Generation method for calibration data, image reconstruction method, and calibration phantom

Abstract

The present invention provides a generation method for calibration data. The calibration data is used for correction of image reconstruction of a scanning imaging device. The method comprises: placing a calibration phantom in a scanning area formed by rays, wherein the calibration phantom comprises M sections respectively composed of M materials, the M materials have M physical property theoretical values, respectively, and M is a positive integer greater than or equal to 2; by means of a detector, collecting rays passing through the scanning area so as to acquire actual projection data; on the basis of the actual projection data, using an image reconstruction algorithm to reconstruct the calibration phantom to obtain a reconstructed image; performing segmentation processing on the reconstructed image to obtain M reconstructed sub-images, wherein the M reconstructed sub-images respectively correspond to the M sections; for the M reconstructed sub-images, respectively calculating M physical property measurement values corresponding to the M sections; and generating calibration data on the basis of the M physical property theoretical values and the M physical property measurement values.

Description

Calibration data generation method, image reconstruction method and calibration phantom

[0001] This application claims priority to Chinese patent application No. 202410275691.X filed on March 11, 2024, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present disclosure relates to the field of scanning imaging technology, and more particularly, to a method for generating calibration data, an image reconstruction method for a scanning imaging device, and a calibration phantom. Background Art

[0003] Computed tomography (CT) technology, as an advanced nondestructive testing method, is widely used in the medical and security fields. The core components of CT equipment are the radiation source and detector. In actual application, different devices may have differences. For example, the energy spectrum emitted by the radiation source may vary depending on the filter, and the detector response may vary depending on the crystal and back-end circuitry. Due to the influence of these factors, after different devices are manufactured, there will be certain deviations in the reconstruction results of the same material. This will lead to a decrease in recognition accuracy and affect device performance. How to quickly and accurately correct the differences between different CT devices is an urgent problem that needs to be solved in the actual application of CT equipment.

[0004] The above information disclosed in this section is only for understanding of the background of the technical concept of the present disclosure and therefore may contain information that does not constitute related art. Summary of the Invention

[0005] The present disclosure provides a method for generating calibration data, an image reconstruction method for a scanning imaging device, and a calibration phantom.

[0006] In one aspect, a method for generating calibration data is provided. The calibration data is used for correcting image reconstruction of a scanning imaging device. The scanning imaging device includes a radiation source for emitting radiation and a detector for receiving radiation. During a calibration process, a calibration phantom is located in a scanning area formed by the radiation. The method includes:

[0007] placing the calibration phantom in a scanning area formed by the ray, wherein the calibration phantom includes M parts respectively formed of M materials, the M materials respectively having M theoretical values ​​of physical properties, where M is a positive integer greater than or equal to 2;

[0008] collecting rays passing through the scanning area by the detector to obtain actual projection data;

[0009] Reconstructing the calibration phantom using an image reconstruction algorithm based on the actual projection data to obtain a reconstructed image;

[0010] Segmenting the reconstructed image to obtain M reconstructed sub-images, wherein the M reconstructed sub-images correspond to the M parts respectively;

[0011] For the M reconstructed sub-images, respectively calculating M physical property measurement values ​​corresponding to the M parts; and

[0012] Calibration data is generated based on the M theoretical values ​​of the physical properties and the M measured values ​​of the physical properties.

[0013] According to some exemplary embodiments, generating calibration data based on the M theoretical physical property values ​​and the M measured physical property values ​​includes executing the following loop process until i equals M; the loop process includes:

[0014] Obtaining a theoretical value of an i-th physical property of the i-th part of the calibration phantom, where 1≤i≤M;

[0015] Obtaining an i-th physical property measurement value calculated for an i-th reconstructed sub-image, wherein the i-th reconstructed sub-image is a reconstructed image of the i-th portion of the calibration phantom; and

[0016] The i-th physical property theoretical value and the i-th physical property measured value are stored in a calibration data table, wherein in the calibration data table, the i-th physical property theoretical value and the i-th physical property measured value have a mapping relationship.

[0017] According to some exemplary embodiments, at least one of the following physical properties of any two of the M materials is different: density, atomic number.

[0018] According to some exemplary embodiments, collecting, by the detector, rays passing through the scanning area to obtain actual projection data includes:

[0019] Scanning the calibration phantom multiple times; and

[0020] The detector collects rays passing through the scanning area to obtain multiple sets of actual projection data.

[0021] According to some exemplary embodiments, after generating the calibration data, the method further includes:

[0022] collecting rays passing through the scanning area by the detector to obtain verification projection data;

[0023] reconstructing the calibration phantom using an image reconstruction algorithm based on the verification projection data and the calibration data to obtain a verification reconstructed image;

[0024] Based on the verification reconstructed image, respectively calculating M physical property verification values ​​corresponding to the M parts;

[0025] comparing the M theoretical physical property values ​​with the M verified physical property values; and

[0026] In response to a first result being the comparison result of the M theoretical physical property values ​​and the M verified physical property values, the calibration data is determined to be valid.

