating the energy E1. The projection image data obtained using this method is complete data that can be used for single-energy CT reconstruction.

[0149] In the second case, one cycle of the trigger pulse sequence includes a trigger pulse signal group corresponding one-to-one to multiple radiation sources 1. The trigger pulse signal group 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-beam of radiation having a first energy and a second sub-beam of radiation having a second energy. The radiation source 1 may be a dual-energy accelerator with adjustable energy.

[0150] For example, Figure 17 shows trigger pulse signal groups corresponding one-to-one with three radiation sources 1, meaning each radiation source 1 emits a beam twice. The horizontal axis indicates time, with the trigger pulse signal groups corresponding one-to-one with the three radiation sources 1 alternating along the time axis. The vertical axis indicates energy, with the first trigger pulse signal in each trigger pulse signal group indicating an energy of E2, and the second trigger pulse signal in each trigger pulse signal group indicating an energy of E3. The projection image data obtained in this manner is complete and can be used for dual-energy CT reconstruction.

[0151] The principle of dual-energy CT image reconstruction is described in detail below.

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

[0153] The base material coefficient projection values ​​corresponding to the dual-energy projection data are then calculated using a pre-created lookup table or by solving a set of equations. The lookup table is created by selecting two base materials and calculating the projection values ​​of the dual-energy rays passing through them at different thicknesses. This lookup table is then generated based on the relationship between high- and low-energy projection values ​​and different thickness combinations. The analytical solution to the set of equations utilizes the actual high- and low-energy projection values ​​to obtain the corresponding thickness combinations by solving the high- and low-energy projection equations for the base material decomposition.

[0154] Then, the projection values ​​of the base material can be used to obtain a distribution image of the base material coefficient. From the base material coefficient distribution, the atomic number of the scanned object, the characteristic density image, and the attenuation coefficient image of the scanned object at any energy can be obtained, thereby classifying and automatically identifying 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 line-scan CT imaging system further includes a decomposition unit that decomposes the first projection data and the second projection data into first sub-projection data and second sub-projection data corresponding to the first sub-beam and the second sub-beam, 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, as well as 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 may be a mono-energy accelerator with adjustable energy. One cycle of the trigger pulse sequence includes trigger pulse signals corresponding to multiple 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 having a first uniform 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 having a second uniform energy.

[0157] For example, during the first scan, all trigger pulse signals indicate an energy of E1 (see FIG16 ); during the second scan, all trigger pulse signals indicate an energy of E4 (see FIG18 ). Projection image data obtained in this manner can also be used for dual-energy CT reconstruction. The resulting image information of the scanned object 30 includes information such as high-energy attenuation coefficient, low-energy attenuation coefficient, atomic number, and electron density, thereby enabling material classification and automatic identification of the scanned object.

[0158] FIG19 is a flow chart of a linear scanning CT imaging method according to an embodiment of the present disclosure, which is applied to the linear scanning CT imaging system described above. The linear scanning CT imaging method in FIG19 includes steps S131 to S134.

[0159] In step S131 , the conveying device 3 drives the scan object to move along a predetermined conveying direction in the scanning channel, wherein the conveying device 3 includes a conveying surface for placing the scan object.

[0160] In step s132 , m ray sources 1 are made to emit ray beams alternately to form a scanning area, wherein the m ray sources 1 are located on one side of the scanning channel, and m is a positive integer greater than or equal to 2.

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

[0162] In step S134, while the scanned object passes through the scanning area, n detectors are used to detect projection data formed after the radiation beam passes through the scanned object, wherein the n detectors are located on the other side of the scanning channel, and the n detectors are arranged in sequence along the transmission direction, n is a positive integer greater than or equal to 3, and 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] FIG20 is a flowchart of a projection data processing method according to an embodiment of the present disclosure. The above step S134 may further include operation steps S1341 to S1343 .

[0164] In step S1341 , n1 first detectors 21 are enabled to detect first projection data formed after the ray beam passes through the scanned object.

[0165] In step S1342 , n2 second detectors 22 are enabled to detect second projection data formed after the ray beam passes through the scanned object.

[0166] In step S1343, a digitized radiographic image of the scanned object is generated based on the second projection data; and a computed tomography image of the scanned object is generated based on 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 and display a three-dimensional reconstructed image of the object under inspection.

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

[0169] In some exemplary embodiments, the 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, wherein the second direction intersects both the conveying direction and the first direction.

[0170] 21A and 21B are schematic diagrams of a second projection data ratio processing method according to an embodiment of the present disclosure.

[0171] In some exemplary embodiments, generating a digitized radiographic image of the scanned object based on the second projection data includes: proportionally adjusting the second projection data detected by the vertical arm detector and the horizontal arm detector, and then combining them to generate a digitized radiographic image of the scanned object, thereby eliminating visual inconsistencies in the image at the junction.

