CT scanning system

Abstract

Provided is a CT scanning system for performing CT scanning on a scanned object in a visual field centered on a predetermined rotation axis, comprising: a light source comprising a target spot for emitting a ray beam to at least a part of the scanned object; the detector is used for receiving at least one part of the ray beam; and the movement device is used for causing relative movement of the light source and the scanning object, so that the light source moves along a preset scanning track relative to the scanning object. The detector comprises a plurality of detector modules, and at least two adjacent detector modules respectively comprise a plurality of detector crystals arranged in a one-dimensional or two-dimensional array form. At least two adjacent detector modules are the same in size in the row direction. At least two adjacent detector modules respectively comprise a first row of detector crystals, and the positions of the first rows of detector crystals respectively included by the at least two adjacent detector modules are different in a first direction parallel to the rotation axis.

Description

Technical Field

[0001] This disclosure relates to the field of radiation scanning detection technology, and more specifically to a CT scanning system. Background Technology

[0002] Computed tomography (CT) utilizes projection data obtained from X-rays penetrating a scanned object at different angles. Algorithms then reconstruct tomographic or 3D images of the object, resolving the aliasing and occlusion problems inherent in X-ray fluoroscopy and enabling precise calculation of spatial values. With evolving imaging needs, CT technology has undergone five generations of development, from the initial "pencil translation-rotation" scanning to current multi-slice spiral cone-beam scanning and electron beam scanning. As CT technology is increasingly applied in 3D imaging, medical navigation, and rapid security checks, new demands such as low-dose imaging, quantitative imaging, and rapid imaging are placing higher requirements on CT scanning technology. However, standard scanning trajectory CT systems, represented by circular and spiral trajectory scanning, have encountered bottlenecks in achieving faster imaging speeds and larger channel sizes.

[0003] The inventors discovered that while circular trajectory cone-beam CT is easy to implement and simple to reconstruct, it cannot meet the data completeness requirements. In helical trajectory cone-beam scanning, there is also relative motion between the light source and the object along the axis, which allows the projection data to meet the requirements for complete reconstruction data, enabling accurate reconstruction and improving scanning efficiency.

[0004] Spiral cone-beam CT is currently one of the most widely used CT technologies. In terms of imaging theory, the necessary conditions for accurate reconstruction using this technology have been extensively studied, namely the Tam window theory. According to the Tam window theory, the minimum amount of projection data required for accurate reconstruction of an object within a spiral is the data within the Tam window. Traditional detectors are mostly rectangular and regularly arranged on the cylindrical mounting surface. However, to completely cover the Tam window with this arrangement, some data will inevitably be wasted; conversely, to avoid data waste, incomplete data will occur. For some cost-sensitive applications, the traditional detector arrangement undoubtedly leads to increased detector costs or decreased image quality.

[0005] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions disclosed herein, and for facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this disclosure. Summary of the Invention

[0006] In view of at least one aspect of the above-mentioned problems, an embodiment of one aspect of this disclosure provides a CT scanning system for performing CT scans on a scanned object in a field of view centered on a predetermined axis of rotation. The CT scanning system includes: a light source including a target point for emitting a beam of radiation to at least a portion of the scanned object; a detector for receiving at least a portion of the beam of radiation; and a motion device for inducing relative motion between the light source and the scanned object, such that the light source moves relative to the scanned object along a predetermined scanning trajectory, the movement of the light source relative to the scanned object along the predetermined scanning trajectory including at least a translational motion of the light source relative to the scanned object; wherein the detector… The device includes multiple detector modules, at least two adjacent detector modules each including multiple detector crystals arranged in a one-dimensional or two-dimensional array, for each of the at least two adjacent detector modules, the multiple detector crystals are arranged at least along a row direction; in the row direction, the at least two adjacent detector modules have the same size; and the at least two adjacent detector modules each include a first row of detector crystals, in the direction of translational movement of the light source relative to the scanning object, the first row of detector crystals is located upstream of the other rows of detector crystals; in a first direction parallel to the rotation axis, the positions of the first rows of detector crystals included in the at least two adjacent detector modules are different.

[0007] In one exemplary embodiment, the ray beam is a cone beam, which includes a light source cone angle direction and a light source fan angle direction; the plurality of detector modules are arranged along the column direction, the light source cone angle direction is parallel to the column direction, and the light source fan angle direction is parallel to the column direction.

[0008] In an exemplary embodiment, the predetermined scanning trajectory is a spiral scanning trajectory. The intersection of the line connecting the target point and the spiral scanning trajectory with the equivalent detection plane forms the first and second boundaries of the window. The closed shape formed by the outer contour of the detector's orthogonal projection on the equivalent detection plane at least partially overlaps with the window. The closed shape formed by the outer contour of the detector's orthogonal projection on the equivalent detection plane has a first projected area. The portion of the closed shape formed by the outer contour of the detector's orthogonal projection on the equivalent detection plane that overlaps with the window has a second projected area. The ratio of the second projected area to the first projected area is greater than 0.7. The light source plane is a plane perpendicular to the rotation axis and passing through the target point. The origin is the intersection of the rotation axis and the light source plane. The equivalent detection plane is a plane passing through the origin and perpendicular to the line connecting the origin and the target point.

[0009] In one exemplary embodiment, the closed shape formed by the outer contour of the detector's orthographic projection on the equivalent detection plane is within the viewing window.

[0010] In an exemplary embodiment, in the direction of translational movement of the light source relative to the scanned object, the first boundary is located upstream of the second boundary; in the equivalent detection plane, the outer contour line of the first row of detector crystals passing through at least one of the detector modules passes through the first boundary.

[0011] In an exemplary embodiment, at least two adjacent detector modules each include an m-th row of detector crystals. In the direction of translational motion of the light source relative to the scanning object, the m-th row of detector crystals is located downstream of the other rows of detector crystals, where m is a positive integer greater than or equal to 2. In the equivalent detection plane, the outer contour line of the m-th row of detector crystals passing through at least one of the detector modules crosses the second boundary.

[0012] In an exemplary embodiment, at least two adjacent detector modules each include a middle row of detector crystals located in the middle of the detector module in the direction of translational motion of the light source relative to the scanned object; the window includes a window centerline located in the middle between the first boundary and the second boundary in the first direction; in the equivalent detection plane, the outer contour line of the middle row of detector crystals of at least one detector module passes through the window centerline.

[0013] In one exemplary embodiment, at least two adjacent detector modules are staggered in the row direction, and the staggered spacing is an integer multiple of the row spacing of the detector crystals in the row direction.

[0014] In an exemplary embodiment, the detector includes a first detector module, a second detector module, a third detector module, a fourth detector module, and a fifth detector module arranged along the column direction; and in the row direction, the first detector module and the second detector module are staggered with a first staggered spacing, the second detector module and the third detector module are staggered with a second staggered spacing, the third detector module and the fourth detector module are staggered with a third staggered spacing, and the fourth detector module and the fifth detector module are staggered with a fourth staggered spacing.

[0015] In one exemplary embodiment, at least two of the first misalignment spacing, the second misalignment spacing, the third misalignment spacing, and the fourth misalignment spacing are equal to each other.

[0016] In one exemplary embodiment, the row direction is parallel to the rotation axis, and the multiple rows of detector crystals of at least one of the detector modules are respectively located on multiple parallel planes perpendicular to the rotation axis.

[0017] In one exemplary embodiment, the row direction is inclined relative to the rotation axis, and in the row direction, the detector crystals of the same row of the plurality of detector modules are aligned and arranged, and the detector crystals of the same row of the plurality of detector modules are located in the same plane.

[0018] In one exemplary embodiment, at least one of the detector modules has multiple rows of detector crystals located on multiple parallel planes intersecting the rotation axis, wherein the angle between the multiple parallel planes and the rotation axis is less than 90°.

[0019] In one exemplary embodiment, the center points of the plurality of detector modules are on a straight line in the equivalent detection plane.

[0020] In one exemplary embodiment, in the equivalent detection plane, the straight line containing the center points of the plurality of detector modules intersects the window centerline.

[0021] In one exemplary embodiment, the row direction is inclined relative to the rotation axis, and in the row direction, the detector crystals of the same row of the plurality of detector modules are staggered and located on different planes.

[0022] In one exemplary embodiment, at least one of the detector modules has multiple rows of detector crystals located on multiple parallel planes intersecting the rotation axis, wherein the angle between the multiple parallel planes and the rotation axis is less than 90°.

[0023] In one exemplary embodiment, the center point of the plurality of detector modules is located on the center line of the window in the equivalent detection plane.

[0024] In one exemplary embodiment, at least one of the detector modules has multiple rows of detector crystals arranged in a staggered manner in the row direction.

[0025] In one exemplary embodiment, the outer contour of at least one of the detector modules is in the same direction as the extension of the first boundary or the second boundary of the window.

[0026] In one exemplary embodiment, the detector crystals of the plurality of detector modules are arranged on a cylindrical or arc-shaped cylindrical surface.

[0027] In an exemplary embodiment, the detector crystals of the plurality of detector modules are staggered along the extension direction of the X-ray beam, and the line connecting the center line of the plurality of detector modules to the target point is perpendicular to the plane in which their respective detector crystals are located. In the equivalent detection plane, the coverage areas of at least two of the detector modules are continuous.

[0028] In one exemplary embodiment, the planes on which the detector crystals of the plurality of detector modules are located are parallel to the axis of rotation; or, the vertical lines passing through the center point of the plurality of detector modules and perpendicular to the planes on which their respective detector crystals are located do not intersect at a point.

[0029] In one exemplary embodiment, the plane containing the detector crystal of at least one of the detector modules is inclined relative to the axis of rotation; and vertical lines passing through the center point of the plurality of detector modules and perpendicular to the plane containing their respective detector crystals intersect at a single point.

[0030] In one exemplary embodiment, the target point is located at the intersection.

[0031] In an exemplary embodiment, in the equivalent detection plane, the first and second boundaries of the viewport are represented by the following formula: ,in, , These respectively represent the distances along the equivalent detection plane DP. Axis and The coordinate values ​​of the axis, the The axis is perpendicular to the first direction, the The axis is parallel to the first direction. This indicates the distance of relative translation between the light source and the scanned object for each revolution of the light source. Let be the radius of rotation of the target point. It is the rotation angle of the target point, and the first boundary corresponds to the interval. The second boundary corresponds to the interval , , These are the rotation angles of the target points corresponding to the endpoint positions of the first boundary and the second boundary, which can be expressed by the following formulas; ,in, The radius of the imaging region.

[0032] In an exemplary embodiment, the window centerline of the viewport in the equivalent detection plane is represented by the following formula: ,in, This indicates the distance of relative translational movement between the light source and the scanned object for each rotation of the light source.

[0033] In an exemplary embodiment, the straight line containing the center points of the plurality of detector modules in the equivalent detection plane is represented by the following formula: ,in, For parameters, parameters The optimal solution for the following optimization function is: .

[0034] In one exemplary embodiment, at least one of the detector modules includes dual-layer detector crystals arranged along the extension direction of the ray beam, wherein the spacing between the dual-layer detector crystals in the arrangement direction is the same or different.

