Multi-view diffraction imaging system and method

Abstract

The invention provides a multistage scanning imaging system and method based on diffraction imaging, and relates to the technical field of radiation imaging. The system comprises a first transmission scanning stage which comprises a first ray source and a first detection assembly, the first ray source is used for emitting a first ray for scanning an inspected object, and the first detection assembly is used for detecting a first transmission ray transmitted by the inspected object to generate a first detection signal; the signal processing device is configured to process the first detection signal to generate a transmission image, and obtain an object of interest in the inspected object according to the transmission image; the second diffraction scanning stage comprises a second ray source and a second detection assembly, the second ray source is used for emitting second rays for scanning the inspected object, and the second detection assembly is used for detecting scattered rays scattered by at least the interested object so as to generate a second detection signal; the signal processing device is further configured to process the second detection signal to generate a diffraction image, and obtain material information of the object of interest according to the diffraction image.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of radiation scanning, and more particularly, to a multi-view diffraction imaging system and method. BACKGROUND

[0002] X-ray diffraction (XRD) technology takes advantage of the wave characteristics of X-rays. The lattice structure of molecular order provides a natural diffraction grating. X-rays passing through the ordered molecular structure will achieve coherent reinforcement in a specific direction. Different molecular structures of objects have different coherent superposition angles, which are reflected in different energy spectrum shapes. These energy spectrum shapes are like "fingerprints" and have very strong specificity, so the substance resolution is extremely high, effectively making up for the shortcomings of transmission imaging. In the field of XRD scanning imaging, how to improve the utilization rate of X-rays and improve the spatial resolution is one of the continuous concerns of researchers.

[0003] It should be noted that the above information disclosed in this part is only for understanding the background of the inventive concept of the present disclosure, and therefore, the above information can include information that does not constitute prior art. SUMMARY

[0004] In view of at least one aspect of the above technical problems, embodiments of the present disclosure provide a multi-view diffraction imaging system, which comprises: a first diffraction scanning stage comprising a first ray source and a first detection assembly, the first ray source being configured to emit a first ray for scanning an object under examination from a first view angle, and the first detection assembly being configured to detect a first scattered ray to generate a first detection signal, wherein the first scattered ray is a ray scattered by the object under examination after the first ray acts on the object under examination; a second diffraction scanning stage comprising a second ray source and a second detection assembly, the second ray source being configured to emit a second ray for scanning the object under examination from a second view angle, and the second detection assembly being configured to detect a second scattered ray to generate a second detection signal, wherein the second scattered ray is a ray scattered by the object under examination after the second ray acts on the object under examination, and the second view angle is different from the first view angle; and a signal processing device, which is electrically connected to the first detection assembly and the second detection assembly, and is configured to process the first detection signal and the second detection signal to generate a diffraction image, and obtain an object of interest in the object under examination and material information of the object of interest according to the diffraction image.

[0005] Exemplarily, the first diffraction scanning stage and the second diffraction scanning stage are arranged at intervals along a first direction, and the object under examination is capable of moving along the first direction.

[0006] Exemplarily, the first and second diffraction scanning stages are located at the same position along a first direction; and the system comprises a radiation source and a detection assembly movable in a fan angle direction, the first radiation source and the first detection assembly comprising a radiation source and a detection assembly at a first position in the fan angle direction respectively, the second radiation source and the second detection assembly comprising a radiation source and a detection assembly at a second position in the fan angle direction respectively, the first position and the second position being different.

[0007] Exemplarily, the system comprises a distributed radiation source comprising a plurality of target points spaced apart in a fan angle direction; the first radiation source comprises at least one target point at a first position in the fan angle direction, and the second radiation source comprises at least another target point at a second position in the fan angle direction, the first position and the second position being different.

[0008] Exemplarily, at least one of the first and second detection assemblies comprises a detection module comprising: an encoding plate for encoding the scattered radiation to form encoded scattered radiation; a post-collimator for blocking radiation scattered by the object under examination having a first scattering angle greater than a preset scattering angle threshold; and a diffraction detector for detecting the encoded scattered radiation, wherein the encoded scattered radiation is radiation scattered by at least the object of interest in the object under examination having a second scattering angle less than or equal to the preset scattering angle threshold.

[0009] Exemplarily, the first radiation source and the first detection assembly are arranged on opposite sides of the object under examination along a second direction perpendicular to the first direction; in the second direction, the encoding plate, the post-collimator and the diffraction detector are arranged in a direction away from the first radiation source in sequence; and / or the second radiation source and the second detection assembly are arranged on opposite sides of the object under examination along a third direction perpendicular to the first direction; in the third direction, the encoding plate, the post-collimator and the diffraction detector are arranged in a direction away from the second radiation source in sequence.

[0010] Exemplarily, the first detection assembly further comprises a first transmission detector configured to detect first transmission rays transmitted through the object under examination to generate a third detection signal; the signal processing device is further configured to obtain first attenuation characteristic information of at least the object of interest in the object under examination according to the third detection signal; and correct the first detection signal by using the first attenuation characteristic information in the process of processing the first detection signal to generate the diffraction image; and / or the second detection assembly further comprises a second transmission detector configured to detect second transmission rays transmitted through the object under examination to generate a fourth detection signal; the signal processing device is further configured to obtain second attenuation characteristic information of at least the object of interest in the object under examination according to the fourth detection signal; and correct the second detection signal by using the second attenuation characteristic information in the process of processing the second detection signal to generate the diffraction image.

[0011] Exemplarily, in the cone angle direction, the first transmission detector is located on the path of the main beam of the first rays, the detection module is offset relative to the path of the main beam of the first rays by a predetermined offset angle, and the predetermined offset angle is less than or equal to a preset scattering angle threshold; and / or in the cone angle direction, the second transmission detector is located on the path of the main beam of the second rays, the detection module is offset relative to the path of the main beam of the second rays by a predetermined offset angle, and the predetermined offset angle is less than or equal to a preset scattering angle threshold.

[0012] Exemplarily, the first ray source comprises a target point for emitting rays; the first detection assembly comprises a plurality of detection modules, and in the fan angle direction, the plurality of detection modules are arranged centripetally relative to the target point; and / or the second ray source comprises a target point for emitting rays; the second detection assembly comprises a plurality of detection modules, and in the fan angle direction, the plurality of detection modules are arranged centripetally relative to the target point.

[0013] Exemplarily, in the fan angle direction, the plurality of detection modules are independently arranged from each other, and the diffraction detectors of the plurality of detection modules respectively comprise detection surfaces; for each of the plurality of detection modules, a connecting line between the detection surface and the target point is perpendicular to the detection surface.

[0014] Exemplarily, the rear collimator comprises collimating sheets, and adjacent two detection modules of the plurality of detection modules share a collimating sheet; in the fan angle direction, the collimating sheets of the plurality of detection modules extend through the target point.

[0015] Exemplarily, the diffraction detector of the detection module comprises a detection surface, and the detection surface is perpendicular to the second direction; or the diffraction detector of the detection module comprises a detection surface, and an extension line perpendicular to the detection surface and passing through the center of the detection surface passes through the object of interest.

[0016] Exemplarily, the rear collimator comprises a shielding cylinder, the encoding plate is located on the side of the shielding cylinder close to the second ray source, and the diffraction detector is located on the side of the shielding cylinder away from the second ray source.

