CN118154711A

CN118154711A - Calibration data generation method, image reconstruction method and calibration die body

Info

Publication number: CN118154711A
Application number: CN202410275691.XA
Authority: CN
Inventors: 张丽; 唐智; 许晓飞; 沈乐; 雷蕾; 常铭; 金鑫; 孙运达
Original assignee: Tsinghua University; Nuctech Co Ltd
Current assignee: Tsinghua University; Nuctech Co Ltd
Priority date: 2024-03-11
Filing date: 2024-03-11
Publication date: 2024-06-07

Abstract

There is provided a method of generating calibration data for correction of image reconstruction of a scanning imaging device, the method comprising: placing a calibration die body in a scanning area formed by rays, wherein the calibration die body comprises M parts respectively formed by M materials, the M materials respectively have M physical attribute theoretical values, and M is a positive integer greater than or equal to 2; collecting rays passing through a scanning area through a detector to obtain actual projection data; reconstructing the calibration phantom by using an image reconstruction algorithm based on actual projection data to obtain a reconstructed image; dividing the reconstructed image to obtain M reconstructed sub-images, wherein the M reconstructed sub-images respectively correspond to M parts; for the M reconstructed sub-images, respectively calculating M physical attribute measurement values corresponding to the M parts; and generating calibration data based on the M physical attribute theoretical values and the M physical attribute measured values.

Description

Calibration data generation method, image reconstruction method and calibration die body

Technical Field

The present disclosure relates to the field of scanning imaging technologies, and more particularly, to a calibration data generating method, an image reconstruction method for a scanning imaging device, and a calibration phantom.

Background

The Computed Tomography (CT) technology, which is known as computed tomography, is widely used in the medical and security fields as an advanced non-destructive testing method. The core components of the CT apparatus are a radiation source and a detector. In practical applications, different devices may differ, for example, the spectrum emitted by the radiation source may differ due to the filter, and the detector response may differ due to the crystal and the back-end circuit. Due to the influence of the factors, after different devices are manufactured, certain deviation exists in the reconstruction result of the same material, and the accuracy in recognition is reduced, so that the device performance is affected. How to quickly and accurately correct the difference between different CT devices is an urgent problem to be solved in practical application of CT devices.

The above information disclosed in this section is only for understanding the background of the technical idea of the present disclosure, and thus, the above information may contain information that does not constitute prior art.

Disclosure of Invention

In order to solve the above problems in the prior art, an embodiment of the present disclosure provides a calibration data generating method, an image reconstructing method for a scanning imaging device, and a calibration phantom.

In one aspect, there is provided a method of generating calibration data for correction of image reconstruction of a scanning imaging apparatus comprising a source for emitting radiation and a detector for receiving radiation, during calibration a calibration phantom being located in a scan region formed by the radiation, the method comprising:

placing the calibration die body in a scanning area formed by the rays, wherein the calibration die body comprises M parts respectively formed by M materials, the M materials respectively have M physical attribute theoretical values, and M is a positive integer greater than or equal to 2;

acquiring rays passing through the scanning area through the detector to acquire actual projection data;

reconstructing the calibration phantom by using an image reconstruction algorithm based on the actual projection data to obtain a reconstructed image;

Dividing the reconstructed image to obtain M reconstructed sub-images, wherein the M reconstructed sub-images respectively correspond to the M parts;

For the M reconstructed sub-images, respectively calculating M physical attribute measurement values corresponding to the M parts; and

And generating calibration data based on the M physical attribute theoretical values and the M physical attribute measured values.

According to some exemplary embodiments, the generating calibration data based on the M physical property theoretical values and the M physical property measured values includes performing a loop process until i is equal to M; the cyclic process includes:

acquiring an ith physical attribute theoretical value of an ith part of the calibration die body, wherein i is more than or equal to 1 and less than or equal to M;

Acquiring an ith physical attribute measured value calculated for an ith reconstructed sub-image, wherein the ith reconstructed sub-image is a reconstructed image of an ith part of the calibration phantom; and

And storing the ith physical attribute theoretical value and the ith physical attribute measured value into a calibration data table, wherein in the calibration data table, the ith physical attribute theoretical value and the ith physical attribute measured value have a mapping relation.

