Distributed ray source CT imaging system and imaging method

Abstract

The present invention discloses a distributed ray source CT imaging system and an imaging method, belonging to the field of radiation imaging. The present invention can freely select the arrangement of ray sources and detectors in combination with actual imaging needs and the regions of interest and structural characteristics of the inspected object, and can improve the scanning angle covering the inspection area and the utilization efficiency of the detector without introducing mechanical movement of the scanned object, the ray source module, and the detector module, provide more complete detection data, and increase the projection viewing angle acquisition speed without reducing the imaging field of view, thereby improving the imaging quality and accuracy.

Description

Technical Field

[0001] The present invention relates to the field of radiation imaging technology, and in particular to a distributed ray source CT imaging system and an imaging method. Background Art

[0002] X-ray CT (computed tomography) imaging technology is widely used in the fields of medical treatment, security inspection, industrial non-destructive testing, etc. In the existing CT scanning system, the ray source and detector surround the inspected object and collect projection data in all directions according to a certain orbit. The distribution of the linear attenuation coefficient of the object in three-dimensional space can be calculated through the image reconstruction algorithm. According to the relative motion relationship between the ray source and the inspected object during the scanning process, the existing CT scanning system mainly includes a dynamic slip ring CT scanning system and a static CT scanning system. Compared with the dynamic slip ring CT scanning system, the static CT scanning system arranges a series of ray sources around the inspected object and performs serialized exposure to obtain complete projection data. Scanning can be achieved without rotating the slip ring, and it has better flexibility in imaging mode and system design. For example, the static CT scanning system can flexibly design the arrangement of the ray source and the detector according to the size and shape of the inspected object. In addition, through the rapid switching exposure of the distributed ray source, the time resolution of static CT scanning imaging is no longer limited by the slip ring rotation speed, and has great potential in high time resolution imaging of moving objects.

[0003] According to CT reconstruction theory, the distribution of the physical characteristic parameters of a section of an object can be calculated by the line integral values ​​of the physical characteristic parameters in all directions. Therefore, as long as the arrangement of the ray source and the detector can make the projection data of the CT scan cover a sufficient scanning angle, the object can be accurately reconstructed. In actual implementation, due to the light path obstruction between the ray sources or between the ray source and the detector, it is difficult to obtain complete projection data when the ray source and the detector are arranged in the same plane. One solution is to set up multiple scanning planes, each plane is arranged with one or more groups of ray sources and one or more groups of detectors corresponding to each plane, and the scanned object passes through each scanning plane in turn through the conveyor to obtain complete projection data. Although this method can effectively improve the scanning coverage angle, the inspected object needs to pass through all scanning planes to complete the scanning, and the imaging time resolution will be limited by the running speed of the conveyor, and ultra-high time resolution real-time imaging cannot be achieved. In addition, in in-situ inspection applications, it is often difficult for the inspected object to move through the conveyor, and the imaging method of multiple scanning planes is difficult to apply. Another solution is to increase the scanning coverage angle by introducing small movements of the radiation source and detector (rotation or translation, etc.), but this method will increase the mechanical complexity of the system, and the movement speed of the radiation source and detector will limit the imaging time resolution of the system.

[0004] In existing CT scanning systems, usually only a single target emits X-rays at the same time, and the detector system can only receive signals after the rays pass through the object in a certain direction at a certain moment, and the imaging time resolution is limited. Static CT scanning systems can increase the emission frequency of distributed radiation sources and improve scanning speed by exposing multiple targets at the same time. However, existing methods often require that the detector pixels corresponding to the ray emission ranges of different targets do not overlap with each other, and the imaging field of view that can be achieved is limited, and can only image a local area of ​​the inspected object. Summary of the invention

[0005] The present invention provides a distributed ray source CT imaging system and imaging method, which optimizes the arrangement of ray sources and detectors, maintains the high time resolution imaging performance of the CT scanning system without introducing mechanical movement of the inspected object, ray sources and detectors, provides projection data that meets the needs of CT reconstruction, and improves the imaging quality.

[0006] A first aspect of the present invention provides a distributed ray source CT imaging system, comprising:

[0007] A ray source module, wherein the ray source module includes a plurality of ray sources, each of which includes at least one target point and is used to emit X-rays;

[0008] A ray source control module, used to control the ray source module to emit rays according to actual imaging requirements, so that one or more target points emit rays at the same time;

[0009] A detector module, wherein the detector module includes a plurality of detector components, each detector component includes a plurality of detector pixels, each detector component simultaneously receives rays emitted by one or more ray sources, and the rays emitted by each ray source target are received by one or more detector components, and the projection data of the region of interest of the inspected object is obtained by completely receiving the rays within the emission range of each target through each detector component, wherein the emission ranges of the targets exposed at the same time do not completely overlap on the detector module;

[0010] A main imaging plane, the main imaging plane includes a plurality of ray sources and a plurality of detector assemblies, the plurality of ray sources and the plurality of detector assemblies form a closed or approximately closed curve, the ray sources and the detector assemblies outside the main imaging plane are arranged on at least one plane along the traveling direction of the inspected object, each plane includes at least one ray source or detector assembly, wherein the ray source module and the detector module have an angular coverage range satisfying a preset imaging condition around a region of interest of the inspected object in the traveling direction of the inspected object;

[0011] The imaging module is used to reconstruct the region of interest of the inspected object using the projection data of the region of interest of the inspected object to obtain a reconstructed image of the region of interest of the inspected object.

[0012] Optionally, in one embodiment of the present invention, the ray source control module is further used to control the beam parameters, focal spot mode, emission range, beam sequence and beam combination mode of each target according to actual imaging requirements.

[0013] Optionally, in one embodiment of the present invention, the ray source module and the detector module have an angular coverage of not less than 180 degrees around a region of interest of the inspected object in a traveling direction of the inspected object.

[0014] Optionally, in one embodiment of the present invention, the imaging module is further used to:

[0015] In the non-aliased projection data, the projection data received by the detector pixels are pre-weighted according to the projection magnification ratio relationship of each ray source target point; the pre-weighted projection data are differentiated along the tangent direction of the line connecting the ray source target points or the line connecting the detector pixels; the differentiated projection data are back-projected to the space of the region of interest of the inspected object to be reconstructed, and the differential back-projection image components from a single ray source and a single detector assembly are obtained; the differential back-projection image components of all ray sources and detector assemblies are integrated for calculation, and the differential back-projection image results from all ray sources and detectors are obtained; the differential back-projection image results are subjected to finite inverse Hilbert transform along a specific direction to obtain a preliminary reconstructed image;

[0016] Taking the preliminary reconstructed image obtained by using the alias-free projection data as the initial value, using the alias-free projection data and the aliased projection data as well as the constraints of the projection relationship and the projection data, combined with iterative reconstruction or deep learning reconstruction technology, a reconstructed image of the area of ​​interest of the inspected object is obtained.