[0017] Exemplarily, a plurality of first holes are formed in the encoding plate, the plurality of first holes are used for passing the first scattered ray or the second scattered ray, and the plurality of first holes form a predetermined first encoding pattern in a projection plane, the projection plane being a plane determined by the intersection of the first direction and the third direction.

[0018] Exemplarily, at least one of the first diffraction scanning stage and the second diffraction scanning stage further comprises a front collimator, the front collimator comprises a plurality of second holes, the plurality of second holes are used for passing the first ray or the second ray, and the plurality of second holes form a predetermined second encoding pattern in a projection plane, the projection plane being a plane determined by the intersection of the first direction and the third direction.

[0019] In another aspect, a multi-view diffraction imaging method is also provided, comprising: a first view scanning step of controlling a first ray source to emit a first ray to scan an object under examination from a first view, and controlling a first detection assembly to detect a first scattered ray scattered by the object under examination to generate a first detection signal; a second view scanning step of controlling a second ray source to emit a second ray to scan the object under examination from a second view, and controlling a second detection assembly to detect a second scattered ray scattered by the object under examination to generate a second detection signal, wherein the second view is different from the first view; and an imaging step of processing the first detection signal and the second detection signal to generate a diffraction image, and obtaining an object of interest in the object under examination and material information of the object of interest according to the diffraction image.

[0020] Exemplarily, the processing the first detection signal and the second detection signal to generate a diffraction image comprises: a first image reconstruction step of reconstructing a first diffraction image based on the first detection signal by using a diffraction image reconstruction algorithm; a second image reconstruction step of reconstructing a second diffraction image based on the second detection signal by using the diffraction image reconstruction algorithm; a pixel merging step of merging the first diffraction image and the second diffraction image according to corresponding pixels to generate a merged diffraction image; an updating step of updating a reconstruction parameter in the first diffraction image and the second diffraction image based on the merged diffraction image; and iteratively performing the first image reconstruction step, the second image reconstruction step, the pixel merging step and the updating step until the accuracy of the merged diffraction image meets a predetermined accuracy requirement.

[0021] Exemplarily, the processing the first detection signal and the second detection signal to generate a diffraction image comprises: jointly solving the first detection signal and the second detection signal in a same equation Ax=b to generate a diffraction image, wherein x is a three-dimensional voxel vector to be reconstructed, b is a detection signal acquired by a detector at each scanning viewing angle, and A is an imaging system matrix. BRIEF DESCRIPTION OF DRAWINGS

[0022] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure, taken in conjunction with the accompanying drawings, in which:

[0023] Figure 1 A schematic diagram illustrating a projection relationship between a ray source, an object to be inspected and a detector;

[0024] Figure 2 A structural schematic diagram of a diffraction imaging system according to some exemplary embodiments of the present disclosure;

[0025] Figure 3 A structural schematic diagram of a multi-view diffraction imaging system provided by embodiments of the present disclosure;

[0026] Figure 4A A structural schematic diagram of a multi-view diffraction imaging system provided by other embodiments of the present disclosure;

[0027] Figure 4B A structural schematic diagram of a multi-view diffraction imaging system provided by yet other embodiments of the present disclosure;

[0028] Figure 5A A sectional schematic diagram of a detection module provided by embodiments of the present disclosure;

[0029] Figure 5B A structural schematic diagram of an encoding plate of a detection module provided by embodiments of the present disclosure;

[0030] Figure 6A A cross-sectional view of a first diffraction scanning stage of a multi-view diffraction imaging system according to an embodiment of the present disclosure, taken along a fan angle principal beam surface thereof;

[0031] Figure 6B A cross-sectional view of a second diffraction scanning stage of a multi-view diffraction imaging system according to an embodiment of the present disclosure, taken along a fan angle principal beam surface thereof;

[0032] Figure 7 A cross-sectional view of two diffraction scanning stages of a multi-view diffraction imaging system according to an embodiment of the present disclosure, taken along a cone angle principal beam surface thereof;

[0033] Figure 8 An arrangement view of a ray source and a detection module of a multi-view diffraction imaging system according to an embodiment of the present disclosure in a fan angle direction;

[0034] Figure 9 A cross-sectional view of at least one diffraction scanning stage of a multi-view diffraction imaging system according to an embodiment of the present disclosure, taken along a cone angle principal beam surface thereof;

[0035] Figure 10 A structure view of a front collimator according to an embodiment of the present disclosure;

[0036] Figure 11 A flow chart of a multi-view diffraction imaging method according to an embodiment of the present disclosure; and

[0037] Figure 12 A flow chart of generating a diffraction image of a multi-view diffraction imaging method according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It is to be understood, however, that the description is merely exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description of the embodiments of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. However, it would be apparent to those skilled in the art that the embodiments of the present disclosure can be practiced without these specific details. In other instances, well-known structures and functions have been omitted to avoid unnecessarily complicating the present disclosure with details that would be apparent to those skilled in the art.

[0039] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure. As used herein, the term "includes" and "comprising" and the like means the inclusion of the stated features, steps, operations, and / or components, but not the exclusion of one or more other features, steps, operations, or components.

[0040] All terms used herein, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art unless otherwise defined. It should be further noted that the use of any terms herein should not be interpreted to exclude from the scope of the specification other equivalents that are within the scope of the specification. Terms used herein should be interpreted not in an idealized or overly formal sense, but in a manner that is consistent with the context in which they are used.

[0041] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted that the expression is inclusive of the possibilities of A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc., unless otherwise specifically stated.

[0042] It should be noted that, in this document, computed tomography (also referred to as CT) imaging refers to the process of using a computed tomography scanner to obtain a set of two-dimensional projection images of an object of interest from a plurality of different angles, and then using a computer to reconstruct a three-dimensional image of the object of interest from the set of two-dimensional projection images.

[0043] X-ray DR imaging (Digital Radiography) refers to a single view, two-dimensional projection imaging technique. It uses X-rays to penetrate an object and a digital detector to receive the transmitted signal and convert it to a digital image. Specifically, X-rays can pass through an object from one side and be captured by a detector on the other side. Because different materials absorb X-rays to different degrees, the resulting image is based on these differences. It should be understood that in X-ray DR imaging, because all information is obtained from a single angle, a two-dimensional image is obtained, which can be referred to herein as a two-dimensional projection image. In the two-dimensional projection image, the structures inside the object along the output direction of the ray are superimposed together.

[0044] X-ray diffraction (XRD) technology is based on the coherent scattering (i.e., Rayleigh scattering) signal generated when X-rays interact with matter to identify the molecular or crystal structure information of the object under test. When a beam of X-rays is incident on a crystalline material with a periodic lattice arrangement, the incident photons will have elastic interactions with the electrons in the material, exciting atoms and then de-exciting, releasing scattered photons with the same energy but a changed direction. Due to the highly ordered arrangement of atoms inside the crystal, these scattered photons will constructively interfere under certain geometric conditions, resulting in significantly enhanced intensity diffraction peaks in certain specific directions, which is the phenomenon of X-ray diffraction. Using this X-ray diffraction technology, material identification can be performed, and its application in imaging systems and imaging methods can be expressed as X-ray diffraction scanning imaging systems and methods.

