Linear scanning CT imaging system and method

Abstract

Provided is a linear scanning CT imaging system and method, the system comprising: a conveying device, used to move a scanned object in a scan channel along a predetermined conveying direction; a ray source, used to alternately emit ray beams to form a scan area; a detector, the detector comprising a first detector and a second detector; the first detector is used to detect first projection data formed after the ray beam passes through the scanned object in the process of the scanned object passing through the scanned area; the second detector is used to detect second projection data formed after the ray beam passes through the scanned object in the process of the scanned object passing through the scanned area; an imaging device, generating a digitized ray image of the scanned object according to the second projection data, and obtaining a computerized tomography image of the scanned object according to the first projection data and the second projection data.

Description

Technical Field

[0001] The present disclosure relates to the field of radiation imaging, and in particular to a linear scanning CT imaging system and method. Background Art

[0002] At present, security issues are receiving increasing attention, and various security equipment are installed in various public places.

[0003] For example, most existing large cargo and container X-ray inspection systems use DR imaging mode, which obtains single-energy or dual-energy perspective images at a single angle or multiple angles for manual image judgment to determine whether there are prohibited items in the cargo.

[0004] 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 parts, and the radiation source and detector are fixed on both sides of the scanning channel. The object is scanned through translational motion. This technology can also obtain attenuation coefficient information inside the object for automatic identification.

[0005] However, based on the current application situation, the above two technologies have at least the following related problems.

[0006] The DR imaging inspection system can only provide perspective images at one or more angles. If the components of the inspected goods are complex and tightly arranged, the perspective images will have serious overlap and occlusion, making it difficult to extract information from different items and identify contraband.

[0007] The linear CT scanning system solves the problem of perspective image occlusion, but the scanning angle is not perfect and the scanning geometry is difficult to accurately locate. In order to improve the scanning 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, reconstruction artifacts that cannot be eliminated, and even distortion of the object shape.

[0008] 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 the prior art.

[0009] Public Content

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

[0011] According to a first aspect of the present disclosure, a linear scanning CT imaging system is provided, wherein the system comprises: a conveying device for moving a scanned object in a scan 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 being used to alternately emit ray beams to form a scan area, wherein the m ray sources are located on one side of the scan channel, and m is a positive integer greater than or equal to 2; and n detectors, the n detectors being used to detect projection data formed after the ray beams pass through the scanned object during the process of the scanned object passing through the scan area, wherein the n detectors are located on the other side of the scan channel, and the n detectors are sequentially spaced along the conveying direction, 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 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 also includes an imaging device, the imaging device is used to: generate a digitized radiographic image of the scanned object according to the second projection data; and generate a computerized tomography image of the scanned 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 of the first detectors.

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

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

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

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

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

[0023] According to an embodiment of the present disclosure, the plane where both the 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 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.

[0025] According to an embodiment of the present disclosure, 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.

[0026] 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.

[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, 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.

[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 a 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 alternately arranged along 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 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°.

[0032] 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.

[0033] 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.

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

[0035] A second aspect of the present disclosure provides a linear scanning CT imaging method, wherein the method comprises: causing a conveying device to drive a scanned object to move in a predetermined conveying direction in a scanning channel, wherein the conveying device comprises 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 in 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 along the scanning direction. 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: the first projection data formed after the n1 first detectors detect the radiation beam passing through the scanned object; and the 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 according to the second projection data; and generating a computerized tomography image of the scanned 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 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.

[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 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; 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.

[0038] 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 one 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. 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] Figure 1 The structural diagram of the linear scanning CT imaging system provided by the embodiment of the present disclosure is schematically shown.

[0041] Figure 2A and Figure 2B The structural schematic diagrams of the first detector and the second detector provided by the embodiments of the present disclosure are schematically shown respectively, wherein the pixel distribution is schematically shown.

[0042] Figure 3A and Figure 3B The structural schematic diagrams of the first detector and the second detector provided by the embodiments of the present disclosure are schematically shown respectively, wherein the distribution of the detector modules is schematically shown.

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

[0044] Figure 5A and Figure 5B The side views of the linear scanning CT imaging system observed along the transmission direction provided by the embodiments of the present disclosure are schematically shown respectively.