[0027] According to some exemplary embodiments, the scanning imaging device includes a scanning channel located between the radiation source and the detector; and the calibration phantom includes a calibration rod, and during the calibration process, the calibration rod is placed in the scanning channel in a direction approximately parallel to the scanning channel.

[0028] In another aspect, an image reconstruction method for a scanning imaging device is provided, wherein the scanning imaging device includes a radiation source for emitting radiation and a detector for receiving radiation, wherein the method includes:

[0029] placing the scanned object in the scanning area formed by the rays;

[0030] collecting rays passing through the scanning area by the detector to obtain actual projection data of the scanned object;

[0031] Obtain calibration data generated by the method described above;

[0032] reconstructing the scanned object using an image reconstruction algorithm based on actual projection data of the scanned object to obtain an initial reconstructed image; and

[0033] The initial reconstructed image is corrected using the calibration data to obtain a corrected reconstructed image.

[0034] On the other hand, a calibration phantom is provided, wherein the calibration phantom is composed of M parts respectively composed of M materials, the M materials respectively having M physical property values, M is a positive integer greater than or equal to 2, and any two of the M physical property values ​​are different; and the calibration phantom also includes a base, the shape of the base is designed to prevent the calibration phantom from rolling around its own axis.

[0035] According to some exemplary embodiments, the calibration phantom is a calibration rod, the M parts include a first part and a second part, and in the extension direction of the calibration rod, the base is located between the first part and the second part.

[0036] According to some exemplary embodiments, the mass of each of the M parts is not less than 50 grams; and / or the diameter of each of the M parts is not greater than 15 centimeters.

[0037] Additional aspects and advantages of the present disclosure will be set forth in part in the following description and, in part, will be obvious from the following description, or may be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] For a more complete understanding of the present disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0039] Figure 1 shows a simplified schematic diagram of a CT device of an exemplary embodiment of the present disclosure.

[0040] FIG2 shows a schematic diagram of a CT device according to an exemplary embodiment of the present disclosure.

[0041] FIG3 schematically shows a schematic diagram of the projection relationship between a ray source, a scanned object, and a detector.

[0042] FIG4 is a schematic structural diagram of a static CT device according to some exemplary embodiments of the present disclosure.

[0043] FIG5A is a schematic structural diagram of a scanning stage included in a static CT device according to some exemplary embodiments of the present disclosure.

[0044] FIG5B is a schematic structural diagram of a scanning stage included in a static CT device according to other exemplary embodiments of the present disclosure.

[0045] FIG6 is a schematic structural diagram of a calibration phantom according to some exemplary embodiments of the present disclosure.

[0046] FIG7 is a flowchart of a method for generating calibration data according to some exemplary embodiments of the present disclosure.

[0047] FIG8 is a flowchart of an image reconstruction method for a scanning imaging device according to some exemplary embodiments of the present disclosure.

[0048] FIG9 schematically shows a structural block diagram of an electronic device used for the above-mentioned calibration data generation method and image reconstruction method according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0049] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure. In addition, the various embodiments provided below and the technical features in the embodiments may be combined with each other in any manner.

[0050] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. In addition, the terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components. All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used here should be interpreted as having meanings consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0051] In the description of the present disclosure, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present disclosure. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present disclosure, unless otherwise specified, "multiple" means two or more.

[0052] In the description of this disclosure, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this disclosure based on the specific circumstances.

[0053] In the present disclosure, computed tomography (CT) imaging refers to the use of radiation to perform a cross-sectional scan of an object, converting the analog signal received by a detector into a digital signal, calculating the attenuation coefficient of each pixel using an electronic computer, and reconstructing the image to display the cross-sectional structure of each part of the object.

[0054] After research, the inventors discovered that the technology generally used in large cargo containers and aviation inspection equipment is single-row detector projection scanning technology. This technology can only form a two-dimensional image. Because the formed image is composed of multiple objects overlapping, it is difficult to identify the interior of the scanned object. This technology cannot perform three-dimensional imaging of objects, and cannot identify each voxel in subsequent processing. Therefore, the equipment does not have high requirements for accuracy and can tolerate differences between devices. With the development of technology, in recent years, the application of slip ring CT equipment in civil aviation, customs and other fields has become increasingly common. It can reconstruct each voxel of a three-dimensional object and identify contraband more efficiently and accurately. However, the core components of different devices may differ, and as the equipment components age, the reconstructed values ​​will deviate, affecting the accuracy of recognition.