According to some exemplary embodiments, at least one of the following physical properties of any two of the M materials are not the same: density, atomic number.

According to some exemplary embodiments, the acquiring, by the detector, radiation passing through the scan region to acquire actual projection data includes:

Scanning the calibration die body for a plurality of times; and

And acquiring rays passing through the scanning area through the detector so as to acquire a plurality of groups of actual projection data.

According to some exemplary embodiments, after generating the calibration data, the method further comprises:

Collecting rays passing through the scanning area by the detector to obtain verification projection data;

Reconstructing the calibration phantom by 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 attribute verification values corresponding to the M parts;

Comparing the M physical attribute theoretical values with the M physical attribute verification values; and

And determining that the calibration data is valid in response to the comparison result of the M physical attribute theoretical values and the M physical attribute verification values being a first result.

According to some exemplary embodiments, the scanning imaging device comprises a scanning channel between the radiation source and the detector; and the calibration phantom includes a calibration rod disposed within the scan channel in a direction substantially parallel to the scan channel during the calibration process.

In another aspect, there is provided an image reconstruction method for a scanning imaging device comprising a radiation source for emitting radiation and a detector for receiving radiation, wherein the method comprises:

Placing a scanned object in a scanning area formed by the rays;

acquiring rays passing through the scanning area through the detector to acquire actual projection data of a scanned object;

Acquiring calibration data generated by the method;

Reconstructing the scanned object by using an image reconstruction algorithm based on actual projection data of the scanned object to obtain an initial reconstructed image; and

And correcting the initial reconstructed image by using the calibration data to obtain a corrected reconstructed image.

In yet another aspect, a calibration phantom is provided, the calibration phantom being each of M portions of M materials, the M materials each having M physical attribute values, M being a positive integer greater than or equal to 2, any two of the M physical attribute values being different; and the calibration phantom further comprises a seat shaped to prevent rolling of the calibration phantom about its own axis.

According to some exemplary embodiments, the calibration phantom is a calibration rod, the M portions include a first portion and a second portion, and the base is located between the first portion and the second portion in an extension direction of the calibration rod.

According to some exemplary embodiments, each of the M portions has a mass of not less than 50 grams; and/or, each of the M portions has a diameter of no more than 15 cm.

Additional aspects and advantages of the disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure.

Drawings

For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

fig. 1 shows a simplified schematic diagram of a CT apparatus of an exemplary embodiment of the present disclosure.

Fig. 2 shows a schematic diagram of a CT apparatus according to an exemplary embodiment of the present disclosure.

Fig. 3 schematically shows a schematic view of a projection relationship between a radiation source, a scanned object and a detector.

Fig. 4 is a schematic structural view of a static CT apparatus according to some exemplary embodiments of the present disclosure.

Fig. 5A is a schematic structural diagram of a scan stage included in a static CT apparatus according to some exemplary embodiments of the present disclosure.

Fig. 5B is a schematic structural view of a scan stage included in a static CT apparatus according to other exemplary embodiments of the present disclosure.

FIG. 6 is a schematic illustration of a calibration phantom according to some exemplary embodiments of the present disclosure.

FIG. 7 is a flowchart of a method of generating calibration data according to some exemplary embodiments of the present disclosure.

Fig. 8 is a flowchart of an image reconstruction method for a scanning imaging device according to some exemplary embodiments of the present disclosure.

Fig. 9 schematically shows a block diagram of an electronic device for the above-described calibration data generation method and image reconstruction method according to an exemplary embodiment of the present disclosure.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure. In addition, the various embodiments provided below of the present disclosure and technical features in the embodiments may be combined with each other in any manner.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. Furthermore, the terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components. All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.

In the description of the present disclosure, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present disclosure. Furthermore, features defining "first", "second" may include one or more such features, either explicitly or implicitly. In the description of the present disclosure, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the description of the present disclosure, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this disclosure will be understood by those of ordinary skill in the art in the specific context.