[0017] Optionally, in one embodiment of the present invention, the imaging module is further used to:

[0018] The projection data received by the detector pixels are pre-weighted by using the aliasing-free projection data and the aliasing projection data at the same time according to the projection magnification ratio of each ray source target point; the pre-weighted projection data is differentiated along the tangent direction of the line connecting the ray source target points or the line connecting the detector pixels; the differential projection data is back-projected to the space of the region of interest of the inspected object to be reconstructed, and the differential back-projection image components from a single ray source and a single detector assembly are obtained; a finite inverse Hilbert transform is performed along a specific direction in the space of the region of interest of the inspected object to obtain a preliminary reconstructed image component; the preliminary reconstructed image components of all ray sources and detector assemblies are accumulated to obtain a reconstructed image containing aliasing artifacts;

[0019] Iterative reconstruction is performed using aliasing-free projection data and aliasing projection data as well as projection relationships and projection data constraints to obtain a complete reconstructed image of the region of interest of the inspected object, or a pre-trained anti-aliasing artifact neural network model is used to remove aliasing artifacts in the reconstructed image to obtain a complete reconstructed image of the region of interest of the inspected object.

[0020] Optionally, in one embodiment of the present invention, the imaging module is further used to optimize the beam emission parameters and combination methods of the ray source target according to the position and structural characteristics or motion laws of the area of ​​interest in the inspected object; use multiple small-field-of-view targets to emit rays simultaneously or sequentially, and the rays are received by the detector unit without aliasing, and optimize the emission range and focal spot pattern to capture the instantaneous motion state and fine structural characteristics of the key focus area; use large-field-of-view targets to expose simultaneously or sequentially, and the rays have partial aliasing on the detector, complete the scanning of other areas, and perform image reconstruction after comprehensively utilizing the projection data of all targets to obtain a reconstructed image of the inspected object.

[0021] A second aspect of the present invention provides a distributed ray source CT imaging method. Using the distributed ray source CT imaging system described in the above embodiment, the imaging method comprises the following steps:

[0022] Determine the target arrangement of the ray source module and the detector module and the ray emission scheme of the ray source module according to the actual imaging requirements;

[0023] Under the target arrangement mode of the ray source module and the detector module, the ray source is controlled to emit a beam according to the ray emission scheme, and the projection data of the region of interest of the inspected object is received by the detector module;

[0024] The projection data of the region of interest of the inspected object is used for reconstruction to obtain a reconstructed image of the region of interest of the inspected object.

[0025] Optionally, in one embodiment of the present invention, determining the target arrangement of the ray source module and the detector module and the ray emission scheme of the ray source module according to actual imaging requirements includes:

[0026] According to actual imaging requirements, multiple ray sources and multiple detector assemblies are arranged on the main imaging plane, the multiple ray sources and multiple detector assemblies form a closed or approximately closed curve, the ray sources and detector assemblies outside the main imaging plane are arranged on at least one plane along the traveling direction of the inspected object, each plane includes at least one ray source and detector assembly, and the ray source module and the detector module have an angular coverage range that meets preset imaging conditions around the region of interest of the inspected object in the traveling direction of the inspected object;

[0027] The beam parameters, focal spot pattern, emission range, beam sequence and beam combination method of each target point of the ray source are determined according to the actual imaging requirements.

[0028] Optionally, in one embodiment of the present invention, reconstructing using the projection data of the region of interest of the inspected object to obtain a reconstructed image of the region of interest of the inspected object includes:

[0029] In the alias-free projection data, the projection data received by the detector pixels are pre-weighted according to the projection magnification ratio relationship of each ray source target point;

[0030] Differentiate the pre-weighted projection data along the tangent direction of the line connecting the ray source and the target points or the line connecting the detector pixels;

[0031] Back-projecting the differentiated projection data to the space of the region of interest of the inspected object to be reconstructed, to obtain a differential back-projection image component from a single ray source and a single detector assembly;

[0032] The differential back-projection image components of all ray sources and detector components are calculated to obtain the differential back-projection image results from all ray sources and detectors; the differential back-projection image results are subjected to finite inverse Hilbert transform along a specific direction to obtain a preliminary reconstructed image;

[0033] Taking the preliminary reconstructed image obtained by using the non-aliasing projection data as the initial value, using the non-aliasing projection data and the aliasing projection data as well as the projection relationship and the constraints of the projection data, combined with iterative reconstruction or deep learning reconstruction technology, a reconstructed image of the region of interest of the inspected object is obtained;

[0034] Optionally, in one embodiment of the present invention, reconstructing using the projection data of the inspected object to obtain a reconstructed image of the inspected object includes:

[0035] At the same time, the projection data received by the detector pixels are pre-weighted according to the projection magnification ratio relationship of each ray source target point by using the non-aliasing projection data and the aliasing projection data;

[0036] Differentiate the pre-weighted projection data along the tangent direction of the line connecting the target points of the ray source or the line connecting the pixels of the detector; back-project the differential projection data to the space of the region of interest of the inspected object to be reconstructed, and obtain a differential back-projection image component from a single ray source and a single detector assembly;

[0037] Performing a finite inverse Hilbert transform along a specific direction in the space of the region of interest of the inspected object obtains a preliminary reconstructed image component;

[0038] Accumulating the preliminary reconstructed image components of all the ray sources and detector components to obtain a reconstructed image containing aliasing artifacts;

[0039] Iterative reconstruction is performed using aliasing-free projection data and aliasing projection data as well as projection relationships and projection data constraints to obtain a complete reconstructed image of the region of interest of the inspected object, or a pre-trained anti-aliasing artifact neural network model is used to remove aliasing artifacts in the reconstructed image to obtain a complete reconstructed image of the region of interest of the inspected object.

[0040] Optionally, in one embodiment of the present invention, the beam emission parameters and combination methods of the radiation source target are optimized according to the position and structural characteristics or motion laws of the area of ​​interest in the inspected object; multiple small-field-of-view targets are used to emit rays simultaneously or sequentially, and the rays are received by the detector unit without aliasing, and the emission range and focal spot pattern are optimized to capture the instantaneous motion state and fine structural characteristics of the key focus area; large-field-of-view targets are used to expose simultaneously or sequentially, and the rays have partial aliasing on the detector, and the scanning of other areas is completed. The projection data of all targets are comprehensively utilized to perform image reconstruction to obtain a reconstructed image of the inspected object.