[0035] In one exemplary embodiment, the CT scanning system further includes a slip ring on which the light source and the detector are located.

[0036] Another embodiment of this disclosure provides a CT scanning system for performing CT scans on a scanned object within a field of view centered on a predetermined axis of rotation. The CT scanning system includes: a light source including a target point for emitting a beam of radiation to at least a portion of the scanned object; a detector for receiving at least a portion of the beam of radiation; and a motion device for inducing relative motion between the light source and the scanned object, such that the light source moves relative to the scanned object along a predetermined scanning trajectory. The predetermined scanning trajectory is a helical scanning trajectory, and the intersection of the line connecting the target point and the helical scanning trajectory with an equivalent detection plane forms a first boundary and a second boundary of a viewing window. The closed shape formed by the outer contour of the detector's orthographic projection on the equivalent detection plane at least partially overlaps with the viewing window. The closed shape formed by the outer contour of the detector's orthographic projection on the equivalent detection plane has a first projected area, and the portion of the closed shape formed by the outer contour of the detector's orthographic projection on the equivalent detection plane that overlaps with the viewing window has a second projected area. The ratio of the second projected area to the first projected area is greater than 0.7. The light source plane is a plane perpendicular to the rotation axis and passing through the target point. The origin is the intersection of the rotation axis and the light source plane. The equivalent detection plane is a plane passing through the origin and perpendicular to the line connecting the origin and the target point.

[0037] In one exemplary embodiment, the closed shape formed by the outer contour of the detector's orthographic projection on the equivalent detection plane is within the viewing window. Attached Figure Description

[0038] The foregoing contents, as well as other objects, features, and advantages of this disclosure, will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0039] Figure 1 This is a schematic diagram of the structure of a CT scanning system according to some exemplary embodiments of the present disclosure;

[0040] Figure 2A This is a schematic diagram illustrating a spiral scanning configuration of a CT scanning system according to some exemplary embodiments of the present disclosure;

[0041] Figure 2B This is a schematic diagram illustrating the correspondence between cone-beam spiral scanning and Tam window in a CT scanning system according to some exemplary embodiments of the present disclosure;

[0042] Figure 2C This is a schematic diagram illustrating the equivalent detection plane;

[0043] Figure 2D This is a schematic diagram illustrating the Tam window;

[0044] Figure 3 This is a schematic diagram illustrating the correspondence between the detector and the viewing window Tam in a CT scanning system according to related technologies;

[0045] Figure 4 Schematic illustration Figure 3 The projection relationship between the detector and the viewing window Tam in the equivalent detection plane is shown in the figure.

[0046] Figure 5 This is a schematic diagram illustrating the correspondence between the detector and the view window Tam of a CT scanning system according to some exemplary embodiments of the present disclosure;

[0047] Figure 6 Schematic illustration Figure 5 The projection relationship between the detector and the viewing window Tam in the equivalent detection plane is shown in the figure.

[0048] Figure 7 This is a schematic diagram illustrating the correspondence between the detector and the view window Tam of a CT scanning system according to some other exemplary embodiments of the present disclosure;

[0049] Figure 8 Schematic illustration Figure 7 The projection relationship between the detector and the viewing window Tam in the equivalent detection plane is shown in the figure.

[0050] Figure 9 The diagram illustrates the projection relationship of the detector and the viewing window Tam of a CT scanning system according to further embodiments of the present disclosure in the equivalent detection plane;

[0051] Figure 10The schematic diagram illustrates the orthographic projection on the equivalent detection plane of the connection line between the middle row of detector crystals of multiple detector modules or the connection line between the center points of multiple detector modules;

[0052] Figure 11 The diagram illustrates the arrangement of detectors in a CT scanning system according to some further exemplary embodiments of the present disclosure;

[0053] Figure 12 This is a plan view schematically illustrating the relative positional relationship between the target and the detector in the xy plane of a CT scanning system according to some exemplary embodiments of the present disclosure;

[0054] Figure 13 This is a plan view schematically illustrating the relative positional relationship between the target and the detector in the xy plane of a CT scanning system according to some other exemplary embodiments of the present disclosure;

[0055] Figure 14 This is a schematic diagram illustrating the relative positional relationship between the target and the detector in xyz space of a CT scanning system according to some exemplary embodiments of the present disclosure;

[0056] Figure 15A This is a schematic diagram illustrating the relative positional relationship between the target and the detector in xyz space of a CT scanning system according to some other exemplary embodiments of the present disclosure;

[0057] Figure 15B This is a schematic diagram illustrating the relative positional relationship between the target and detector in xyz space of a CT scanning system according to some further exemplary embodiments of the present disclosure; and

[0058] Figure 16A and Figure 16B This is a schematic diagram illustrating the double-layer structure of the detector of a CT scanning system according to some exemplary embodiments of the present disclosure. Detailed Implementation

[0059] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0060] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0061] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0062] When using expressions such as "at least one of A, B, and C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C. Similarly, when using expressions such as "at least one of A, B, or C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C.

[0063] Figure 1 This is a schematic diagram of the structure of a CT scanning system according to some exemplary embodiments of the present disclosure. Figure 2A This is a schematic diagram illustrating a spiral scanning configuration of a CT scanning system according to some exemplary embodiments of the present disclosure. Figure 2B This is a schematic diagram illustrating the correspondence between cone-beam spiral scanning and the Tam window in a CT scanning system according to some exemplary embodiments of the present disclosure. Figure 2C This is a schematic diagram illustrating the equivalent detection plane. Figure 2D This is a schematic diagram illustrating the Tam window.

[0064] like Figure 1 As shown, a CT scanning system according to some exemplary embodiments of the present disclosure includes: a light source 10, a slip ring 20, a detector 30, a motion device 40, a controller 50, and a data processor 60, etc.

[0065] For example, the slip ring 20 may include a rotating end and a fixed end. The rotating end of the slip ring 20 may include a conductive brush and a conductive ring, with a cantilever spring maintaining contact pressure to ensure reliable electrical contact during rotation. The fixed end of the slip ring 20 may include a data receiving electrode plate, forming capacitive coupling with the rotating end for non-contact transmission, avoiding signal attenuation caused by mechanical wear. The light source 10 and the detector 30 may be mounted on the slip ring 20. Specifically, the light source 10 and the detector 30 may be located at the rotating end of the slip ring 20, for example, the light source 10 and the detector 30 may be symmetrically fixed to the rotating end of the slip ring 20. Driven by the slip ring 20, the light source 10 and the detector 30 may rotate around a predetermined rotation axis AX1. In the embodiments of this disclosure, the CT scanning system can perform CT scans on the scanning object 70 in the field of view centered on the predetermined rotation axis AX1. Exemplarily, the scanning object 70 may include luggage or a package; however, the embodiments of this disclosure do not particularly limit the specific form of the scanning object.

[0066] For example, the light source 10 can be an X-ray machine. (Referring to reference...) Figures 1 to 2B The light source 10 may include a target point S, which is used to emit a beam of light to at least a portion of the scanned object 70.

[0067] For example, detector 30 can be used to receive at least a portion of the X-ray beam emitted from target S. Detector 30 may include multiple detector modules for detecting the X-ray beam of the transmission scan object 70, obtaining analog signals, and converting the analog signals into digital signals to output projection data of the scan object 70 against X-rays. Controller 50 is used to control the synchronous operation of various parts of the entire system. Data processor 60 is used to process the data acquired by the data acquisition unit, process and reconstruct the data, and output the results.

[0068] like Figure 1 As shown, the light source 10 is positioned on one side of the scanned object 70, and the detector 30 is positioned on the other side. During the operation of the CT scanning system, the target point S of the light source 10 emits a beam of radiation, and the detector 30 acquires the transmission data and / or multi-angle projection data of the scanned object 70. For example, the data acquisition unit in the detector 30 may include a data amplification and shaping circuit, which can operate in (current) integration mode or pulse (counting) mode. The data output cable of the detector 30 is connected to the controller 50 and the data processor 60, and the acquired data is stored in the data processor 60 according to the trigger command.

[0069] The motion device 40 carries the scanning object 70 and passes through the scanning area between the light source 10 and the detector 30 via the slip ring 20. Simultaneously, the slip ring 20 rotates around the translational direction of the scanning object 70, allowing the cone-beam rays emitted by the light source 10 to pass through the scanning object 70 and perform a CT scan. In other words, the motion device 40 can cause relative motion between the light source 10 and the scanning object 70, causing the light source 10 to move relative to the scanning object 70 along a predetermined scanning trajectory.

[0070] Reference Figure 2A and Figure 2B For ease of description, an xyz coordinate system is established. The translational motion direction of the scanned object 70 relative to the light source 10 is defined as the first direction z, that is, the first direction z is parallel to the rotation axis AX1. The propagation direction of the ray beam emitted from the target point S to the detector 30 in the plane perpendicular to the first direction z is defined as the second direction x. For example, the extension direction of the line connecting the target point S and the origin O in the plane perpendicular to the first direction z can be defined as the second direction x. The direction perpendicular to the second direction x in the plane perpendicular to the first direction z is defined as the third direction y.

[0071] It should be noted that the definitions and descriptions of various coordinate systems and directions in the embodiments of this disclosure are merely exemplary descriptions for the convenience of describing the embodiments of this disclosure, and are not intended to limit the embodiments of this disclosure.

[0072] For example, the fan-shaped beam emitted from the target point S of the light source 20 is a cone beam. A cone beam can refer to a beam of rays emitted from a single target point of the light source, spreading out at a solid angle, with its cross-section gradually expanding along the propagation direction to form a cone. With the target point S as the vertex, after being constrained by a collimator, a cone-shaped ray beam is formed, covering the two-dimensional detection area of ​​the detector 30. (Refer to...) Figure 2A The spatial range of the cone beam can be defined by the cone angle α and the fan angle β, which correspond to the angles in the vertical and horizontal directions, respectively. For example, the cone angle direction represented by cone angle α (i.e., the cone angle direction of the light source) can describe the diffusion characteristics of the ray beam in the first direction z, affecting the imaging field of view coverage in the first direction z; the fan angle direction represented by fan angle β (i.e., the fan angle direction of the light source) can describe the diffusion characteristics of the ray beam in the xy plane, affecting the horizontal coverage of a single projection.

[0073] In some exemplary embodiments, driven by the slip ring 20, the light source 10 rotates relative to the scanning object 70, that is, the light source 10 rotates relative to the scanning object 70 around a predetermined rotation axis AX1; driven by the motion device 40, the scanning object 70 moves relative to the light source 10, for example, the scanning object 70 moves relative to the light source 10 in the positive direction of the first direction z. Due to the relativity of motion, it can be considered that the light source 10 moves relative to the scanning object 70 in the opposite direction of the first direction z (i.e., translational motion). In other words, relative to the scanning object 70, the light source 10 has the following two motions: rotational motion around the predetermined rotation axis AX1, and translational motion in the opposite direction of the first direction z. Based on this, the target point S of the light source 10 moves relative to the scanning object 70 along a predetermined scanning trajectory. It should be understood that the movement of the light source 10 relative to the scanning object 70 along the predetermined scanning trajectory includes translational motion of the light source 10 relative to the scanning object 70 (e.g., translational motion of the light source 10 relative to the scanning object 70 in the opposite direction of the first direction z) and rotational motion of the light source 10 relative to the scanning object 70 (e.g., rotation of the light source 10 relative to the scanning object 70 around a predetermined rotation axis AX1). For example, the predetermined scanning trajectory can be a helical scanning trajectory, such as... Figure 2A and Figure 2B As shown.