In the present disclosure, computed tomography (Computed Tomography, abbreviated as CT) imaging refers to a process of performing a tomographic scan on a detection object using radiation, converting an analog signal received by a detector into a digital signal, calculating an attenuation coefficient of each pixel by an electronic computer, and reconstructing an image, thereby displaying a tomographic structure of each portion of the detection object.

The inventor finds that the technology generally adopted by large cargo containers and aviation detection equipment is a single-column detector projection scanning technology. This technique can only form a two-dimensional image, and since a plurality of objects are superimposed on each other, it is difficult to recognize the interior of the scanned object. This technique does not allow three-dimensional imaging of an object and does not allow identification of each voxel in subsequent processing, so that the accuracy of the device is not so high that differences between devices can be tolerated. With the development of technology, in recent years, slip ring CT equipment is gradually popular in the fields of civil aviation, customs and the like, and can reconstruct each voxel of a three-dimensional object, so that contraband can be identified more efficiently and accurately. However, there may be differences in the core components of the different devices, and as the device components age, there may be deviations in their reconstructed values, affecting the accuracy of the identification.

In view of at least one of the above problems, an embodiment of the present disclosure provides a method of generating calibration data for correction of image reconstruction of a scanning imaging apparatus including a radiation source for emitting radiation and a detector for receiving radiation, the calibration phantom being located in a scanning area formed by the radiation during calibration, the method comprising: placing the calibration die body in a scanning area formed by the rays, wherein the calibration die body comprises M parts respectively formed by M materials, the M materials respectively have M physical attribute theoretical values, and M is a positive integer greater than or equal to 2; acquiring rays passing through the scanning area through the detector to acquire actual projection data; reconstructing the calibration phantom by using an image reconstruction algorithm based on the actual projection data to obtain a reconstructed image; dividing the reconstructed image to obtain M reconstructed sub-images, wherein the M reconstructed sub-images respectively correspond to the M parts; for the M reconstructed sub-images, respectively calculating M physical attribute measurement values corresponding to the M parts; and generating calibration data based on the M physical attribute theoretical values and the M physical attribute measured values. Calibration data generated in accordance with methods of embodiments of the present disclosure may correct images in image reconstruction, thereby at least partially mitigating or resolving problems of reconstruction inaccuracy due to inter-device differences and/or device aging.

Embodiments of the present disclosure are described in further detail below with reference to the accompanying drawings.

FIG. 1 shows a simplified schematic diagram of a CT apparatus of an exemplary embodiment of the present disclosure; fig. 2 shows a schematic diagram of a CT apparatus according to an exemplary embodiment of the present disclosure.

In an exemplary embodiment, referring to fig. 1 and 2, a ct apparatus 100 is adapted to check for the presence of contraband such as drugs, explosives, combustibles, etc. in a scanned object 120 such as a parcel, trunk, handbag, etc. at a station, airport, dock, etc. The CT apparatus 100 includes: scanning channel 400; a conveying device 110 for conveying the scanned object 120 in the scanning channel 400; and a scanning device configured to inspect the scanned object 120 conveyed by the conveying device 110.

For example, the conveyor 110 includes a conveyor belt adapted to carry the scanned object and a drive roller to drive the movement of the conveyor belt.

As shown in fig. 2, the scanning device may include a radiation source 20 and a detector 30. The source 20 and detector 30 may be disposed on opposite sides of the scan path 400, forming a scan region in the scan path 400 when the source 20 emits radiation.

In one exemplary embodiment, referring to fig. 2, the ct apparatus 100 further includes: a support frame 200 having an outer contour of a substantially square shape; a slip ring 190 rotatably supported in the support frame 200, and a scan path 400 passes through the slip ring 190. The radiation source 20 and the detector 30 are mounted on a slip ring 190, and the radiation source 20 and the detector 30 can be driven by the slip ring to rotate under the drive of the driving mechanism.

For example, the conveying device 110 carries the scanned object 120 to move through a scanning area between the radiation source 20 and the detector 3o, and at the same time, the radiation source 20 and the detector 30 are driven to rotate by the slip ring, so that a ray bundle emitted by the radiation source 20 can penetrate through the scanned object 120 to perform CT scanning on the scanned object 120.