[0045] Figure 1 A schematic diagram illustrating the projection relationship between the ray source, the object under examination and the detector is shown. Referring to Figure 1 In embodiments of the present disclosure, the rays (e.g. X-rays) emitted by the ray source 1 are incident on the object under examination 6, for example, the X-rays are incident on a spatial position P1 in the object under examination 6, the matter at the spatial position P1 interacts with the incident X-rays, Rayleigh scattering occurs, and the scattered rays are detected by the detector 2. The spatial point P1 on the object under examination 6 is imaged to the image point P2 on the detector 2 by the ray source 1. In forward projection (also known as forward projection), the voxel value of the spatial point on the object under examination 6 is known, and the pixel value of the image point on the detector 2 is calculated. In back projection (also known as back projection), the pixel value of the image point on the detector 2 is known, and the voxel value of the spatial point on the object under examination 6 is calculated.

[0046] It should be understood that the scattered photons will undergo constructive interference under certain geometric conditions, thereby forming a diffraction peak with significantly enhanced intensity in certain specific directions. Referring to Figure 1 In the XRD-based diffraction imaging system, the diffraction behavior follows the Bragg's law, which is mathematically expressed as: 2d sin(θ / 2) = nλ, where d represents the interplanar spacing of the crystal, θ is the angle between the incident ray and the scattered ray (i.e. the scattering angle), λ is the wavelength of the incident X-rays, and n is any positive integer. The formula shows that for a given crystal substance, its interplanar spacing d is fixed, so only when the wavelength λ of the incident X-rays and the scattering angle θ satisfy the above relationship, a significant diffraction peak will be observed on the detector. Different substances have different interplanar spacing combinations due to their unique crystal structures, resulting in their own unique diffraction patterns, which are like the "fingerprint" or "DNA" of the substance, with extremely high specificity and discrimination.

[0047] Therefore, in the XRD-based diffraction imaging system, through the image reconstruction algorithm, the voxel value of the spatial point on the object under examination 6 can be calculated from the pixel value of the image point on the detector 2, and based on the information of different diffraction peaks, the material composition at the spatial point on the object under examination 6 can also be identified.

[0048] In practical applications, the Bragg formula can be combined with the photon energy formula E = hc / λ to be transformed to obtain an expression with energy E and scattering angle θ as variables. Based on this, the X-ray diffraction detection technology can be divided into two main modes: angular dispersive X-ray diffraction (ADXRD) and energy dispersive X-ray diffraction (EDXRD). The angular dispersion adopts a monochromatic light source, and the light intensity at different angles of the detector is detected after the object is irradiated, thereby obtaining an angle-intensity spectrum. According to the Bragg formula, under the condition of a certain energy, the change in momentum and the angle are one-to-one corresponding, and therefore the change in momentum-intensity spectrum can be calculated. The angle dispersion tests the light intensity, and therefore an energy-integrating detector can meet the demand. The energy dispersion adopts a continuous spectrum light source, and measures the energy-intensity distribution at a specific angle. Similarly, when the angle is fixed, the energy and the change in momentum are one-to-one corresponding, and therefore the change in momentum-intensity spectrum can be calculated. The difference between EDXRD and ADXRD is that the EDXRD has a short scanning time, and a single exposure can obtain the diffraction spectrum of the scanned object, and the demand for the detector is higher, and a spectrum detector is adopted. The ADXRD can use an energy-integrating detector. The disadvantage of the EDXRD is that the energy resolution of the measured diffraction spectrum is low, and the noise is large. The ADXRD is more common in laboratory research, and the EDXRD is commonly used in security checks.

[0049] The inventors have found that, since the XRD detects scattered signals, compared with CT transmission imaging, the signal noise detected by the XRD is large, the energy resolution is low, and a long time is needed to obtain a distinguishable energy spectrum. The single pixel of the traditional long collimation type detector can only collect a point signal at a single time, the utilization rate of the rays is low, and it cannot meet the actual application of the bag scanning requirement. Another problem of the XRD is that the spatial resolution of the material is low, since the diffraction angle is very small, the projection of the object to be inspected along the ray direction is on one or several pixels. Solving the voxels of the object to be inspected from a very small number of pixels will cause the spatial resolution to be reduced in that direction.

[0050] To address at least one aspect of the aforementioned problems, embodiments of this disclosure provide a multi-view diffraction imaging system and method. The embodiments of this disclosure will be described in detail below using an imaging system for objects such as luggage and inspected objects as an example. It should be understood that the embodiments of this disclosure are not limited to imaging scenarios for objects such as luggage and inspected objects; they can be applied to various scanning imaging scenarios. For example, they can be applied to scanning imaging scenarios involving various different inspection objects, including but not limited to vehicle scanning imaging, luggage / inspected object scanning imaging, human or animal scanning imaging, organ / tissue scanning imaging, small object scanning imaging, and large object scanning imaging such as containers. It should be noted that the description of scanning imaging scenarios herein is not exhaustive, and the exemplary descriptions below should not be construed as limiting the scope of protection of this disclosure.

[0051] Figure 2 This is a schematic diagram of the structure of a diffraction imaging system according to some exemplary embodiments of the present disclosure. (Refer to...) Figure 2 The diffraction imaging system according to embodiments of this disclosure may include multiple scanning stages (e.g., first scanning stage A, second scanning stage B, ...), a transmission mechanism 8, a control device 7, and a signal processing device 5. For example, the scanning stage may include an X-ray source and a detection component.

[0052] It should be noted that, for ease of description, this paper establishes a coordinate system XYZ based on the first direction Z, the second direction X, and the third direction Y. For example, the first direction Z can be parallel to the direction of motion of the object being inspected. Figure 2 The left and right directions; the third direction Y can be parallel to the emission direction of the rays in a scan level, that is, the direction from the ray source to the detector, for example. Figure 2 The vertical direction; the second direction X can intersect with the third direction Y and the first direction Z respectively, for example. Figure 2 The front and back directions in the coordinate system, for example, any two of the first direction Z, the second direction X, and the third direction Y are perpendicular to each other. It should be understood that the coordinate system XYZ established based on the first direction Z, the second direction X, and the third direction Y is only for the convenience of description and is not intended to limit the embodiments of this disclosure.

[0053] In embodiments of this disclosure, the diffraction imaging system may include at least two scanning stages, such as a first scanning stage A and a second scanning stage B, wherein different scanning stages can scan the object 6 being examined from different perspectives. Figure 2In this context, A and B can represent the principal beam planes in the fan-angle directions of two scanning stages, respectively. That is, in the embodiments of this disclosure, a multi-view diffraction imaging system is proposed, comprising: a first diffraction scanning stage (e.g., first scanning stage A), including a first X-ray source and a first detection component, wherein the first X-ray source is used to emit a first X-ray to scan the object under inspection from a first viewpoint, and the first detection component is used to detect a first scattered X-ray scattered by the object under inspection to generate a first detection signal; for example, the first scattered X-ray is the X-ray scattered by the object after the first X-ray acts on the object under inspection; and a second diffraction scanning stage (e.g., first scanning stage B), including a second X-ray source and a second detection component, wherein the second X-ray source is used to emit a first X-ray to scan the object from a second viewpoint. The system employs a second ray to scan the inspected object, and a second detection component to detect the second scattered rays scattered by the inspected object to generate a second detection signal. The second scattered rays are rays scattered by the inspected object after the second ray has acted upon it, and the second viewing angle differs from the first viewing angle. A signal processing device 5 is also included, electrically connected to both the first and second detection components. The signal processing device 5 is configured to process the first and second detection signals to generate a diffraction image, and to obtain the object of interest and its material information from the diffraction image. In embodiments of this disclosure, a multi-view X-ray diffraction (XRD) scanning imaging system is used. Through the synergistic effect of multiple scanning perspectives, the inherent spatial resolution anisotropy problem in single-view XRD imaging is effectively overcome, particularly significantly improving the positioning capability and overall imaging quality along the ray propagation direction (i.e., the depth direction). Furthermore, this multi-view X-ray diffraction (XRD) scanning imaging system can operate independently of other security inspection scanning systems.