[0045] Figure 6 and Figure 7 They are schematic structural diagrams of the linear scanning CT imaging system provided in the embodiments of the present disclosure, which schematically show that the second detector includes a plurality of sub-detectors.

[0046] Figure 8 A side view schematic diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure is schematically shown, wherein the second detector is schematically shown to include a U-shaped detector.

[0047] Fig. 9 A schematic top view of a linear scanning CT imaging system provided by an embodiment of the present disclosure is schematically shown, wherein the relative position relationship between the second detector and the conveying device is schematically shown.

[0048] Fig.10 A side view schematic diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure is schematically shown, wherein an arrangement of a cross-arm detector of the second detector is schematically shown.

[0049] Fig.11 A side view schematic diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure is schematically shown, wherein another arrangement of the cross-arm detector of the second detector is schematically shown.

[0050] Fig.12 A schematic structural diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure is schematically shown, wherein a plurality of second detectors are schematically shown.

[0051] Fig.13 A schematic structural diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure is schematically shown, wherein a plurality of L-shaped second detectors are schematically shown.

[0052] Fig.14 The structural diagram of the linear scanning CT imaging system provided by the embodiment of the present disclosure is schematically shown, wherein a rotating device is schematically shown.

[0053] Fig.15 The structural block diagram of the linear scanning CT imaging system provided by the embodiment of the present disclosure is schematically shown.

[0054] Fig.16 A schematic diagram of a trigger pulse sequence provided by an embodiment of the present disclosure is schematically shown.

[0055] Fig.17 A schematic diagram of another trigger pulse sequence provided by an embodiment of the present disclosure is schematically shown.

[0056] Fig.18 A schematic diagram of another trigger pulse sequence provided by an embodiment of the present disclosure is schematically shown.

[0057] Fig.19 The flowchart of the linear scanning CT imaging method provided by the embodiment of the present disclosure is schematically shown.

[0058] Fig. 20 The flowchart of the projection data processing method provided by the embodiment of the present disclosure is schematically shown.

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

[0060] Fig. 22 A block diagram schematically shows an imaging device of a linear scanning CT imaging system provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0061] The specific embodiments of the present disclosure will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present disclosure. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it is obvious to those of ordinary skill in the art that these specific details do not have to be adopted to implement the present disclosure. In other examples, in order to avoid confusing the present disclosure, known structures, materials or methods are not specifically described.

[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 conjunction with the embodiment or example is included in at least one embodiment of the present disclosure. Therefore, the phrases "in one embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any appropriate combination and / or subcombination. In addition, those of ordinary skill in the art will appreciate 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 existence of features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0064] All terms (including technical and scientific terms) used herein 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 X-ray (also known as DR) imaging refers to a technology that directly performs digital X-ray photography under computer control. For example, an amorphous silicon flat-panel detector can be used to convert the radiation information that penetrates 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 X-ray image of the scanned object.

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

[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, 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 A schematic diagram of the structure of a linear scanning CT imaging system provided in an embodiment of the present disclosure. Figure 1 The linear scanning CT imaging system in the embodiment includes: a transmission device 3, m ray 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 make the scanning object 30 move along a predetermined conveying direction D3 (eg, Figure 1 The conveyor 3 moves in the direction indicated by the arrow in the middle, wherein the conveyor 3 includes a conveying surface 3S on which the scanned object 30 is placed. Exemplarily, the conveyor 3 may be implemented in the form of belt transmission, chain transmission, gear transmission or other transmission methods, which are not limited here. 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 unidirectional transmission or bidirectional transmission.

[0070] exist Figure 1 In the embodiment, 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] Continue to refer to Figure 1 , m ray sources 1 are used to alternately emit ray beams to form a scanning area, wherein the m ray sources 1 are located on one side of the scanning channel 4. In some exemplary embodiments of the present disclosure, the m ray sources 1 are sequentially arranged 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 transmission surface 3S. That is, the multiple ray sources 1 are distributed at different height positions on the vertical line, and the multiple ray sources 1 alternately emit ray beams to form a scanning area.