[0074] It should be noted that, unless otherwise specified, the term "movement" in this document refers to translational motion, such as motion along a straight line trajectory. When the scanned object 70 translates relative to the light source 10 in the positive direction of the first direction z, the direction of translational motion of the light source 10 relative to the scanned object 70 can be considered as the opposite direction of the first direction z.

[0075] Combined with reference Figures 2A to 2D Let the center of rotation be the origin O, and let the plane passing through the origin O and perpendicular to the line connecting the target point S and the origin O be defined as the equivalent detection plane DP. Within the equivalent detection plane DP, the direction perpendicular to the first direction z is called... The direction parallel to the first direction z is called the axis. Towards the axis. That is, within the equivalent detection plane DP, establish Coordinate system. The radius of rotation of target point S is... The pitch is defined as:

[0076] ,

[0077] in, This indicates the distance of relative translation between the light source and the scanned object for each revolution of the light source. This indicates the rotational speed (for example, the unit can be revolutions per minute). (For example, the unit can be millimeters per second) represents the translational speed of the motion device, and the imaging area is centered at the origin O with a radius of... The cylindrical area.

[0078] It should be noted that in spiral CT scanning, the imaging region is a cylindrical spatial area formed around the center of rotation of the equipment. This cylindrical region is characterized by: its axis coinciding with the axis passing through the center of rotation; the radius of the cylinder being pre-set according to scanning requirements to define the lateral range of the scan coverage; and the length of the cylinder extending along the axis of rotation, covering the longitudinal range from the start to the end of the scan. The entire cylindrical region constitutes the target space for the X-ray beam to cover and acquire data during spiral CT scanning. The scanned object is located within this cylindrical region, allowing the equipment to acquire continuous and complete tomographic imaging data of the tissue or structure within the cylindrical region through the coordinated movement of spiral rotation and longitudinal translation.

[0079] According to the theory of 3D image reconstruction, the accurate reconstruction condition in 3D image reconstruction is: if there is at least one cone-beam target point on each plane intersecting with the scanned object, then the scanned object can be accurately reconstructed. In the embodiments of this disclosure, the helical scanning trajectory satisfies this accurate reconstruction condition and can be used to acquire cone-beam projection data to accurately reconstruct the image. Furthermore, research shows that the image can be accurately reconstructed from the projection data within the Tam window. The Tam window is described as follows: at a certain rotation angle, the projection area on the equivalent detection plane of all rays emanating from the target point of the light source and passing between two helices adjacent to the target point of the light source. Figures 2B to 2D The Tam window region is shown. According to the theory of spiral CT reconstruction, in the equivalent detection plane, when the detector's coverage area in the equivalent detection plane can completely cover the Tam window region, theoretically, accurate CT image reconstruction of the scanned object can be performed.

[0080] It should be noted that, for ease of description, the Tam window will be referred to as the view window Tam in this article. (Refer to the references.) Figures 2B to 2D The intersection of the line connecting the target point S and the helical scan trajectory with the equivalent probe plane DP forms the first boundary C1 and the second boundary C2 of the view window Tam. For example, in the equivalent probe plane DP, along... The first boundary C1 of the window Tam is located upstream of the second boundary C2, along the direction of extension of the axis, or in other words, along the direction of translational movement of the target point S of the light source along the scanning trajectory.

[0081] It should be noted that in the illustrated embodiment, the light source 10 has the following two movements relative to the scanning object 70: rotational movement around a predetermined rotation axis AX1, and translational movement in the opposite direction of the first direction z. The light source 10 performs a helical motion from top to bottom relative to the scanning object 70. From the perspective of this relative motion direction, the first boundary C1 located at the top of the figure can be described as upstream of the second boundary C2 located at the bottom of the figure. Alternatively, since the light source 10 performs translational movement relative to the scanning object 70 in the opposite direction of the first direction z, from the perspective of only this relative motion direction, the first boundary C1 located at the top of the figure can be described as upstream of the second boundary C2 located at the bottom of the figure.

[0082] The first boundary C1 and the second boundary C2 of the window Tam can be represented by the following formula (1):

[0083] ,

[0084] in, It is the rotation angle of the target point S. , These respectively represent the distances along the equivalent detection plane DP. Axis and The coordinate values ​​of the axis, the interval corresponding to the first boundary C1 The second boundary C2 corresponds to the interval , , The rotation angles of the target point S corresponding to the endpoints of the first and second boundaries can be expressed by the following formula (2):

[0085] ,

[0086] The center line C0 between the first boundary C1 and the second boundary C2 of the viewport Tam can be represented by the following formula (3):

[0087] ,

[0088] According to the theory of spiral CT reconstruction, when the projection of the detector in the equivalent detection plane covers the viewing window Tam, accurate CT reconstruction of the scanned object can theoretically be performed. Typically, the crystal area of ​​a CT detector module has a rectangular outline, and during installation, they are aligned sequentially to form a cylindrical or rectangular plane.

[0089] Figure 3 This is a schematic diagram illustrating the correspondence between the detector and the viewing window Tam in a CT scanning system according to related technologies. Figure 4 Schematic illustration Figure 3 The projection relationship between the detector and the viewing window Tam in the equivalent detection plane is shown. Figure 3 and Figure 4 As shown, for the arrangement shown, if the detector is required to completely cover the window Tam in the equivalent detection plane, some detector crystals will be located outside the range of the window Tam, resulting in wasted detectors and increased costs. If all detectors are within the window Tam, the arrangement cannot completely cover the range of the window Tam, resulting in missing and wasted reconstructed data, which affects the imaging quality.

[0090] To address at least one aspect of the aforementioned problems, some embodiments of this disclosure provide a CT scanning system for performing CT scans on a scanned object within a field of view centered on a predetermined axis of rotation. The CT scanning system includes: a light source including a target point for emitting a beam of radiation to at least a portion of the scanned object; a detector for receiving at least a portion of the beam of radiation; and a motion device for inducing relative motion between the light source and the scanned object, such that the light source moves relative to the scanned object along a predetermined scanning trajectory. The predetermined scanning trajectory is a helical scanning trajectory, and the intersection of the line connecting the target point and the helical scanning trajectory with an equivalent detection plane forms a first boundary and a second boundary of a viewing window. The closed shape formed by the outer contour of the detector's orthographic projection onto the equivalent detection plane approximates the viewing window as closely as possible. In other words, embodiments of this disclosure propose an optimized detector arrangement based on the coverage range of the viewing window Tam within the equivalent detection plane. By adjusting the detector arrangement, its coverage range within the equivalent detection plane is made as close as possible to the viewing window Tam, thereby maximizing the effective coverage range of the detector and reducing detector costs.

[0091] Figure 5 This is a schematic diagram illustrating the correspondence between the detector and the viewing window Tam of a CT scanning system according to some exemplary embodiments of the present disclosure. Figure 6 Schematic illustration Figure 5 The projection relationship between the detector and the view window Tam in the equivalent detection plane is shown. Figure 7 This is a schematic diagram illustrating the correspondence between the detector and the viewing window Tam of a CT scanning system according to some other exemplary embodiments of the present disclosure. Figure 8 Schematic illustration Figure 7 The projection relationship between the detector and the view window Tam in the equivalent detection plane is shown. Figure 9 The diagram illustrates the projection relationship of the detector and the view window Tam of a CT scanning system according to further embodiments of the present disclosure in the equivalent detection plane. Figure 10 The schematic diagram illustrates the orthographic projection of the connection lines of the middle row of detector crystals of multiple detector modules or the connection lines of the center points of multiple detector modules onto the equivalent detection plane. Figure 11 The diagram illustrates the arrangement of detectors in a CT scanning system according to some further exemplary embodiments of the present disclosure.

[0092] Combined with reference Figures 2A to 2D as well as Figures 5 to 11 In the embodiments of this disclosure, the closed shape formed by the outer contour of the orthographic projection of the detector 30 on the equivalent detection plane DP at least partially overlaps with the view window Tam. The closed shape formed by the outer contour of the orthographic projection of the detector 30 on the equivalent detection plane DP has a first projection area, and the portion of the closed shape formed by the outer contour of the orthographic projection of the detector 30 on the equivalent detection plane DP overlapping with the view window Tam has a second projection area. The ratio of the second projection area to the first projection area is 0.7 or higher. For example, the ratio of the second projection area to the first projection area is 0.75 or higher, 0.8 or higher, 0.85 or higher, or 0.9 or higher. Exemplarily, the ratio of the second projection area to the first projection area is 0.7, 0.75, 0.8, 0.85, 0.9, or 0.95. Preferably, the closed shape formed by the outer contour of the orthographic projection of the detector 30 on the equivalent detection plane DP is within the view window Tam, that is, the orthographic projection of the detector 30 on the equivalent detection plane DP completely falls within the range of the view window Tam. In this way, the closed shape formed by the outer contour of the orthographic projection of the detector 30 onto the equivalent detection plane DP approximates the viewing window Tam as closely as possible.

[0093] Continue to refer to Figures 2A to 2D as well as Figures 5 to 10 In embodiments of this disclosure, detector 30 may include multiple detector modules 30M. At least two adjacent detector modules 30M each include multiple detector crystals 300 arranged in a two-dimensional array. For example, detector modules 30M are schematically shown as rectangles enclosed by dashed lines, with multiple solid dots within each dashed frame, each solid dot schematically representing a detector crystal 300. For each of at least two adjacent detector modules, the multiple detector crystals 300 are arranged along row direction D1 and column direction D2. Exemplarily, the beam is a conical beam, which includes a light source cone angle direction and a light source fan angle direction. Row direction D1 is parallel to the light source cone angle direction, and column direction D2 is parallel to the light source fan angle direction.

[0094] In the embodiments of this disclosure, the detector 30 adopts a modular design architecture, including multiple detector modules 30M arranged in an array. Each detector module 30M is a highly integrated functional unit, independently undertaking the task of radiation detection in a specific area.

[0095] For example, at least two adjacent detector modules 30M each contain multiple detector crystals 300 arranged in a two-dimensional array. This two-dimensional array arrangement is designed based on the dual requirements of CT scanning systems for multi-dimensional X-ray capture and spatial resolution. For each of the at least two adjacent detector modules, the multiple detector crystals 300 are arranged in an orderly manner along the row direction D1 and the column direction D2. In the row direction D1, the detector crystals 300 form a linear array, the extension direction of which is parallel to the z-axis scanning path of the CT scanning system, enabling continuous capture of X-ray penetration information at different positions during movement; while in the column direction D2, the arrangement direction of the detector crystals 300 is perpendicular to the row direction D1, adapting to the rotating scanning path of the CT scanning system, so that X-ray detection of the target area can be performed from different angles during rotation.