[0041] The distributed ray source CT imaging system and imaging method described in the embodiments of the present invention have the following beneficial effects:

[0042] 1. The imaging system can improve the scanning angle of the inspection area covered by the existing system without introducing mechanical movement of the scanned object, the radiation source module, and the detector module. It can provide more complete detection data, improve imaging quality and accuracy, and achieve fast scanning and high time resolution imaging;

[0043] 2. In the imaging system, the projection relationship between the ray source and the detector is flexible, multiple ray source components can share the same detector component, and the rays emitted by one ray source component can be received by multiple detector components. Compared with the method of forming multiple sub-imaging chains with "one-to-one correspondence" sources and detectors, the comprehensive utilization efficiency of the ray source and detector of the system of the present invention is higher, and more complete data sampling can be achieved;

[0044] 3. The arrangement of the ray source and detector of the imaging system effectively improves the data sampling quality of the distributed ray source static CT, which not only avoids the loss of scanning angle caused by the light path shielding in the source-detector coplanar arrangement, but also improves the data incompleteness caused by the oblique ray in the source-detector non-planar arrangement, thus achieving the comprehensive optimization of scanning angle coverage and data completeness;

[0045] 4. The imaging system makes full use of the flexibility of distributed ray source CT imaging in scanning mode, and can realize personalized, task-oriented source and detector arrangement optimization design. In practical applications, according to the imaging requirements and the location of interest and spatial structure characteristics of the inspected object, the arrangement of ray sources or detectors can be freely selected under the system architecture of the present invention to improve the scanning range of the imaging system and the signal acquisition quality of the area of ​​interest;

[0046] 5. The imaging method proposed based on this imaging system can greatly improve the utilization efficiency of the detector, increase the projection viewing angle acquisition speed and improve the imaging time resolution while ensuring the imaging field of view;

[0047] 6. The imaging method proposed based on this imaging system can effectively improve the imaging effect of dynamic imaging. According to the distribution and change law of the internal motion state of the object in time and space scales, a personalized ray beam strategy is provided, which can not only improve the refinement of the scanning of the motion process, but also ensure the quality of the sampling data of the static area.

[0048] 7. The CT image reconstruction method can be applied to static CT or dynamic slip ring CT imaging systems in which the radiation source and detector are arranged in any form (multi-plane, multi-segment, etc.), and can effectively solve the signal aliasing problem caused by the simultaneous beam output of multiple targets, thereby improving the flexibility and freedom of system design and scanning strategies.

[0049] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0051] Figure 1 A schematic diagram of the structure of a distributed ray source CT imaging system according to an embodiment of the present invention;

[0052] Figure 2 A schematic diagram of geometric parameter definition according to an embodiment of the present invention;

[0053] Figure 3 A typical system structure diagram according to an embodiment of the present invention;

[0054] Figure 4 A schematic diagram of a "double C-shaped" system structure according to an embodiment of the present invention;

[0055] Figure 5 A schematic diagram of a system optimization structure for improving sampling density of perspectives of interest according to an embodiment of the present invention;

[0056] Figure 6 A schematic diagram of a system optimization structure for changing the spatial position of the optimal imaging area according to an embodiment of the present invention;

[0057] Figure 7 Schematic diagram of simultaneous full-view multi-target scanning imaging according to an embodiment of the present invention;

[0058] Figure 8 A schematic diagram of simultaneous scanning and imaging of multiple targets at different fields of view according to an embodiment of the present invention;

[0059] Fig. 9 The present invention provides a flowchart of a distributed ray source CT imaging method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0060] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0061] Figure 1 FIG. 4 is a schematic diagram of the structure of a distributed ray source CT imaging system according to an embodiment of the present invention.

[0062] like Figure 1 As shown, the distributed ray source CT imaging system 10 includes:

[0063] A ray source module 100, the ray source module includes a plurality of ray sources, each of which includes at least one target point, and is used to emit X-rays;

[0064] A ray source control module 200, used to control the ray source module to emit rays according to actual imaging requirements, so that one or more target points emit X-rays at the same time;

[0065] A detector module 300, wherein the detector module includes a plurality of detector components, each of which includes a plurality of detector pixels, each of which simultaneously receives rays emitted by one or more ray sources, and the rays emitted by each ray source target are received by one or more detector components, and the projection data of the region of interest of the inspected object is obtained by completely receiving the rays within the emission range of each target through each detector component, wherein the emission ranges of the targets exposed at the same time do not completely overlap on the detector module;

[0066] The main imaging plane ( Figure 1(not shown), a plurality of ray sources and a plurality of detector assemblies are included on the main imaging plane, the plurality of ray sources and the plurality of detector assemblies form a closed or approximately closed curve, the ray sources and the detector assemblies outside the main imaging plane are arranged on at least one plane along the traveling direction of the inspected object, each plane includes at least one ray source or detector assembly, wherein the ray source module and the detector module have an angular coverage range satisfying a preset imaging condition around the region of interest of the inspected object in the traveling direction of the inspected object;

[0067] The imaging module 400 is used to reconstruct the region of interest of the inspected object using the projection data of the region of interest of the inspected object to obtain a reconstructed image of the region of interest of the inspected object.

[0068] It is understandable that in an actual distributed ray source CT imaging system, the arrangement of the ray source and the detector unit can be reset according to the actual imaging requirements, and the emission scheme of the ray source and the receiving scheme of the detector unit can be adjusted in combination with the existing arrangement of the ray source and the detector unit to meet the actual imaging requirements. In this regard, the present invention does not make specific limitations, and is intended to adjust and select the ray emission and receiving schemes of the ray source and the detector unit according to the actual imaging requirements and the region of interest and structural characteristics of the object under examination.

[0069] When imaging is performed, the carrying device carries the inspected object along the traveling direction so that the inspected object can enter the imaging area. Observed along the traveling direction, the ray source module and the detector module have an angle coverage around the inspected object's region of interest that meets the preset imaging conditions. Specifically, the ray source module and the detector module are adjusted according to the conditions required for imaging. For example, when the region of interest becomes larger or smaller, the monitoring coverage is increased or decreased. In a specific embodiment, the ray source module and the detector module have an angle coverage of not less than 180 degrees around the inspected object's region of interest in the traveling direction of the inspected object.

[0070] In order to minimize the impact of oblique radiation, the system includes a main imaging plane, and multiple radiation sources and detector assemblies are arranged on the main imaging plane. In order to reduce the impact of light path obstruction and improve the utilization efficiency of the detector, the radiation sources and detector assemblies in the main imaging plane form a closed or nearly closed curve, without blocking each other, and the detector module has an angular coverage range around the inspected object that meets the preset imaging conditions. The remaining radiation sources and detector assemblies can be arranged in one or more planes along the direction of travel, and each plane can include one or more radiation sources and one or more detector assemblies. Multiple detector assemblies at least cover the radiation emission range of the radiation source module, and the emission range of the target exposed at the same time can be allowed to partially overlap but not completely overlap on the detector module.