[0055] Based on at least one aspect of the above-mentioned problems, embodiments of the present disclosure provide a method for generating calibration data, wherein the calibration data is used for correcting image reconstruction of a scanning imaging device, the scanning imaging device comprising a radiation source for emitting radiation and a detector for receiving radiation. During a calibration process, a calibration phantom is located in a scanning area formed by the radiation. The method comprises: placing the calibration phantom in the scanning area formed by the radiation, wherein the calibration phantom comprises M parts respectively composed of M types of materials, the M types of materials respectively having M theoretical values ​​of physical properties, where M is a positive integer greater than or equal to 2; collecting radiation passing through the scanning area via the detector to obtain actual projection data; reconstructing the calibration phantom based on the actual projection data using an image reconstruction algorithm to obtain a reconstructed image; segmenting the reconstructed image to obtain M reconstructed sub-images, wherein the M reconstructed sub-images respectively correspond to the M parts; calculating, for each of the M reconstructed sub-images, M physical property measurement values ​​corresponding to the M parts; and generating calibration data based on the M theoretical physical property values ​​and the M physical property measurement values. The calibration data generated by the method according to the embodiments of the present disclosure can correct the image during image reconstruction, thereby at least partially alleviating or solving the problem of inaccurate reconstruction due to differences between devices and / or device aging.

[0056] The embodiments of the present disclosure are described in further detail below with reference to the accompanying drawings.

[0057] FIG1 shows a simplified schematic diagram of a CT device according to an exemplary embodiment of the present disclosure; FIG2 shows a principle schematic diagram of a CT device according to an exemplary embodiment of the present disclosure.

[0058] In an exemplary embodiment, referring to Figures 1 and 2 , a CT device 100 is suitable for use in locations such as train stations, airports, and docks to inspect scanned objects 120, such as packages, suitcases, and handbags, for prohibited items such as drugs, explosives, and flammable materials. The CT device 100 includes a scanning channel 400 , a conveyor device 110 for conveying the scanned object 120 within the scanning channel 400 , and a scanning device configured to inspect the scanned object 120 conveyed by the conveyor device 110 .

[0059] For example, the conveying device 110 includes a conveyor belt suitable for carrying the scanned object and a driving roller for driving the conveyor belt to move.

[0060] 2 , the scanning device may include a radiation source 20 and a detector 30. The radiation source 20 and the detector 30 may be disposed on opposite sides of a scanning channel 400. When the radiation source 20 emits radiation, a scanning area is formed in the scanning channel 400.

[0061] In an exemplary embodiment, referring to FIG2 , the CT apparatus 100 further includes: a support frame 200 having a generally cube-shaped outer contour; and a slip ring 190 rotatably supported within the support frame 200, through which the scanning channel 400 passes. A radiation source 20 and a detector 30 are mounted on the slip ring 190 and, driven by a drive mechanism, are capable of rotating.

[0062] For example, the conveying device 110 carries the scanned object 120 and moves it through the scanning area between the radiation source 20 and the detector 30. At the same time, the radiation source 20 and the detector 30 rotate driven by the slip ring. The radiation beam emitted by the radiation source 20 can pass through the scanned object 120 to perform a CT scan on the scanned object 120.

[0063] During scanning of the scanned object 120, the controller 150 receives operation instructions input by the user through the computer 160 at the workstation, and controls the operation of the driving mechanism according to the operation instructions; the slip ring 190 drives the radiation source 20 and the detector 30 to rotate under the drive mechanism, and at the same time, the radiation source 20 can generate an X-ray beam under the control of the controller, and the X-ray beam passes through the scanned object 120 moving on the conveying device 110 and irradiates the detector 30; the detector 30 converts the received X-ray beam into an electrical signal and transmits it to the data acquisition module 170; the image reconstruction module 180 receives data from the data acquisition module, reconstructs the received data and generates image data; the generated image data is transmitted to the computer 160, so as to identify and inspect the scanned object 120.

[0064] FIG3 schematically illustrates a schematic diagram of the projection relationship between a ray source, a scanned object, and a detector. Referring to FIG3 , in an embodiment of the present disclosure, rays (e.g., X-rays, gamma rays, etc.) emitted by a ray source 20 are incident on a scanned object 120, and rays transmitted through the scanned object 120 are detected by a detector 30. A spatial point X on the scanned object 120 is acted upon by the ray source 20 to an image point Y on the detector 30. In forward projection (also known as forward projection), the pixel value of the spatial point on the scanned object 120 is known, and the projection value of the image point on the detector 30 is obtained. In reverse projection (also known as backward projection), the projection value of the image point on the detector 30 is known, and the pixel value of the spatial point on the scanned object 120 is obtained.