[0054] Specifically, firstly, in a single-view XRD imaging system, the signal received by the detector originates from a surface (such as an ellipsoid) that satisfies the Bragg condition, causing high aliasing of voxel signals at different depths on the detector, resulting in severe "depth blurring." Multi-view scanning scans the same object from different perspectives, constraining each voxel by multiple diffraction paths with different geometric configurations. The blurred surfaces corresponding to these paths intersect each other in space, and their unique intersection point is the true position of the voxel. By jointly solving the data from all perspectives, the reconstruction algorithm can "focus" the originally blurred depth information, thereby achieving precise positioning of the hazardous material's three-dimensional coordinates within the inspected object. Secondly, single-view XRD imaging exhibits strong anisotropy in spatial resolution: the resolution is relatively high in the transverse plane perpendicular to the rays, but extremely low in the depth direction along the rays. Multi-view XRD scanning imaging can transform the original "depth direction" into a "transverse direction" from other perspectives. Through this complementarity between perspectives, the system can achieve relatively balanced resolution in all directions of three-dimensional space, ultimately reconstructing a near-isotropic high-resolution image, avoiding missed detections or misjudgments caused by directional ambiguity. Furthermore, in actual security inspections, dangerous goods are often intentionally hidden behind high-density items. In single-view XRD imaging, high-absorbent materials in front severely attenuate diffracted photons, resulting in extremely weak or even undetectable signals from dangerous goods behind. In a multi-view XRD imaging system, diffraction information of the region can be obtained from angles that are not completely obstructed. Even if the data from a certain perspective is of poor quality due to obstruction, data from other high-quality perspectives can provide strong prior information during the joint solution process, helping the algorithm to more reliably infer the composition of the obstructed area, thereby significantly improving the system's overall analytical capability for complex and disguised objects.

[0055] In some exemplary embodiments, first and second diffraction scanning stages with different scanning angles can be arranged at intervals along the first direction z, that is, at least two diffraction scanning stages are positioned differently in the first direction z. For example, the first and second diffraction scanning stages can be arranged at intervals along the first direction z, and the object 6 being inspected can move along the first direction z.

[0056] Figure 3 This is a schematic diagram of the structure of a multi-view diffraction imaging system provided in an embodiment of this disclosure. It should be understood that... Figure 3 The structure shown can represent Figure 2 An exemplary embodiment of the diffraction imaging system shown is illustrated. (Referring to reference...) Figure 2 and Figure 3 The multi-view diffraction imaging system may include: a transmission mechanism 8, two diffraction scanning stages, a scanning channel 4, and a shielding housing 9.

[0057] It should be noted that, inFigure 2 and Figure 3 In the illustrated embodiment, two diffraction scanning levels are shown as an example. The multi-view diffraction imaging system provided in this disclosure may include more than one diffraction scanning level, i.e., more than two diffraction scanning levels. Each diffraction scanning level may scan the object under inspection from different viewpoints to obtain diffraction detection signals obtained from different viewpoints.

[0058] In the following description, for ease of description, the two diffraction scanning orders will be referred to as a first diffraction scanning order and a second diffraction scanning order. It should be understood that this description is merely an example to illustrate embodiments of the present disclosure and is not intended to limit the embodiments of the present disclosure.

[0059] like Figure 3 As shown, two scanning stages can be arranged at intervals along a first direction z. The first diffraction scanning stage includes at least one X-ray source 1 and at least one detector component 2, and the second diffraction scanning stage includes at least one X-ray source 1 and at least one detector component 2. In this document, for ease of description, the X-ray source and detector component included in the first diffraction scanning stage are referred to as the first X-ray source 11 and the first detector component 21, respectively, and the X-ray source and detector component included in the second diffraction scanning stage are referred to as the second X-ray source 12 and the second detector component 22, respectively.

[0060] For example, in the location Figure 3 In the first diffraction scanning stage on the left side, the first X-ray source 11 can be used to emit a first X-ray to scan the object 6 under inspection from a first viewing angle. For example, the first X-ray source 11 may include a target point for emitting X-rays, and the first X-ray emitted from the target point of the first X-ray source 11 scans the object 6 under inspection from the first viewing angle. The first detection component 21 can be used to detect the first X-rays scattered by the object 6 under inspection to generate a first detection signal.

[0061] For example, in the location Figure 3 In the second diffraction scanning stage on the right side, the second X-ray source 12 can be used to emit a second X-ray to scan the object 6 under inspection from a second viewing angle. For example, the second X-ray source 12 can include a target point for emitting the X-ray, and the second X-ray emitted from the target point of the second X-ray source 12 scans the object 6 under inspection from a second viewing angle. The second detection component 22 can be used to detect the second X-ray scattered by the object 6 under inspection to generate a second detection signal.

[0062] For example, when observing along the direction of movement of the object 6 in the scanning channel 4 (i.e., the first direction z), the first viewing angle can represent the direction from right to left, and the second viewing angle can represent the direction from bottom to top. That is, in the first diffraction scanning stage, the first ray scans the object 6 in the direction from the right side to the left side; in the second diffraction scanning stage, the second ray scans the object 6 in the direction from the bottom side to the top side.

[0063] In some exemplary embodiments, the radiation beam emitted by at least one of the first radiation source 11 and the second radiation source 12 is a cone-shaped radiation beam. For example, refer to... Figure 3 Each set of source probes marks the central section of the intermediate ray source beam cone. The thin dashed line is the main beam surface in the fan-angle direction, and the extension direction of the main beam surface in the fan-angle direction is the fan-angle direction; the thick dashed line is the main beam surface in the cone-angle direction, and the extension direction of the main beam surface in the cone-angle direction is the cone-angle direction.

[0064] Continue to refer to Figure 3 In the first diffraction scanning stage, the fan-angle direction of the first X-ray source 11 extends into the xy-plane; in the second diffraction scanning stage, the fan-angle direction of the second X-ray source 12 extends into the yz-plane. Thus, the first viewing angle in the first diffraction scanning stage differs from the second viewing angle in the second diffraction scanning stage by 90°. In this way, positions that are difficult to distinguish at a 0° viewing angle become left and right positions at a 90° viewing angle, and the latter is precisely the direction with higher resolution at that viewing angle. Through this complementarity between viewing angles, the system can obtain relatively balanced resolution in all directions of three-dimensional space, ultimately reconstructing a near-isotropic high-resolution image, avoiding missed detections or misjudgments caused by directional blurring.

[0065] It should be noted that, in Figure 3 In the example shown, a circle schematically represents the target point of the radiation source. The radiation source can have a more complex structure. Exemplarily, at least one of the first radiation source 11 and the second radiation source 12 can be an accelerator, such as a MeV-level accelerator. The accelerator's energy is adjustable and it has strong penetrating power. It should be noted that the embodiments of this disclosure do not impose any special limitations on the type of radiation source. In other embodiments, other types of radiation sources can be used, such as a keV-level X-ray machine.

[0066] It should also be noted that, in Figure 3In the example shown, multiple parallel straight lines represent the detection components. The detection components can have more complex structures. For example, the detection components can include various forms such as area array detectors and linear array detectors, and can include different detector arrangements such as linear, L-shaped, and U-shaped structures. Unless otherwise specified, the embodiments of this disclosure do not impose special limitations on the structural form or arrangement of the detection components.