[0096] It should be noted that, in the embodiments of this disclosure, the detector module 30M may include a plurality of detector crystals 300 arranged in a one-dimensional array. For example, the plurality of detector crystals 300 may be arranged only along the row direction. In this case, in the detector module 30M, the plurality of detector crystals 300 may be arranged in a multi-row, single-column manner to form a one-dimensional array.

[0097] For example, the detector crystal 300 can be made of a scintillation crystal material with a high atomic number and high light yield, such as cadmium zinc telluride or lutetium yttrium silicate. These materials can rapidly convert the energy of X-ray photons into visible light photons after absorption. As another example, the detector crystal 300 can be equipped with a highly sensitive photoelectric conversion element, such as a photomultiplier tube or silicon photomultiplier tube, to further convert visible light photons into electrical signals.

[0098] In some exemplary embodiments, at least two adjacent detector modules 30M are of the same size along the row direction D1. That is, in the illustrated embodiment, at least two adjacent detector modules 30M have the same height. During the operation of the scanning system, adjacent detector modules 30M of the same size can ensure the mechanical stability of the detector 30 along the row direction D1, reduce stress concentration problems caused by differences in module size, reduce the risk of module loosening or misalignment due to vibration or long-term use, and ensure the reliable operation of the CT scanning system. In terms of signal processing, adjacent detector modules 30M of the same size along the row direction D1 can achieve uniformity and consistency in signal acquisition. Since the modules are of the same size, the scanning area covered by each module is of the same length. When moving along the row direction D1 for z-axis scanning, the signal data acquired by adjacent modules have the same spatial resolution and temporal correspondence. This eliminates the need for complex spatial calibration and temporal synchronization processing of data acquired by modules of different sizes when processing signals and reconstructing images. This simplifies the signal processing algorithm, improves data processing efficiency, and helps to generate high-quality CT images quickly and accurately.

[0099] Continue to refer to Figures 2A to 2D as well as Figures 5 to 11 In embodiments of this disclosure, each detector module 30M includes a plurality of detector crystals 300 arranged in an m*n configuration, i.e., each detector module 30M includes m rows of detector crystals 300 and n columns of detector crystals 300. In some embodiments, the number of rows m of detector crystals included in at least two detector modules 30M may be the same as each other, and / or the number of columns n of detector crystals included in at least two detector modules 30M may be the same as each other. In some embodiments, the number of rows m of detector crystals included in at least two detector modules 30M may be the same as each other, and / or the number of columns n of detector crystals included in at least two detector modules 30M may be different from each other. In some embodiments, the number of rows m of detector crystals included in at least two detector modules 30M may be different from each other, and / or the number of columns n of detector crystals included in at least two detector modules 30M may be the same as each other. In some embodiments, the number of rows m of detector crystals included in at least two detector modules 30M may be different from each other, and / or the number of columns n of detector crystals included in at least two detector modules 30M may be different from each other.

[0100] It should be noted that in the embodiments of this disclosure, each detector module 30M includes a plurality of detector crystals 300 arranged in an m*1 configuration, that is, each detector module 30M includes m rows of detector crystals 300 and 1 column of detector crystals 300.

[0101] In some exemplary embodiments, the detector 30 includes multiple detector modules 30M that can have the same specifications. For example, the multiple detector modules 30M included in the detector 30 have the same dimensions in the row direction D1 and column direction D2, the number of rows m of detector crystals included in the multiple detector modules 30M are the same, and the number of columns n of detector crystals included in the multiple detector modules 30M are the same. This design has significant advantages in the large-scale production and maintenance of CT scanning systems. Detector modules 30M of the same specifications adopt unified design standards and manufacturing processes, maintaining consistency from the selection of crystal materials and the configuration of photoelectric conversion elements to the internal circuit layout and packaging structure. In the production process, standardized production processes can effectively reduce manufacturing costs, improve production efficiency, and facilitate mass production. At the same time, detector modules 30M of the same specifications have high interchangeability. During system maintenance, if a module fails, technicians can quickly select a spare module for replacement without considering compatibility issues between modules of different specifications, greatly shortening equipment downtime and improving the availability and stability of the CT scanning system. Furthermore, the consistent performance parameters of detector modules 30M of the same specifications facilitate unified calibration and debugging of the system, ensuring that the entire detector 30 has uniform detection sensitivity and spatial resolution within the scanning field of view, thereby guaranteeing the consistency and reliability of CT image quality.

[0102] In some exemplary embodiments, the detector 30 includes multiple detector modules 30M that can have different specifications. For example, at least two detector modules 30M may have different dimensions in the row direction D1, and / or at least two detector modules 30M may have different dimensions in the column direction D2, and / or at least two detector modules 30M may have different numbers of rows m of detector crystals, and / or at least two detector modules 30M may have different numbers of columns n of detector crystals. This differentiated design allows for performance optimization for different application scenarios and imaging requirements of the CT scanning system. For example, detector modules 30M located near the center of the scanning field of view can employ a higher resolution detector crystal array 300 and more sophisticated signal processing circuitry to meet the requirements of fine imaging; while detector modules 30M located at the edge of the scanning field of view can appropriately reduce crystal resolution and increase crystal size and sensitivity, thereby improving the detection capability of low-dose X-rays and reducing radiation dose while ensuring image quality.

[0103] Continue to refer to Figures 2A to 2D as well as Figures 5 to 11In the embodiments of this disclosure, at least two adjacent detector modules each include a first row of detector crystals. In the direction of translational motion of the light source relative to the scanning object, the first row of detector crystals is located upstream of the other rows of detector crystals. In the first direction z parallel to the rotation axis, the positions of the first rows of detector crystals in the at least two adjacent detector modules are different. This detector arrangement allows the closed shape formed by the outer contour of the orthographic projection of the detector 30 onto the equivalent detection plane DP to approximate the viewing window Tam as closely as possible. That is, by staggering the first rows of detector crystals in the first direction z of adjacent detector modules, the closed shape formed by the outer contour of the detector's orthographic projection onto the equivalent detection plane can better fit the boundary shape of the viewing window Tam (e.g., an arc or sloping boundary). Compared to the regular arrangement of traditional rectangular detectors, the staggered design reduces the invalid area where the detector edges extend beyond the viewing window Tam, while avoiding data loss due to insufficient detection range. In other words, this arrangement significantly increases the effective coverage area of ​​the detector, approaching or covering the core area of ​​the viewing window Tam, ensuring the integrity of the reconstructed data. Furthermore, in traditional detectors, the physical size needs to be increased to cover the viewing window Tam, resulting in edge crystals being in an ineffective detection state for a long time, increasing material costs. In this embodiment, by staggered or tilted arrangement, the detector module achieves "shape fitting" to the viewing window Tam within a limited physical space through positional offset, covering the target area with virtually no additional crystals, thereby reducing the cost of the detector.

[0104] like Figures 5 to 11 As shown, a detector module may include m rows of detector crystals, which may be referred to as the 1st row, 2nd row, ..., mth row detectors, respectively. In the direction of translational motion of the light source relative to the scanning object, or in other words, in the row direction D1, the first row of detector crystals is located upstream of the other rows of detector crystals (e.g., rows 2 to m), and the mth row of detector crystals is located downstream of the other rows of detector crystals (e.g., rows 1 to m-1). For example, in... Figures 5 to 11 In the illustrated embodiment, for each detector module, the top row of detector crystals is the first row of detector crystals, and correspondingly, the bottom row of detector crystals is the m-th row of detector crystals.

[0105] like Figures 5 to 11 As shown, in the first direction z parallel to the rotation axis, at least two adjacent detector modules have different positions of the first row of detector crystals. That is, the z-direction position or z-direction coordinate of the first row of detector crystals in each of at least two adjacent detector modules is different. Figure 5 and Figure 6As shown, at least two adjacent detector modules are staggered in the first direction z, such that the z-position or z-coordinate of the first row of detector crystals in each of the detector modules is different. Figure 7 , Figure 8 , Figure 9 and Figure 10 As shown, at least two adjacent detector modules are arranged at an angle relative to the first direction z, such that the z-direction position or z-direction coordinate of the first row of detector crystals included in each of the detector modules is different.

[0106] In the embodiments of this disclosure, by optimizing the arrangement of each detector module and / or detector crystal within the detector, the closed pattern formed by the outer contour of the orthogonal projection of the detector 30 on the equivalent detection plane DP is made as close as possible to the viewing window Tam. This can ensure the effective coverage of the detector to a large extent, ensure the accuracy of CT reconstruction, and reduce the cost of the detector. In other words, it can balance high accuracy of CT reconstruction with low detector cost.

[0107] In some exemplary embodiments, in the direction of translational motion of the light source relative to the scanned object, or in other words, in the row direction D1, the first boundary C1 is located upstream of the second boundary C2. In the equivalent detection plane DP, the outer contour line DL1 of the first row of detector crystals passing through at least one detector module crosses the first boundary C1.

[0108] In some exemplary embodiments, in the equivalent detection plane DP, the outer contour line DLm of the m-th row of detector crystals passing through at least one detector module crosses the second boundary C2.

[0109] In some exemplary embodiments, in the equivalent detection plane DP, the outer contour line DL1 of the first row of detector crystals passing through at least one detector module is located within the first boundary C1, and the outer contour line DL1 does not intersect with the first boundary C1; the outer contour line DLm of the m-th row of detector crystals passing through at least one detector module is located within the second boundary C2, and the outer contour line DLm does not intersect with the second boundary C2. That is, both the outer contour line DL1 of the first row of detector crystals and the outer contour line DLm of the m-th row of detector crystals of at least one detector module are located within the region defined by the first boundary C1 and the second boundary C2.

[0110] In some exemplary embodiments, at least two adjacent detector modules each include a middle row of detector crystals, which are located in the middle of the detector module in the direction of translational movement of the light source relative to the scanned object, or in other words, in the row direction D1. For example, if the number of rows m of detector crystals included in the detector module is odd, the middle row of detector crystals included in the detector module is the (m+1) / 2th row of detector crystals; if the number of rows m of detector crystals included in the detector module is even, the middle row of detector crystals included in the detector module is either the m / 2th or (m / 2)+1th row of detector crystals. The window Tam includes a window center line C0, which is located in the middle between the first boundary C1 and the second boundary C2 in the first direction z. In the equivalent detection plane DP, the outer contour line DL0 of the middle row of detector crystals of at least one detector module passes through the window center line C0.