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

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

[0074] In the embodiments of the present disclosure, Figure 1 As shown, the n detectors 2 include n1 first detectors 21 ( Figure 1 ) and n2 second detectors 22 ( Figure 1 ), 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 ray beam passes through the scanned object 30 during the process of the scanned object 30 passing through the scanned area. The n2 second detectors 22 are used to detect second projection data formed after the ray beam passes through the scanned object 30 during the process of the scanned object 30 passing through the scanned area.

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

[0076] In the linear scanning CT imaging system according to the embodiment of the present disclosure, when the scanned object is subjected to a security check, the conveying device 3 can move the scanned object along the conveying direction in the scanning channel and pass through the scanning area formed by the multiple ray sources 1 alternately emitting ray beams; then, the multiple first detectors and the second detectors detect the first projection data and the second projection data formed after the ray beams emitted by the multiple ray sources 1 pass through the scanned object during the scanning area; then, the imaging device generates a computerized tomography image of the scanned object according to the first projection data and the second projection data of the multiple ray sources 1, and generates a digitized ray image of the scanned object according to the second projection data of the multiple ray sources 1. On this basis, image judgment can be performed based on the digitized ray image and the computerized tomography image of the scanned object at the same time to identify whether there are prohibited items. That is, 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 one scan, and problems such as stacking or occlusion can be avoided through CT imaging, and problems such as resolution deterioration and artifacts can be improved through DR imaging.

[0077] It should be noted that, in conjunction with the reference Figure 1, the scanned object 30 moves in the scanning channel 4 and passes through the scanning area. In the process of passing through the scanning area, the multiple radiation sources 1 emit radiation beams alternately, and the first detector 21 and the second detector 22 respectively detect the first projection data and the second projection data at the same time. In this way, DR imaging and CT imaging can be performed simultaneously through one 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 section of DR imaging and the scanning section of CT imaging. Therefore, from a spatial point of view, the occupied space of the linear scanning CT imaging system can be reduced, and a compact linear scanning CT imaging system can be realized; from a temporal point of view, 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 embodiment of the present disclosure, by simultaneously arranging the first detector 21 and the second detector 22 for multiple ray sources 1, DR imaging and CT imaging can be performed simultaneously through one scan, and the scanned object 30 does not need to pass through the scan area multiple times. For example, the conveyor 3 does not need to drive the scanned object 30 to move in both directions to pass through the scan area multiple times. Therefore, from a structural point of view, the structure of the conveyor 3 can be simplified; from a time point of view, the imaging time of forming DR images and CT images can be shortened, which is conducive to 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 in the embodiments of the present disclosure are particularly suitable for security inspection of large items (such as containers).

[0080] It should also be noted that in the embodiment of the present disclosure, 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. 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 up rotating motion parts such as slip rings with complex structures, which is conducive 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 embodiment of the present disclosure, a plurality of ray sources 1 are arranged along a first straight line, that is, ray sources distributed along a straight line are formed, and the plurality of ray sources are controlled to emit beams alternately, so as to scan and image the scanned object 30 from multiple angles. In this way, it is possible to avoid setting a rotating motion component such as a slip ring with a complex structure to drive the movement of the ray source, which is conducive 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 other first detectors 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 at least one second detector 22 is higher than the resolution of each first detector 21.

[0084] Figure 2A and Figure 2B The structural schematic diagrams of the first detector and the second detector are schematically shown respectively.

[0085] For example, combined with reference Figure 2A and Figure 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, continue to refer to Figure 3A and Figure 3B 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 in the form of r1 rows and c1 columns, and the plurality of second detector modules 22M may be arranged in an array in the form of r2 rows and c2 columns, wherein 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 example, in conjunction with reference Figure 2A and Figure 2B, the pixel size of at least one second detector 22 is smaller than the pixel size 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, and at least one of the length and width of the pixel 21P is smaller than at least one of the length and width of the pixel 22P. It should be noted that the shape of the pixels of the first detector and the second detector is not limited to a rectangular shape, and may include any suitable shape, and the embodiments of the present disclosure do not impose any particular limitation on this.

[0088] In an embodiment of the present disclosure, by setting the pixel size, pixel arrangement and / or module arrangement 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, so that 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 ray beam emitted by the ray source 1 passes through the light receiving surface and enters each crystal, it will be absorbed by the crystal to generate an attenuated projection image, which will still remain for a period of time.