During scanning of the scanned object 120, the controller 150 receives an operation instruction input by a user through the computer 160 at the workstation, and controls the driving mechanism to act according to the operation instruction; the slip ring 190 drives the ray source 20 and the detector 30 to rotate under the drive of the driving mechanism, and meanwhile, the ray 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; detector 30 converts the received X-ray beam into an electrical signal and transmits it to data acquisition module 170; the image reconstruction module 180 receives the data of the data acquisition module, and reconstructs the received data and generates image data; the generated image data is transmitted to the computer 160 so that the scanned object 120 is recognized and inspected.

Fig. 3 schematically shows a schematic view of a projection relationship between a radiation source, a scanned object and a detector. Referring to fig. 3, in an embodiment of the present disclosure, radiation (e.g., X-rays, gamma rays, etc.) from a radiation source 20 is incident on a scanned object 120 and radiation transmitted through the scanned object 120 is detected by a detector 30. The spatial point X on the scanned object 120 is applied by the source 20 to the image point Y of the detector 30. In forward projection (also called forward projection), the pixel values of the spatial points on the scanned object 120 are known, and the projection values of the image points on the detector 30 are obtained. In back projection (also called back projection), the pixel values of the spatial points on the scanned object 120 are determined knowing the projection values of the image points on the detector 30.

The computerized tomography technique has an important role in security inspection, medical field, and the like, because it can eliminate the influence of object overlapping. The conventional CT acquires projection data at different angles by rotation of an X-ray source and a detector using a slip ring device, and acquires tomographic images by a reconstruction method, thereby obtaining internal information of a baggage item to be detected. The traditional CT device usually adopts a slip ring for rotation in the data acquisition process, so that the scanning speed is limited, the size is huge, the machining precision requirement is high, the cost is high, and the wide application of the CT device in practice is limited. In recent years, carbon nanotube X-ray tube technology has entered the practical field. Unlike conventional ray source, it does not need to use high temperature to generate ray, but generates cathode ray according to the principle of carbon nanotube tip discharge, and targets to generate X-ray. Its advantages are quick opening and closing, and small size. The X-ray sources are arranged in a ring shape, and the static CT without rotation can be manufactured by irradiating objects at different angles, so that the speed of ray imaging is greatly improved, and meanwhile, the structure of a slip ring is omitted, the cost is saved, and the X-ray source has very important significance in the fields of safety inspection and the like.

Fig. 4 is a schematic structural view of a static CT apparatus according to some exemplary embodiments of the present disclosure. Referring to fig. 4, a static CT apparatus according to an embodiment of the present disclosure may include a scan stage, a conveying device 110, a control device 140, and an imaging device 130. For example, the scan stage may include a radiation source, a detector, and an acquisition device.

For example, in embodiments of the present disclosure, the radiation source may be a distributed radiation source, which may include multiple targets, e.g., multiple X-targets. In a distributed X-ray source, the target point refers to the emission point or focal spot of the source. Specifically, high energy electrons are emitted from the cathode and bombard a 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 current intensity and the electron energy striking the anode target. In a distributed X-ray source, a plurality of cathodes are in one-to-one correspondence with a plurality of targets such that the plurality of targets receive electron beams from the plurality of cathodes to generate a plurality of X-rays. The design enables the distributed X-ray source to achieve the effect of generating more X-ray radiation sources by using fewer cathode assemblies, improves the stability of the system, reduces the use quantity of the cathode assemblies, and reduces the production cost of equipment.

In a static CT apparatus using a distributed radiation source, multiple projection data sets may be acquired from various angles by combining multiple targets together and activating them sequentially at different angles. These projection datasets can be used in a computer reconstruction algorithm to generate high quality cross-sectional images. One advantage of using a distributed X-ray source is that artifacts can be reduced and image quality improved. By using multiple targets, the emission position distribution of the X-ray beam is more uniform, more projection angles and data can be provided, artifacts in the reconstructed image are reduced, and more accurate anatomical information is provided. That is, the target point in a distributed X-ray source refers to the point or region from which the X-ray beam is emitted, and their distribution form helps to obtain high quality projection data for reconstruction of a static CT image.