[0065] Computed tomography (CT) technology, because it can eliminate the effects of overlapping objects, has played a vital role in security inspections and medical fields. Traditional CT systems use a slip-ring mechanism to acquire projection data at different angles by rotating the X-ray source and detector. Reconstruction methods produce tomographic images, thereby revealing internal information about the inspected baggage. Traditional CT systems typically rely on slip-ring rotation during data acquisition, which not only limits scanning speed and is bulky, but also requires high machining precision and is expensive, limiting their widespread practical application. In recent years, carbon nanotube X-ray tube technology has entered the practical field. Unlike traditional X-ray sources, it does not require high temperatures to generate X-rays. Instead, it generates cathode rays based on discharge at the tip of the carbon nanotube, which then strikes the target to produce X-rays. Its advantages include fast switching on and off and a smaller size. Arranging these X-ray sources in a ring shape to irradiate objects at different angles creates a "static CT" system that does not require rotation. This significantly improves X-ray imaging speed and, by eliminating the slip-ring mechanism, reduces costs. This holds significant significance for applications in security inspections and other fields.

[0066] FIG4 is a schematic diagram of the structure of a static CT device according to some exemplary embodiments of the present disclosure. Referring to FIG4 , the static CT device according to an embodiment of the present disclosure may include a scanning stage, a conveying device 110, a control device 140, and an imaging device 130. For example, the scanning stage may include a radiation source, a detector, and an acquisition device.

[0067] For example, in an embodiment of the present disclosure, the ray source may be a distributed ray source, which may include multiple target points, for example, multiple X-ray target points. In a distributed X-ray source, the target point refers to the emission point or focus of the ray source. Specifically, high-energy electrons are emitted from the cathode and bombard the metal anode target, thereby generating X-rays. The energy of the emitted X-rays depends on the material of the anode target, while the intensity of the X-rays depends on the electron flux and electron energy bombarding the anode target. In a distributed X-ray source, multiple cathodes correspond one-to-one to multiple target points, so that multiple target points receive electron beams from multiple cathodes to generate multiple beams of X-rays. This design enables the distributed X-ray source to achieve the effect of generating more X-ray radiation sources using fewer cathode components, thereby improving the stability of the system, reducing the number of cathode components used, and reducing the production cost of the equipment.

[0068] In static CT devices that utilize distributed radiation sources, multiple targets are combined and activated sequentially at different angles to acquire multiple projection data sets from various angles. These projection data sets can be used in computer reconstruction algorithms to generate high-quality cross-sectional images. One advantage of using a distributed X-ray source is that it can reduce artifacts and improve image quality. By using multiple targets, the emission positions of the X-ray beam are more evenly distributed, providing more projection angles and data, reducing artifacts in the reconstructed image, and providing more accurate anatomical information. In other words, the targets in a distributed X-ray source refer to the points or areas that emit X-ray beams, and their distribution helps to obtain high-quality projection data for the reconstruction of static CT images.

[0069] In the embodiments of the present disclosure, multiple targets in a distributed radiation source can be arranged along a predetermined first direction. For example, the predetermined first direction can be a straight line or an arc. The embodiments of the present disclosure do not impose any particular restrictions on the arrangement of the targets in the distributed radiation source.

[0070] FIG5A is a schematic diagram of the structure of a scanning stage included in a static CT device according to some exemplary embodiments of the present disclosure. FIG5B is a schematic diagram of the structure of a scanning stage included in a static CT device according to other exemplary embodiments of the present disclosure. Referring to FIG5A and FIG5B , in an embodiment of the present disclosure, the static CT device includes a distributed radiation source 20 and a detector 30. The distributed radiation source 20 may include multiple targets 210. In some embodiments, as shown in FIG5A , the multiple targets 210 may be arranged in an arc shape. Accordingly, the detector 30 may include multiple detection units 310 arranged in an arc shape or a circle. In some embodiments, as shown in FIG5B , the multiple targets 210 may be arranged along a straight line. Accordingly, the detector 30 may include multiple detection units 310 arranged along a straight line. It should be noted that the embodiments of FIG2 to FIG5B are merely schematic diagrams of the structures of static CT devices according to some exemplary embodiments of the present disclosure, and do not represent all embodiments of the present disclosure. In the embodiments of the present disclosure, any suitable arrangement of distributed radiation sources and detectors may be employed.

[0071] In the embodiment of the present disclosure, the multiple target points 210 each emit radiation toward the scanned object 120, and the multiple detection units 310 are used to detect the radiation that has passed through the scanned object 120. For example, in the embodiment shown in Figures 5A and 5B, the multiple target points 210 emit X-rays, and the multiple detection units 310 receive portions of the X-rays emitted from the multiple target points 210 that have passed through the scanned object 120. Thus, a scanning area is formed between the radiation source 20 and the detector 30 for scanning the scanned object 120. Within this scanning area, at least one plane located approximately in the middle of the scanning area and perpendicular to the conveying direction of the conveyor device 110 can be referred to as a scanning plane.

[0072] For example, the detection unit 310 may include at least one detector crystal. For example, the detection unit 310 may include one detector crystal. For another example, the detection unit 310 may include multiple detector crystals, and the multiple detector crystals may be arranged along a one-dimensional direction, or the multiple detector crystals may be arranged along a two-dimensional direction.

