Linear scanning CT imaging system and method

Abstract

The linear scanning CT imaging system includes a transport device (3) that moves a scanning target (30) in a predetermined transport direction (D3) along a scanning path (4), a radiation source (1) that alternately emits radiation beams to form a scanning area, a detector (2) including a first detector (21) that detects first projection data formed after the radiation beam has passed through the scanning target (30) as the scanning target (30) passes through the scanning area, and a second detector (22) that detects second projection data formed after the radiation beam has passed through the scanning target (30) as the scanning target (30) passes through the scanning area, and an imaging device (5) that generates a digitized radiation image of the scanning target (30) based on the second projection data and acquires a computed tomography scan image of the scanning target (30) based on the first and second projection data.

Description

Technical Field

[0001] (Cross - reference to related applications) This application claims the priority of Chinese Patent Application No. 202311490080.9 filed on November 9, 2023, and incorporates its content by reference in its entirety.

[0002] This disclosure relates to the field of radiation imaging, and particularly to a linear scanning CT imaging system and method.

Background Art

[0003] Currently, safety issues are being increasingly emphasized, and various security inspection facilities are provided in each public place.

[0004] For example, related large - luggage and container X - ray inspection systems often adopt the DR imaging mode, obtaining single - energy or dual - energy fluoroscopic images at a single angle or multiple angles and manually judging the images to check whether there are prohibited products in the luggage.

[0005] Also, for example, a CT inspection system based on a linear scanning trajectory may be used for luggage security inspection. This technology does not require a rotating member, and the radiation source and detector are stationary and fixed on both sides of the scanning path. The object completes the scanning through translational motion. This technology can obtain the attenuation coefficient information inside the object and may be used for automatic identification.

[0006] However, according to the current application situation, at least the following problems exist in the above two technologies.

[0007] The DR imaging inspection system can only provide fluoroscopic images at one or more angles. When the components of the inspected luggage are complex and closely arranged, there are serious overlaps and occlusions in the fluoroscopic images, making it difficult to extract information on different items and judge prohibited products.

[0008] While linear CT scanning systems have solved the problem of occlusion of fluoroscopic images, the scanning angle is insufficient, making it difficult to accurately position the scanning geometry. Furthermore, the data processing process is inadequate to improve the efficiency of scanned image output. As a result, CT images, compared to those provided by conventional DR systems, inevitably suffer from a degradation in spatial resolution, unremovable reconstruction artifacts, and ultimately, distortion of object shapes.

[0009] The information disclosed in this section is intended solely to provide an understanding of the background of the disclosure philosophy, and therefore may include information that does not constitute prior art. [Overview of the project]

[0010] This disclosure provides a linear scanning CT imaging system and an imaging method thereof.

[0011] According to a first aspect of this disclosure, a linear scanning CT imaging system is provided, comprising: a transport device that moves a scanning object in a predetermined transport direction along a scanning path and includes a transport surface on which the scanning object is placed; m radiation sources (where m is a positive integer of 2 or more) located on one side of the scanning path that alternately emit radiation beams to form a scanning area; and n detectors (where n is a positive integer of 3 or more) located on the other side of the scanning path and arranged sequentially at intervals along the transport direction, which detect projection data formed after the radiation beams have passed through the scanning object as the scanning object passes through the scanning area, wherein the n detectors include n1 first detectors The system further includes an imaging device comprising n2 second detectors, where n1 is a positive integer greater than or equal to 2 and n2 is a positive integer greater than or equal to 1, wherein the n1 first detectors detect first projection data formed after the radiation beam has passed through the object as the object passes through the scanning region, and the n2 second detectors detect second projection data formed after the radiation beam has passed through the object as the object passes through the scanning region, and the system further includes an imaging device that generates a digitized radiation image of the object based on the second projection data and generates a computed tomography image of the object based on the first and second projection data.

[0012] According to embodiments of this disclosure, at least one second detector is different from each first detector.

[0013] According to the embodiments of this disclosure, the resolution of at least one second detector is higher than the resolution of each first detector.

[0014] According to embodiments 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 embodiments of this disclosure, at least one second detector and each first detector are made of different crystalline materials, and / or at least one second detector and each first detector are made of different thicknesses along the radiation incidence direction.

[0016] According to embodiments of the present disclosure, the crystalline afterglow of at least one second detector is less than the crystalline 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 embodiments of this disclosure, the first detector includes a plurality of first detector modules, the second detector includes a plurality of second detector modules, and the arrangement of the plurality of first detector modules is different from the arrangement of the plurality of second detector modules.

[0018] According to embodiments of this disclosure, each of the n1 first detectors is a linear detector array, and / or each of the n2 second detectors is a linear detector array.

[0019] According to embodiments of the present disclosure, each of the n1 first detectors is a linear detector array, and / or at least one second detector includes a longitudinal arm detector arranged along a first direction and a transverse arm detector arranged along a second direction, the second direction intersecting both the transport direction and the first direction.

[0020] According to embodiments of the present disclosure, each of the n1 first detectors is a linear detector array, and / or at least one second detector includes a longitudinal arm detector arranged along a first direction, a first transverse arm detector arranged along a second direction, and a second transverse arm detector arranged along a second direction, wherein the first and second transverse arm detectors are located above and below the longitudinal arm detector in the first direction, and the second direction intersects both the transport direction and the first direction.

[0021] According to embodiments of the present disclosure, the m radiation sources are arranged sequentially at intervals along a first straight line, the first straight line being a virtual straight line extending along a first direction, and the first direction being perpendicular to the transport surface.

[0022] According to embodiments of the present disclosure, the n detectors include only one second detector, and at least one first detector is positioned on each side of the second detector along the transport direction.

[0023] According to embodiments of this disclosure, the plane in which both a second detector and a first straight line are located is perpendicular to the transport direction.

[0024] According to embodiments of the present disclosure, at least one second detector includes k sub-detectors, where k is a positive integer greater than or equal to 2, and the k sub-detectors are arranged sequentially at intervals along the transport direction, and the spacing along the transport direction between any two adjacent sub-detectors among the k sub-detectors is smaller than the spacing along the transport direction between any two adjacent first detectors among the n1 first detectors.

[0025] According to embodiments of this disclosure, the imaging apparatus combines second projection data from k sub-detectors to generate a digitized radiation image of the object being scanned.

[0026] According to embodiments of the present disclosure, the lateral arm detector includes a plurality of detector modules, the plurality of detector modules being connected end to end in sequence.

[0027] According to an embodiment of the present disclosure, the horizontal arm detector includes a plurality of detector modules, and the plurality of detector modules are 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 a second straight line, and the second straight line is a straight line connecting the i-th radiation source and a predetermined point on the light receiving surface, and the predetermined point is located at the boundary of the light receiving surface or within the light receiving surface, and i is a positive integer from 1 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 horizontal arm detector is located in the gap between two adjacent conveying rollers.

[0030] According to an embodiment of the present disclosure, the number n2 of the second detectors is 2 or more, and the n2 second detectors and the n^1 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 in which one second detector and the first straight line are both located is perpendicular to the conveying direction, and the included angle between the plane in which the other second detectors and the first straight line are both located and the conveying 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 a second direction intersecting both the conveying direction and the first direction.