[0067] In some exemplary embodiments, a first diffraction scanning stage and a second diffraction scanning stage with different scanning angles can be arranged at the same position along the first direction z, but at different positions in the xy plane. That is, at least two diffraction scanning stages are at the same position in the first direction z, but at different positions in the xy plane. For example, the first diffraction scanning stage and the second diffraction scanning stage can be arranged at intervals in the xy plane.

[0068] Figure 4A This is a schematic diagram of the structure of a multi-view diffraction imaging system provided in other embodiments of this disclosure. For example... Figure 4A As shown, the system may include a radiation source 1 and a detection component 2 capable of moving in the fan-angle direction (i.e., within the xy-plane). The radiation source 1 and detection component 2 can be mounted on a slip ring 30 and can rotate. When the radiation source 1 and detection component 2 rotate to a first position p11, the object 6 being inspected can be scanned from a first perspective; when the radiation source 1 and detection component 2 rotate to a second position p12, the object 6 being inspected can be scanned from a second perspective different from the first perspective. That is, the first radiation source and the first detection component each include radiation source 1 and detection component 2 in the first position in the fan-angle direction, and the second radiation source and the second detection component each include radiation source 1 and detection component 2 in the second position in the fan-angle direction, the first position and the second position being different. In this embodiment, multiple perspectives can be achieved by moving the target point and the detector.

[0069] Figure 4B This is a schematic diagram of the structure of a multi-view diffraction imaging system provided in some embodiments of this disclosure. For example... Figure 4B As shown, the system may include a distributed X-ray source 13, which includes multiple target points spaced apart in a fan-angle direction (i.e., within the xy-plane). The first X-ray source includes at least one target point at a first position in the fan-angle direction, and the second X-ray source includes at least another target point at a second position in the fan-angle direction, the first and second positions being different. In this embodiment, multiple viewpoints can be achieved through the multiple target points of the distributed X-ray source.

[0070] In embodiments of this disclosure, at least one of the first detection component and the second detection component includes a detection module.

[0071] Figure 5A This is a cross-sectional schematic diagram of the detection module provided in an embodiment of this disclosure. Figure 5B This is a schematic diagram of the structure of the encoding board of the detection module provided in the embodiments of this disclosure.

[0072] Combined with reference Figure 5A and Figure 5B The detection module 3 may include: an encoding plate 31, which is used to encode the first scattered rays and / or the second rays to form encoded scattered rays; a post-collimator 32, which is used to block rays with a first scattering angle scattered by the object under inspection 6, wherein the first scattering angle is greater than a preset scattering angle threshold; and a diffraction detector 33, which is used to detect the encoded scattered rays, wherein the encoded scattered rays are rays with a second scattering angle scattered by at least one object of interest in the object under inspection 6, wherein the second scattering angle is less than or equal to a preset scattering angle threshold.

[0073] In some embodiments, such as Figure 5B As shown, the encoding plate 31 has multiple first holes 311 for allowing scattered rays to pass through. These first holes 311 form a predetermined first encoding pattern in a projection plane, which is the plane defined by the intersection of the first direction x and the third direction z. It should be noted that... Figure 5B In the image, against a white background, multiple first holes 311 are represented as multiple small black dots.

[0074] For example, the encoding plate 31 can be disposed between the object under inspection 6 and the diffraction detector 33. Its function is to spatially modulate the scattered rays to form encoded scattered rays with a specific encoding pattern. The encoding plate 31 can be made of a high X-ray absorption material (e.g., lead, tungsten, or their alloys) and has multiple transmission holes or slits arranged according to a preset pattern to form a one-dimensional or two-dimensional encoding mask array, such as a corrected uniform redundancy array, a random array, or a fractal structure. Through this encoding structure, the originally uniform or divergent X-ray beam is modulated into a beam with known spatial distribution characteristics; correspondingly, the coherent diffraction signal scattered from the object under inspection 6 is also given the same encoding characteristics. This encoding method can improve the system's collection efficiency of scattered photons without significantly sacrificing angular resolution, thereby enhancing the signal-to-noise ratio and providing a physical basis for subsequent high-resolution imaging through decoding algorithms.

[0075] The post-collimator 32 can be located between the object under inspection 6 and the diffraction detector 33, adjacent to or integrated into the incident surface of the diffraction detector 33. Its main function is to act as a spatial and angular filter to block stray radiation that deviates from the target diffraction direction.

[0076] For example, the back collimator 32 may include a shielding cylinder 321, the encoder plate 31 may be located on the side of the shielding cylinder 321 closer to the radiation source, and the diffraction detector 33 may be located on the side of the shielding cylinder 321 away from the radiation source.

[0077] For example, the rear collimator 32 may include a plurality of collimating plates 322 (see reference). Figure 6A For example, the collimator is a thin sheet of high-absorption material (e.g., lead or tungsten sheet) forming a honeycomb or multi-slit structure, allowing only X-rays with incident directions within a preset scattering angle threshold range to pass through.

[0078] Since X-ray diffraction signals (especially coherent scattering from crystalline materials) are concentrated in a small forward scattering angle range (e.g., less than 10°), while background noise such as Compton scattering is distributed over a wider angle range, the post-collimator 32 can effectively suppress interference from large-angle incoherent scattering and environmental stray scattering by setting an appropriate scattering angle threshold. This ensures that only useful signals that meet or are close to the Bragg diffraction condition and have a second scattering angle (i.e., less than or equal to the scattering angle threshold, for example, the scattering angle threshold can be about 10°) reach the detector, thereby improving the purity of the diffraction spectrum and the accuracy of material identification.

[0079] The diffraction detector 33 is used to receive the coded scattered rays filtered by the post-collimator 32 and convert them into a processable electrical signal. The diffraction detector 33 can be an energy-resolved photon counting detector, such as a pixelated array made of semiconductor materials like cadmium zinc telluride (CZT), mercury cadmium telluride (HgI2), or silicon drift detectors (SDD). Such detectors can not only record the spatial position information of incident photons but also accurately measure the energy of each photon, thereby outputting a diffraction energy spectrum in intensity-energy form. In embodiments of this disclosure, the coded scattered rays detected by the diffraction detector 33 specifically refer to coherent scattered signals produced by at least one object of interest (e.g., a potential explosive or other contraband) inside the object being inspected 6, possessing a specific material microstructure (e.g., molecular structure, atomic arrangement, or lattice structure), whose scattering angle (i.e., the second scattering angle) is confined within a narrow angle window defined by the post-collimator 32. By combining the spatial coding information introduced by the coding plate 31 with the energy resolution data obtained by the diffraction detector 33, the subsequent image reconstruction algorithm can decode and invert the aliased projection signals, and finally realize the three-dimensional spatial positioning and component identification of the object of interest inside the inspected object.

[0080] Figure 6A This is a schematic cross-sectional view of the first diffraction scanning stage of the multi-view diffraction imaging system provided in this embodiment of the present disclosure, taken along its fan-angle principal beam plane. Figure 6BThis is a schematic cross-sectional view of the second diffraction scanning stage of the multi-view diffraction imaging system provided in the embodiments of this disclosure, taken along its fan-angle principal beam plane.