[0073] It should be understood that each detector crystal is a basic unit of the detector, which can absorb radiation (such as X-rays) and convert it into other forms of energy, such as light or electrical signals. For example, the materials of the detector crystals can include oxides and halides (such as iodide and fluoride).

[0074] For example, in the embodiment shown in FIG4 , the transport device 110 carries the scanned object 120 and drives the scanned object 120 in linear motion. The control device 140 controls the beam emission sequence of the multiple target points 210 of the radiation source 20, causing the detector 30 to output digital signals corresponding to the projection data. The imaging device 130 reconstructs a CT image of the scanned object 120 based on the digital signals.

[0075] It should be noted that in the embodiments of the present disclosure, the image reconstruction module 180 shown in FIG. 2 or the imaging device 130 shown in FIG. 4 can employ various known reconstruction algorithms to reconstruct a CT image of the scanned object. For example, the reconstruction algorithm can be an iterative, analytical, or other reconstruction algorithm, and the embodiments of the present disclosure do not impose any particular limitation on the reconstruction algorithm.

[0076] In some embodiments of the present disclosure, each distributed ray source 20 has one or more targets, the energy of the targets can be set, and the order of target activation can be set. For example, the targets can be distributed on multiple scanning planes (for example, the scanning plane is perpendicular to the direction of passage). In each plane, the target distribution can be continuous or discontinuous, one or more straight lines or arcs. Since the target energy can be set, a variety of scanning modes can be achieved during the beam emission process, such as different targets having different energy spectra, or targets located in different planes having different energies. The targets can be designed in groups, such as the targets of each module as a group, or the targets of each plane as a group. The order of electronic targeting of targets in the same group can be adjusted, and sequential beam emission and alternating beam emission can be achieved. Targets in different groups can be activated at the same time for scanning to speed up the scanning speed.

[0077] The detector 30 may be a single row or multiple rows, and the detector type may be a single energy, dual energy or energy spectrum detector.

[0078] The conveyor 110 includes a stage or conveyor belt, while the control unit 140 controls the X-ray machine and detector frames. By controlling the beam emission pattern of the distributed X-ray source and the linear translation of the object, or a combination of the two, spiral scanning trajectories, circular scanning trajectories, or other special trajectories can be achieved. The control unit 140 is responsible for controlling the operation of the CT system, including mechanical rotation, electrical control, and safety interlock control. Specifically, it controls the X-ray source's beam emission speed / frequency, beam energy, and beam sequence, and controls detector data readout and reconstruction.

[0079] FIG6 is a schematic diagram of the structure of a calibration phantom according to some exemplary embodiments of the present disclosure. It should be noted that, unless otherwise specified, the calibration phantom and method described below can be applied to the scanning imaging devices described in the various embodiments above. That is, the calibration phantom and method described below can be applied to both the slip-ring CT device shown in FIG1 and FIG2 and the static CT device shown in FIG4, FIG5A, and FIG5B.

[0080] 6 , the calibration phantom 60 includes M parts respectively made of M materials, wherein the M materials respectively have M physical property values, where M is a positive integer greater than or equal to 2, and any two of the M physical property values ​​are different.

[0081] For example, the physical property value may be at least one of density and atomic number, that is, at least one of the physical property values ​​of density and atomic number of the M materials is different.

[0082] Exemplarily, the M portions include a first portion 61 and a second portion 62. For example, the density of the material of the first portion 61 is different from the density of the material of the second portion 62. Alternatively, the atomic number of the material of the first portion 61 is different from the atomic number of the material of the second portion 62. For another example, the density of the material of the first portion 61 is different from the density of the material of the second portion 62, and the atomic number of the material of the first portion 61 is different from the atomic number of the material of the second portion 62.

[0083] 6 , the calibration phantom 60 further includes a base 610 . The shape of the base 610 is designed to prevent the calibration phantom 60 from rolling around its own axis AX1 .

[0084] Exemplarily, the calibration phantom 60 is formed as a calibration rod. Specifically, the first portion 61 and the second portion 62 are both cylindrical. The outer profile of at least a portion of the base 610 is formed into a rectangular shape. For example, in the extension direction of the calibration rod, the base 610 is located between the first portion 61 and the second portion 62.

[0085] 1 to 6 , during the calibration process, a calibration phantom 60, serving as a scanned object, is placed on the conveyor device 110 to pass through the scanning area. The calibration phantom 60 can be placed on the conveyor device 110 along the extension direction of the scanning channel 400. Specifically, the axis AX1 of the calibration phantom 60, or its extension direction, is substantially parallel to the extension direction of the scanning channel 400.