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

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

[0035] A second aspect of this disclosure provides a linear scanning CT imaging method comprising: a transport device including a transport surface on which a scanning object is placed moves the scanning object along a scanning path in a predetermined transport direction; m radiation sources (where m is a positive integer of 2 or more) located on one side of the scanning path alternately emit radiation beams to form a scanning area; the scanning object is moved through the scanning area; and, in the process of the scanning object moving through the scanning area, projection data formed after the radiation beams have passed through the scanning object is detected by n detectors (where n is a positive integer of 3 or more), wherein the n detectors are located on the other side of the scanning path and are arranged sequentially at intervals along the transport direction, and the n detectors The output device includes n1 first detectors and n2 second detectors, where n1 is a positive integer greater than or equal to 2 and n2 is a positive integer greater than or equal to 1. The method for causing the n detectors to detect projection data formed after a radiation beam has passed through a scanning target includes causing the n1 first detectors to detect first projection data formed after a radiation beam has passed through a scanning target and causing the n2 second detectors to detect second projection data formed after a radiation beam has passed through a scanning target. The method further includes generating a digitized radiation image of the scanning target based on the second projection data and generating a computed tomography scan image of the scanning target based on the first and second projection data.

[0036] According to embodiments of the present disclosure, at least one second detector includes a vertical arm detector positioned along a first direction and a horizontal arm detector positioned along a second direction, the second direction intersecting both the transport direction and the first direction, and generating a digitized radiation image of the object being scanned based on the second projection data includes performing proportional adjustments to the second projection data detected by the vertical arm detector and the horizontal arm detector, and then combining them to generate a digitized radiation image of the object being scanned.

[0037] According to embodiments of the present disclosure, at least one second detector includes k sub-detectors, where k is a positive integer of 2 or more, the k sub-detectors are arranged sequentially at intervals along the transport direction, the array spacing along the transport direction between any two adjacent sub-detectors among the k sub-detectors is smaller than the array spacing along the transport direction between any two adjacent first detectors among the n1 first detectors, and generating a digitized radiation image of the scanned object based on second projection data includes combining the second projection data of the k sub-detectors to generate a digitized radiation image of the scanned object.

[0038] To better understand this disclosure, it will be described in detail based on the following drawings. [Brief explanation of the drawing]

[0039] [Figure 1] Figure 1 schematically shows a linear scanning CT imaging system according to an embodiment of the present disclosure. [Figure 2A] Figure 2A schematically shows the structures of the first and second detectors according to the embodiment of this disclosure, and outlines the pixel distribution. [Figure 2B] Figure 2B schematically shows the structures of the first and second detectors according to the embodiment of this disclosure, and outlines the pixel distribution. [Figure 3A] Figure 3A schematically shows the structures of the first and second detectors according to the embodiment of this disclosure, and roughly illustrates the distribution of the detector modules. [Figure 3B] Figure 3B schematically shows the structures of the first and second detectors according to the embodiment of this disclosure, and roughly illustrates the distribution of the detector modules. [Figure 4] Figure 4 schematically shows the structure of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows that the second detector includes an L-type detector. [Figure 5A] Figure 5A schematically shows a side view of a linear scanning CT imaging system for observation along the transport direction according to an embodiment of the present disclosure. [Figure 5B] Figure 5B schematically shows a side view of a linear scanning CT imaging system for observation along the transport direction according to an embodiment of the present disclosure. [Figure 6] Figure 6 is a schematic diagram of the structure of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows that the second detector includes a plurality of sub-detectors. [Figure 7] Figure 7 is a schematic diagram of the structure of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows that the second detector includes a plurality of sub-detectors. [Figure 8] Figure 8 schematically shows a side view of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows that the second detector includes a U-shaped detector. [Figure 9] Figure 9 schematically shows a top view schematic of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows the relative positional relationship between the second detector and the transport device. [Figure 10] Figure 10 schematically shows a side view of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows the arrangement of the lateral arm detector of the second detector. [Figure 11] Figure 11 schematically shows a side view of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically illustrates other arrangement methods for the lateral arm detector of the second detector. [Figure 12] Figure 12 schematically shows the structure of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows a plurality of second detectors. [Figure 13] Figure 13 schematically shows the structure of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows a plurality of L-type second detectors. [Figure 14] Figure 14 schematically shows the structure of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows the rotating device. [Figure 15] Figure 15 schematically shows a structural block diagram of a linear scanning CT imaging system according to an embodiment of the present disclosure. [Figure 16]Figure 16 schematically shows a trigger pulse sequence according to an embodiment of the present disclosure. [Figure 17] Figure 17 schematically shows another trigger pulse sequence according to one embodiment of the present disclosure. [Figure 18] Figure 18 schematically shows yet another trigger pulse sequence according to one embodiment of the present disclosure. [Figure 19] Figure 19 schematically shows a flowchart of a linear scanning CT imaging method according to an embodiment of the present disclosure. [Figure 20] Figure 20 schematically shows a flowchart of the projection data processing method according to an embodiment of the present disclosure. [Figure 21A] Figure 21A schematically shows a second projection data proportional processing method according to an embodiment of the present disclosure. [Figure 21B] Figure 21B schematically shows a second projection data proportional processing method according to an embodiment of the present disclosure. [Figure 22] Figure 22 schematically shows a block diagram of the imaging apparatus of a linear scanning CT imaging system according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0040] The following describes specific embodiments of this disclosure in detail, but these embodiments are illustrative only and do not limit the disclosure. A large number of specific details are described in the following description for the sake of a full understanding of this disclosure. However, as will be apparent to those skilled in the art, it is not necessary to use these specific details to implement this disclosure. In other embodiments, known structures, materials, or methods are not specifically described to avoid confusion with this disclosure.

[0041] Throughout the specification, any reference to “one embodiment,” “an example,” “a sample,” or “a case” means that the specific features, structures, or properties described in accordance with that embodiment or case are included in at least one embodiment of the present disclosure. Therefore, the phrases “in one embodiment,” “in an example,” “a case,” or “a case” appearing in various places throughout the specification do not necessarily refer to the same embodiment or case. Furthermore, specific features, structures, or properties may be combined in any suitable combination and / or subcombinations in one or more embodiments or cases. Also, those skilled in the art should understand that the term “and / or” as used herein includes any and all combinations of one or more related items.

[0042] The terms used herein are for illustrative purposes only and are not intended to limit the disclosure. Terms such as “includes” and “contains” as used herein indicate the presence of features, steps, operations and / or components, but do not preclude the presence or addition of one or more other features, steps, operations or components.

[0043] All terms used herein (including technical and scientific terms) have the meanings that a person skilled in the art would ordinarily understand unless otherwise defined. Terms used herein should be interpreted to have meanings consistent with the context of this specification, and not in an idealistic or overly rigid manner.

[0044] In this disclosure, digitized radiation (also known as DR) imaging refers to a technique that directly performs digitized radiation imaging under computer control. For example, it is possible to convert radiation information transmitted through a target object using an amorphous silicon flat panel detector into a digital signal, reconstruct the image using a computer, perform a series of image post-processing steps, and generate a digitized radiation image of the scanned object.

[0045] Computed tomography (also known as CT) imaging uses radiation to perform a cross-sectional scan of the target object. The analog signals acquired by the detector are then converted into digital signals, and the attenuation coefficient for each pixel is calculated by a computer. By reconstructing the image, the cross-sectional structure of each part of the target object can be displayed.

[0046] Furthermore, the linear scanning CT imaging system and method according to the embodiments of this disclosure are applicable to conducting security inspections of articles in various public places, can acquire an internal attenuation coefficient distribution map of the object to automatically identify hazardous materials, and are advantageous in security inspections of large articles (e.g., containers).