[0172] For example, with reference to FIG7 , 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 in sequence along the transmission direction; the arrangement interval between any two adjacent sub-detectors among the k sub-detectors along the transmission direction is smaller than the arrangement interval between any two adjacent first detectors 21 among the n1 first detectors 21 along the transmission direction, and generating a digitized X-ray 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 digitized X-ray image of the scanned object.

[0173] If the second detectors 22 are arranged in double rows or multiple rows with a small row spacing, multiple rows of data can be combined to form a row of DR images for display in data processing.

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

[0175] Among them, one cycle of the trigger pulse sequence may include trigger pulse signals corresponding to multiple ray sources 1 one by one, and the trigger pulse signals are used to control the corresponding ray sources 1 to emit ray beams with the same energy.

[0176] A cycle of the trigger pulse sequence may also include a trigger pulse signal group corresponding one-to-one to multiple radiation sources 1, and the trigger pulse signal group 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-beam of radiation with a first energy and a second sub-beam of radiation with a second energy.

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

[0178] In some exemplary embodiments, the ray source 1 adopts a dual-energy beam mode, and the second detector 22 adopts a detector with energy resolution capability, which can achieve energy spectrum DR for more energy spectrum measurements, is more accurate in image color, and can achieve the classification of more substances.

[0179] FIG22 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 shown in FIG22 , 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 can 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 portion 408 into a random access memory (RAM) 403. The processor 401 may, for example, include a general-purpose microprocessor (e.g., a 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 an onboard memory for caching purposes. The processor 401 may include a single processing unit or multiple processing units for executing different actions of the method flow according to an embodiment of the present disclosure.

[0181] Various programs and data required for the operation of the electronic device 400 are stored in the RAM 403. The processor 401, ROM 402, and RAM 403 are connected to each other via a bus 404. The processor 401 executes the various operations of the method flow according to the embodiment of the present disclosure by executing the programs in the ROM 402 and / or 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 execute the various operations of the method flow according to the embodiment of the present disclosure by executing the programs stored in the one or more memories.

[0182] According to an embodiment of the present disclosure, electronic device 400 may further include an input / output (I / O) interface 405, which is also connected to bus 404. Electronic device 400 may further include one or more of the following components connected to I / O interface 405: an input portion 406 including a keyboard, a mouse, etc.; an output portion 407 including devices such as a cathode ray tube (CRT), a liquid crystal display (LCD), and speakers; a storage portion 408 including a hard disk; and a communication portion 409 including a network interface card such as a LAN card or a modem. Communication portion 409 performs communication processing via a network such as the Internet. A drive 410 is also connected to I / O interface 405 as needed. Removable media 411, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed in drive 410 as needed, so that computer programs read therefrom can be installed into storage portion 408 as needed.

[0183] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or a part of code, and the above-mentioned module, program segment, or a part of code 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 box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0184] In an embodiment of the present disclosure, a linear scanning CT imaging system and a corresponding linear scanning CT imaging method are provided. In this linear scanning CT imaging system, a DR system design based on linear CT is implemented, without any impact on the original linear CT scanning method and without adding any additional linear CT scanning steps. By simply replacing one or several detector columns, a clearer and more complete DR image can be obtained without degrading the three-dimensional reconstructed image. When the ray source adopts a dual-energy beam mode, the DR image color is also more accurate. When the ray source adopts a dual-energy beam mode, the second detector adopts a detector with energy resolution capability, thereby enabling spectral DR with more energy spectrum measurements, more accurate image color, and the classification of more substances.

[0185] In the linear scanning CT imaging system according to the embodiment of the present disclosure, DR imaging and CT imaging can be performed simultaneously through a single scan. Through CT imaging, problems such as stacking or occlusion can be avoided. Through DR imaging, the image quality can be improved, the detailed structure of the scanned object can be observed, and problems such as resolution deterioration and artifacts can be avoided.

[0186] The embodiments of the present disclosure are described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be used in combination to advantage. 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 may make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A linear scanning CT imaging system, wherein: The system comprises: A conveying device, used to move the scanned object in the scanning channel along a predetermined conveying direction, wherein the conveying device comprises a conveying surface for placing the scanned object; m ray sources, the m ray sources are used to alternately emit ray beams 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; and n detectors, the n detectors are used to detect projection data formed after the ray beam passes through the scanned object when the scanned object passes through the scanned area, wherein the n detectors are located on the other side of the scanning channel, and the n detectors are sequentially spaced along the transmission direction, and n is a positive integer greater than or equal to 3, 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 to detect first projection data formed after the ray beam passes through the scanned object during the process of the scanned object passing through the scanned area; the n2 second detectors are used to detect second projection data formed after the ray beam passes through the scanned object during the process of the scanned object passing through the scanned area; and The system further includes an imaging device, which is used to: generate a digitized radiographic image of the scanned object based on the second projection data; and generate a computed tomography image of the scanned object based on the first projection data and the second projection data.