[0071] In one embodiment of the present invention, the radiation source and detector assembly outside the main imaging plane are arranged in at least one plane along the traveling direction of the inspected object, and the angle between each plane and the traveling direction is adjusted according to actual imaging requirements so that the angle between each plane and the traveling direction is perpendicular or at a preset angle.

[0072] Specifically, according to actual imaging requirements and structural features of the inspected object, each plane can be perpendicular to the direction of travel or at a specific angle, and the arrangement of the ray source and detector components in each plane can be flexibly adjusted.

[0073] In one embodiment of the present invention, the ray source control module 300 is further used to control the beam parameters, focal spot mode, emission range, beam sequence and beam combination mode of each target according to actual imaging requirements.

[0074] During the scanning process, the carrier device first transports the inspected object to the imaging area along the traveling direction. The ray source control device controls each ray source to emit rays, wherein one or more targets may emit rays at the same time; the beam parameters (tube current, tube voltage, etc.) and focal spot mode (focal spot size and beam power mode) of each target can be optimized and adjusted according to specific imaging requirements (such as dose optimization, local area high-resolution imaging, multi-energy imaging, etc.) to meet personalized scanning requirements; the target beam sequence and combination method can be optimized according to the structural characteristics of the imaging object and the position of the region of interest; each ray source can include a collimator to limit the ray emission range, and the emission range of each target can be different. Each detector component in the detector module can completely receive all the rays within the emission range of each target, and the emission range of the target exposed at the same time can be partially overlapped but not completely overlapped on the detector module. The rays within the emission range of each ray source may be received by one or more detector components, and each detector component may simultaneously receive rays emitted by one or more targets, and the corresponding relationship between different ray sources and detectors is different. After multiple rounds of exposure of each target point, when the projection data meets the requirements of CT image reconstruction, the carrying device transports the inspected object away from the imaging area along the direction of travel to complete the scan.

[0075] In one embodiment of the present invention, the imaging module is further used to pre-weight the projection data received by the detector pixels according to the projection magnification ratio relationship of each ray source target point in the non-aliasing projection data; differentiate the pre-weighted projection data along the tangent direction of the line connecting the ray source target points or the line connecting the detector pixels; back-project the differentiated projection data to the space of the region of interest of the inspected object to be reconstructed to obtain the differential back-projection image component from a single ray source and a single detector assembly; comprehensively calculate the differential back-projection image components of all ray sources and detector assemblies to obtain the differential back-projection image results from all ray sources and detectors; perform a finite inverse Hilbert transform on the differential back-projection image result along a specific direction to obtain a preliminary reconstructed image;

[0076] Taking the preliminary reconstructed image obtained by using the alias-free projection data as the initial value, using the alias-free projection data and the aliased projection data as well as the constraints of the projection relationship and the projection data, combined with iterative reconstruction or deep learning reconstruction technology, a reconstructed image of the area of ​​interest of the inspected object is obtained.

[0077] In the embodiment of the present application, the radiation source assembly consists of N S The ray sources consist of (N S ≥1), the rays within the emission range of each ray source can be D The detector components receive (N D ≥1). Generally, each ray source (ray source number is i, target coordinate parameter is l) and detector assembly (detector assembly number is j, crystal coordinate parameter is s) are regarded as an imaging subsystem. The projection data p collected by the detector assembly i,j (l,s) can be divided into two parts: ① Non-aliased projection: the detector crystal only receives rays within the emission range of a single target; ② Aligned projection: the detector crystal receives rays within the emission range of two or more targets. A rectangular coordinate system is established with the center of the scanned object as the origin. The geometric parameters are defined as follows: Figure 2 shown.

[0078] In a specific embodiment, image reconstruction can be completed through the following three steps:

[0079] (A) According to the projection relationship adopted by the actual system, the projection data is divided into aliased projections With no-aliasing projection

[0080] (B) Using alias-free projection data

[0081] ① According to the relationship between the distance between the ray source, the detector and the area to be reconstructed and the projection magnification ratio, an "equivalent detector" (with the crystal coordinate parameter u) passing through the coordinate origin and parallel to the detector is introduced. The projection data under the equivalent detector can be expressed as And pre-weight the projection:

[0082]

[0083] Among them, α i,j represents the angle between the ray source i and the detector j, D so Indicates the distance from the origin to the ray source, L i,j (l,u) represents the distance from the target point l to the equivalent detector crystal u, ξ is the angle between the defined Hilbert transform direction and the positive half axis of the y-axis, and θ is the angle between the ray and the positive half axis of the y-axis.

[0084] ② Differentiate the weighted projection along the tangent direction of the detector crystal line:

[0085]

[0086] ③ Back-project the data processed by ② to the object space to be reconstructed to obtain the differential back-projection image components of a single ray source module and a detector module

[0087]

[0088] Among them, R i,j (l) is the length of the vertical line from the target point l to the equivalent detector, Represents the target point l and the point to be reconstructed The length of the line projected from the target point to the perpendicular line of the equivalent detector, Indicates the point to be rebuilt Coordinates projected onto the equivalent detector.

[0089] Repeat steps ①-③ for all ray source modules and detector components and add them up to get the differential back-projection image.

[0090] ④ Perform a finite inverse Hilbert transform along the ξ direction in the object space to obtain the reconstructed image

[0091] (C) Comprehensively utilize the aliased projection and non-aliased projection data, take the reconstructed image obtained in (B) as the initial value, and use the projection relationship and the constraints of the projection data to perform iterative reconstruction to obtain a complete reconstructed image of the scanned object: ① For each detector component j, model the projection relationship of each target point emitting X-rays ② Construct a de-aliasing neural network or use an iterative reconstruction method to obtain a complete three-dimensional reconstructed image of the inspected object

[0092] In one embodiment of the present invention, the imaging module is further configured to:

[0093] The projection data received by the detector pixels are pre-weighted by using the aliasing-free projection data and the aliasing projection data at the same time according to the projection magnification ratio of each ray source target point; the pre-weighted projection data is differentiated along the tangent direction of the line connecting the ray source target points or the line connecting the detector pixels; the differential projection data is back-projected to the space of the region of interest of the inspected object to be reconstructed, and the differential back-projection image components from a single ray source and a single detector assembly are obtained; a finite inverse Hilbert transform is performed along a specific direction in the space of the region of interest of the inspected object to obtain a preliminary reconstructed image component; the preliminary reconstructed image components of all ray sources and detector assemblies are accumulated to obtain a reconstructed image containing aliasing artifacts;

[0094] Iterative reconstruction is performed using aliasing-free projection data and aliasing projection data as well as projection relationships and projection data constraints to obtain a complete reconstructed image of the region of interest of the inspected object, or a pre-trained anti-aliasing artifact neural network model is used to remove aliasing artifacts in the reconstructed image to obtain a complete reconstructed image of the region of interest of the inspected object.