[0081] like Figure 6A As shown, in the first diffraction scanning stage, the first detection assembly includes at least one detection module. Along the fan-angle direction, the first X-ray source 11 and the detection module of the first detection assembly are positioned on opposite sides of the object 6 to be inspected along the second direction y. In the second direction y, the encoding plate 31, the back collimator 32, and the diffraction detector 33 are arranged sequentially away from the first X-ray source 11.

[0082] like Figure 6B As shown, in the second diffraction scanning stage, the second detection assembly includes at least one detection module. Along the fan-angle direction, the second X-ray source 12 and the detection modules of the second detection assembly are positioned on opposite sides of the object 6 to be inspected along the third direction x. In the third direction x, the encoding plate 31, the back collimator 32, and the diffraction detector 33 are arranged sequentially away from the second X-ray source 12.

[0083] Figure 7 This is a schematic diagram of the cross-sections taken along the main beam plane of the cone angle of the two diffraction scanning stages of the multi-view diffraction imaging system provided in the embodiments of this disclosure.

[0084] like Figure 7 As shown, the first detection component 21 may further include a first transmission detector 211, which is used to detect the first transmitted ray LT1 transmitted through the object 6 being inspected, in order to generate a third detection signal. The signal processing device 5 may also be configured to: acquire first attenuation feature information of at least one object of interest in the object 6 being inspected based on the third detection signal; and correct the first detection signal using the first attenuation feature information during the process of processing the first detection signal to generate a diffraction image.

[0085] The second detection component 22 may further include a second transmission detector 221, which is used to detect the second transmitted ray LT2 transmitted through the object 6 being inspected, in order to generate a fourth detection signal. The signal processing device 5 may also be configured to: acquire second attenuation characteristic information of at least one object of interest in the object 6 being inspected based on the fourth detection signal; and correct the second detection signal using the second attenuation characteristic information during the processing of the second detection signal to generate a diffraction image.

[0086] In the embodiments of this disclosure, by introducing a transmission detector to acquire the attenuation characteristic information of the inspected object, and by physically correcting the diffraction signal during the diffraction image reconstruction process, the absorption attenuation of X-rays along the incident and exit paths is effectively compensated. Attenuation correction improves the quantitative accuracy of the diffraction signal, enabling the accurate reconstruction of characteristic signals of hazardous materials that are deeply buried or obscured by high-density materials, thereby reducing missed detections and misjudgments caused by attenuation. Furthermore, the fusion of the corrected diffraction image with the transmission structure information achieves a precise combination of component identification and spatial positioning, significantly enhancing the system's detection sensitivity, reliability, and practicality in complex package scenarios.

[0087] In the cone angle direction, the first transmission detector 211 can be located on the path of the main beam of the first ray LR1. The detection module 3 is deviated from the path of the main beam of the first ray LR1 by a predetermined deviation angle α, which is less than or equal to a preset scattering angle threshold.

[0088] In the cone angle direction, the second transmission detector 221 is located on the path of the main beam of the second ray LR2, and the detection module 3 is deviated from the path of the main beam of the second ray LR2 by a predetermined deviation angle β, which is less than or equal to a preset scattering angle threshold.

[0089] In some examples, the deviation angles α and β are substantially equal. Alternatively, the deviation angles α and β may not be equal.

[0090] In the embodiments of this disclosure, by arranging transmission detectors on the direct paths of the first and second X-ray main beams respectively, and simultaneously offsetting the detection module used for diffraction from the main beam path at a small angle less than or equal to a preset scattering angle threshold, compact coaxial integration of transmission imaging and X-ray diffraction detection is achieved. This arrangement ensures that the detection module receives only forward small-angle coherent scattering signals (i.e., effective diffraction signals) from the object being inspected, effectively avoiding background noise interference such as large-angle Compton scattering; at the same time, the transmission detector can simultaneously acquire high signal-to-noise ratio attenuation data for accurate reconstruction of the object's three-dimensional density distribution. Thus, the program system can simultaneously obtain structural information (transmission) and compositional information (diffraction) during the same scanning process, which not only saves space and simplifies the mechanical structure, but also provides high-quality prior information for subsequent accurate absorption correction of the diffraction signal using the transmission attenuation map, thereby improving the detection rate and identification accuracy of hidden crystalline hazardous materials.

[0091] Figure 8 This is a schematic diagram showing the arrangement of the X-ray source and detection module in the fan-angle direction of the multi-view diffraction imaging system provided in the embodiments of this disclosure.

[0092] It should be noted that, Figure 8The arrangement of the X-ray source and detection module in the fan-angle direction can be the arrangement of the X-ray source and detection module in the fan-angle direction of either the first diffraction scanning stage or the second diffraction scanning stage.

[0093] Reference Figure 8 The radiation source 1 (e.g., it may be at least one of the first radiation source 11 and the second radiation source 12) may include a target for emitting radiation, and the detection assembly (e.g., it may be at least one of the first detection assembly 21 and the second detection assembly 22) may include a plurality of detection modules 3, which are arranged centripetally relative to the target of the radiation source 1 in the fan-angle direction.

[0094] For example, in the sector direction, multiple detection modules 3 are arranged independently of each other, and the diffraction detectors 33 of the multiple detection modules 3 each include a detection surface 331. For example, the detection surface 331 can be the surface of the diffraction detector 33 facing the X-ray source. For each of the multiple detection modules 3, the line connecting the detection surface 331 and the target point is perpendicular to the detection surface 331.

[0095] For example, such as Figure 6A and Figure 6B As shown, the rear collimator 32 may include a collimating plate 322, and two adjacent detection modules 3 in the plurality of detection modules 3 share the collimating plate 322. In the fan-angle direction, the collimating plates 322 of the plurality of detection modules 3 extend through the target point.

[0096] In this embodiment, by arranging multiple detection modules centripetally around the target point of the X-ray source in the fan-angle direction, forming an arc-shaped or approximately arc-shaped detection array centered on the target point, efficient and synchronous acquisition of the scattered signals from the inspected object is achieved. This geometric layout ensures that the distance between each detection module and the target point is basically consistent, and the incident-scattering path satisfies consistent small-angle diffraction geometry conditions, which is beneficial for obtaining uniform angular resolution and signal intensity response. At the same time, the centripetal arrangement maximizes the coverage of the forward small-angle scattering region, improving photon collection efficiency and spatial sampling density without increasing scanning time, effectively enhancing the signal-to-noise ratio of the diffraction signal. In addition, this structure, matched with the fan-shaped beam, can support rapid single exposure or multi-angle continuous scanning, significantly improving system throughput, and is particularly suitable for high-throughput security inspection scenarios such as baggage and parcels, balancing imaging quality, detection speed, and system compactness.

[0097] Optionally, such as Figure 7 As shown, in the cone angle direction, the detection surface 331 can be perpendicular to the second direction y.

[0098] Figure 9 This is a schematic cross-sectional view of at least one diffraction scanning stage of the multi-view diffraction imaging system provided in this embodiment of the present disclosure, taken along the main beam plane at the cone angle. (See diagram below.) Figure 9As shown, the diffraction detector 33 of the detection module 3 includes a detection surface 331, and an extension line L2 perpendicular to the detection surface 331 and passing through the center of the detection surface passes through the object of interest.

[0099] In some exemplary embodiments, such as Figure 10 As shown, at least one of the first diffraction scanning stage and the second diffraction scanning stage may further include a precollimator 15. The precollimator 15 may include a plurality of second holes 152 for allowing the first ray or the second ray to pass through. The plurality of second holes 152 form a predetermined second coding pattern in the projection plane (i.e. the xz plane). The projection plane is a plane determined by the intersection of the first direction z and the third direction x.