[0091] In some exemplary embodiments, the thickness of 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, Figure 1 As shown, the n1 first detectors 21 are linear detector arrays; and / or the n2 second detectors 22 are 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, 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 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 in one scanning process.

[0095] Figure 4 This is a schematic structural diagram of a linear scanning CT imaging system provided in an embodiment of the present disclosure, which schematically shows that the second detector includes an L-shaped detector. Figure 4 The linear scanning CT imaging system in the embodiment includes: a transmission device 3, m ray 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 the embodiments of the present disclosure, Figure 4 As shown, the n detectors 2 include n1 first detectors 21 ( Figure 4 ) and n2 second detectors 22 ( Figure 4 ), 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 ray beam passes through the scanned object 30 during the process of the scanned object 30 passing through the scanned area. The n2 second detectors 22 are used to detect second projection data formed after the ray beam passes through the scanned object 30 during the process of the scanned object 30 passing through the scanned area.

[0097] like Figure 4 As shown, 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 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] Continue to refer to Figure 4 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 scanning object.

[0100] Figure 5A and Figure 5B They are side views of the linear scanning CT imaging system observed along the transmission direction. Figure 5A and Figure 5B , the cone angle of the ray source 1 at the bottom 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] Figure 6 and Figure 7 They are schematic structural diagrams of the linear scanning CT imaging system provided in the embodiments of the present disclosure, which schematically show that the second detector includes a plurality of sub-detectors.

[0102] like Figure 6 and Figure 7 As 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 sequentially arranged at intervals along the transmission 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] like Figure 6 As shown, each sub-detector is a linear detector array. Figure 7 As 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 k sub-detectors to generate a digitized radiographic image of the scanned object. By arranging 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 "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 arranged alternately, so that an image with 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 7 In the illustrated embodiment, it is schematically shown that the second detectors are 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] Figure 8 A side view schematic diagram of a linear scanning CT imaging system provided in an embodiment of the present disclosure, schematically showing that the second detector includes a U-shaped detector.

[0109] like Figure 8 The n1 first detectors 21 are linear detector arrays. The at least one second detector 22 includes a vertical arm detector 221 arranged along the first direction D1, a first horizontal arm detector 222 arranged along the second direction D2, and a second horizontal arm detector 223 arranged along the second direction D2, wherein the first horizontal arm detector 222 and the second horizontal arm detector 223 are respectively located at the upper side and the lower side of the vertical arm detector 221 in the first direction D1.

[0110] Continue to refer to Figure 8 , 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 being attenuated by the scanned object. Figure 8 In the embodiment shown, the cone angles of the beams emitted by the three ray sources 1 are 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] Fig. 9 A schematic top view of a linear scanning CT imaging system provided in an embodiment of the present disclosure, wherein the relative position relationship between the second detector and the conveying device is schematically shown.

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

[0114] Combined with reference Figure 8 and Fig. 9 When the linear track transmission adopts the roller method, there are rail cars and turntables at both ends of the linear motion to realize operations such as cargo entry and exit and rotation. A cross arm detector 223 can be laid in the gap between the two rollers. At this time, all the beams emitted by the radiation source 1 can be used for DR imaging, that is, DR imaging of multiple viewing angles can be performed, and the transmission roller 31 will not block the signal received by the cross arm detector 223, which is conducive to further improving the quality of DR imaging.

[0115] Fig.10A side view schematic diagram of a linear scanning CT imaging system provided by an embodiment of the present disclosure, wherein a layout of a cross arm detector of the second detector is schematically shown. Figure 3B and Fig.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, 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. Fig.10 In the embodiment shown, the cone angles of the 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] Fig.11 A side view schematic diagram 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. Figure 3B and Fig.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, 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, and the embodiments of the present disclosure do not impose any special restrictions on this.

[0120] By such a setting, each detector module of the cross arm detector can be directed toward a certain ray source 1. For example, Fig.11 In the illustrated embodiment, each detector module of the cross-arm detector faces the ray source 1 located at the lowermost side, and on this basis, a clearer DR image can be acquired through the second detector.