[0047] Figure 1 is a schematic diagram of the structure of a linear scanning CT imaging system according to an embodiment of the present disclosure. The linear scanning CT imaging system in Figure 1 includes a transport device 3, m radiation sources 1, n detectors 2, and an imaging device 5. Exemplarily, m is a positive integer of 2 or more, and n is a positive integer of 3 or more.

[0048] Specifically, the conveying device 3 moves the object to be scanned 30 in a predetermined conveying direction D3 (direction of the arrow in Figure 1) within the scanning passage 4 and has a conveying surface 3S on which the object to be scanned 30 is placed. Exemplarily, the implementation of the conveying device 3 may be a belt conveying system, a chain conveying system, a gear conveying system, or another transmission system, and is not limited thereto. The object to be scanned 30 is placed, for example, on the conveying surface 3S of the conveying device 3. In some exemplary embodiments, the power mechanism of the conveying device 3 can support both unidirectional and bidirectional conveying.

[0049] In the embodiment shown in Figure 1, the scanning path 4 is a linear scanning path, meaning that the movement trajectory of the object to be scanned 30 in the scanning area is a linear trajectory.

[0050] Continuing to refer to Figure 1, m radiation sources 1 alternately emit radiation beams to form a scanning area, where the m radiation sources 1 are located on one side of the scanning path 4. In some exemplary embodiments of this disclosure, the m radiation sources 1 are arranged sequentially at intervals along a first straight line L1, which is a virtual straight line extending along a first direction D1, which is perpendicular to the transport surface 3S. That is, the multiple radiation sources 1 are distributed at different height positions on the vertical line, and the multiple radiation sources 1 alternately emit radiation beams to form a scanning area.

[0051] For example, the radiation source 1 may be an accelerator, the energy of which is adjustable and which has strong penetrating power. The embodiments of this disclosure do not particularly limit the type of radiation source 1, and in other embodiments, other types of radiation sources, such as an X-ray device, may be used for the radiation source 1.

[0052] Continuing to refer to Figure 1, the n detectors 2 detect projection data formed after the radiation beam has passed through the scanning object 30 as the scanning object 30 passes through the scanning area. Here, the n detectors are located on the other side of the scanning path 4, and the n detectors 2 are arranged sequentially at intervals along the transport direction D3.

[0053] In the embodiments of this disclosure, as shown in Figure 1, the n detectors 2 include n1 first detectors 21 (schematically shown by solid lines in Figure 1) and n2 second detectors 22 (schematically shown by dashed lines in Figure 1), where, for example, n1 is a positive integer of 2 or more, and n2 is a positive integer of 1 or more. The n1 first detectors 21 detect first projection data formed after the radiation beam has passed through the scanning target 30 as the scanning target 30 passes through the scanning area. The n2 second detectors 22 detect second projection data formed after the radiation beam has passed through the scanning target 30 as the scanning target 30 passes through the scanning area.

[0054] The imaging device 5 generates a digitized radiographic image (i.e., a DR image) of the scanning target 30 based on the second projection data, and generates a computed tomography scan image (i.e., a CT image) of the scanning target 30 based on the first projection data and the second projection data.

[0055] In the linear scanning CT imaging system according to the embodiment of this disclosure, when performing a security inspection on a scanning target, the transport device 3 moves the scanning target along the transport direction in the scanning path, passing through a scanning area formed by the alternating emission of radiation beams from multiple radiation sources 1. Next, multiple first and second detectors detect first and second projection data formed after the radiation beams emitted from the multiple radiation sources 1 have passed through the scanning target as the scanning target passes through the scanning area. Next, the imaging device generates a computed tomography scan image of the scanning target based on the first and second projection data of the multiple radiation sources 1, and generates a digitized radiation image of the scanning target based on the second projection data of the multiple radiation sources 1. Based on this, the image can be judged based on the digitized radiation image and computed tomography scan image of the scanning target to identify whether or not prohibited items are present. In other words, in the linear scanning CT imaging system according to the embodiment of this disclosure, DR imaging and CT imaging can be performed simultaneously in a single scan, CT imaging can avoid problems such as overlap or shielding, and DR imaging can improve image quality and avoid problems such as resolution degradation and artifacts.

[0056] Referring also to Figure 1, the scanning target 30 moves along the scanning path 4 and passes through the scanning area. During this process, the multiple radiation sources 1 alternately emit radiation beams, and the first detector 21 and the second detector 22 simultaneously detect the first projection data and the second projection data, respectively. In this way, DR imaging and CT imaging can be performed simultaneously in a single scan. That is, in the embodiment of this disclosure, there is no need to perform DR imaging on the scanning target 30 before performing CT imaging; in other words, there is no need to separate the scanning segment for DR imaging and the scanning segment for CT imaging. Therefore, spatially, the space occupied by the linear scanning CT imaging system can be reduced, enabling the realization of a compact linear scanning CT imaging system. Temporally, the imaging time required to form the DR image and CT image can be shortened, which is advantageous for improving detection efficiency.

[0057] In the embodiments of this disclosure, by simultaneously arranging the first detector 21 and the second detector 22 for multiple radiation sources 1, DR imaging and CT imaging can be performed simultaneously in a single scan, eliminating the need for the scanning target 30 to pass through the scanning area multiple times. For example, the transport device 3 does not need to move the scanning target 30 bidirectionally to pass through the scanning area multiple times. Therefore, structurally, the structure of the transport device 3 can be simplified, and temporally, the imaging time required to form DR and CT images can be shortened, which is advantageous for improving detection efficiency.

[0058] Particularly advantageous is that DR imaging and CT imaging can be performed simultaneously in a single scan, and the object to be scanned 30 does not need to pass through the scanning area multiple times. Therefore, the linear scanning CT imaging system and method according to the embodiments of this disclosure are particularly applicable to security inspections of large items (e.g., containers).

[0059] In the embodiments of this disclosure, the scanning path 4 is a linear scanning path, meaning that the motion trajectory of the scanning target 30 in the scanning area is a linear trajectory. That is, the scanning target 30 moves along a single linear trajectory relative to the radiation source and detector, eliminating the need to provide rotational motion members such as slip rings with complex structures. This simplifies the structural complexity of the linear scanning CT imaging system and is advantageous in improving the reliability of the linear scanning CT imaging system.

[0060] In the embodiments of this disclosure, the multiple radiation sources 1 are arranged along a first straight line, that is, they form radiation sources distributed along a straight line, and the multiple radiation sources are controlled to emit beams alternately. In this manner, the scanning target 30 is scanned and imaged from multiple angles. This avoids the need to drive the motion of the radiation sources by providing rotational moving members such as slip rings, which have complex structures. This simplifies the structure of the linear scanning CT imaging system and is advantageous in improving the reliability of the linear scanning CT imaging system.

[0061] In the embodiments of this disclosure, the second detector for DR imaging and the first detector for other CT imaging are arranged along the transport direction, and by changing the arrangement of the detectors, DR imaging and CT imaging can be achieved simultaneously, improving the quality of the imaging images without increasing the complexity of the system structure.

[0062] In the embodiments of this disclosure, at least one second detector 22 is different from each first detector 21. Specifically, the second detector 22 is used for DR imaging, and the first detector 21 is used for CT imaging, meaning that 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.

[0063] Figures 2A and 2B show schematic diagrams of the structures of the first and second detectors, respectively.

[0064] For example, referring to Figures 2A and 2B, the first detector 21 may include multiple pixels 21P, and the second detector 22 may include multiple pixels 22P, with at least one second detector 22 having a greater number of pixels than each first detector 21.