[0095] In a specific embodiment, image reconstruction can be completed through the following three steps:

[0096] (A) Using all projection data (including aliased and non-aliased projections).

[0097] ① According to the relationship between the distance between the ray source, the detector and the area to be reconstructed and the projection magnification ratio, an "equivalent detector" (with the crystal coordinate parameter u) passing through the coordinate origin and parallel to the detector is introduced. The projection data under the equivalent detector can be expressed as p i,j (l,u), and pre-weight the projection:

[0098]

[0099] Among them, α i,j represents the angle between the ray source i and the detector j, D SO Indicates the distance from the origin to the ray source, L i,j (l,u) represents the distance from the target point l to the equivalent detector crystal u, ξ i,j is the angle between the defined Hilbert transform direction and the positive half axis of the y-axis, and θ is the angle between the ray and the positive half axis of the y-axis.

[0100] ② Differentiate the weighted projection along the tangent direction of the detector crystal line:

[0101]

[0102] ③ Back-project the data processed by ② to the object space to be reconstructed to obtain the differential back-projection image components of a single ray source module and a detector module

[0103]

[0104] Among them, R i,j (l) is the length of the vertical line from the target point l to the equivalent detector, Represents the target point l and the point to be reconstructed The length of the line projected from the target point to the perpendicular line of the equivalent detector, Indicates the point to be rebuilt Coordinates projected onto the equivalent detector.

[0105] ④ In the object space along ξ i,j The finite inverse Hilbert transform is performed in the direction to obtain the initial reconstructed image components

[0106] (B) Repeat steps ①-④ for all ray source modules and detector units and add them together to obtain a preliminary reconstructed image containing aliasing artifacts.

[0107] (C) Based on the projection relationship adopted by the actual system, the public data set available in the field is used to simulate the projection data, and the paired reconstructed image with aliasing artifacts and the true value image are obtained through the steps in (A). On the simulated data set, an artificial neural network is trained to remove aliasing artifacts.

[0108] (D) For the aliased projection data collected by the actual system, the steps in (A) are used to obtain a reconstructed image containing aliasing artifacts. The artificial neural network trained in (B) is used to remove the aliasing artifacts and obtain the final reconstructed image. On this basis, the quality of the reconstructed image can be further improved by combining strategies such as multi-stage reasoning and iterative fine-tuning of the neural network.

[0109] Optionally, in one embodiment of the present invention, the imaging module is further used to optimize the beam emission parameters and combination methods of the radiation source target according to the position and structural characteristics or motion laws of the area of ​​interest in the inspected object; use multiple small-field-of-view targets to emit rays simultaneously or sequentially, and the rays are received by the detector unit without aliasing, and optimize the emission range and focal spot pattern to capture the instantaneous motion state and fine structural characteristics of the key focus area; use large-field-of-view targets to expose simultaneously or sequentially, and the rays have partial aliasing on the detector, and complete the scanning of other areas, and perform image reconstruction after comprehensively utilizing the projection data of all targets to obtain a reconstructed image of the inspected object.

[0110] The distributed ray source CT imaging system of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0111] Example 1

[0112] System structure Figure 3 As shown in (a), the moving direction of the scanned object is defined as the axial direction (z direction), and all detector modules 200 are arranged in the main imaging plane, which is substantially perpendicular to the axial direction. Figure 3 (b)), all detector components have a coverage of greater than 180 degrees around the imaging area (e.g. Figure 3 (c)); the ray source target points of the ray source module 100 are arranged in the main imaging plane and the second ray source plane. The positions of the target points and the detector assembly in the main imaging plane do not overlap, and the rays emitted by each target point can pass through the imaging area and be received by the detector assembly. The second ray source plane is parallel to the main imaging plane or has a specific deflection angle, and the rays emitted by each target point in the second ray source plane can pass through the imaging area and be received by the detector assembly, and are not blocked by the detector assembly and the ray source in the main imaging plane. The ray source target points and the detector assembly can be arranged in various forms in the plane, including but not limited to straight lines, arcs, multi-segment broken lines, etc. When viewed along the axial direction, each target point in the main imaging plane has a coverage range of less than 180 degrees around the imaging area, and each target point in the main imaging plane and the second ray source plane has a combined scanning angle of greater than 180 degrees around the imaging area (such as Figure 3 (c)) can achieve high-quality reconstruction of the scanned object.

[0113] Example 2

[0114] System structure Figure 4 As shown, the moving direction of the scanned object is defined as the axial direction, all detector components of the detector module are arranged in the main imaging plane, and when observed in the axial direction, all detector components have a coverage range of more than 180 degrees around the imaging area; the ray source target of the ray source module is arranged in the main imaging plane and the second ray source plane, and when observed in the axial direction, all ray source targets have a coverage range of more than 180 degrees around the imaging area. The main imaging plane is substantially perpendicular to the axial direction, and the second ray source plane intersects with the main imaging plane. The ray source and the detector module in the main imaging plane and the second ray source plane are not closed, which helps to improve the flexibility and convenience of the scanning system in special application scenarios such as in-situ inspection.

[0115] Example 3

[0116] The system structure can be further optimized by combining the location and structural features of the region of interest. In some applications, the density of the arrangement of the ray source target is often limited by many factors such as hardware and process, and it is difficult to improve. In all or part of the specific sampling angles, increasing the angular sampling density will help improve the imaging quality of fine structures. Therefore, according to the structural features of the scanned object, the arrangement of the ray source in part of the projection angle can be optimized to improve the sampling density. Under the system structure of Example 1, observing along the axial direction, the sampling density of the angle of interest in a local area of ​​the imaging area is as follows: Figure 5 An improved system structure is shown in (a). Figure 5 As shown in (b), by optimizing the arrangement of the ray sources, the sampling density of the angle of interest can be increased without changing the existing device process, thereby improving the imaging effect. Without loss of generality, in some scenarios, the detector sampling density can also be increased in a similar manner.

[0117] Example 4

[0118] The system structure can be further optimized by combining the location and structural characteristics of the region of interest. The direction of travel of the scanned object is defined as the axial direction, the direction radiating outward from the central axis in a plane perpendicular to the travel direction is defined as the radial direction, and the direction perpendicular to the radial direction in a plane perpendicular to the travel direction is defined as the circumferential direction. In most systems, the arrangement or trajectory of the radiation source target and the detector is basically arranged in a circularly symmetrical manner along the circumferential direction, so the sampling signal quality on the central axis is optimal, and the imaging field of view is symmetrically distributed along the central axis (such as Figure 6 (a)). However, in some applications (such as human heart examination), the region of interest is not located on the central axis, so the sampling signal quality of the region of interest can be improved by optimizing the arrangement of the ray sources. Under the system structure of Example 1, the spatial position of the second ray source plane and the focus position and arrangement in the plane can be optimized. For the region of interest that deviates from the central axis, in order to obtain a larger axial field of view, the second ray source plane may be non-parallel to the main imaging plane but at a specific angle, and the distance between the ray source module and the central axis can be adjusted so that the area with the largest axial field of view deviates from the central axis and is near the region of interest (such as Figure 6 (b)). In order to improve the sampling density or signal quality at certain viewing angles, the distances between each target point in the second ray source plane and the central axis may be different, and the design may be optimized as needed. In some embodiments, a third ray source plane may be added, and at certain specific viewing angles, the ray source module may be arranged to improve the angular sampling density.