2. The system of claim 1, wherein: At least one of the second detectors is different from each of the first detectors.

3. The system of claim 2, wherein: The resolution of at least one of the second detectors is higher than the resolution of each of the first detectors.

4. The system of claim 3, wherein: The number of pixels of at least one of the second detectors is greater than the number of pixels of each of the first detectors; and / or, A pixel size of at least one of the second detectors is smaller than a pixel size of each of the first detectors.

5. The system according to any one of claims 2 to 4, 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 is different from that of each of the first detectors along the radiation incident direction.

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

7. The system of any one of claims 2 to 6, wherein: The first detector includes a plurality of first detector modules, the second detector includes a plurality of second detector modules, and an arrangement of the plurality of first detector modules is different from an arrangement of the plurality of second detector modules.

8. The system of any one of claims 1 to 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 of any one of claims 1 to 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 the 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.

10. The system of any one of claims 1 to 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 the first direction, a first horizontal arm detector arranged along the 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 and lower sides of the vertical arm detector in the first direction, and the second direction intersects both the transmission direction and the first direction.

11. The system of any one of claims 1 to 10, wherein: The m ray sources are sequentially arranged at intervals 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 transmission surface.

12. The system of any one of claims 1 to 11, wherein: The n detectors include only one second detector, and at least one first detector is respectively arranged on both sides of the one second detector along the conveying direction.

13. The system of claim 12, wherein: The plane where the one second detector and the first straight line are located is perpendicular to the transmission direction.

14. The system of any one of claims 1 to 11, 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 sequentially spaced apart along the transmission direction; An arrangement interval along the transmission direction between any two adjacent sub-detectors among the k sub-detectors is smaller than an arrangement interval along the transmission direction between any two adjacent first detectors among the n1 first detectors.

15. The system of claim 14, wherein: The imaging device is used for combining the second projection data of the k sub-detectors to generate a digitized radiographic image of the scanned object.

16. The system of claim 9 or 10, wherein: The cross arm detector includes a plurality of detector modules, and the plurality of detector modules are sequentially connected end to end.

17. The system of claim 9 or 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.

18. The system of claim 16, 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 ray 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, and i is a positive integer greater than or equal to 1 and less than or equal to m.

19. The system of claim 10, wherein: The conveying device comprises a plurality of conveying rollers. In the conveying direction, the second cross arm detector is located at a gap between two adjacent conveying rollers.

20. The system of any one of claims 1-10 and 14-19, 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 alternately arranged along the conveying direction.

21. The system of claim 20, wherein: Among the n2 second detectors, a plane where one second detector and the first straight line are located is perpendicular to the transmission direction, and an angle between a plane where other second detectors and the first straight line are located and the transmission direction is greater than 90° or less than 90°.

22. The system of claim 20 or 21, wherein: Among the n2 second detectors, each of the second detectors includes a vertical arm detector arranged along the first direction and a horizontal arm detector arranged along a second direction, wherein the second direction intersects both the transmission direction and the first direction.

23. The system of claim 22, wherein: A plane formed by the intersection of the vertical arm detector and the horizontal arm detector of each of the second detectors extends through the first straight line.

24. The system of any one of claims 1 to 23, wherein: The scanning channel is a straight line channel.

25. A linear scanning CT imaging method, wherein: The method comprises: The conveying device drives the scanning object to move along a predetermined conveying direction in the scanning channel, wherein the conveying device includes a conveying surface for placing the scanning object; Make m ray sources emit ray beams alternately 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; Allowing the scan object to pass through the scan area; In the process of the scanned object passing through the scanned area, n detectors are used to detect projection data formed after the ray beam passes through the scanned object, wherein the n detectors are located at the scanning passage. On the other side of the conveying path, the n detectors are sequentially spaced apart along the conveying direction, where 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; The step of causing the n detectors to detect the projection data formed after the ray beam passes through the scanned object comprises: causing the n1 first detectors to detect the first projection data formed after the ray beam passes through the scanned object; and causing the n2 second detectors to detect the second projection data formed after the ray beam passes through the scanned object; and The method further includes: generating a digitized 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.

26. The method of claim 25, wherein: 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, Generating the digitized radiographic image of the scanned object according to the second projection data includes: proportionally adjusting the second projection data detected by the vertical arm detector and the horizontal arm detector, and then combining them to generate the digitized radiographic image of the scanned object.

27. The method of claim 25 or 26, 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 sequentially spaced along the transmission direction; the arrangement interval between any two adjacent sub-detectors among the k sub-detectors along the transmission direction is smaller than the arrangement interval between any two adjacent first detectors among the n1 first detectors along the transmission direction, Generating the digitized 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 digitized radiographic image of the scanned object.

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