In embodiments of the present disclosure, a plurality of targets in a distributed radiation source may be arranged along a predetermined first direction. For example, the predetermined first direction may be a straight direction, or may be an arc direction. Embodiments of the present disclosure are not particularly limited in terms of placement of targets in a distributed radiation source.

Fig. 5A is a schematic structural diagram of a scan stage included in a static CT apparatus according to some exemplary embodiments of the present disclosure. Fig. 5B is a schematic structural view of a scan stage included in a static CT apparatus according to other exemplary embodiments of the present disclosure. Referring to fig. 5A and 5B, in an embodiment of the present disclosure, the stationary CT apparatus includes a distributed radiation source 20 and a detector 30, the distributed radiation source 20 may include a plurality of targets 210. In some embodiments, as shown in fig. 5A, the plurality of targets 210 may be arranged in an arc, and accordingly, the detector 30 may include a plurality of detection units 310 arranged in an arc or circle. In some embodiments, as shown in fig. 5B, the plurality of targets 210 may be arranged along a straight line, and accordingly, the detector 30 may include a plurality of detection units 310 arranged along a straight line. Note that, in the embodiments of fig. 2 to 5B, only a structural schematic diagram of a static CT apparatus according to some exemplary embodiments of the present disclosure is schematically shown, but not all embodiments of the present disclosure. In embodiments of the present disclosure, any suitable arrangement of distributed radiation sources and detectors may be employed.

In an embodiment of the present disclosure, the plurality of targets 210 respectively emit radiation toward the scanned object 120, and the plurality of detecting units 310 are used for detecting radiation passing through the scanned object 120. For example, in the embodiment shown in fig. 5A and 5B, the plurality of targets 210 emit X-rays and the plurality of detection units 310 receive portions of the X-rays emitted from the plurality of targets 210 and passing through the scanned object 120. In this way, a scanning region for scanning the scanned object 120 is formed between the radiation source 20 and the detector 30. In the scanning area, at least one plane located at a substantially middle position of the scanning area and perpendicular to the conveying direction of the conveying device 110 may be referred to as a scanning plane.

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 a plurality of detector crystals arranged in a one-dimensional direction, or a plurality of detector crystals arranged in a two-dimensional direction.

It should be understood that each detector crystal is the basic unit of a detector that can absorb radiation (e.g., X-rays) and convert it to other forms of energy, such as light or electrical signals. For example, the material of the detector crystal may include oxides and halides (e.g., iodides and fluorides), and the like.

For example, in the embodiment shown in fig. 4, the conveying device 110 carries the scanned object 120 and drives the scanned object 120 to make a linear motion. The control device 140 controls the beam-out sequence of the plurality of targets 210 of the radiation source 20 such that the detector 30 outputs 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.

It should be noted that, in the embodiment of the present disclosure, the image reconstruction module 180 shown in fig. 2 or the imaging device 130 shown in fig. 4 may reconstruct a CT image of the scanned object using various known reconstruction algorithms. For example, the reconstruction algorithm may be an iterative, analytical, or other reconstruction algorithm, and embodiments of the present disclosure are not limited in particular to reconstruction algorithms.

In some embodiments of the present disclosure, each distributed source 20 has one or more targets thereon, the energy of which can be set, and the order in which the targets are activated can be set. For example, the targets may be distributed over multiple scan planes (e.g., the scan planes are perpendicular to the direction of travel of the channel). In each plane, the target point distribution can be one or more sections of straight lines or arcs, which are continuous or discontinuous. Because the target energy can be set, various scanning modes such as different energy spectrums of different targets or different target energy in different planes can be realized in the beam outlet process. The targets can be grouped, for example, the targets of each module are used as a group, or the targets of each plane are used as a group, the sequence of electronic targeting of the targets in the same group is adjustable, sequential beam output and alternate beam output can be realized, and the targets in different groups can be simultaneously activated for scanning, so that the scanning speed is increased.