[0111] In some exemplary embodiments, such as Figure 5 and Figure 6 As shown, the row direction D1 is parallel to the rotation axis AX1 or the first direction z. Along row direction D1, the m rows of detector crystals from the same detector module are located in multiple planes perpendicular to the rotation axis AX1 or the first direction z. Along row direction D1, some rows of detector crystals from different detector modules are aligned, and the same row of detector crystals from multiple detector modules is located in the same plane perpendicular to the rotation axis AX1 or the first direction z. For example, in the row direction D1, the first detector module 30M1 and the second detector module 30M2 are staggered by a first misalignment distance DC1. The 3rd to mth rows of detector crystals of the first detector module 30M1 are aligned with the 1st to (m-2)th rows of detector crystals of the second detector module 30M2. The 3rd row of detector crystals of the first detector module 30M1 and the 1st row of detector crystals of the second detector module 30M2 are located in the same plane perpendicular to the rotation axis AX1 or the first direction z. The 4th row of detector crystals of the first detector module 30M1 and the 2nd row of detector crystals of the second detector module 30M2 are located in the same plane perpendicular to the rotation axis AX1 or the first direction z, and so on, until the mth row of detector crystals of the first detector module 30M1 and the (m-2)th row of detector crystals of the second detector module 30M2 are located in the same plane perpendicular to the rotation axis AX1 or the first direction z.

[0112] In other words, in some exemplary embodiments, a three-layer positioning method of "upstream boundary - center - downstream boundary" is constructed by arranging different rows of detector crystals in the detector module, achieving depth geometric matching between the detector's detection range and the viewing window Tam. Specifically, by having the outer contour line of the first row of detector crystals pass through the first boundary of the viewing window, and the outer contour line of the m-th row of crystals pass through the second boundary of the viewing window, it is ensured that data in the extreme regions covered by the beam during helical scanning is directly acquired, avoiding axial truncation artifacts or blurring effects caused by missing boundary data. The middle row of crystals extends through or aligns with the center line of the window, ensuring the spatial resolution of the central region of the viewing window and guaranteeing the overall uniformity of the reconstructed image.

[0113] like Figure 5 and Figure 6 As shown, at least two adjacent detector modules are staggered in the row direction D1, and the staggered spacing is an integer multiple of the row spacing of the detector crystals in the row direction D1.

[0114] For example, detector 30 may include a first detector module 30M1, a second detector module 30M2, a third detector module 30M3, a fourth detector module 30M4, and a fifth detector module 30M5 arranged along column direction D2. For instance, detector 30 may include one first detector module 30M1, multiple second detector modules 30M2, multiple third detector modules 30M3, multiple fourth detector modules 30M4, and one fifth detector module 30M5 arranged sequentially along column direction D2. That is, the number of first and fifth detector modules located on both sides of column direction D2 is one, and the number of second, third, and fourth detector modules located in the middle of column direction D2 is multiple. In this case, the specifications of each detector module can be the same. As another example, detector 30 may include one first detector module 30M1, one second detector module 30M2, one third detector module 30M3, one fourth detector module 30M4, and one fifth detector module 30M5 arranged sequentially along column direction D2. In this case, at least two detector modules may have different specifications. For example, the first detector module and the fifth detector module may have the same specifications, the second detector module, the third detector module and the fourth detector module may have the same specifications, and the first detector module and the second detector module may have different specifications.

[0115] It should be noted that, in the embodiments disclosed herein, the number of detector modules included in detector 30 is not particularly limited; however, in other embodiments, the number of detector modules included in detector 30 may be greater than... Figure 5 or Figure 6 The number of detector modules shown is fewer or more.

[0116] In at least one of the detector modules 30M1, 30M2, 30M3, 30M4, and 30M5, the distance between two adjacent rows of detector crystals in the m-row detector crystals along the row direction D1 is DD1. This distance DD1 can be referred to as the row spacing of the detector crystals in the row direction D1. It should be noted that adjacent rows of detector crystals in the m-row detector crystals can be closely arranged, i.e., there is no gap between adjacent rows, or, considering process or manufacturing factors, there is no gap between adjacent rows; or adjacent rows of detector crystals in the m-row detector crystals can be sparsely arranged, i.e., there can be a predetermined gap between adjacent rows. Whether closely or sparsely arranged, the row spacing of the detector crystals in the row direction D1 can be expressed as: the distance between the center lines of one row of detector crystals and the center lines of the other row of detector crystals in the row direction D1.

[0117] In the row direction D1, the first detector module 30M1 and the second detector module 30M2 are staggered by a first misalignment distance DC1; the second detector module 30M2 and the third detector module 30M3 are staggered by a second misalignment distance DC2; the third detector module 30M3 and the fourth detector module 30M4 are staggered by a third misalignment distance DC4; and the fourth detector module 30M4 and the fifth detector module 30M5 are staggered by a fourth misalignment distance DC4. It should be noted that the "misalignment distance" between the two detector modules in the row direction can be expressed as the row spacing between the first row of detector crystals of one detector module and the first row of detector crystals of the other detector module in the row direction D1.

[0118] For example, in Figure 5 and Figure 6In the example shown, the first misalignment spacing DC1 is approximately equal to twice the array spacing DD1 of the detector crystals in the array direction D1; the second misalignment spacing DC2 is approximately equal to twice the array spacing DD1 of the detector crystals in the array direction D1; the third misalignment spacing DC3 is approximately equal to twice the array spacing DD1 of the detector crystals in the array direction D1; and the fourth misalignment spacing DC4 is approximately equal to twice the array spacing DD1 of the detector crystals in the array direction D1. In some examples, at least two of the first misalignment spacing DC1, the second misalignment spacing DC2, the third misalignment spacing DC3, and the fourth misalignment spacing DC4 are equal to each other, or any two of the first misalignment spacing DC1, the second misalignment spacing DC2, the third misalignment spacing DC3, and the fourth misalignment spacing DC4 are equal to each other. Optionally, in some embodiments, at least two of the first misalignment spacing DC1, the second misalignment spacing DC2, the third misalignment spacing DC3, and the fourth misalignment spacing DC4 may be unequal to each other. For example, any two of the first misalignment spacing DC1, the second misalignment spacing DC2, the third misalignment spacing DC3, and the fourth misalignment spacing DC4 may be unequal to each other.

[0119] It should be noted that, in Figure 5 and Figure 6 In the example shown, each misalignment spacing is set to twice the row spacing DD1 of the detector crystal in the row direction D1. This is not a limitation of the embodiments of this disclosure. In other embodiments, each misalignment spacing can be set to other integer multiples of the row spacing DD1 of the detector crystal in the row direction D1, such as 1, more than 2, 3, 4, etc.

[0120] In some embodiments of this disclosure, a detection system that combines flexibility and efficiency is constructed through the regular staggered arrangement of adjacent detector modules in the row direction and a modular array design. For example, the staggered spacing is an integer multiple of the spacing between detector crystal rows, so that the detector crystals of adjacent modules form a stepped staggered distribution in the row direction. For example, the first row of crystals of the first module is aligned with the third row of crystals of the second module, forming a layered coverage of the boundary C1 or boundary C2 of the viewing window Tam. This design allows the projection edge of the detector on the equivalent detection plane to extend along the arc-shaped boundary of the viewing window Tam, thereby enabling the ratio of the second projection area to the first projection area to reach more than 0.85, ensuring that at least most of the critical boundary data can be collected without omission, while avoiding redundant waste of edge crystals. In addition, the regular staggered arrangement makes the detector crystals form equally spaced sampling units in the row direction, and the signal acquisition areas of adjacent modules are continuously connected in the equivalent detection plane. For example, when the light source moves along a spiral trajectory, the staggered crystal array can dynamically compensate for the axial displacement, ensuring that the X-ray beams at different rotation angles are incident on the detector at uniform intervals, thus avoiding reconstruction artifacts caused by inconsistent sampling intervals.

[0121] In some exemplary embodiments, such as Figure 7 and Figure 8 As shown, the row direction D1 is inclined relative to the rotation axis AX1 or the first direction z. The detector 30 may include a first detector module 30M1, a second detector module 30M2, a third detector module 30M3, a fourth detector module 30M4, and a fifth detector module 30M5 arranged along the column direction D2. For example, the detector 30 may include at least one first detector module 30M1, at least one second detector module 30M2, at least one third detector module 30M3, at least one fourth detector module 30M4, and at least one fifth detector module 30M5 arranged sequentially along the column direction D2. Optionally, the detector 30 may include a plurality of first detector modules 30M1 arranged along the column direction D2.

[0122] Along the row direction D1, the m rows of detector crystals of the same detector module are respectively located in multiple planes inclined relative to the rotation axis AX1 or the first direction z. For example, in at least one of the first detector module 30M1, the second detector module 30M2, the third detector module 30M3, the fourth detector module 30M4, and the fifth detector module 30M5, the m rows of detector crystals of the same detector module are respectively located in multiple parallel planes inclined relative to the rotation axis AX1 or the first direction z. For example, the angle between the multiple parallel planes and the rotation axis AX1 or the first direction z is less than 90°.

[0123] Along the row direction D1, at least some rows of detector crystals from the m rows of detector crystals in different detector modules are aligned and arranged, for example, all rows of detector crystals from the m rows of detector crystals in different detector modules are aligned and arranged respectively. The same row of detector crystals from multiple detector modules are located in the same plane inclined relative to the rotation axis AX1 or the first direction z.

[0124] In some exemplary embodiments, the detector modules are arranged at an angle relative to the rotation axis AX1 or the first direction z, and the detector modules are aligned in the row direction D1 without misalignment. For example, in the row direction D1, the first detector module 30M1 and the second detector module 30M2 are aligned, and the first to m rows of detector crystals of the first detector module 30M1 are aligned with the first to m rows of detector crystals of the second detector module 30M2, respectively. The first row of detector crystals of the first detector module 30M1 and the first row of detector crystals of the second detector module 30M2 are located in the same plane inclined relative to the rotation axis AX1 or the first direction z, the second row of detector crystals of the first detector module 30M1 and the second row of detector crystals of the second detector module 30M2 are located in the same plane inclined relative to the rotation axis AX1 or the first direction z, and so on, until the m row of detector crystals of the first detector module 30M1 and the m row of detector crystals of the second detector module 30M2 are located in the same plane inclined relative to the rotation axis AX1 or the first direction z.

[0125] like Figure 8 As shown, in the equivalent detection plane DP, the center points of multiple detector modules 30M1~30M5 lie on a straight line DM0. For example, each detector module can have a rectangular outer contour, and the geometric center of this rectangle can be used as the center point of the detector module. As another example, each detector can include m rows of detector crystals and n columns of detector crystals, and the intersection of the center lines of the m rows and n columns of detector crystals can be used as the center point of the detector module. In the equivalent detection plane DP, the center points of the multiple detector modules 30M1~30M5 are O1, O2, O3, O4, and O5, respectively, and these center points O1, O2, O3, O4, and O5 lie on a straight line DM0.

[0126] Continue to refer to Figure 8 In the equivalent detection plane DP, the straight line DM0 containing the center points of multiple detector modules intersects the window centerline C0. For example, the center points of some detector modules are located upstream of the window centerline C0, and the center points of some detector modules are located downstream of the window centerline C0, such that the straight line DM0 containing the center points of multiple detector modules intersects the window centerline C0.