[0100] In the above embodiments, diffraction scanning stages with different perspectives can acquire diffraction information based on the same physical principles.

[0101] It should be noted that, in the embodiments of this disclosure, diffraction scanning stages with different viewing angles can acquire diffraction information based on different physical principles. For example, some viewing angle diffraction scanning stages can employ a long collimator scheme, achieving angle selection through a high aspect ratio rear collimator; other viewing angle diffraction scanning stages can employ coded aperture technology, using a preset coding plate to spatially modulate the scattered field, thereby significantly improving signal throughput while maintaining angular resolution. Furthermore, a front collimator coded aperture scheme (such as...) can also be further employed. Figure 10 As shown in the diagram, a coded mask is placed at the X-ray source end to give the incident light itself structured characteristics. The above schemes can be used in any combination—for example, one viewpoint can use pre-coding + a long collimator, and another viewpoint can use post-coding. In this way, the complementary advantages of different technologies in terms of signal-to-noise ratio, spatial resolution, penetration capability, or resistance to obstruction can be fully utilized.

[0102] Figure 11 A flowchart illustrating a multi-view diffraction imaging method provided in an embodiment of this disclosure. Figure 11 As shown, the radiation imaging method may include steps S1110 to S1130.

[0103] Step S1110 is a first-view scanning step. In this step, the first X-ray source is controlled to emit a first X-ray to scan the object under inspection from a first viewpoint; the first detection component is controlled to detect the first scattered X-rays scattered by the object under inspection to generate a first detection signal.

[0104] Step S1120 is a second-view scanning step. In this step, the second ray source is controlled to emit a second ray to scan the object being inspected from a second viewpoint; the second detection component is controlled to detect the second scattered ray scattered by the object being inspected to generate a second detection signal, wherein the second viewpoint is different from the first viewpoint.

[0105] Step S1130 is an imaging step, in which the first detection signal and the second detection signal are processed to generate a diffraction image, and the object of interest in the object under inspection and the material information of the object of interest are obtained based on the diffraction image.

[0106] It is understood that a portion of the multi-view diffraction imaging method can be executed by the control device 7, and another portion can be executed by the signal processing device 5. For example, steps S1110 and S1120 can be executed by the control device 7, which can control the X-ray sources and detectors of the first and second diffraction scanning stages to perform the corresponding scanning steps; step S1130 can be executed by the signal processing device 5, that is, the relevant functions and steps executed by the signal processor 130 can be included as part of the multi-view diffraction imaging method, i.e., the relevant functions and steps executed by the signal processor 130 can be incorporated into the multi-view diffraction imaging method. For the sake of brevity, these will not be elaborated further here.

[0107] In some exemplary embodiments, in step S1130, the detection signals obtained from the diffraction scanning stage at different viewpoints can be reconstructed separately. Based on the images reconstructed from different viewpoints, they can be merged. During the merging process, effective contour information from other viewpoints can be used to merge voxels or pixels of the current viewpoint to increase the statistical quantity and reduce the signal-to-noise ratio. Then, the above-mentioned separate image reconstruction and merging process is iteratively executed until a preset iteration condition is met. For example, the preset iteration condition may include that the accuracy of the acquired image meets the required accuracy.

[0108] For example, Figure 12 This is a flowchart illustrating the generation of diffraction images using a multi-view diffraction imaging method provided in this embodiment of the disclosure. (Refer to...) Figure 12 In step S1130, processing the first detection signal and the second detection signal to generate a diffraction image may include steps S1131 to S1135.

[0109] Step S1131 can be a first image reconstruction step, in which a first diffraction image is reconstructed based on the first detection signal using a diffraction image reconstruction algorithm.

[0110] Step S1132 can be a second image reconstruction step, in which a second diffraction image is reconstructed based on the second detection signal using a diffraction image reconstruction algorithm;

[0111] Step S1133 can be a pixel merging step, in which the first diffraction image and the second diffraction image are merged according to the corresponding pixels to generate a merged diffraction image.

[0112] Step S1134 can be an update step, in which the reconstruction parameters in the first diffraction image and the second diffraction image are updated based on the merged diffraction images; and

[0113] Step S1135 can be an iterative step, in which the first image reconstruction step, the second image reconstruction step, the pixel merging step, and the update step are executed iteratively until the accuracy of the merged diffraction image meets the predetermined accuracy requirements.

[0114] It should be understood that in XRD imaging systems and methods, based on the detection data acquired by the detector, an image of at least the object of interest of the inspected object can be reconstructed using an image reconstruction algorithm. The reconstruction process is essentially a process of solving the following linear equation (1), that is, given the imaging system matrix A and the detection signal b (i.e., projection data), the internal structure x of the inspected object is solved.

[0115] ,

[0116] Where x is the three-dimensional voxel vector to be reconstructed, and each element in the vector represents the feature information of the object being inspected at that voxel; b is the detection signal acquired by the detector under the scanning view; A is the imaging system matrix (or projection matrix), and each element in matrix A is used to describe the influence weight of each voxel of the object being inspected on each detection signal.

[0117] In this embodiment, each diffraction scanning level is solved separately using equation (1), and then the images reconstructed from each viewpoint are fused by pixel fusion and iterated, thereby improving the accuracy of the final image.

[0118] In some exemplary embodiments, in step S1130, for the detection signals obtained by the diffraction scanning stage at different viewpoints, the detection signals at all viewpoints can be put into the same equation (1) for iterative solution, and the data weight along the ray direction can be reduced during the solution process.

[0119] For example, the object being examined is discretized into a three-dimensional voxel mesh x. For each energy i at each scanning viewpoint, the contribution weight aij of each voxel j to the diffraction detection signal at that viewpoint is calculated. For example, the weight aij can be determined by at least the following factors: whether the geometric path satisfies the Bragg condition, the absorption attenuation of the incident path and the diffraction path, the spatial resolvability of the voxel at that viewpoint, etc. The above-mentioned contribution weight aij is used to construct the above-mentioned imaging system matrix A. The detection signals at all views are merged to construct a detection signal vector b with a higher dimension. The constructed imaging system matrix A and the detection signal vector b are substituted into equation (1), and the reconstructed image is solved by iterative solution.

[0120] In this embodiment, a multi-view joint solution framework is established, integrating the detection signals from all perspectives into a unified linear equation. In this way, the phase concentration or presence of each voxel within the examined object is no longer determined solely by a single, potentially noisy, detection signal, but rather by redundant observations from multiple independent perspectives. This data fusion mechanism has a noise suppression effect: random noise, which is uncorrelated across different perspectives, is weakened through joint optimization; while the true material signal remains consistent across all relevant perspectives, thus being effectively enhanced. The end result is a higher signal-to-noise ratio in the reconstructed diffraction spectrum, significantly improving the accuracy and robustness of material identification.

[0121] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0122] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A multi-view diffractive imaging system, comprising: The system comprises: a first diffraction scanning stage comprising a first radiation source configured to emit a first radiation for scanning a subject object from a first view angle, and a first detection assembly configured to detect a first scattered radiation to generate a first detection signal, wherein the first scattered radiation is a radiation scattered by the subject object after the first radiation acts on the subject object; a second diffraction scanning stage comprising a second radiation source configured to emit a second radiation for scanning the subject object from a second view angle, and a second detection assembly configured to detect a second scattered radiation to generate a second detection signal, wherein the second scattered radiation is a radiation scattered by the subject object after the second radiation acts on the subject object, and the second view angle is different from the first view angle; and a signal processing device electrically connected to the first detection assembly and the second detection assembly, and configured to process the first detection signal and the second detection signal to generate a diffraction image, and obtain an object of interest in the subject object and material information of the object of interest according to the diffraction image.