[0119] The distributed ray source CT imaging strategy of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0120] Example 1

[0121] Observed along the axial direction, the arrangement of the radiation source target and the detector assembly is as follows: Figure 7 As shown. Without loss of generality, in this embodiment, the ray source target and the detector assembly are arranged in a folded line. During the imaging process, the scanned object is transported from the carrying device along the travel direction to the imaging area (such as Figure 7 The central gray circular area). During the scanning process, multiple radiation source targets of the radiation source module can be exposed and emitted at the same time. The figure shows a schematic diagram of four targets emitting radiation at the same time at a certain moment. After the rays emitted by multiple targets pass through the imaging area, they can all be received by the detector assembly, among which some detector assembly pixels only receive the radiation signal from one target, which is called non-aliasing projection (such as Figure 7 The red part of the detector in the middle), some detector component pixels receive radiation signals from two or more targets at the same time, which is called aliasing projection (such as Figure 7 The blue part in the middle). The X-ray flux and tube voltage of each ray source target can be optimized according to actual needs to achieve specific goals such as multi-energy imaging and radiation dose optimization. After multiple groups of targets are exposed and the projection data meets the image reconstruction requirements, the scan is completed.

[0122] Example 2

[0123] Observed along the axial direction, the arrangement of the radiation source target and the detector assembly is as follows: Figure 8 During the imaging process, the scanned object is transported by the carrying device along the travel direction to the imaging area (such as Figure 8 In some application scenarios, the local area of ​​interest of the scanned object changes dynamically (such as Figure 8 The orange circular area in the middle is where the light is, while the rest of the area remains still. In order to ensure high temporal resolution imaging effect in the local area of ​​interest, effectively reduce the projection aliasing effect, and improve the overall imaging quality, the ray source module also includes a collimator to limit the ray emission range, and the emission range corresponding to each target point may be different. Without loss of generality, after being limited by the collimator, each ray source target point can be divided into at least two categories according to the emission range: ① Large field of view target (gray dots in the figure): the emission range can completely cover the scanned object; ② Small field of view target (black dots in the figure): the emission range can only cover the local area of ​​interest of the scanned object, and can be switched to a smaller focal spot mode to obtain a higher projection resolution. At any time, the detector component pixels that only receive rays from one target point are defined as non-aliasing signal detector pixels, and the detector component pixels that receive rays from two or more targets at the same time are defined as aliasing signal detector pixels. During the scanning process, multiple radiation source targets can be exposed and emitted at the same time, and there can be many different combinations: ① Multiple small field of view targets are exposed at the same time, and the radiation emitted by each target is received by the non-aliased signal detector pixel to capture the instantaneous motion state of the local area of ​​interest (such as Figure 8 (a)); large field of view targets are exposed sequentially or simultaneously to complete the scanning of the static area. ② Combined exposure of multiple large field of view and small field of view targets (such as Figure 8 (b)), the rays emitted by some targets are only received by the pixels of the non-aliasing signal detector, and the non-aliasing signal is obtained; the rays emitted by the remaining targets are partially aliased, and the aliased signal is obtained after being received by the detector component. The scanning process can be completed by using multiple rounds of the above combination, and the scanning is completed after the projection data meets the image reconstruction requirements.

[0124] The distributed ray source CT imaging system of the present invention optimizes the arrangement of the ray source and the detector, maintains the high time resolution imaging performance of the CT scanning system without introducing mechanical movement of the inspected object, the ray source and the detector, provides projection data that meets the needs of CT reconstruction, and improves the imaging quality. In practical applications, the arrangement of the ray source is flexibly designed in combination with actual imaging requirements (for example, encrypted angle sampling, expanded imaging field of view, etc.), the position and structural characteristics of the region of interest of the inspected object, and improves the scanning range of the imaging system and the signal acquisition quality of the region of interest. The present invention can be flexibly applied to different CT scanning modes and system architectures, and can be used in the fields of medical diagnosis, industrial non-destructive testing, and security inspection.

[0125] Next, the distributed ray source CT imaging method proposed in an embodiment of the present invention is described with reference to the accompanying drawings.

[0126] Fig. 9 4 is a flow chart of a distributed ray source CT imaging method according to an embodiment of the present invention.

[0127] like Fig. 9 As shown, the distributed ray source CT imaging method utilizes the distributed ray source CT imaging system of the above embodiment, and the distributed ray source CT imaging method includes the following steps:

[0128] In step S101, a target arrangement of ray source modules and detector modules and a ray emission scheme of the ray source modules are determined according to actual imaging requirements.

[0129] In step S102, under the target arrangement of the ray source module and the detector module, the ray source is controlled to emit a beam according to the ray emission plan, and the detector module is used to receive projection data of the region of interest of the inspected object.

[0130] In step S103, reconstruction is performed using the projection data of the region of interest of the inspected object to obtain a reconstructed image of the region of interest of the inspected object.

[0131] Optionally, in one embodiment of the present invention, determining the target arrangement of the ray source module and the detector module and the ray emission scheme of the ray source module according to actual imaging requirements includes:

[0132] According to actual imaging requirements, multiple ray sources and multiple detector assemblies are arranged on the main imaging plane, the multiple ray sources and multiple detector assemblies form a closed or approximately closed curve, the ray sources and detector assemblies outside the main imaging plane are arranged on at least one plane along the traveling direction of the inspected object, each plane includes at least one ray source and detector assembly, and the ray source module and the detector module have an angular coverage range that meets preset imaging conditions around the region of interest of the inspected object in the traveling direction of the inspected object;

[0133] The beam parameters, focal spot pattern, emission range, beam sequence and beam combination method of each target point of the ray source are determined according to the actual imaging requirements.

[0134] Optionally, in one embodiment of the present invention, the ray source module and the detector module have an angular coverage of not less than 180 degrees around the region of interest of the inspected object in the traveling direction of the inspected object.