[0065] In some exemplary embodiments, continuing with reference to Figures 3A and 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 manner of r1 rows c1 columns, and the plurality of second detector modules 22M may be arranged in an array in the manner of r2 rows c2 columns, where r1, r2, c1, and c2 are each positive integers greater than or equal to 2, and r1 may not be equal to r2, and / or c1 may not be equal to c2.

[0066] Furthermore, referring to Figures 2A and 2B together, for example, the pixel size of at least one second detector 22 is smaller than the pixel size of each first detector 21. Exemplarily, one pixel 21P of the first detector 21 may have a substantially rectangular shape, and one pixel 22P of the second detector 22 may have a substantially rectangular shape, with at least one of the length and width of pixel 21P being smaller than at least one of the length and width of pixel 22P. Note that the pixel shapes of the first and second detectors are not limited to rectangular shapes and may include any suitable shape; the embodiments of this disclosure do not particularly limit this.

[0067] In the embodiments of this disclosure, by setting the pixel size, pixel arrangement, and / or module arrangement of the first and second detectors, the number of pixels per unit area of ​​the first detector becomes smaller than the number of pixels per unit area of ​​the second detector, and thus the resolution of the image formed by the second detector becomes higher than the resolution of the image formed by the first detector.

[0068] In some exemplary embodiments, at least one second detector 22 is made of a different crystalline material than each first detector 21. The crystalline afterglow of at least one second detector 22 is less than the crystalline afterglow of each first detector 21.

[0069] In this context, "crystal afterglow" refers to the afterglow effect of crystals. The radiation beam emitted from radiation source 1 passes through the light-receiving surface and enters the interior of each crystal. After being absorbed by the crystal, an attenuated projection image is generated, which remains for a while.

[0070] In some exemplary embodiments, at least one second detector 22 has a thickness along the radiation incidence direction that differs from that of each first detector 21.

[0071] 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.

[0072] In some exemplary embodiments, as shown in Figure 1, each of the n1 first detectors 21 is a linear detector array, and / or each of the n2 second detectors 22 is a linear detector array. Compared to area array detectors, linear detector arrays offer greater flexibility in installation and lower costs.

[0073] In some exemplary embodiments, the number of radiation sources 1 is m, the number of detectors is n, where m is a positive integer greater than or equal to 2, and n is a positive integer greater than or equal to 3. Each detector can collect the attenuation signal of the radiation beam emitted from each radiation source 1 at a certain angle, i.e., one projection data, and m × n projection data can be obtained in a single scanning process.

[0074] Figure 4 is a schematic diagram of the structure of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows that the second detector includes an L-type detector. The linear scanning CT imaging system in Figure 4 includes a transport device 3, m radiation sources 1, n detectors 2, and an imaging device 5. Exemplarily, m is a positive integer of 2 or more, and n is a positive integer of 3 or more.

[0075] In the embodiments of this disclosure, as shown in Figure 4, the n detectors 2 include n1 first detectors 21 (schematically shown by solid lines in Figure 4) and n2 second detectors 22 (schematically shown by dashed lines in Figure 4), where, for example, n1 is a positive integer of 2 or more, and n2 is a positive integer of 1 or more. The n1 first detectors 21 detect first projection data formed after the radiation beam has passed through the scanning target 30 as the scanning target 30 passes through the scanning area. The n2 second detectors 22 detect second projection data formed after the radiation beam has passed through the scanning target 30 as the scanning target 30 passes through the scanning area.

[0076] As shown in Figure 4, each of the n1 first detectors 21 is a linear detector array, and / or at least one second detector 22 includes a vertical arm detector 221 positioned along a first direction D1 and a horizontal arm detector 222 positioned along a second direction D2, the second direction D2 intersects both the transport direction D3 and the first direction D1.

[0077] By adding a lateral arm detector, the second detector can scan the target at a larger scanning angle and perform imaging, which is advantageous in improving the quality of DR images.

[0078] Continuing to refer to Figure 4, the added horizontal arm detector mainly corresponds to the lowest radiation source 1, that is, during the scanning process, the horizontal arm detector 222 can receive signals that have been attenuated after the radiation beam emitted from the lowest radiation source 1 has passed through the scanning target.

[0079] Figures 5A and 5B are side views of a linear scanning CT imaging system, respectively, viewed along the transport direction. Referring to Figures 5A and 5B, the taper angle φ1 of the lowest radiation source 1 is larger than the taper angle φ2 of the other radiation sources 1. Thus, during the scanning process, the taper angle of the radiation beam emitted from the lowest radiation source 1 is large, allowing the vertical arm detector 221 and the horizontal arm detector 222 to detect the signal that has been attenuated by the radiation beam emitted from the lowest radiation source 1 passing through the scanning target. The taper angles of the radiation beams emitted from the other radiation sources 1 are small, so the radiation beams emitted from the other radiation sources 1 do not adversely affect DR imaging due to scattering or other reasons.

[0080] Figures 6 and 7 are schematic diagrams of the linear scanning CT imaging system according to an embodiment of the present disclosure, respectively, and schematically show that the second detector includes a plurality of sub-detectors.

[0081] As shown in Figures 6 and 7, at least one second detector 22 includes k sub-detectors, where k is a positive integer of 2 or more, and the k sub-detectors are arranged sequentially at intervals along the transport direction.

[0082] The spacing between any two adjacent sub-detectors in the transport direction of the k sub-detectors is smaller than the spacing between any two adjacent first detectors 21 in the transport direction of the n1 first detectors 21.

[0083] As shown in Figure 6, each sub-detector is a linear detector array. As shown in Figure 7, each sub-detector is an L-type detector, meaning that each sub-detector can include a vertical arm detector and a horizontal arm detector.

[0084] In this embodiment, the imaging device generates a digitized radiation image of the target being scanned by combining the second projection data of k sub-detectors. By configuring the second detector with multiple sub-detectors arranged in a close proximity, the DR imaging quality of the target being scanned can be further improved.

[0085] Note that "combination" here includes multiple 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 1000 data points in one scan, then by alternating the 1000 rows of data collected by the two sub-detectors, an image of 2000 rows can be obtained, which corresponds to doubling the spatial sampling rate in the direction of motion.

[0086] In the embodiments shown in Figures 6 and 7, a schematic representation is given of a second detector with two rows (i.e., k=2) and a small spacing between rows. However, the embodiments of this disclosure are not limited to this, and in other embodiments, the second detector may employ an array with more rows and a smaller spacing between rows.

[0087] Figure 8 is a schematic side view of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows that the second detector includes a U-shaped detector.

[0088] As shown in Figure 8, each of the n1 first detectors 21 is a linear detector array. At least one second detector 22 includes a vertical arm detector 221 positioned along a first direction D1, a first horizontal arm detector 222 positioned along a second direction D2, and a second horizontal arm detector 223 positioned along the second direction D2, with the first horizontal arm detector 222 and the second horizontal arm detector 223 positioned above and below the vertical arm detector 221 in the first direction D1, respectively.

[0089] Continuing to refer to Figure 8, the two additional lateral arm detectors correspond to all radiation sources 1. That is, during the scanning process, the first lateral arm detector 222 and the second lateral arm detector 223 can receive signals from all radiation sources 1 that have been attenuated after passing through the scanning target. Accordingly, in the embodiment shown in Figure 8, the taper angles φ of the radiation beams emitted from the three radiation sources 1 are all large.

[0090] By adding two lateral arm detectors, the second detector can scan the target at a larger scanning angle for imaging, which is advantageous in improving the quality of DR images.

[0091] Figure 9 is a schematic top view of a linear scanning CT imaging system according to an embodiment of the present disclosure, illustrating the relative positional relationship between the second detector and the transport device.