[0086] It should be noted that "approximately parallel" here means that the axis AX1 of the calibration model 60 or its extension direction is parallel to the extension direction of the scanning channel 400, or the angle between the axis AX1 of the calibration model 60 or its extension direction and the extension direction of the scanning channel 400 is within the range of ±10°.

[0087] Since the calibration phantom 60 is provided with a base 610 serving as an anti-rolling portion, the calibration phantom 60 can be ensured not to roll on the conveying device 110 during the calibration process, which is beneficial to ensuring the accuracy of the calibration result.

[0088] The M parts of the calibration model 60 are arranged in sequence along the extension direction of the axis AX1. In this way, during the calibration process, the M parts composed of M kinds of materials pass through the scanning surface in sequence, which can avoid interference between various materials and is conducive to improving the accuracy of the calibration results.

[0089] For example, each of the M parts may be designed to be cylindrical. However, the embodiments of the present disclosure are not limited thereto. In other embodiments, at least one of the M parts may be designed to be other shapes.

[0090] In some exemplary embodiments, the mass of each of the M parts is not less than 50 grams. This ensures that a sufficient amount of data can be obtained for each material, which is conducive to improving the accuracy of calibration.

[0091] In some exemplary embodiments, the diameter of each of the M parts is no greater than 15 centimeters. This can avoid reconstruction deviation caused by radiation hardening and help improve the accuracy of calibration phantom reconstruction.

[0092] In some exemplary embodiments, calibration phantom 60 includes at least three different materials, i.e., M is greater than or equal to 3. For example, one of the M materials in calibration phantom 60 can be an explosive simulant, which closely resembles real explosives in physical properties such as density and equivalent atomic number. This design allows for verification of the effectiveness of the recognition algorithm during device operation. For another example, the materials in calibration phantom 60 can be highly consistent, maintaining consistent properties regardless of manufacturing time and location, and readily available and cost-effective.

[0093] Based on the calibration phantom 60 provided in the embodiments of the present disclosure, some exemplary embodiments of the present disclosure further provide a method for generating calibration data, wherein the calibration data is used to correct image reconstruction of a scanning imaging device. FIG7 is a flowchart of the method for generating calibration data according to some exemplary embodiments of the present disclosure. The method may include steps S710 to S760.

[0094] It should be noted that, in this document, unless otherwise specifically stated, in the method provided in the embodiments of the present disclosure, the execution order of the steps is not limited to the order in which the steps are recorded in this document. In the absence of conflict, the steps may be executed in an order different from the order recorded in this document. For example, some steps may be executed in parallel or in reverse order.

[0095] In step S710 , the calibration phantom 60 is placed in a scanning area formed by the rays.

[0096] In step S720 , the detector 30 collects rays passing through the scanning area to obtain actual projection data.

[0097] In some exemplary embodiments of the present disclosure, in this step, a single scan may be performed on the calibration phantom; and rays passing through the scanned area may be collected by a detector to obtain a single set of actual projection data.

[0098] In some exemplary embodiments of the present disclosure, during this step, the calibration phantom can be scanned multiple times, and the detector can capture rays passing through the scanned area to obtain multiple sets of actual projection data. This method can obtain more projection data, which is beneficial for improving the accuracy of subsequent calibration.

[0099] In step S730 , the calibration phantom 60 is reconstructed using an image reconstruction algorithm based on the actual projection data to obtain a reconstructed image.

[0100] In step S740 , segmentation processing is performed on the reconstructed image to obtain M reconstructed sub-images, wherein the M reconstructed sub-images correspond to the M parts respectively.

[0101] In step S750 , for the M reconstructed sub-images, M physical property measurement values ​​corresponding to the M parts are calculated respectively.

[0102] In step S760 , calibration data is generated based on the M theoretical values ​​of the physical properties and the M measured values ​​of the physical properties.

[0103] In some exemplary embodiments of the present disclosure, the calibration data may be presented and stored in the form of a calibration data table, which facilitates storage and reading and writing of the calibration data in a computer.

[0104] Exemplarily, in step S760 , calibration data is generated based on M theoretical values ​​of physical properties and M measured values ​​of physical properties, including executing the following loop process until i equals M.

[0105] Specifically, the loop process includes: obtaining the i-th physical property theoretical value of the i-th part of the calibration phantom, where 1≤i≤M; obtaining the i-th physical property measurement value calculated for the i-th reconstructed sub-image, where the i-th reconstructed sub-image is the reconstructed image of the i-th part of the calibration phantom; and storing the i-th physical property theoretical value and the i-th physical property measurement value in a calibration data table, where in the calibration data table, the i-th physical property theoretical value and the i-th physical property measurement value have a mapping relationship.

[0106] In other words, the theoretical and measured values ​​of the physical properties of the M parts are stored in a data table in a one-to-one mapping order from 1st to Mth, forming a calibration data table. This calibration data table is stored in a computer. During the actual image reconstruction process, the required calibration data can be quickly read from this calibration data table, which helps to improve the speed of image reconstruction. Furthermore, after calibration using another calibration phantom, new calibration data can be easily inserted into this calibration data table.