[0135] Optionally, in one embodiment of the present invention, reconstructing using projection data of a region of interest of the inspected object to obtain a reconstructed image of the region of interest of the inspected object includes:

[0136] In the alias-free projection data, the projection data received by the detector pixels are pre-weighted according to the projection magnification ratio relationship of each ray source target point;

[0137] Differentiate the pre-weighted projection data along the tangent direction of the line connecting the ray source and the target points or the line connecting the detector pixels;

[0138] Back-projecting the differentiated projection data to the space of the region of interest of the inspected object to be reconstructed, to obtain a differential back-projection image component from a single ray source and a single detector assembly;

[0139] The differential back-projection image components of all ray sources and detector components are calculated to obtain the differential back-projection image results from all ray sources and detectors; the differential back-projection image results are subjected to finite inverse Hilbert transform along a specific direction to obtain a preliminary reconstructed image;

[0140] Taking the preliminary reconstructed image obtained by using the aliasing-free projection data as the initial value, using the aliasing-free projection data and the aliasing projection data as well as the constraints of the projection relationship and the projection data, combined with iterative reconstruction or deep learning reconstruction technology, a reconstructed image of the area of ​​interest of the inspected object is obtained.

[0141] Optionally, in one embodiment of the present invention, reconstructing using projection data of the inspected object to obtain a reconstructed image of the inspected object includes:

[0142] At the same time, the projection data received by the detector pixels are pre-weighted according to the projection magnification ratio relationship of each ray source target point by using the non-aliasing projection data and the aliasing projection data;

[0143] Differentiate the pre-weighted projection data along the tangent direction of the line connecting the target points of the ray source or the line connecting the pixels of the detector; back-project the differential projection data to the space of the region of interest of the inspected object to be reconstructed, and obtain a differential back-projection image component from a single ray source and a single detector assembly;

[0144] Performing a finite inverse Hilbert transform along a specific direction in the space of the region of interest of the inspected object obtains a preliminary reconstructed image component;

[0145] Accumulating the preliminary reconstructed image components of all the ray sources and detector components to obtain a reconstructed image containing aliasing artifacts;

[0146] Iterative reconstruction is performed using aliasing-free projection data and aliasing projection data as well as projection relationships and projection data constraints to obtain a complete reconstructed image of the region of interest of the inspected object, or a pre-trained anti-aliasing artifact neural network model is used to remove aliasing artifacts in the reconstructed image to obtain a complete reconstructed image of the region of interest of the inspected object.

[0147] Optionally, in one embodiment of the present invention, the beam emission parameters and combination methods of the radiation source target are optimized according to the position and structural characteristics or motion laws of the area of ​​interest in the inspected object; multiple small-field-of-view targets are used to emit rays simultaneously or sequentially, and the rays are received by the detector unit without aliasing, and the emission range and focal spot pattern are optimized to capture the instantaneous motion state and fine structural characteristics of the key focus area; large-field-of-view targets are used to expose simultaneously or sequentially, and the rays have partial aliasing on the detector, and the scanning of other areas is completed. The projection data of all targets are comprehensively utilized to perform image reconstruction to obtain a reconstructed image of the inspected object.

[0148] In one embodiment of the present invention, the radiation source and detector assembly outside the main imaging plane are arranged in at least one plane along the traveling direction of the inspected object, and the angle between each plane and the traveling direction is adjusted according to actual imaging requirements so that the angle between each plane and the traveling direction is perpendicular or at a preset angle.

[0149] It should be noted that the aforementioned explanation of the embodiment of the distributed ray source CT imaging system is also applicable to the distributed ray source CT imaging method of this embodiment, and will not be repeated here.

[0150] The distributed ray source CT imaging method proposed in an embodiment of the present invention can be applied to static CT or dynamic slip ring CT imaging systems in which ray sources and detectors are arranged in any form (multi-plane, multi-segment, etc.), and can effectively solve the aliasing problem caused by simultaneous beam emission of multiple targets, thereby improving the flexibility and freedom of system design and scanning strategies.

[0151] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0152] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0153] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

Claims

1. A distributed ray source CT imaging system, characterized in that: include: A ray source module, wherein the ray source module includes a plurality of ray sources, each of which includes at least one target point for emitting X-rays, and each ray source target point is divided into a large field of view target point and a small field of view target point according to an emission range, wherein the emission range of the large field of view target point completely covers the inspected object, and the emission range of the small field of view target point only covers the region of interest of the inspected object, and during the scanning process, the small field of view target point and the large field of view target point emit rays simultaneously or sequentially; A ray source control module, used to control the ray source module to emit rays according to actual imaging requirements, so that one or more target points emit rays at the same time; A main imaging plane, the main imaging plane includes a plurality of ray sources and a plurality of detector assemblies, the plurality of ray sources and the plurality of detector assemblies form a closed or approximately closed curve, the ray sources outside the main imaging plane are arranged on at least one plane along the traveling direction of the inspected object, each plane includes at least one ray source, the rays emitted by each target point of the ray sources on the main imaging plane and the plane outside the main imaging plane pass through the imaging area and can be received by the detector assembly on the main imaging plane, wherein the ray source module and the detector module have an angular coverage range satisfying a preset imaging condition around the region of interest of the inspected object in the traveling direction of the inspected object; A detector module, wherein the detector module comprises a plurality of detector components, and the plurality of detector components are distributed on a main imaging plane, and are used to receive rays emitted from each target point of a ray source in the main imaging plane and a plane outside the main imaging plane, wherein each detector component comprises a plurality of detector pixels, and each detector component simultaneously receives rays emitted from one or more ray sources, and rays emitted from each ray source target point are received by one or more detector components, and projection data of an area of ​​interest of the inspected object is obtained by completely receiving rays within an emission range of each target point through each detector component, wherein the emission ranges of the targets exposed at the same time do not completely overlap on the detector module, and when the detector component receives rays within the emission range of only a single target point, the projection data is non-aliasing projection data, and when the detector component receives rays within the emission ranges of two or more targets, the projection data is aliasing projection data; The imaging module is used to reconstruct the region of interest of the inspected object using the projection data of the region of interest of the inspected object to obtain a reconstructed image of the region of interest of the inspected object.

2. The system according to claim 1, characterized in that The ray source control module is further used to control the beam parameters, focal spot mode, emission range, beam sequence and beam combination mode of each target point according to actual imaging requirements.

3. The system according to claim 1, characterized in that The ray source module and the detector module have an angular coverage range of not less than 180 degrees around a region of interest of the inspected object in a traveling direction of the inspected object.