[0092] Referring to Figure 9, the conveying device 3 may include a plurality of conveying rollers 31, and in the conveying direction D3, the second lateral arm detector 223 is located in the gap between two adjacent conveying rollers 31.

[0093] Referring to Figures 8 and 9 together, when linear track transport employs a roller track system, there are trolleys and turntables at both ends of the linear motion to enable operations such as loading and unloading of cargo and rotation. Another lateral arm detector 223 can be installed in the gap between the two roller tracks. In this case, all radiation beams emitted from the radiation source 1 can be used for DR imaging, that is, DR imaging can be performed at multiple viewing angles. Furthermore, the transport rollers 31 do not shield the signals received by the lateral arm detector 223, which is advantageous in further improving the quality of DR imaging.

[0094] Figure 10 is a schematic side view of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows the arrangement of the lateral arm detector of the second detector. Referring together to Figure 3B and Figure 10, the lateral 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.

[0095] In this embodiment, the horizontal arm detector corresponds to all radiation sources 1, meaning that during the scanning process, the horizontal arm detector 222 can receive signals that have been attenuated after the radiation beams emitted from all radiation sources 1 have passed through the scanning target. Accordingly, in the embodiment shown in Figure 10, the taper angles φ of the radiation beams emitted from the three radiation sources 1 are all large. In this way, the DR images produced by the radiation beams emitted from all radiation sources 1 are all continuous and uninterrupted images.

[0096] Figure 11 is a schematic side view of a linear scanning CT imaging system according to an embodiment of the present disclosure, illustrating other arrangements of the lateral arm detector of the second detector. Referring together to Figure 3B and Figure 11, the lateral arm detector 222 may include a plurality of detector modules 22M arranged at intervals in the second direction D2.

[0097] In this embodiment, the light-receiving surface 22MS of each detector module 22M is perpendicular to the second straight line L2, and the second straight line L2 is a straight line connecting the i-th radiation source 1 and a predetermined point P on the light-receiving surface 22MS, where i is a positive integer between 1 and m.

[0098] The "predetermined point P on the light-receiving surface 22MS" may be one endpoint, 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 at the boundary of the light-receiving surface 22MS or within the light-receiving surface 22MS, and the embodiments of this disclosure are not particularly limited thereto.

[0099] With this installation method, each detector module of the horizontal arm detector can be directed towards a radiation source 1. For example, in the embodiment shown in Figure 11, each detector module of the horizontal arm detector can be directed towards the lowest radiation source 1, and based on this, a clearer DR image can be obtained by the second detector.

[0100] In this embodiment, the radiation beam emitted from the radiation source 1 is incident perpendicularly to the crystal of the lateral arm detector. When the radiation beam is incident perpendicularly to the crystal, the thickness through which it passes is equal to the thickness of the crystal, 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 this disclosure, the method of incident perpendicularly to the crystal increases the thickness through which the radiation beam effectively passes, improving the penetrating power of the radiation beam and allowing for a more comprehensive representation of the projection data included in the detected projection image. At the same time, by making the equivalent crystal area equal to the actual area of ​​the light-receiving surface, the spatial resolution of the radiation beam is improved, and the resolution of the projection data included in the detected projection image can be increased.

[0101] In some exemplary embodiments of this disclosure, the n detectors may include only one second detector 22, and at least one first detector 21 is positioned on each side along the transport direction D3 of the second detector 22. In this embodiment, replacing only one row of detectors ensures low cost, allows for clearer and more complete DR images, and does not degrade the CT image.

[0102] For example, referring to Figure 1, the plane P1 on which both the second detector 22 and the first straight line L1 are located is perpendicular to the transport direction D3. If the radiation beam emitted from the radiation source 1 is a cone beam, this setup allows the central beam plane of the cone beam to be directly aligned with the second detector 22, which is advantageous for obtaining a clearer and more complete DR image.

[0103] In some other exemplary embodiments of the present disclosure, the n detectors may include a plurality of second detectors, i.e., the number n2 of the second detectors 22 is 2 or more.

[0104] In some exemplary embodiments of this disclosure, the sum of the number of first detectors 21 and second detectors 22 is odd, the odd number of detectors are spaced apart along the transport direction, and the intermediate detector is the second detector 22. For example, the plane P1 on which both the intermediate second detector 22 and the first line L1 are located is perpendicular to the transport direction D3. Alternatively, for example, the other even number of detectors are arranged symmetrically with respect to the intermediate second detector 22. This installation method allows the central beam plane of the cone beam to be directly aligned with the second detector 22, which is advantageous for obtaining a clearer and more complete DR image.

[0105] In some other exemplary embodiments of this disclosure, the sum of the number of first detectors 21 and second detectors 22 is even, the even number of detectors are spaced apart along the transport direction, and at least one of the two intermediate detectors is a second detector 22, for example, the plane P1 on which both the intermediate second detector 22 and the first line L1 are located is not perpendicular to the transport direction D3.

[0106] Figure 12 is a schematic diagram of the structure of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows a plurality of second detectors.

[0107] Referring to Figure 12, the number n2 of the second detectors 22 is 2 or more, and the n2 second detectors 22 and the n1 first detectors 21 are arranged alternately along the transport direction D3.

[0108] Here, "arranged alternately" may mean that, along the transport direction D3, at least one first detector 21 is arranged on both sides of at least one second detector 22, and / or at least one first detector 21 is arranged on both sides of at least two second detectors 22. As shown in Figure 12, along the transport direction D3, for some of the second detectors 22, one first detector 21 is arranged on both sides of each second detector 22, and for other parts of the second detectors 22, one first detector 21 is arranged on both sides of two second detectors 22.

[0109] In this embodiment, increasing the number of second detectors 22 makes it possible to acquire DR images from multiple viewing angles, which is advantageous in improving the quality of DR imaging.

[0110] Continuing to refer to Figure 12, in the n2 second detectors 22, the plane on which both one second detector 22 and the first line L1 are located is perpendicular to the transport direction D3, and the angle between the plane on which both the other second detector 22 and the first line L1 are located and the transport direction D3 is greater than or less than 90°.

[0111] For example, as shown in Figure 12, the angle α0 between the plane where both the second second detector 22 and the first straight line L1 are located and the transport direction D3 is approximately 90°, the angle α1 between the plane where both the second second detector 22 and the first straight line L1 are located and the transport direction D3 is greater than 90°, and the angles α2 and α3 between the plane where both the third and fourth second detectors 22 and the first straight line L1 are located and the transport direction D3 are both less than 90°. Exemplarily, α1 > α0 > α2 > α3, that is, the angle between the plane where each second detector and the first straight line L1 arranged along the transport direction are located and the transport direction D3 decreases in order.

[0112] By rationally arranging the angle between each second detector and the central beam plane of the radiation source, it is possible to rationally design each viewing angle for acquiring DR images, which is advantageous in further improving the quality of DR imaging.

[0113] Figure 13 is a schematic diagram of the structure of a linear scanning CT imaging system according to an embodiment of the present disclosure, and schematically shows a plurality of L-type second detectors.

[0114] Referring to Figure 13, the number n2 of the second detectors 22 is 2 or more, and the n2 second detectors 22 and the n1 first detector 21 are arranged alternately along the transport direction D3. Each of the n2 second detectors includes a vertical arm detector 221 arranged along the first direction D1 and a horizontal arm detector 222 arranged along the second direction D2.

[0115] Continuing to refer to Figure 13, the planes formed by the intersection of the vertical arm detector 221 and the horizontal arm detector 222 of each second detector all extend through the first straight line L1.