[0127] In some exemplary embodiments of this disclosure, when the row direction is tilted, the crystals in the same row are aligned with the tilted plane, so that the detector projection edge fits the outer contour of the window Tam. For example, the tilted plane design allows the outer contour line of the first row of detector crystals in the detector module to pass through the first boundary C1 of the window Tam, the outer contour line of the m-th row of detector crystals to pass through the second boundary C2 of the window Tam, and the middle row of detector crystals to be aligned with the window center line C0 of the window Tam. For example, the center points of multiple detector modules are collinear on the equivalent detection plane, and this straight line intersects the window center line C0, ensuring the geometric symmetry of the detector array. For example, when the line connecting the center points passes through the window center line C0, the detection sensitivity of each module to the central region is consistent, avoiding signal strength differences caused by layout offset, and improving the uniformity of the center contrast of the reconstructed image. At the same time, the aligned arrangement of crystals in the tilted plane ensures that the sampling interval of adjacent modules is consistent in the row direction, reducing the ring artifacts caused by sampling misalignment in helical scanning.

[0128] Optionally, in some exemplary embodiments, the straight line DM0 containing the center points of multiple detector modules in the equivalent detector plane DP can be represented by the following equation (4):

[0129] ,

[0130] Among them, parameters The optimal solution for the following optimization function is:

[0131] ,

[0132] in, Let be the radius of rotation of the target point. It is the rotation angle of the target point, and the first boundary corresponds to the interval. The second boundary corresponds to the interval , , It is the rotation angle of the target point corresponding to the endpoint positions of the first boundary and the second boundary.

[0133] In this embodiment, by constructing and satisfying the optimization function, the middle row of detector crystals is aligned as precisely as possible with the window center line C0 of the viewing window Tam. This makes the closed shape formed by the outer contour of the orthogonal projection of the detector 30 on the equivalent detection plane DP as close as possible to the viewing window Tam. In this way, the effective coverage of the detector can be ensured to a large extent, the accuracy of CT reconstruction can be ensured, and the cost of the detector can be reduced. That is to say, it can balance high accuracy of CT reconstruction and low detector cost.

[0134] In some exemplary embodiments, such as Figure 8 and Figure 9As shown, the row direction D1 is inclined relative to the rotation axis AX1 or the first direction z. The detector 30 may include a first detector module 30M1, a second detector module 30M2, a third detector module 30M3, a fourth detector module 30M4, and a fifth detector module 30M5 arranged along the column direction D2. For example, the detector 30 may include at least one first detector module 30M1, at least one second detector module 30M2, at least one third detector module 30M3, at least one fourth detector module 30M4, and at least one fifth detector module 30M5 arranged sequentially along the column direction D2. Optionally, the detector 30 may include a plurality of first detector modules 30M1 arranged along the column direction D2.

[0135] Along the row direction D1, the m rows of detector crystals of the same detector module are respectively located in multiple planes inclined relative to the rotation axis AX1 or the first direction z. For example, in at least one of the first detector module 30M1, the second detector module 30M2, the third detector module 30M3, the fourth detector module 30M4, and the fifth detector module 30M5, the m rows of detector crystals of the same detector module are respectively located in multiple parallel planes inclined relative to the rotation axis AX1 or the first direction z. For example, the angle between the multiple parallel planes and the rotation axis AX1 or the first direction z is less than 90°.

[0136] Along the row direction D1, at least some rows of detector crystals in the m rows of detector crystals of different detector modules are staggered; for example, all rows of detector crystals in the m rows of detector crystals of different detector modules are staggered respectively. The same row of detector crystals of multiple detector modules are located in different planes inclined relative to the rotation axis AX1 or the first direction z.

[0137] In some exemplary embodiments, the detector modules are arranged at an angle relative to the rotation axis AX1 or the first direction z, and the detector modules are staggered in the row direction D1. For example, in the row direction D1, the first detector module 30M1 and the second detector module 30M2 are staggered, the first to m rows of detector crystals of the first detector module 30M1 are staggered from the first to m rows of detector crystals of the second detector module 30M2, the first row of detector crystals of the first detector module 30M1 and the first row of detector crystals of the second detector module 30M2 are located in different planes inclined relative to the rotation axis AX1 or the first direction z, the second row of detector crystals of the first detector module 30M1 and the second row of detector crystals of the second detector module 30M2 are located in different planes inclined relative to the rotation axis AX1 or the first direction z, and so on, until the m row of detector crystals of the first detector module 30M1 and the m row of detector crystals of the second detector module 30M2 are located in different planes inclined relative to the rotation axis AX1 or the first direction z.

[0138] like Figure 9 As shown, in the equivalent detection plane DP, the center points of multiple detector modules 30M1~30M5 are located on the window center line C0. For example, in the equivalent detection plane DP, the center points of multiple detector modules 30M1~30M5 are O1, O2, O3, O4, and O5, respectively, and the center points O1, O2, O3, O4, and O5 are located on the window center line C0.

[0139] like Figure 10 As shown, the orthogonal projection of the line connecting the middle row of detector crystals of multiple detector modules or the line connecting the center points of multiple detector modules onto the equivalent detection plane DP is a line segment parallel to the u-axis. In some implementations, the orientation of the detector modules can be adjusted to ensure that the line connecting the middle row of detector crystals or the center points of the detector modules is located on the window centerline C0, so that the projection line of the line connecting the middle row of detector crystals or the center points of the detector modules onto the equivalent detection plane approaches the centerline of the viewing window Tam, further improving the utilization rate of the detector.

[0140] In some exemplary embodiments of this disclosure, multiple rows of detector crystals are distributed on a parallel plane with an angle of less than 90° to the axis of rotation, so that the physical arrangement of the detector modules conforms to the arc or tilted boundary of the window Tam. The center points of the multiple detector modules can be strictly located on the window centerline C0, ensuring the geometric symmetry of the detector array. For example, when the line connecting the center points coincides with C0, the ray receiving angle of each detector module in the central region is consistent, avoiding the decrease in resolution or uneven signal attenuation in the central region due to layout offset.

[0141] In some exemplary embodiments, the outer contour of at least one detector module is a non-rectangular region; for example, the outer contour line of at least one detector module extends in the same direction as the first or second boundary of the window. Figure 11 As shown, detector 30 may include a first detector module 30M1 and a second detector module 30M2 arranged along column direction D2. For example, detector 30 may include at least one first detector module 30M1 and at least one second detector module 30M2 arranged sequentially along column direction D2. Optionally, detector 30 may include multiple first detector modules 30M1 or multiple second detector modules 30M2 arranged along column direction D2. For example, the outer contour line of a first detector module 30M1 is in the same direction as the extension of the first boundary C1 or the second boundary C2 of the viewport Tam. As another example, the outer contour line of a second detector module 30M2 is in the same direction as the extension of the first boundary C1 or the second boundary C2 of the viewport Tam.

[0142] Continue to refer to Figure 11 A row of detector crystals is aligned with each other on a straight line, which can be parallel to the rotation axis AX1 or the first direction z. In a single detector module, different rows of detector crystals can be staggered. The staggered distance allows the contour lines of the detector crystals at the top and bottom edges in the equivalent detection plane to approach the first boundary C1 or the second boundary C2 of the viewing window Tam after multiple detector modules are combined, resulting in higher detector data utilization.

[0143] In some exemplary embodiments of this disclosure, the outer contour of the detector module is aligned with the extension direction of the first boundary C1 or the second boundary C2 of the window Tam, allowing the physical boundary of the detector to directly approximate the geometry of the window Tam. Single-row detector crystals are aligned along the rotation axis, and crystals from different rows are staggered within the module, causing the upper and lower edges of the combined detector to form continuous curves that conform to the spatial orientation of the first boundary C1 or the second boundary C2 of the window Tam. For example, the edge crystals of adjacent modules are staggered by 1-2 crystal spacings in the column direction, allowing their equivalent projected edges to seamlessly connect along the window boundary, ensuring complete reception of the boundary ray beam during helical scanning.

[0144] In the embodiments of this disclosure, by designing the arrangement of the detector modules and / or detector crystals within the detector, the shape of the detector in the equivalent detection plane can approximate the shape of the window Tam, and / or the coverage area of ​​the detector in the equivalent detection plane can approximate the coverage area of ​​the window Tam, which is beneficial to achieving greater data utilization efficiency.

[0145] Figure 12 This is a plan view schematically illustrating the relative positional relationship between the target and the detector in the xy plane of a CT scanning system according to some exemplary embodiments of the present disclosure.

[0146] In some exemplary embodiments of this disclosure, the detector crystals of the plurality of detector modules 30M1 to 30M5 of the detector 30 can be arranged on a cylindrical surface or an arc-shaped cylindrical surface.

[0147] like Figure 12 As shown, the detector crystals of multiple detector modules 30M1~30M5 of detector 30 can be continuously arranged on a cylindrical surface. For example, the central axis of the cylindrical surface can be parallel to the rotation axis AX1. This central axis can pass through the target point position, meaning that the rays emitted from the target point S can be incident perpendicularly to the detector crystal. In this mounting configuration, the rays emitted from the target point S can directly incident on the detector surface at a perpendicular angle. This perpendicular incident design allows the detector crystal to absorb ray energy to the maximum extent, reducing ray attenuation and scattering caused by oblique incident, thereby significantly improving detection efficiency and accuracy.

[0148] Optionally, the central axis of the cylindrical surface may not pass through the target point, meaning the rays emitted from target point S are not perpendicular to the detector crystal. While this mounting method eliminates the perpendicular incidence of rays from target point S, it offers significant advantages in reducing detector costs and optimizing system design. Because the rays are not perpendicular, the detector does not need to cover the entire scanning field of view in its spatial layout. By adjusting the position and size of the cylindrical surface, only critical areas can be detected. This design drastically reduces the number and area of ​​required detector modules, effectively lowering material costs, manufacturing costs, and subsequent maintenance costs. Simultaneously, the smaller detector layout simplifies the detector's signal processing and data transmission systems, reducing overall system complexity and power consumption.

[0149] Figure 13 This is a plan view schematically illustrating the relative positional relationship between the target and detector in the xy plane of a CT scanning system according to some other exemplary embodiments of the present disclosure.

[0150] like Figure 13 As shown, detector 30 includes multiple detector modules. For example, these multiple detector modules may include a first detector module 30M1, a second detector module 30M2, a third detector module 30M3, a fourth detector module 30M4, a fifth detector module 30M5, and a sixth detector module 30M6. The detector crystals of the multiple detector modules 30M1 to 30M6 are staggered along the extension direction of the X-ray beam. The line connecting the center line of each detector module to the target point is perpendicular to the plane where its respective detector crystal is located. In the equivalent detection plane, the coverage areas of at least two detector modules are continuous.

[0151] Continue to refer to Figure 13 The detector crystals of multiple detector modules 30M1~30M6 are staggered along the extension direction of the X-ray beam (i.e., from the target point S of the X-ray source to the detector 30). Figure 13 For example, in the xy plane, the ray beam diverges outward from the target point S. The crystals of different detector modules are not neatly arranged on the same plane perpendicular to the central axis of the ray, but are staggered by a certain distance along the ray extension path.