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 type detector.

The conveying device 110 comprises a stage or a conveying belt, the control device 140 controls the X-ray machine and the frame of the detector, and the scanning of the spiral scanning track, the circumferential scanning track or other special tracks can be realized by controlling the beam outlet mode of the distributed ray source and the linear translation motion of the object or the combination of the two. The control device 140 is responsible for completing the control of the operation process of the CT system, including mechanical rotation, electrical control and safety interlocking control, and is especially responsible for controlling the beam-out speed/frequency, beam-out energy and beam-out sequence of the ray source, and controlling the data reading and data reconstruction of the detector.

FIG. 6 is a schematic illustration of a calibration phantom according to some exemplary embodiments of the present disclosure. It should be noted that the calibration phantom and the method described below may be applied to the scanning imaging apparatus described in the above embodiments unless otherwise specifically noted, that is, the calibration phantom and the method described below may be applied to the slip ring CT apparatus shown in fig. 1 and 2 or the stationary CT apparatus shown in fig. 4, 5A and 5B.

Referring to fig. 6, the calibration phantom 60 includes M portions each composed of M materials having M physical attribute values, M being a positive integer of 2 or more, respectively, any two of the M physical attribute values being different.

For example, the physical property value may be at least one of density, atomic number, that is, the at least one physical property value of density, atomic number of the M materials is different.

Illustratively, 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. Or 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 first portion 61 is different than the density of the material of second portion 62, and the atomic number of the material of first portion 61 is different than the atomic number of the material of second portion 62.

With continued reference to FIG. 6, the calibration phantom 60 further includes a seat 610, the seat 610 being shaped to resist rolling of the calibration phantom 60 about its own axis AX 1.

Illustratively, the calibration phantom 60 is integrally formed as a calibration rod, and specifically, the first portion 61 and the second portion 62 are each cylindrical. The contour of at least a portion of the base 610 is formed as a rectangle, for example, in the direction of extension of the calibration rod, the base 610 being located between the first portion 61 and the second portion 62.

Referring to fig. 1 to 6 in combination, during calibration, a calibration phantom 60 is placed as a scanned object on a conveyor 110 to pass through a scanning zone. The calibration phantom 60 may be placed on the conveyor 110 along the extension of the scan channel 400, i.e. the axis AX1 of the calibration phantom 60 or its extension is substantially parallel to the extension of the scan channel 400.

Here, "substantially parallel" means: the axis AX1 of the calibration phantom 60 or the extending direction thereof is parallel to the extending direction of the scan channel 400, or an angle between the axis AX1 of the calibration phantom 60 or the extending direction thereof and the extending direction of the scan channel 400 is within ±10°.

Since the base 610 serving as the rolling prevention part is provided on the calibration phantom 60, it is ensured that the calibration phantom 60 does not roll on the conveyor 110 during the calibration process, which is advantageous for ensuring the accuracy of the calibration result.

The M portions of the calibration phantom 60 are sequentially arranged along the extending direction of the axis AX1, so that in the calibration process, the M portions formed by the M materials sequentially pass through the scanning surface, which can avoid interference between the various materials, and is beneficial to improving the accuracy of the calibration result.

For example, each of the M portions may be designed in a cylindrical shape. Embodiments of the present disclosure are not limited in this regard and in other embodiments at least one of the M portions may be designed in other shapes.

In some exemplary embodiments, the mass of each of the M portions is not less than 50 grams, which may ensure that a sufficient amount of data is available for each material, which may be beneficial to improve the accuracy of calibration.

In some exemplary embodiments, the diameter of each of the M portions is not greater than 15 cm, which may avoid reconstruction bias caused by radiation hardening and may facilitate improving accuracy of calibration phantom reconstruction.

In some exemplary embodiments, the calibration phantom 60 includes no less than 3 material types, i.e., M is 3 or more. For example, one of the M materials of calibration phantom 60 may be selected to be an explosive simulated material that approximates the actual explosive in physical properties of density, equivalent atomic number, etc., and this design may be used to verify the validity of the identification algorithm during operation of the device. As another example, the materials in the calibration phantom 60 may have good consistency, may be manufactured at different times and locations, may be of similar quality, and may be readily available on a daily basis and may be cost-effective.