[0121] In this embodiment, the ray beam emitted by the ray source 1 is incident vertically on the crystal of the cross-arm detector. When the ray beam is incident vertically on the crystal, the thickness of the ray beam passing through the crystal 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 embodiment of the present disclosure, by vertically incident on the crystal, on the one hand, the thickness of the ray beam passing through the crystal can be increased, thereby improving the penetration of the ray beam, and thus making the projection data carried by the detected projection image more comprehensive; on the other hand, the equivalent crystal area can be made equal to the actual area of ​​the light receiving surface, thereby improving the spatial resolution of the ray beam, and thus 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, and at least one first detector 21 is arranged on both sides of the second detector 22 along the transmission 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 while ensuring low cost, and the CT image will not be deteriorated.

[0123] For example, refer to Figure 1 , a plane P1 where the second detector 22 and the first straight line L1 are located is perpendicular to the transmission direction D3. When the ray beam emitted by the ray source 1 is a cone beam, such a setting can make the central beam plane of the cone beam face the second detector 22, which is conducive to obtaining 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 the first detector 21 and the second detector 22 is an odd number, the odd number of detectors are arranged at intervals along the transmission direction, and the detector in the middle position is the second detector 22. For example, the plane P1 where the second detector 22 in the middle position and the first straight line L1 are located is perpendicular to the transmission direction D3. For another example, the other even number of detectors are arranged symmetrically relative to the second detector 22 in the middle position. Through such a setting, the central beam plane of the cone beam can be directly opposite to the second detector 22, which is conducive 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 numbers of the first detectors 21 and the 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] Fig.12 A schematic structural diagram of a linear scanning CT imaging system provided in an embodiment of the present disclosure, wherein a plurality of second detectors are schematically shown.

[0128] Reference Fig.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 "alternating 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. Fig.12 As shown, along the conveying direction D3 , for some of the second detectors 22 , a first detector 21 is arranged on both sides of each second detector 22 ; for another part of the second detectors 22 , a first detector 21 is arranged 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] Continue to refer to Fig.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, Fig.12As shown, the angle α0 between the plane where the second second detector 22 and the first straight line L1 are located from left to right and the conveying direction D3 is about 90°, the angle α1 between the plane where the second second detector 22 and the first straight line L1 are located from left to right and the conveying direction D3 is greater than 90°, and the angles α2 and α3 between the plane where the third and fourth second detectors 22 and the first straight line L1 are located from left to right and the conveying direction D3 are both less than 90°. Exemplarily, α1>α0>α2>α3, that is, the angles between the planes where the second detectors arranged along the conveying direction and the first straight line L1 are located and the conveying direction D3 decrease successively.

[0133] By reasonably 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 reasonably designed, which is beneficial to further improve the quality of DR imaging.

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

[0135] Reference Fig.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] Continue 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 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 Fig.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 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 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 in 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 according to the second projection data, and obtain a three-dimensional reconstructed image of the scanning object according to 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 scanned area may be multiple times. Those skilled in the art should understand that the more times the scanned object passes through the scanned area in one inspection, the more comprehensive the angles at which the scanned object is illuminated, and thus the higher the quality of the reconstructed image obtained.

[0141] The working process of the linear scanning CT imaging system of 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 in the vertical direction emit beams alternately 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 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 the embodiments of the present disclosure, referring to Fig.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. The pulse trigger sequence may specifically 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, Fig.16The trigger pulse signals corresponding to the three ray sources 1 are shown in FIG. The horizontal axis indicates time, and the trigger pulse signals corresponding to the three ray sources 1 are arranged alternately along the time axis. The vertical axis 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 single-energy CT reconstruction.

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

[0150] For example, Fig.17 The trigger pulse signal groups corresponding to the three ray sources 1 are shown in FIG. 1 , that is, each ray source 1 emits a beam twice. The horizontal axis indicates time, and the trigger pulse signal groups corresponding to the three ray sources 1 are arranged alternately along the time axis. The vertical axis indicates energy, and the energy indicated by the first trigger pulse signal in each trigger pulse signal group is E2, and the energy indicated by the second trigger pulse signal in each trigger pulse signal group is 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 image reconstruction is described in detail below.