[0116] This installation method allows for the generation of distortion-free DR image data by aligning the installation angle of the horizontal arm detector with the optical path of the radiation beam emitted from the radiation source.

[0117] In some exemplary embodiments of the present disclosure, referring to Figure 14, the linear scanning CT imaging system may further include a rotating device 6 located at one or both ends of the transport device 3, which rotates the object being scanned by a predetermined angle when the object has passed through the scanning area and moved to the end of the transport device 3.

[0118] For example, the transport device 3 may be configured to pass the rotated object through the scanning area again, the detector 2 may be configured to detect first and second projection data formed after the radiation beams emitted from the multiple radiation sources 1 have passed through the rotated object as the object passes through the scanning area again, and the imaging device 5 may be configured to generate a digitized radiation image of the object based on the second projection data and to obtain a three-dimensional reconstructed image of the object based on the first and second projection data.

[0119] Furthermore, the step of the object being scanned rotating by a predetermined angle and passing through the scanning area may be performed multiple times. Those skilled in the art should understand that the more times the object being scanned passes through the scanning area in a single inspection, the more comprehensive the angle at which the object is illuminated becomes, and the higher the quality of the resulting reconstructed image.

[0120] The operation process of the linear scanning CT imaging system of the embodiments of this disclosure will be described in detail below, and exemplary the operation process of the linear scanning CT imaging system may include the following steps.

[0121] First, the object to be scanned 30 is fixed to the transport device 3, and the object to be scanned 30 is moved in the transport direction D3 of the transport device 3 along the scanning passage 4. Next, beams are alternately emitted from multiple radiation sources 1 distributed vertically to form a scanning area.

[0122] The first detector 21 and the second detector 22 then detect the first projection data and the second projection data, respectively, that are formed after the radiation beams emitted from the multiple radiation sources 1 have passed through the scanning target as the scanning target passes through the scanning area.

[0123] The imaging device 4 then generates a digitized radiographic image of the object to be scanned based on the second projection data, and obtains a computed tomographic scan image of the object to be scanned based on the first and second projection data.

[0124] According to embodiments of the present disclosure, with reference to Figure 15, the linear scanning CT imaging system may further include a pulse generator 7 for generating a trigger pulse sequence that controls a plurality of radiation sources 1 to alternately emit radiation beams. Here, the trigger pulse sequence may specifically include several of the following situations:

[0125] In Situation 1, within one cycle of the trigger pulse sequence, there are trigger pulse signals that correspond one-to-one with multiple radiation sources 1, and the trigger pulse signals control the corresponding radiation sources 1 to emit radiation beams having the same energy.

[0126] As an example, Figure 16 shows trigger pulse signals corresponding one-to-one with three radiation sources 1. Here, the horizontal axis represents time, and the trigger pulse signals corresponding one-to-one with the three radiation sources 1 are arranged alternately along the time axis. The vertical axis represents energy, and the energy indicated by all trigger pulse signals is E1. The projection image data obtained using this method is complete data used for single-energy CT reconstruction.

[0127] In Situation 2, within one period of the trigger pulse sequence, there is a group of trigger pulse signals that correspond one-to-one with multiple radiation sources 1, the group of trigger pulse signals includes a first trigger pulse signal and a second trigger pulse signal, the first and second trigger pulse signals controlling the corresponding radiation source 1 to sequentially emit a first sub-radiation beam having a first energy and a second sub-radiation beam having a second energy. Here, the radiation source 1 may be an energy-adjustable dual-energy accelerator.

[0128] Illustratively, Figure 17 shows a set of trigger pulse signals corresponding one-to-one to three radiation sources 1, i.e., each radiation source 1 emits a beam twice. Here, the horizontal axis represents time, and the trigger pulse signal sets corresponding one-to-one to the three radiation sources 1 are arranged alternately along the time axis. The vertical axis represents energy, with the energy of the first trigger pulse signal in each trigger pulse signal set being E2, and the energy of the second trigger pulse signal in each trigger pulse signal set being E3. The projection image data obtained using this method is complete data used for dual-energy CT reconstruction.

[0129] The principle of dual-energy CT reconstruction images will be explained in detail below.

[0130] First, the target is scanned using dual-energy radiation, and dual-energy projection data is acquired.

[0131] Then, the projection values ​​of the basic material coefficients corresponding to the dual-energy projection data are calculated using a pre-created lookup table or by solving a system of linear equations. The method of creating a lookup table involves selecting two types of basic materials, calculating the projection values ​​when dual-energy radiation passes through these two types of materials at different thicknesses, and obtaining a lookup table according to the relationship between the high and low energy projection values ​​and the combinations of different thicknesses. The method of solving the system of linear equations involves solving the system of linear equations for high and low energy projection under basic material decomposition using the actually obtained high and low energy projection values ​​to obtain the corresponding thickness combinations.

[0132] Furthermore, a distribution image of the basic material coefficients can be obtained from the projection values ​​of the basic material. From the distribution of the basic material coefficients, the atomic number of the scanned object, a feature density image, and an attenuation coefficient image of the scanned object at any energy can be obtained, enabling material classification and automatic recognition of the scanned object.

[0133] Furthermore, in order to perform dual-energy CT reconstruction on the projection image data obtained in Situation 2, the linear scanning CT imaging system further includes a decomposition unit that decomposes the first sub-projection data and the second sub-projection data corresponding to the first sub-radiation beam and the second sub-radiation beam from the first projection data and the second projection data, respectively. The imaging device obtains a reconstructed image of the scanned object based on the first sub-projection data and the second sub-projection data of the first projection data, and the first sub-projection data and the second sub-projection data of the second projection data.

[0134] In Situation 3, the radiation source 1 may be an energy-adjustable single-energy accelerator. Within one period of the trigger pulse sequence, there are trigger pulse signals corresponding one-to-one with multiple radiation sources 1, and in the first scanning process of the object to be scanned 30, the trigger pulse signals control the corresponding radiation source 1 to emit a first radiation beam of the same energy, and in the second scanning process of the object to be scanned 30, the trigger pulse signals control the corresponding radiation source 1 to emit a second radiation beam of the same energy.

[0135] For example, in the first scanning process, the energy of all trigger pulse signals is E1 (see Figure 16), and in the second scanning process, the energy of all trigger pulse signals is E4 (see Figure 18). The projection image data obtained using this method may be used for dual-energy CT reconstruction, and the obtained image information of the scanned object 30 includes information such as high-energy attenuation coefficient, low-energy attenuation coefficient, atomic number, and electron density, which are used to perform material classification and automatic identification of the scanned object.

[0136] Figure 19 is a flowchart of a linear scanning CT imaging method according to an embodiment of the present disclosure, which is applied to the linear scanning CT imaging system described above. The linear scanning CT imaging method in Figure 19 includes steps S131 to S134.

[0137] In step S131, the transport device 3, which includes a transport surface on which the object to be scanned is placed, moves the object to be scanned along a predetermined transport direction in the scanning passage.

[0138] In step S132, m radiation sources 1 alternately emit radiation beams to form a scanning region, where the m radiation sources 1 are located on one side of the scanning path, and m is a positive integer greater than or equal to 2.

[0139] In step S133, the scanning area is passed over the object to be scanned.

[0140] In step S134, as the object to be scanned passes through the scanning area, n detectors are made to detect projection data formed after the radiation beam has passed through the object to be scanned, where the n detectors are located on the other side of the scanning path, the n detectors are arranged sequentially at intervals along the transport direction, n is a positive integer of 3 or more, and the n detectors include n1 first detectors 21 and n2 second detectors 22, where n1 is a positive integer of 2 or more and n2 is a positive integer of 1 or more.