[0152] Each detector module has a centerline (which can be understood as the module's symmetrical central axis). The line connecting this centerline and the target point S is perpendicular to the plane of the respective detector crystal. In other words, for any detector module, if a line segment is formed by connecting its centerline and the target point S, this line segment forms a 90° angle with the detector crystal plane. This ensures that the detector crystal plane is adapted to the incident angle of the radiation, which is beneficial for the detector to efficiently receive radiation signals.

[0153] In the equivalent detection plane, the coverage areas of at least two detector modules are continuous. For example... Figure 13 As shown, on the equivalent detection plane, the detectable ray areas of adjacent detector modules are connected without obvious gaps, ensuring continuous acquisition of rays.

[0154] In this embodiment, since the line connecting the centerline of each detector module to the target point is perpendicular to the detector crystal plane, the incident angle of the ray is more compatible with the detection characteristics of the detector crystal. This allows the detector crystal to capture ray energy more efficiently, reducing scattering and reflection losses caused by improper incident angles, and improving the efficiency of converting ray energy into electrical signals. This, in turn, improves the signal acquisition quality of CT scans, providing a foundation for clear imaging. Furthermore, by staggering the detector modules along the ray beam extension direction and achieving continuous coverage on the equivalent detection plane, comprehensive and gapless detection of the ray beam emanating from the target point can be ensured in the xy plane. This allows for the acquisition of continuous and complete ray attenuation data, avoiding artifacts and information loss in image reconstruction due to detection gaps, thus improving the accuracy and reliability of CT images. In practical applications, the degree and number of detector modules can be adjusted according to different scanning needs, flexibly adapting to different scanning fields on the equivalent detection plane. This allows for various scanning scenarios without significant changes to the detector hardware structure, reducing system design and usage costs. Furthermore, the staggered arrangement along the direction of the ray extension, compared to the traditional planar neat arrangement, allows for more rational planning of module positions within the limited detector installation space, making full use of the space along the ray propagation path. This expands the detection coverage without increasing the overall space occupied by the detector, improving the space utilization efficiency of the CT scanning system and contributing to the miniaturization and lightweight design of the equipment.

[0155] Figure 14 This is a schematic diagram illustrating the relative positional relationship between the target and the detector in xyz space of a CT scanning system according to some exemplary embodiments of the present disclosure.

[0156] like Figure 14 As shown, detector 30 includes multiple detector modules, such as a first detector module 30M1, a second detector module 30M2, a third detector module 30M3, ..., and a k-th detector module 30Mk. The planes containing the detector crystals of the multiple detector modules 30M1~30Mk are parallel to the rotation axis AX1 or the first direction z, respectively. The perpendicular lines (i.e., the normals to the center points of the detector modules) passing through the center points of the multiple detector modules 30M1~30Mk and perpendicular to the planes containing their respective detector crystals do not intersect at a single point.

[0157] For example, in some scanning scenarios, the detector crystals of multiple detector modules are positioned on planes parallel to either the rotation axis or the first direction z. Specifically, the crystal plane of each detector module is rectangular or square, with its long or short side parallel to either the rotation axis or the first direction z. For instance, the detector crystals are arranged in a rectangular array, with the normal direction of the crystal plane in the xy plane (perpendicular to the rotation axis or the first direction z), making the entire crystal plane parallel to either the rotation axis or the first direction z. In this arrangement, the X-ray beam emitted from the target point S, centered on the target point, can be uniformly received by the detector crystals in a direction parallel to the rotation axis, allowing the acquisition of multi-layer image information distributed along the rotation axis or the first direction z.

[0158] Reference Figure 14 Each detector module has its own center point. Perpendicular lines (vertical straight lines) are drawn from this point to the crystal plane. These perpendicular lines are dispersed in space and do not converge at the same point. With this configuration, the detector modules can flexibly adjust their spatial orientation according to the spatial shape of different objects being scanned, thus meeting actual scanning requirements and accurately acquiring X-ray signals from various regions.

[0159] Figure 15A This is a schematic diagram illustrating the relative positional relationship between the target and the detector in xyz space of a CT scanning system according to some other exemplary embodiments of the present disclosure. Figure 15B This is a schematic diagram illustrating the relative positional relationship between the target and the detector in xyz space of a CT scanning system according to some further exemplary embodiments of the present disclosure.

[0160] like Figure 15A and Figure 15BAs shown, detector 30 includes multiple detector modules, such as a first detector module 30M1, a second detector module 30M2, a third detector module 30M3, ..., and a k-th detector module 30Mk. The plane containing the detector crystal of at least one of the multiple detector modules 30M1 to 30Mk is inclined relative to the rotation axis AX1 or the first direction z. Vertical lines passing through the center point of the multiple detector modules 30M1 to 30Mk and perpendicular to the plane containing their respective detector crystals intersect at a single point.

[0161] like Figure 15B As shown, target point S is located at the intersection point, that is, the vertical lines passing through the center points of multiple detector modules 30M1~30Mk and perpendicular to the plane where their respective detector crystals are located intersect at target point S.

[0162] In this embodiment, on the one hand, the plane of the detector crystal of at least one detector module is tilted relative to the axis of rotation; on the other hand, vertical lines passing through the center points of multiple detector modules and perpendicular to their respective crystal planes intersect at a point, and this point is set as the target location, thereby constructing a unique space detection architecture.

[0163] For example, in practical implementation, the attitude of the detector module can be adjusted by the controller according to the scanning requirements. For instance, the detector module can be driven to rotate around its own mechanical axis, causing the plane of the detector crystal to form a specific angle with the rotation axis AX1 or the first direction z, thus achieving the tilt of the crystal plane relative to the rotation axis AX1 or the first direction z. For example, high-precision spatial positioning and attitude calibration algorithms can be used to ensure that the vertical line passing through the center point of each detector module (i.e., the extension of the normal direction of the crystal plane) accurately intersects the target point. In terms of hardware implementation, the detector module can be equipped with a microelectromechanical system (MEMS) attitude sensor and a servo motor drive mechanism. The sensor provides real-time feedback of the module's spatial attitude data, and the servo motor fine-tunes the module angle according to control commands, ensuring the accuracy of the vertical line intersecting the target point.

[0164] In this embodiment, by controlling the perpendicular lines of the detector modules to intersect at, for example, the target point, the circular motion characteristics of CT scans can be adapted. During rotation around the axis of rotation, the detector modules can maintain precise detection coverage of the target area. For scanning planes at different angles, the tilted crystal plane can adjust the X-ray receiving range, reducing the detection blind spots of traditional parallel layouts. Simultaneously, the perpendicular lines intersecting the target point ensure consistent detection geometry for the target point and surrounding area by each detector module, enabling more accurate reconstruction of tissue spatial location and improving spatial resolution during image reconstruction.

[0165] Figure 16A and Figure 16BThis is a schematic diagram illustrating the double-layer structure of the detector of a CT scanning system according to some exemplary embodiments of the present disclosure.

[0166] like Figure 16A As shown, at least one detector module includes a dual-layer detector crystal, which is arranged along the extension direction of the X-ray beam, and the spacing between the two layers of detector crystals in the row direction is the same. For example, the spacing between the upper detector crystal 300 and the lower detector crystal 300 in the row direction is DD1, and the spacing between the lower detector crystal is DD2. The spacing between DD1 and DD2 is substantially equal.

[0167] For example, within the detector module, dual-layer detector crystals are arranged sequentially along the direction in which the X-ray beam penetrates the scanned object (i.e., the direction of beam extension), with uniform spacing between the layers. For instance, both the first and second layers of detector crystals utilize large-size, low-cost scintillation crystal arrays (e.g., cesium iodide crystals), and the spacing between the crystals along the row direction is consistent. When, for example, luggage passes through the scanning area on a conveyor belt, the X-rays penetrate the luggage and are first detected by the first-layer detector crystal. For example, the first-layer detector crystal can detect low-energy X-rays and convert them into electrical signals; the remaining high-energy X-rays are then incident on the second-layer detector crystal. Due to the uniform spacing, the sampling positions of the dual-layer crystals are synchronized along the row direction, allowing the scanning system to quickly superimpose the dual-layer signals, thus clearly revealing the outlines of high-density items within the luggage. Simultaneously, by comparing the differences between the dual-layer signals, areas suspected of containing prohibited items can be preliminarily marked, assisting security personnel in rapid screening. In other words, the two layers of detector crystals use the same row spacing design, simplifying the signal processing flow and eliminating the need for complex spatial calibration algorithms. The two-layer signals can be directly superimposed or quickly compared, adapting to the "high-speed flow" requirements of baggage security checks. Furthermore, the clear outline and difference markers after superposition allow security personnel to identify the distribution of items in baggage within seconds, improving security clearance efficiency. In addition, by using two-layer crystals with the same row spacing, the detector module can reuse mature manufacturing processes, reducing the cost of the CT scanning system.

[0168] like Figure 16B As shown, at least one detector module includes a dual-layer detector crystal array arranged along the extension direction of the X-ray beam. The spacing between the two layers of detector crystals in the array direction is different. For example, the spacing between one layer of detector crystals in the array direction can be an integer multiple of the spacing between the other layer of detector crystals in the array direction. For example, the spacing between the upper layer detector crystal 300 and the lower layer detector crystal 300 in the array direction is DD1, and the spacing between the lower layer detector crystals in the array direction is DD2. For example, the spacing DD2 is twice the spacing DD1.

[0169] Within the detector module, dual-layer detector crystals are arranged in layers along the ray direction, with differentiated spacing between the layers: for example, the first layer uses a high-resolution array with small spacing to accurately capture the spatial location of tiny items within a scanned object, such as luggage; the second layer uses a high-energy detection array with large spacing. When the rays penetrate the luggage, the first layer of small-spaced crystals clearly records the fine structure of the tiny items along the row direction; the second layer of large-spaced crystals utilizes the attenuation differences of high and low energy rays by different materials to distinguish the composition of the items. Due to the different spacing, the scanning system can use a joint algorithm to calibrate the energy data of the large-spaced crystals with the spatial coordinates of the small-spaced crystals, eliminating energy spectrum misjudgments caused by sampling position deviations; simultaneously, based on the energy spectrum differences of the dual-layer crystals, a material identification model is constructed to accurately mark contraband.

[0170] In some exemplary embodiments of this disclosure, the light source, collimator, and detector can be designed in a synergistic manner in a CT scanning system to improve X-ray utilization efficiency, imaging quality, and contraband identification capabilities.