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

[0153] Then, the base material coefficient projection value corresponding to the dual-energy projection data is calculated according to a pre-created lookup table or by solving a set of equations. Among them, the method of creating a lookup table is to select two base materials, calculate the projection values ​​of the dual-energy rays passing through the two materials at different thicknesses, and obtain a lookup table according to the relationship between the high and low energy projection values ​​and different thickness combinations. The method of analytically solving the set of equations is to use the actual high and low energy projection values ​​to obtain the corresponding thickness combination by solving the high and low energy projection equations under the decomposition of the base material.

[0154] Then, the distribution image of the base material coefficient can be obtained from the projection value of the base material. From the distribution of the base material coefficient, 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, so as to classify and automatically identify the material 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 scanning CT imaging system further includes a decomposition unit, which 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-ray beam and the second sub-ray beam, respectively. The imaging device obtains a 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 ray source 1 may be a mono-energy accelerator with adjustable energy. A period of the trigger pulse sequence includes trigger pulse signals corresponding to the plurality of ray sources 1. During the first scanning process of the scanned object 30, the trigger pulse signal is used to control the corresponding ray source 1 to emit a ray beam with the first same energy; during the second scanning process of the scanned object 30, the trigger pulse signal is used to control the corresponding ray source 1 to emit a ray beam with the second same energy.

[0157] For example, the energy indicated by all trigger pulse signals in the first scanning process is E1 (see Fig.16 ); During the second scan, the energy indicated by all trigger pulse signals is E4 (see Fig.18 ). The projection image data obtained in this way can also be used for dual-energy CT reconstruction, and 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 material of the scanned object.

[0158] Fig.19 A schematic flow chart of a linear scanning CT imaging method provided in an embodiment of the present disclosure is applied to the linear scanning CT imaging system as described above. Fig.19 The linear scanning CT imaging method 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 at 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, when the scanned object passes through the scanned 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 scan 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] Fig. 20 2 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 radiation beam passes through the scanned object.

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

[0166] In step S1343, a digitized radiographic 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 and display a three-dimensional reconstructed image of the object under inspection.

[0168] For example, the data of the second detector 22 may be directly used for reconstruction, or the data of the second detector 22 may be made equivalent to the data of 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] Fig.21A and Fig.21B Schematic diagram of a second projection data ratio processing method according to an embodiment of the present disclosure.

[0171] In some exemplary embodiments, 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, thereby eliminating visual inconsistencies in the image at the junction.

[0172] For example, combined with reference 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 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 be equivalent to one row of DR image display in data processing.

[0174] In some exemplary embodiments, the linear scanning CT imaging system also 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 also includes: the pulse trigger generates a trigger pulse sequence for controlling the multiple radiation sources 1 to alternately emit radiation 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 to multiple radiation sources 1 one by one, the trigger pulse signal group including 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 projection data and the second projection data into first sub-projection data and second sub-projection data corresponding to the first sub-ray beam and the second sub-ray beam, respectively, from the first projection data and the second projection data. 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, the ray source 1 adopts a dual-energy beam mode, and the second detector 22 adopts a detector with energy resolution capability, so that more energy spectrum DRs can be measured, which is more accurate in image color and can realize the classification of more substances.

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

[0180] like Fig. 22 As shown, the imaging device 4 of the linear scanning CT imaging system according to the embodiment of the present disclosure may include a processor 401, which can perform various appropriate actions and processes according to the program stored in the read-only memory (ROM) 402 or the program loaded from the storage part 408 to the random access memory (RAM) 403. The processor 401 may include, for example, a general-purpose microprocessor (such as a CPU), an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (for example, an application-specific integrated circuit (ASIC)), etc. The processor 401 may also include an 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 the embodiment of the present disclosure.

[0181] In RAM 403, various programs and data required for the operation of electronic device 400 are stored. Processor 401, ROM 402 and RAM 403 are connected to each other via bus 404. Processor 401 performs various operations of the method flow according to the embodiment of the present disclosure by executing the program in ROM 402 and / or RAM 403. It should be noted that the program can also be stored in one or more memories other than ROM 402 and RAM 403. Processor 401 can also perform various operations of the method flow according to the embodiment of the present disclosure by executing the program 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, which 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 portion 406 including a keyboard, a mouse, etc.; an output portion 407 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage portion 408 including a hard disk, etc.; and a communication portion 409 including a network interface card such as a LAN card, a modem, etc. The communication portion 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 therefrom is installed into the storage portion 408 as needed.