[0141] Figure 20 is a schematic flowchart of a projection data processing method according to an embodiment of the present disclosure, and step S134 may further include steps S1341 to S1343.

[0142] In step S1341, the n1 first detectors 21 are made to detect the first projection data formed after the radiation beam has passed through the scanning target.

[0143] In step S1342, the n2 second detectors 22 are made to detect the second projection data formed after the radiation beam has passed through the scanning target.

[0144] In step S1343, a digitized radiographic image of the target to be scanned is generated based on the second projection data, and a computed tomographic scan image of the target to be scanned is generated based on the first projection data and the second projection data.

[0145] As an example, data obtained from both the second detector 22 and the first detector 21 are used for CT reconstruction to obtain and display a three-dimensional reconstructed image of the subject.

[0146] For example, the reconstruction may be performed using the data from the second detector 22 directly, or the data from the second detector 22 may be equivalent to the data from the first detector 21 at the same location, and then a normal linear CT reconstruction may be performed.

[0147] In some exemplary embodiments, at least one second detector 22 includes a longitudinal arm detector positioned along a first direction and a transverse arm detector positioned along a second direction, the second direction intersecting both the transport direction and the first direction.

[0148] Figures 21A and 21B are schematic diagrams of a second projection data proportional processing method according to an embodiment of the present disclosure.

[0149] In some exemplary embodiments, generating a digitized radiation image of the scanned object based on second projection data includes resolving visual inconsistencies in the images at intersections by 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 radiation image of the scanned object.

[0150] For example, referring to Figure 7, at least one second detector 22 includes k sub-detectors, where k is a positive integer greater than or equal to 2, the k sub-detectors are arranged sequentially at intervals along the transport direction, the spacing along the transport direction between any two adjacent sub-detectors among the k sub-detectors is smaller than the spacing along the transport direction between any two adjacent first detectors 21 among the n1 first detectors 21, and generating a digitized radiation image of the scanned object based on the second projection data includes combining the second projection data of the k sub-detectors to generate a digitized radiation image of the scanned object.

[0151] When the second detector 22 employs an array configuration with two or more columns and small spacing between columns, the data from multiple columns can be combined and displayed as a single-column DR image during data processing.

[0152] In some exemplary embodiments, the linear scanning CT imaging system further includes a pulse trigger, and prior to the step of multiple radiation sources 1 alternately emitting radiation beams to form a scanning region, the linear scanning CT imaging method further includes the step of generating a trigger pulse sequence to control the multiple radiation sources 1 to alternately emitting radiation beams by the pulse trigger.

[0153] Here, within one period of the trigger pulse sequence, there may be multiple trigger pulse signals corresponding one-to-one with multiple radiation sources 1, and the trigger pulse signals are used to control the corresponding radiation sources 1 to emit radiation beams having the same energy.

[0154] Within one period of the trigger pulse sequence, there may be a group of trigger pulse signals that correspond one-to-one with multiple radiation sources 1, the group of trigger pulse signals including a first trigger pulse signal and a second trigger pulse signal, the first trigger pulse signal and the second trigger pulse signal controlling the corresponding radiation source 1 to sequentially emit a first sub-radiation beam having a first energy and a second sub-radiation beam having a second energy.

[0155] The imaging device decomposes the first and second projection data into the first and second projection data, respectively, to separate the first and second subprojection data corresponding to the first and second sub-radiation beams. Based on the first and second subprojection data of the first projection data, and the first and second subprojection data of the second projection data, the imaging device obtains a reconstructed image of the scanned object.

[0156] In some exemplary embodiments, if the radiation source 1 employs a dual-energy beam emission mode and the second detector 22 employs a detector with energy resolution, more energy spectral DR can be achieved for energy spectral measurements, resulting in more accurate image color and enabling classification of more materials.

[0157] Figure 22 schematically shows a block diagram of the imaging apparatus of a linear scanning CT imaging system according to an embodiment of the present disclosure.

[0158] As shown in Figure 22, the imaging apparatus 4 of the linear scanning CT imaging system according to an embodiment of the present disclosure may include a processor 401 capable of performing various appropriate operations and processes based on a program stored in a read-only memory (ROM) 402 or a program loaded from a storage unit 408 into a random access memory (RAM) 403. The processor 401 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor, and / or an associated chipset, and / or a dedicated microprocessor (e.g., an application-specific integrated circuit (ASIC)). The processor 401 may further include onboard memory used for caching purposes. The processor 401 may include a single processing unit or a plurality of processing units for performing different operations of the method flow according to an embodiment of the present disclosure.

[0159] RAM 403 stores various programs and data necessary for operating the electronic device 400. The processor 401, ROM 402, and RAM 403 are connected to each other via bus 404. The processor 401 executes various operations of the method flow according to the embodiment of this disclosure by executing the programs in ROM 402 and / or RAM 403. The programs may also be stored in one or more memories other than ROM 402 and RAM 403. The processor 401 may also execute various operations of the method flow according to the embodiment of this disclosure by executing the programs stored in the one or more memories.

[0160] According to embodiments of this disclosure, 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: an input unit 406 including a keyboard, mouse, etc., connected to the I / O interface 405; an output unit 407 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and a speaker, etc.; a storage unit 408 including a hard disk, etc.; and a communication unit 409 including a network interface card such as a LAN card or modem. The communication unit 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. Removable media 411 such as a magnetic disk, optical disk, magneto-optical disk, or semiconductor memory is installed in the drive 410 as needed, and a computer program read from there is installed in the storage unit 408 as needed.

[0161] The flowcharts and block diagrams in the drawings illustrate the implementable architectures, functions, and operations of systems, methods, and computer program products relating to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, program segment, or part of code, which includes one or more executable instructions for implementing a predetermined logical function. In some alternative implementations, the functions attached to a block may occur in a different order than those attached to the drawings. For example, two consecutively represented blocks may be executed substantially in parallel, or in some cases in reverse order, depending on their function. Furthermore, each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented in a system based on dedicated hardware for performing a predetermined function or operation, or in a combination of dedicated hardware and computer instructions.

[0162] Embodiments of this disclosure provide a linear scanning CT imaging system and a corresponding linear scanning CT imaging method. In this linear scanning CT imaging system, a system design of DR based on linear CT is realized, without any impact on the original scanning method of linear CT, without increasing the linear CT scanning steps, and by simply replacing one or more rows of detectors, a clearer and more complete DR image can be obtained without degrading the 3D reconstructed image. When the radiation source employs a dual-energy beam emission mode, the color of the DR image becomes more accurate, and when the radiation source employs a dual-energy beam emission mode, if the second detector is a detector with energy resolution, energy spectral DR of more energy spectral measurements can be achieved, the color of the image becomes more accurate, and classification of more materials can be realized.

[0163] In the linear scanning CT imaging system according to the embodiment of this disclosure, DR imaging and CT imaging can be performed simultaneously in a single scan. CT imaging can avoid problems such as overlap or occlusion, while DR imaging can improve image quality, observe the fine structure of the scanned object, and avoid problems such as resolution degradation and artifacts.

[0164] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and do not limit the scope of the present invention. Although each embodiment has been described individually above, this does not mean that the measures in each embodiment cannot be suitably combined and used. The scope of this disclosure is limited by the claims and their equivalents. A person skilled in the art can make various substitutions and modifications without departing from the scope of this disclosure, and such substitutions and modifications should remain within the scope of this disclosure.