[0171] For example, to identify contraband in luggage, the outer contour of the detector crystal array is first analyzed. In baggage security CT scans, the detector crystals are arranged in a rectangular array. The line connecting the vertices of their outer contours to the target point outlines the theoretically "precise pre-collimator shape." This shape perfectly matches the effective area to be detected inside the luggage. After the X-ray is collimated by this shape, it can precisely cover the effective detection range of the detector crystal. To simplify the pre-collimator manufacturing process, a "minimum rectangle coverage" strategy can be adopted. For example, the largest circumscribed rectangle of the theoretical pre-collimator shape can be used as the physical structure of the pre-collimator. For instance, if the line connecting the outer contour of the detector crystal and the target point forms an irregular polygon, the smallest rectangle that can enclose this polygon is found, and this rectangle is used as the opening shape of the pre-collimator. This design results in a slightly larger X-ray beam coverage area than the effective detection range of the detector crystal, appropriately increasing the X-ray irradiation area, but significantly reducing the machining accuracy requirements of the pre-collimator. In baggage security checks, the coverage area of ​​the X-ray beam is slightly larger than that of the detector crystal array. For example, the excess area can be 5%-10% of the area outside the edge of the detector crystal array, which can effectively compensate for detection loopholes caused by baggage placement deviations and uneven response at the edge of the detector. Although some redundant X-ray irradiation is added, since the redundant area is only a small area at the edge of the detector and the restrictions on X-ray dosage in baggage security checks are relatively lenient, it will not have a substantial impact on the operation of the equipment or the baggage.

[0172] Those skilled in the art will understand that the features described in the various embodiments of this disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments of this disclosure can be combined and / or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

Claims

1. A CT scanning system for CT scanning a scan object in a field of view centered on a predetermined rotation axis, characterized by The CT scanning system comprises: a light source comprising a target point for emitting a ray beam to at least a part of the scanning object; a detector for receiving at least a part of the ray beam; a motion device for causing relative motion of the light source and the scanning object, so that the light source moves along a predetermined scanning trajectory relative to the scanning object, the light source moving along the predetermined scanning trajectory relative to the scanning object at least comprising translational motion of the light source relative to the scanning object; wherein the detector comprises a plurality of detector modules, at least two adjacent detector modules each comprising a plurality of detector crystals arranged in a one-dimensional array or a two-dimensional array, for each of the at least two adjacent detector modules, the plurality of detector crystals are arranged at least along a row direction; in the row direction, the sizes of the at least two adjacent detector modules are the same; and the at least two adjacent detector modules each comprise a first row of detector crystals, in a direction of the translational motion of the light source relative to the scanning object, the first row of detector crystals is located upstream of other rows of detector crystals; in a first direction parallel to the rotation axis, the positions of the first row of detector crystals comprised by the at least two adjacent detector modules are different.

2. The system of claim 1, wherein, The ray beam is a cone beam, the cone beam comprises a light source cone angle direction and a light source fan angle direction; the plurality of detector modules are arranged along a column direction, the light source cone angle direction is parallel to the row direction, and the light source fan angle direction is parallel to the column direction.

3. The system of claim 2, wherein, The predetermined scanning trajectory is a helical scanning trajectory, a line connecting the target point and the helical scanning trajectory forms a first boundary and a second boundary of a viewing window, an outer contour of a positive projection of the detector on an equivalent detection plane encloses a closed figure which at least partially overlaps with the viewing window, the closed figure enclosed by the outer contour of the positive projection of the detector on the equivalent detection plane has a first projection area, a part of the closed figure enclosed by the outer contour of the positive projection of the detector on the equivalent detection plane which overlaps with the viewing window has a second projection area, a ratio of the second projection area to the first projection area is above 0.7, wherein a light source plane is a plane perpendicular to the rotation axis and passing through the target point, an origin is an intersection of the rotation axis and the light source plane, and the equivalent detection plane is a plane passing through the origin and perpendicular to a line connecting the origin and the target point.

4. The system of claim 3, wherein, The closed figure enclosed by the outer contour of the positive projection of the detector on the equivalent detection plane is within the viewing window.

5. The system of claim 3 or 4, wherein, In the direction of the translational motion of the light source relative to the scanning object, the first boundary is located upstream of the second boundary; in the equivalent detection plane, an outer contour line passing through the first row of detector crystals of at least one of the detector modules passes through the first boundary.

6. The system of any of claims 3-5, wherein, At least two adjacent detector modules respectively comprise an mth row of detector crystals, which are located downstream of other rows of detector crystals in a translation direction of the light source relative to the scanning object, m being a positive integer greater than or equal to 2; In the equivalent detection plane, an outer contour line of the mth row of detector crystals of at least one detector module passes through the second boundary.

7. The system of any of claims 3-6, wherein, At least two adjacent detector modules respectively comprise an intermediate row of detector crystals, which are located at an intermediate position of the detector modules in the translation direction of the light source relative to the scanning object; The view window comprises a window center line, which is located at an intermediate position between the first boundary and the second boundary in the first direction; In the equivalent detection plane, an outer contour line of the intermediate row of detector crystals of at least one detector module passes through the window center line.

8. The system of any one of claims 1-7, wherein, In the row direction, at least two adjacent detector modules are arranged with a staggered arrangement, and a staggered interval is an integer multiple of a row interval of the detector crystals in the row direction.

9. The system of claim 8, wherein, The detector comprises a first detector module, a second detector module, a third detector module, a fourth detector module and a fifth detector module arranged along the column direction; and In the row direction, the first detector module and the second detector module are arranged with a first staggered interval, the second detector module and the third detector module are arranged with a second staggered interval, the third detector module and the fourth detector module are arranged with a third staggered interval, and the fourth detector module and the fifth detector module are arranged with a fourth staggered interval.

10. The system of claim 9, wherein, At least two of the first staggered interval, the second staggered interval, the third staggered interval and the fourth staggered interval are equal to each other.

11. The system of any one of claims 1-10, wherein, The row direction is parallel to the rotation axis, and a plurality of rows of detector crystals of at least one detector module are respectively located on a plurality of parallel planes perpendicular to the rotation axis.

12. The system of any one of claims 1-10, wherein, The row direction is inclined relative to the rotation axis, and the same row of detector crystals of the plurality of detector modules are arranged in alignment in the row direction, and the same row of detector crystals of the plurality of detector modules are located on the same plane.

13. The system of claim 12, wherein, The plurality of rows of detector crystals of at least one detector module are respectively located on a plurality of parallel planes intersecting the rotation axis, and the plurality of parallel planes intersect the rotation axis at an angle less than 90°.

14. The system of any one of claims 3-7, wherein, In the equivalent detection plane, the center points of the plurality of detector modules are on a straight line.

15. The system of any one of claims 3-7, wherein, In the equivalent detection plane, the straight line on which the center points of the plurality of detector modules are located intersects the window center line.

16. The system of any one of claims 1-10, wherein, The row direction is inclined relative to the rotation axis, and the same row of detector crystals of the plurality of detector modules are arranged with a staggered arrangement in the row direction, and the same row of detector crystals of the plurality of detector modules are located on different planes.

17. The system of claim 16, wherein, The plurality of rows of detector crystals of at least one detector module are respectively located on a plurality of parallel planes intersecting the rotation axis, and the plurality of parallel planes intersect the rotation axis at an angle less than 90°.

18. The system of claim 14, wherein, In the equivalent detection plane, the center points of the plurality of detector modules are located on the window center line.

19. The system of any one of claims 2-18, wherein, The plurality of detector modules are arranged in a staggered manner in the row direction.

20. The system of any one of claims 3-7, wherein, The outer contour line of at least one of the detector modules is parallel to the first boundary or the second boundary of the view window.

21. The system of any one of claims 1-20, wherein, The detector crystals of the plurality of detector modules are arranged on a cylindrical surface or an arc-shaped cylindrical surface.

22. The system of any one of claims 1-21, wherein, The detector crystals of the plurality of detector modules are arranged in a staggered manner along the extension direction of the ray bundle, the connecting lines between the center lines of the plurality of detector modules and the target point are respectively perpendicular to the planes in which the detector crystals of the plurality of detector modules are located, and in the equivalent detection plane, the coverage ranges of at least two of the detector modules are continuous.

23. The system of any one of claims 1-22, wherein, The planes in which the detector crystals of the plurality of detector modules are located are respectively parallel to the rotation axis; or The perpendicular lines that pass through the center points of the plurality of detector modules and are perpendicular to the planes in which the detector crystals of the plurality of detector modules are located do not intersect at a point.

24. The system of any one of claims 1-22, wherein, The planes in which the detector crystals of at least one of the detector modules are located are inclined relative to the rotation axis; and The perpendicular lines that pass through the center points of the plurality of detector modules and are perpendicular to the planes in which the detector crystals of the plurality of detector modules are located intersect at a point.

25. The system of claim 24, wherein, The target point is located at the intersection point.

26. The system of any one of claims 3-7, wherein, In the equivalent detection plane, the first boundary and the second boundary of the view window are represented by the following formula: ， wherein, , respectively represent coordinate values along the axis and the axis in the equivalent detection plane DP, the axis being perpendicular to the first direction, the axis being parallel to the first direction, represents the distance of the relative translational motion between the light source and the scanning object per revolution of the light source, is the rotational radius of the target point, is the rotational angle of the target point, the first boundary corresponding interval , the second boundary corresponding interval , , is the rotational angle of the target point corresponding to the end point position of the first boundary and the second boundary, which can be expressed by the following formula; ， wherein is the radius of the imaging region.

27. The system of claim 26, wherein, In the equivalent detection plane, the window center line of the view window is represented by the following formula: ， wherein represents the distance of the relative translational movement between the light source and the scanning object per one revolution of the light source.

28. The system of claim 27, wherein, In the equivalent detection plane, the straight line in which the center points of the plurality of detector modules are located is represented by the following formula: ， wherein is a parameter, and parameter is the optimal solution of the following optimization function: 。 29. The system of any one of claims 1-28, wherein, At least one of the detector modules includes double-layer detector crystals, the double-layer detector crystals are arranged along the extension direction of the ray bundle, and the interval distances of the double-layer detector crystals in the row direction are the same or different.

30. The system of any one of claims 1-29, wherein, The CT scanning system further includes a slip ring, and the light source and the detector are located on the slip ring.

31. A CT scanning system for CT scanning a scan object in a field of view centered on a predetermined axis of rotation, characterized by The CT scanning system includes: a light source, the light source including a target point, the target point being used to emit a ray bundle to at least a part of the scanning object; a detector, the detector being used to receive at least a part of the ray bundle; a motion device, the motion device being used to cause relative motion of the light source and the scanning object, so that the light source moves along a predetermined scanning track relative to the scanning object; The predetermined scanning trajectory is a spiral scanning trajectory, a line connecting the target point and the spiral scanning trajectory forms a first boundary and a second boundary of a viewing window, an outer contour of a projection of the detector on an equivalent detection plane encloses a closed figure which at least partially overlaps with the viewing window, the closed figure enclosed by the outer contour of the projection of the detector on the equivalent detection plane has a first projection area, a part of the closed figure enclosed by the outer contour of the projection of the detector on the equivalent detection plane which overlaps with the viewing window has a second projection area, a ratio of the second projection area to the first projection area is greater than or equal to 0.7, wherein a light source plane is a plane which is perpendicular to the rotation axis and passes through the target point, an origin is an intersection of the rotation axis and the light source plane, and the equivalent detection plane is a plane which passes through the origin and is perpendicular to a line connecting the origin and the target point.

32. The system of claim 31, wherein, The closed figure enclosed by the outer contour of the projection of the detector on the equivalent detection plane is within the viewing window.

Images