[0107] In some optional embodiments, the method may further include a step of verifying the generated calibration data. Specifically, after generating the calibration data, the method further includes: collecting rays passing through the scanning area through a detector to obtain verification projection data; reconstructing the calibration phantom using an image reconstruction algorithm based on the verification projection data and the calibration data to obtain a verification reconstructed image; calculating M physical property verification values ​​corresponding to the M parts based on the verification reconstructed image; comparing the M physical property theoretical values ​​with the M physical property verification values; and determining that the calibration data is valid in response to the comparison result of the M physical property theoretical values ​​and the M physical property verification values ​​being a first result.

[0108] For example, the first result may be: the gap between the M theoretical values ​​of the physical properties and the M verified values ​​of the physical properties is small. Here, "small gap" may be: the mean square error of the M theoretical values ​​of the physical properties and the M verified values ​​of the physical properties is smaller than a preset threshold.

[0109] Optionally, in some other exemplary embodiments of the present disclosure, the method may further include: in response to the comparison result of the M theoretical values ​​of physical properties and the M verified values ​​of physical properties being a second result, repeatedly executing the calibration method to regenerate calibration data.

[0110] For example, the second result may be: a large gap between the M theoretical values ​​of the physical properties and the M verified values ​​of the physical properties. Here, "large gap" may be: the mean square error of the M theoretical values ​​of the physical properties and the M verified values ​​of the physical properties is greater than a preset threshold.

[0111] Some exemplary embodiments of the present disclosure also provide an image reconstruction method for a scanning imaging device. Figure 8 is a flowchart of an image reconstruction method for a scanning imaging device according to some exemplary embodiments of the present disclosure. The method may include steps S810 to S850.

[0112] In step S810 , the scanned object 120 is placed in a scanning area formed by the rays.

[0113] In step S820 , the detector 30 collects rays passing through the scanning area to obtain actual projection data of the scanned object 120 .

[0114] In step S830, calibration data is obtained, which may be calibration data generated using the above method.

[0115] In step S840 , the scanned object 120 is reconstructed using an image reconstruction algorithm based on the actual projection data of the scanned object 120 to obtain an initial reconstructed image.

[0116] In step S850, the initial reconstructed image is corrected using the calibration data to obtain a corrected reconstructed image.

[0117] FIG9 schematically shows a structural block diagram of an electronic device used for the above-mentioned calibration data generation method and image reconstruction method according to an exemplary embodiment of the present disclosure.

[0118] As shown in Figure 9, the electronic device according to an embodiment of the present disclosure may include a processor 1001, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from a storage part 1008 into a random access memory (RAM) 1003. The processor 1001 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or a related chipset and / or a dedicated microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 1001 may also include an onboard memory for caching purposes. The processor 1001 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present disclosure.

[0119] Various programs and data required for the method are stored in RAM 1003. Processor 1001, ROM 1002, and RAM 1003 are connected to each other via bus 1004. Processor 1001 executes the various operations of the method flow according to the embodiment of the present disclosure by executing the programs in ROM 1002 and / or RAM 1003. It should be noted that the programs may also be stored in one or more memories other than ROM 1002 and RAM 1003. Processor 1001 may also execute the various operations of the method flow according to the embodiment of the present disclosure by executing the programs stored in the one or more memories.

[0120] According to an embodiment of the present disclosure, the electronic device may further include an input / output (I / O) interface 1005, which is also connected to the bus 1004. The electronic device may further include one or more of the following components connected to the I / O interface 1005: an input portion 1006 including a keyboard, a mouse, etc.; an output portion 1007 including a cathode ray tube (CRT), a liquid crystal display (LCD), a speaker, etc.; a storage portion 1008 including a hard disk, etc.; and a communication portion 1009 including a network interface card such as a LAN card or a modem. The communication portion 1009 performs communication processing via a network such as the Internet. A drive 1010 is also connected to the I / O interface 1005 as needed. A removable medium 1011, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed in the drive 1010 as needed, so that a computer program read therefrom can be installed into the storage portion 1008 as needed.

[0121] The present disclosure also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments, or may exist independently and not be incorporated into the device / apparatus / system. The computer-readable storage medium carries one or more programs, and when executed, implements the method according to the embodiments of the present disclosure.

[0122] According to an embodiment of the present disclosure, a computer-readable storage medium may be a non-volatile computer-readable storage medium, for example, it may include but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, apparatus, or device. For example, according to an embodiment of the present disclosure, a computer-readable storage medium may include the ROM 1002 and / or RAM 1003 described above and / or one or more memories other than ROM 1002 and RAM 1003.