Claims

1. A linear scanning CT imaging system, A conveying device that moves the object to be scanned in a predetermined conveying direction along a scanning path, and includes a conveying surface on which the object to be scanned is placed. A scanning area is formed by alternately emitting radiation beams, and m radiation sources (where m is a positive integer of 2 or more) are located on one side of the scanning path. The system includes n detectors (where n is a positive integer of 3 or more) located on the other side of the scanning path and arranged sequentially at intervals along the transport direction, which detect projection data formed after the radiation beam has passed through the scanning object as the scanning object passes through the scanning region. The n detectors include n1 first detectors and n2 second detectors, where n1 is a positive integer of 2 or more and n2 is a positive integer of 1 or more. The n1 first detectors detect first projection data formed after the radiation beam has passed through the scanning target as the scanning target passes through the scanning area, and the n2 second detectors detect second projection data formed after the radiation beam has passed through the scanning target as the scanning target passes through the scanning area. The system further includes an imaging device that generates a digitized radiographic image of the target to be scanned based on the second projection data, and generates a computed tomography scan image of the target to be scanned based on the first projection data and the second projection data. A linear scanning CT imaging system characterized by the following features.

2. At least one of the second detectors is different from each of the first detectors. The system according to feature 1.

3. The resolution of at least one of the second detectors is higher than the resolution of each of the first detectors. The system according to feature 2.

4. 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 The pixel size of at least one of the second detectors is smaller than the pixel size of each of the first detectors. The system according to claim 3.

5. At least one of the second detectors and each of the first detectors are made of different crystalline materials, and / or at least one of the second detectors and each of the first detectors have different thicknesses along the direction of radiation incidence. The system according to any one of claims 2 to 4.

6. 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. The system according to claim 5, characterized in that it is the same as described in claim 5.

7. The first detector includes a plurality of first detector modules, the second detector includes a plurality of second detector modules, and the arrangement of the plurality of first detector modules is different from the arrangement of the plurality of second detector modules. The system according to any one of claims 2 to 6, characterized by the features described herein.

8. Each of the n1 first detectors is a linear detector array, and / or each of the n2 second detectors is a linear detector array. The system according to any one of claims 1 to 7.

9. Each of the n1 first detectors is a linear detector array and / or At least one of the second detectors includes a longitudinal arm detector positioned along the first direction and a transverse arm detector positioned along the second direction, the second direction intersecting both the transport direction and the first direction. The system according to any one of claims 1 to 7.

10. Each of the n1 first detectors is a linear detector array and / or At least one of the second detectors includes a longitudinal arm detector arranged along the first direction, a first transverse arm detector arranged along the second direction, and a second transverse arm detector arranged along the second direction, wherein the first and second transverse arm detectors are located above and below the longitudinal arm detector in the first direction, and the second direction intersects both the transport direction and the first direction. The system according to any one of claims 1 to 7.

11. The m radiation sources are arranged sequentially at intervals along a first straight line, the first straight line being a virtual straight line extending in a first direction, and the first direction being perpendicular to the transport surface. The system according to any one of claims 1 to 10.

12. The n detectors include only one second detector, and at least one of the first detectors is positioned on each side of the first second detector along the transport direction. The system according to any one of claims 1 to 11.

13. The plane on which both the first second detector and the first straight line are located is perpendicular to the transport direction. The system according to feature 12.

14. At least one of the second detectors includes k sub-detectors, where k is a positive integer of 2 or more, and the k sub-detectors are arranged sequentially at intervals along the transport direction. The spacing between any two adjacent sub-detectors among the k sub-detectors along the transport direction is smaller than the spacing between any two adjacent first detectors among the n1 first detectors along the transport direction. The system according to any one of claims 1 to 11.

15. The imaging device combines the second projection data from the k sub-detectors to generate a digitized radiation image of the scanned object. The system according to feature 14.

16. The horizontal arm detector includes a plurality of detector modules, the plurality of detector modules being connected end to end in sequence. The system according to claim 9 or 10, characterized by the features described herein.

17. The lateral arm detector includes a plurality of detector modules, and the plurality of detector modules are arranged at intervals in the second direction. The system according to claim 9 or 10, characterized by the features described herein.

18. The light-receiving surface of each detector module is perpendicular to a second line, the second line is a line connecting the i-th radiation source and a predetermined point on the light-receiving surface, the predetermined point is located at the boundary of the light-receiving surface or within the light-receiving surface, and i is a positive integer between 1 and m. The system described in claim 16.

19. The transport device includes a plurality of transport rollers, and in the transport direction, the second transverse arm detector is located in the gap between two adjacent transport rollers. The system according to feature 10.

20. The number n2 of the second detectors is 2 or more, and the n2 second detectors and n1 first detectors are arranged alternately along the transport direction. The system according to any one of claims 1 to 10 or 14 to 19.

21. In the n2 second detectors, the plane on which both one second detector and the first straight line are located is perpendicular to the transport direction, and the angle between the plane on which both the other second detector and the first straight line are located and the transport direction is greater than 90° or less than 90°. The system according to claim 20, characterized in that it is as described above.

22. In the n2 second detectors, each second detector includes a vertical arm detector positioned along the first direction and a horizontal arm detector positioned along a second direction that intersects both the transport direction and the first direction. The system according to claim 20 or 21, characterized in that it is the same as described above.

23. The 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. The system according to claim 22, characterized in that it is the same as described above.

24. The scanning path is a straight path. The system according to any one of claims 1 to 23, characterized by the features described herein.

25. A linear scanning CT imaging method, A transport device, including a transport surface on which a scanning target is placed, moves the scanning target along a scanning path in a predetermined transport direction. m radiation sources (where m is a positive integer of 2 or more) located on one side of the scanning path alternately emit radiation beams to form a scanning area, To allow the scanning target to pass through the scanning area, The process of the scanning target passing through the scanning region includes causing n detectors (where n is a positive integer of 3 or more) to detect projection data formed after the radiation beam has passed through the scanning target, wherein the n detectors are located on the other side of the scanning path and are arranged sequentially at intervals along the transport direction. The n detectors include n1 first detectors and n2 second detectors, where n1 is a positive integer of 2 or more, and n2 is a positive integer of 1 or more. Having n detectors detect projection data formed after the radiation beam has passed through the scanning target includes having n1 first detectors detect first projection data formed after the radiation beam has passed through the scanning target, and having n2 second detectors detect second projection data formed after the radiation beam has passed through the scanning target. The method further includes generating a digitized radiographic image of the object to be scanned based on the second projection data, and generating a computed tomography scan image of the object to be scanned based on the first projection data and the second projection data. A linear scanning CT imaging method characterized by the following:

26. At least one of the second detectors includes a longitudinal arm detector arranged along a first direction and a transverse arm detector arranged along a second direction, the second direction intersects both the transport direction and the first direction. Generating a digitized radiation image of the scanning target based on the second projection data includes performing proportional adjustments to the second projection data detected by the vertical arm detector and the horizontal arm detector, and then combining them to generate a digitized radiation image of the scanning target. The method according to the present invention of the present invention.

27. At least one of the second detectors includes k sub-detectors, where k is a positive integer of 2 or more, and the k sub-detectors are arranged sequentially at intervals along the transport direction, and the spacing between any two adjacent sub-detectors among the k sub-detectors along the transport direction is smaller than the spacing between any two adjacent first detectors among the n1 first detectors along the transport direction. Generating a digitized radiation image of the scanning target based on the second projection data includes combining the second projection data of the k sub-detectors to generate a digitized radiation image of the scanning target. The method according to 25 or 26, characterized by the features described herein.

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