[0183] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present invention. In this regard, each box in the flow chart or block diagram can represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of a code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order 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 flow chart, and the combination of the boxes in the block diagram or flow chart can be implemented with a dedicated hardware-based system that performs a 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 the linear scanning CT imaging system, a system design of DR based on linear CT is implemented, which has no effect on the original scanning mode of linear CT and no increase in the scanning steps of linear CT; only one or several columns of detectors need to be replaced to obtain a clearer and more complete DR image without deteriorating the three-dimensional reconstructed image; when the ray source adopts a dual-energy beam mode, the color of the DR image will also be more accurate; when the ray source adopts a dual-energy beam mode, the second detector adopts a detector with energy resolution capability, which can realize more energy spectrum DR with more energy spectrum measurement, more accurate in image color, and can also realize the classification of more substances.

[0185] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of 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, m is a positive integer greater than or equal to 2, and the m ray sources are sequentially arranged at intervals 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 transmission surface; 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, 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 used to detect first projection data formed after the ray beam passes through the scanned object in a process in which the scanned object passes 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 in a process in which the scanned object passes through the scanned area; and The system further includes an imaging device, the imaging device being used to: generate a digitized radiographic image of the scanned object according to the second projection data; and generate 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 simultaneously perform digitized radiographic imaging and computed tomography imaging through one scan, wherein the resolution of the digitized radiographic image is higher than the resolution of the computed tomography image; 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 arranged at intervals along the transmission direction; An arrangement interval between any two adjacent sub-detectors among the k sub-detectors along the transmission direction is smaller than an arrangement interval between any two adjacent first detectors among the n1 first detectors along the transmission direction; 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.

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

3. The system of claim 2, 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.

4. The system according to any one of claims 1 to 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 is different from that of each of the first detectors along the radiation incident direction.

5. The system of claim 4, 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.

6. The system of any one of claims 1 to 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 an arrangement of the plurality of first detector modules is different from an arrangement of the plurality of second detector modules.

7. The system of claim 4, 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 1-3, 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 of 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 of 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 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.

11. The system of 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 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.

12. The system of 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 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.

13. The system of 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 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.

14. The system of any one of claims 1-3, 5, 7, 9, 11 and 13, 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.

15. The system of claim 14, wherein: The plane where the one second detector and the first straight line are located is perpendicular to the transmission direction.

16. The system of claim 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 11, wherein: The cross arm detector includes a plurality of detector modules, and the plurality of detector modules are sequentially connected end to end.

18. The system of claim 12, wherein: The cross arm detector includes a plurality of detector modules, and the plurality of detector modules are sequentially connected end to end.

19. The system of claim 13, wherein: The cross arm detector includes a plurality of detector modules, and the plurality of detector modules are sequentially connected end to end.

20. The system of 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.

21. The system of 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.

22. The system of 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.

23. The system of 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.

24. The system of any one of claims 16-19, 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.

25. The system of claim 12, 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.

26. The system of claim 13, 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.

27. The system of any one of claims 1-3, 5, 7, 9, 11, 13, 16-23, 25 and 26, 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.

28. The system of claim 27, 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°.

29. The system of 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 alternately arranged along the conveying direction.

30. The system of claim 29, 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°.

31. The system of claim 24, 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.

32. The system of claim 31, 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°.

33. The system of claim 27, 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.

34. The system of claim 28, 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.

35. The system of any one of claims 29-32, 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.

36. The system of claim 33 or 34, 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.

37. The system of claim 35, 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.

38. The system of any one of claims 1-3, 5, 7, 9, 11, 13, 15-23, 25, 26, 28-34, and 37, wherein: The scanning channel is a straight line channel.

39. The system of claim 4, wherein: The scanning channel is a straight line channel.

40. 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 at 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 other side of the scan channel, and the n detectors are sequentially arranged at intervals 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, 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 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 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, so that digital radiographic imaging and computed tomography imaging can be performed simultaneously through one scan, wherein the resolution of the digitized radiographic image is higher than that of the computed tomography image. 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 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, 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.

41. The method of claim 40, 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 further 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.

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