[0123] According to an embodiment of the present disclosure, the program code for executing the computer program provided by the embodiment of the present disclosure can be written in any combination of one or more programming languages. Specifically, these computer programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, languages ​​such as Java, C++, python, "C" or similar programming languages. The program code can be executed entirely on the user computing device, partially on the user device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving a remote computing device, the remote computing device can be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (for example, using an Internet service provider to connect via the Internet).

[0124] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or a part of code, and the above-mentioned module, program segment, or a part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0125] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" 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 disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0126] Although embodiments of the present disclosure have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and purpose of the present disclosure, and that the scope of the present disclosure is defined by the claims and their equivalents. It will be understood by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in various ways, without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

Claims

1. A method for generating calibration data, wherein the calibration data is used for correcting image reconstruction of a scanning imaging device, wherein the scanning imaging device includes a radiation source for emitting radiation and a detector for receiving radiation, wherein during the calibration process, a calibration phantom is located in a scanning area formed by the radiation, wherein: The method comprises: placing the calibration phantom in a scanning area formed by the ray, wherein the calibration phantom includes M parts respectively formed of M materials, the M materials respectively having M theoretical values ​​of physical properties, where M is a positive integer greater than or equal to 2; collecting rays passing through the scanning area by the detector to obtain actual projection data; Reconstructing the calibration phantom using an image reconstruction algorithm based on the actual projection data to obtain a reconstructed image; Segmenting the reconstructed image to obtain M reconstructed sub-images, wherein the M reconstructed sub-images correspond to the M parts respectively; For the M reconstructed sub-images, respectively calculating M physical property measurement values ​​corresponding to the M parts; and Calibration data is generated based on the M theoretical values ​​of the physical properties and the M measured values ​​of the physical properties.

2. The method according to claim 1, wherein Generating calibration data based on the M theoretical values ​​of the physical properties and the M measured values ​​of the physical properties includes executing the following loop process until i equals M; The cycle process includes: Obtaining a theoretical value of an i-th physical property of the i-th part of the calibration phantom, where 1≤i≤M; Obtaining an i-th physical property measurement value calculated for an i-th reconstructed sub-image, wherein the i-th reconstructed sub-image is a reconstructed image of the i-th portion of the calibration phantom; and The i-th physical property theoretical value and the i-th physical property measured value are stored in a calibration data table, wherein in the calibration data table, the i-th physical property theoretical value and the i-th physical property measured value have a mapping relationship.

3. The method according to claim 1 or 2, wherein: Any two of the M materials have at least one different physical property: density, atomic number.

4. The method according to claim 1 or 2, wherein: The collecting, by the detector, rays passing through the scanning area to obtain actual projection data includes: Scanning the calibration phantom multiple times; and The detector collects rays passing through the scanning area to obtain multiple sets of actual projection data.

5. The method according to claim 1 or 2, wherein: After generating the calibration data, the method further includes: collecting rays passing through the scanning area by the detector to obtain verification projection data; reconstructing the calibration phantom using an image reconstruction algorithm based on the verification projection data and the calibration data to obtain a verification reconstructed image; Based on the verification reconstructed image, respectively calculating M physical property verification values ​​corresponding to the M parts; comparing the M theoretical physical property values ​​with the M verified physical property values; and In response to a first result being the comparison result of the M theoretical physical property values ​​and the M verified physical property values, the calibration data is determined to be valid.

6. The method according to claim 1 or 2, wherein: The scanning imaging device includes a scanning channel located between the ray source and the detector; and The calibration phantom includes a calibration rod. During the calibration process, the calibration rod is placed in the scanning channel in a direction substantially parallel to the scanning channel.

7. An image reconstruction method for a scanning imaging device, wherein the scanning imaging device comprises a radiation source for emitting radiation and a detector for receiving radiation, wherein: The method comprises: placing the scanned object in the scanning area formed by the rays; collecting rays passing through the scanning area by the detector to obtain actual projection data of the scanned object; Obtaining calibration data generated by the method according to any one of claims 1 to 5; reconstructing the scanned object using an image reconstruction algorithm based on actual projection data of the scanned object to obtain an initial reconstructed image; and The initial reconstructed image is corrected using the calibration data to obtain a corrected reconstructed image.

8. A calibration phantom, wherein: The calibration phantom is composed of M parts composed of M materials, each of the M materials has M physical property values, where M is a positive integer greater than or equal to 2, and any two of the M physical property values ​​are different; as well as The calibration phantom further includes a base, the shape of which is designed to prevent the calibration phantom from rolling around its own axis.

9. The calibration phantom according to claim 8, wherein: The calibration phantom is a calibration rod, the M parts include a first part and a second part, and in the extension direction of the calibration rod, the base is located between the first part and the second part.

10. The calibration phantom according to claim 8 or 9, wherein: The mass of each of the M parts is not less than 50 grams; and / or, The diameter of each of the M parts is no greater than 15 cm.

Images