2. The system of claim 1, wherein, The first diffraction scanning stage and the second diffraction scanning stage are spaced apart along a first direction, and the subject object is movable along the first direction.

3. The system of claim 1, wherein, The first diffraction scanning stage and the second diffraction scanning stage are located at the same position along the first direction; and The system comprises a radiation source and a detection assembly movable in a fan angle direction, the first radiation source and the first detection assembly comprise a radiation source and a detection assembly at a first position in the fan angle direction respectively, the second radiation source and the second detection assembly comprise a radiation source and a detection assembly at a second position in the fan angle direction respectively, and the first position and the second position are different.

4. The system of claim 1, wherein, The system comprises a distributed radiation source comprising a plurality of target points spaced apart in the fan angle direction, the first radiation source comprises at least one target point at a first position in the fan angle direction, the second radiation source comprises at least another target point at a second position in the fan angle direction, and the first position and the second position are different.

5. The system of any one of claims 1-4, wherein, At least one of the first detection assembly and the second detection assembly comprises a detection module comprising: an encoding plate configured to encode the scattered radiation to form an encoded scattered radiation; a rear collimator configured to block a radiation having a first scattering angle scattered by the subject object, wherein the first scattering angle is greater than a preset scattering angle threshold; and a diffraction detector configured to detect the encoded scattered radiation, wherein the encoded scattered radiation is a radiation having a second scattering angle scattered by at least the object of interest in the subject object, and the second scattering angle is less than or equal to the preset scattering angle threshold.

6. The system of claim 5, wherein, The first radiation source and the first detection assembly are arranged on opposite sides of the object to be inspected along a second direction perpendicular to the first direction; in the second direction, the encoding plate, the post-collimator and the diffraction detector are arranged in a sequence of directions away from the first radiation source; and / or, The second radiation source and the second detection assembly are arranged on opposite sides of the object to be inspected along a third direction perpendicular to the first direction; in the third direction, the encoding plate, the post-collimator and the diffraction detector are arranged in a sequence of directions away from the second radiation source.

7. The system of claim 5, wherein, The first detection assembly further comprises a first transmission detector for detecting first transmission radiation transmitted through the object to be inspected to generate a third detection signal; the signal processing device is further configured to: obtain first attenuation characteristic information of at least the object of interest in the object to be inspected according to the third detection signal; and correct the first detection signal using the first attenuation characteristic information in the process of processing the first detection signal to generate a diffraction image; and / or, The second detection assembly further comprises a second transmission detector for detecting second transmission radiation transmitted through the object to be inspected to generate a fourth detection signal; the signal processing device is further configured to: obtain second attenuation characteristic information of at least the object of interest in the object to be inspected according to the fourth detection signal; and correct the second detection signal using the second attenuation characteristic information in the process of processing the second detection signal to generate a diffraction image.

8. The system of claim 5, wherein, In the cone angle direction, the first transmission detector is located on the path of the main beam of the first radiation, and the detection module is offset at a predetermined offset angle relative to the path of the main beam of the first radiation, the predetermined offset angle being less than or equal to a preset scattering angle threshold; and / or, In the cone angle direction, the second transmission detector is located on the path of the main beam of the second radiation, and the detection module is offset at a predetermined offset angle relative to the path of the main beam of the second radiation, the predetermined offset angle being less than or equal to a preset scattering angle threshold.

9. The system of claim 5, wherein, The first radiation source comprises a target point for emitting radiation; the first detection assembly comprises a plurality of detection modules, which are arranged centripetally relative to the target point in the fan angle direction; and / or, The second radiation source comprises a target point for emitting radiation; the second detection assembly comprises a plurality of detection modules, which are arranged centripetally relative to the target point in the fan angle direction.

10. The system of claim 9, wherein, In the fan angle direction, the plurality of detection modules are independently arranged from each other, and the diffraction detectors of the plurality of detection modules respectively comprise detection surfaces; for each of the plurality of detection modules, a connecting line of the detection surface and the target point is perpendicular to the detection surface.

11. The system of claim 5, wherein, The post-collimator comprises collimating sheets, and adjacent two detection modules of the plurality of detection modules share a collimating sheet; In the fan angle direction, the collimating sheets of the plurality of detection modules extend through the target point.

12. The system of claim 10, wherein, The diffraction detector of the detection module comprises a detection surface, and the detection surface is perpendicular to the second direction; or The diffraction detector of the detection module comprises a detection surface, and an extension line perpendicular to the detection surface and passing through the center of the detection surface passes through the object of interest.

13. The system of claim 5, wherein, The rear collimator comprises a shielding cylinder, the encoding plate is located on one side of the shielding cylinder close to the second ray source, and the diffraction detector is located on the other side of the shielding cylinder away from the second ray source.

14. The system of claim 5, wherein, A plurality of first holes are formed in the encoding plate, the plurality of first holes are used for the first scattered rays or the second scattered rays to pass through, and the plurality of first holes form a predetermined first encoding pattern in a projection plane, the projection plane being a plane determined by the intersection of the first direction and the third direction.

15. The system of claim 5, wherein, At least one of the first diffraction scanning stage and the second diffraction scanning stage further comprises a front collimator, the front collimator comprises a plurality of second holes, the plurality of second holes are used for the first rays or the second rays to pass through, and the plurality of second holes form a predetermined second encoding pattern in a projection plane, the projection plane being a plane determined by the intersection of the first direction and the third direction.

16. A multi-view diffractive imaging method, comprising: Comprise: A first view angle scanning step: controlling a first ray source to emit first rays to scan a checked object from a first view angle; Controlling a first detection assembly to detect first scattered rays scattered by the checked object to generate a first detection signal; A second view angle scanning step: controlling a second ray source to emit second rays to scan a checked object from a second view angle; Controlling a second detection assembly to detect second scattered rays scattered by the checked object to generate a second detection signal, wherein the second view angle is different from the first view angle; And An imaging step: processing the first detection signal and the second detection signal to generate a diffraction image, and obtaining an object of interest in the checked object and material information of the object of interest according to the diffraction image.

17. The method of claim 16, wherein, The processing of the first detection signal and the second detection signal to generate a diffraction image comprises: A first image reconstruction step: reconstructing a first diffraction image based on the first detection signal by using a diffraction image reconstruction algorithm; A second image reconstruction step: reconstructing a second diffraction image based on the second detection signal by using a diffraction image reconstruction algorithm; A pixel merging step: merging the first diffraction image and the second diffraction image according to corresponding pixels to generate a merged diffraction image; An updating step: updating the reconstruction parameters in the first diffraction image and the second diffraction image based on the merged diffraction image; and Iteratively performing the first image reconstruction step, the second image reconstruction step, the pixel merging step and the updating step until the accuracy of the merged diffraction image meets the predetermined accuracy requirement.

18. The method of claim 16, wherein, The processing the first detection signals and the second detection signals to generate a diffraction image comprises: jointly solving a same equation Ax=b by substituting the first detection signals and the second detection signals into the equation, to generate a diffraction image, wherein x is a three-dimensional voxel vector to be reconstructed, b is a detection signal acquired by a detector under each scanning viewing angle, and A is an imaging system matrix.

Images