4. The system according to claim 1, characterized in that The imaging module is further used to: In the non-aliased projection data, the projection data received by the detector pixels are pre-weighted according to the projection magnification ratio relationship of each ray source target point; the pre-weighted projection data are differentiated along the tangent direction of the line connecting the ray source target points or the line connecting the detector pixels; the differentiated projection data are back-projected to the space of the region of interest of the inspected object to be reconstructed, and the differential back-projection image components from a single ray source and a single detector assembly are obtained; the differential back-projection image components of all ray sources and detector assemblies are integrated for calculation, and the differential back-projection image results from all ray sources and detectors are obtained; the differential back-projection image results are subjected to finite inverse Hilbert transform along a specific direction to obtain a preliminary reconstructed image; Taking the preliminary reconstructed image obtained by using the alias-free projection data as the initial value, using the alias-free projection data and the aliased projection data as well as the constraints of the projection relationship and the projection data, combined with iterative reconstruction or deep learning reconstruction technology, a reconstructed image of the area of ​​interest of the inspected object is obtained.

5. The system according to claim 1, characterized in that The imaging module is further used to: The projection data received by the detector pixels are pre-weighted by using the aliasing-free projection data and the aliasing projection data at the same time according to the projection magnification ratio of each ray source target point; the pre-weighted projection data is differentiated along the tangent direction of the line connecting the ray source target points or the line connecting the detector pixels; the differential projection data is back-projected to the space of the region of interest of the inspected object to be reconstructed, and the differential back-projection image components from a single ray source and a single detector assembly are obtained; a finite inverse Hilbert transform is performed along a specific direction in the space of the region of interest of the inspected object to obtain a preliminary reconstructed image component; the preliminary reconstructed image components of all ray sources and detector assemblies are accumulated to obtain a reconstructed image containing aliasing artifacts; Iterative reconstruction is performed using aliasing-free projection data and aliasing projection data as well as projection relationships and projection data constraints to obtain a complete reconstructed image of the region of interest of the inspected object, or a pre-trained anti-aliasing artifact neural network model is used to remove aliasing artifacts in the reconstructed image to obtain a complete reconstructed image of the region of interest of the inspected object.

6. The system according to claim 1, characterized in that The imaging module is further used to optimize the beam emission parameters and combination methods of the ray source target according to the position and structural characteristics or movement laws of the area of ​​interest in the inspected object; use multiple small-field-of-view targets to emit rays simultaneously or sequentially, and the rays are received by the detector unit without aliasing, and optimize the emission range and focal spot pattern to capture the instantaneous motion state and fine structural characteristics of the key focus area; use large-field-of-view targets to expose simultaneously or sequentially, and the rays have partial aliasing on the detector to complete the scanning of other areas, and reconstruct the image after comprehensively utilizing the projection data of all targets to obtain a reconstructed image of the inspected object.

7. A distributed ray source CT imaging method, using the distributed ray source CT imaging system according to any one of claims 1 to 6, characterized in that: The imaging method comprises the following steps: Determine the target arrangement of the ray source module and the detector module and the ray emission scheme of the ray source module according to the actual imaging requirements; Under the target arrangement mode of the ray source module and the detector module, the ray source is controlled to emit a beam according to the ray emission scheme, and the projection data of the region of interest of the inspected object is received by the detector module; The projection data of the region of interest of the inspected object is used for reconstruction to obtain a reconstructed image of the region of interest of the inspected object.

8. The method according to claim 7, characterized in that Determine the target arrangement of the ray source module and the detector module and the ray emission scheme of the ray source module according to the actual imaging requirements, including: According to actual imaging requirements, multiple ray sources and multiple detector assemblies are arranged on the main imaging plane, the multiple ray sources and multiple detector assemblies form a closed or approximately closed curve, the ray sources and detector assemblies outside the main imaging plane are arranged on at least one plane along the traveling direction of the inspected object, each plane includes at least one ray source and detector assembly, and the ray source module and the detector module have an angular coverage range that meets preset imaging conditions around the region of interest of the inspected object in the traveling direction of the inspected object; The beam parameters, focal spot pattern, emission range, beam sequence and beam combination method of each target point of the ray source are determined according to the actual imaging requirements.

9. The method according to claim 7, characterized in that: Reconstructing the image of the region of interest of the inspected object by using the projection data of the region of interest of the inspected object includes: In the alias-free projection data, the projection data received by the detector pixels are pre-weighted according to the projection magnification ratio relationship of each ray source target point; Differentiate the pre-weighted projection data along the tangent direction of the line connecting the ray source and the target points or the line connecting the detector pixels; Back-projecting the differentiated projection data to the space of the region of interest of the inspected object to be reconstructed, to obtain a differential back-projection image component from a single ray source and a single detector assembly; The differential back-projection image components of all ray sources and detector components are calculated to obtain the differential back-projection image results from all ray sources and detectors; the differential back-projection image results are subjected to finite inverse Hilbert transform along a specific direction to obtain a preliminary reconstructed image; Taking the preliminary reconstructed image obtained by using the non-aliasing projection data as the initial value, using the non-aliasing projection data and the aliasing projection data as well as the projection relationship and the constraints of the projection data, combined with iterative reconstruction or deep learning reconstruction technology, a reconstructed image of the region of interest of the inspected object is obtained; Reconstructing the image of the region of interest of the inspected object by using the projection data of the region of interest of the inspected object, and obtaining a reconstructed image of the region of interest of the inspected object, further comprising: At the same time, the projection data received by the detector pixels are pre-weighted according to the projection magnification ratio relationship of each ray source target point by using the non-aliasing projection data and the aliasing projection data; Differentiate the pre-weighted projection data along the tangent direction of the line connecting the target points of the ray source or the line connecting the pixels of the detector; back-project the differential projection data to the space of the region of interest of the inspected object to be reconstructed, and obtain a differential back-projection image component from a single ray source and a single detector assembly; Performing a finite inverse Hilbert transform along a specific direction in the space of the region of interest of the inspected object obtains a preliminary reconstructed image component; Accumulating the preliminary reconstructed image components of all the ray sources and detector components to obtain a reconstructed image containing aliasing artifacts; Iterative reconstruction is performed using aliasing-free projection data and aliasing projection data as well as projection relationships and projection data constraints to obtain a complete reconstructed image of the region of interest of the inspected object, or a pre-trained anti-aliasing artifact neural network model is used to remove aliasing artifacts in the reconstructed image to obtain a complete reconstructed image of the region of interest of the inspected object.

10. The method according to claim 7, characterized in that According to the position and structural characteristics or movement laws of the area of ​​interest in the inspected object, the beam emission parameters and combination methods of the ray source target are optimized; multiple small-field-of-view targets are used to emit rays simultaneously or sequentially, and the rays are received by the detector unit without aliasing, and the emission range and focal spot pattern are optimized to capture the instantaneous motion state and fine structural characteristics of the key focus area; large-field-of-view targets are used to expose simultaneously or sequentially, and the rays have partial aliasing on the detector, and the scanning of other areas is completed. The projection data of all targets are comprehensively used to reconstruct the image to obtain the reconstructed image of the inspected object.

Images