Based on the calibration phantom 60 provided by embodiments of the present disclosure, some exemplary embodiments of the present disclosure also provide a method of generating calibration data for correction of image reconstruction of a scanning imaging device. FIG. 7 is a flowchart of a method of generating calibration data according to some exemplary embodiments of the present disclosure. The method may include steps S710 to S760.

It should be noted that, in the method provided in the embodiment of the present disclosure, the order of execution of the steps is not limited to the order in which the steps are described herein, and the steps may be executed in an order different from the order described herein, for example, some of the steps may be executed in parallel or in reverse order, without conflict, unless otherwise specifically stated.

In step S710, the calibration phantom 60 is placed in a radiographed scan region.

In step S720, the radiation passing through the scanning area is acquired by the detector 30 to acquire actual projection data.

In some exemplary embodiments of the present disclosure, a single scan of the calibration phantom may be performed during this step; and acquiring rays passing through the scan region by means of a detector to obtain a single set of actual projection data.

In some exemplary embodiments of the present disclosure, during this step, a plurality of scans of the calibration phantom may be performed; and acquiring rays passing through the scanning area by the detector to acquire a plurality of sets of actual projection data. By the mode, more projection data can be obtained, and the accuracy of later calibration is improved.

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.

In step S740, the reconstructed image is subjected to segmentation processing to obtain M reconstructed sub-images, where the M reconstructed sub-images respectively correspond to the M portions.

In step S750, M physical attribute measurement values corresponding to the M parts are calculated for the M reconstructed sub-images, respectively.

In step S760, calibration data is generated based on the M physical attribute theory values and the M physical attribute measurement values.

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

Illustratively, in step S760, calibration data is generated based on the M physical property theoretical values and the M physical property measured values, including performing the following loop process until i is equal to M.

Specifically, the cyclic process includes: obtaining the ith physical attribute theoretical value of the ith part of the calibration die body, wherein i is more than or equal to 1 and less than or equal to M; acquiring an ith physical attribute measured value calculated for an ith reconstructed sub-image, wherein the ith reconstructed sub-image is a reconstructed image of an ith part of the calibration phantom; and storing the ith physical attribute theoretical value and the ith physical attribute measured value into a calibration data table, wherein the ith physical attribute theoretical value and the ith physical attribute measured value have a mapping relation in the calibration data table.

That is, the physical attribute theoretical values and measured values of the M parts are stored in the data table in a one-to-one mapping manner in the order of 1 st to M to form the calibration data table. The calibration data table is stored in a computer, and in the actual image reconstruction process, the required calibration data can be read from the calibration data table at a high speed, so that the image reconstruction speed is improved. And, after calibrating using another calibration phantom, new calibration data can be conveniently inserted into the calibration data table.

In some alternative embodiments, the method may further comprise the step of verifying the generated calibration data. Specifically, after generating the calibration data, the method further comprises: collecting rays passing through a scanning area through a detector to obtain verification projection data; reconstructing the calibration phantom by 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, M physical attribute verification values corresponding to the M parts are respectively calculated; comparing the M physical attribute theoretical values with the M physical attribute verification values; and determining that the calibration data is valid in response to the comparison of the M physical attribute theory values and the M physical attribute verification values being the first result.

For example, the first result may be: the differences between the M physical property theory values and the M physical property verification values are small. The "smaller gap" here may be: the mean square error of the M physical attribute theoretical values and the M physical attribute verification values is smaller than a preset threshold value.

Optionally, in other exemplary embodiments of the present disclosure, the method may further include: and responding to the comparison result of the M physical attribute theoretical values and the M physical attribute verification values as a second result, repeatedly executing the calibration method, and regenerating calibration data.

For example, the second result may be: the gap between the M physical property theoretical values and the M physical property verification values is large. The "gap larger" here may be: the mean square error of the M physical attribute theoretical values and the M physical attribute verification values is larger than a preset threshold value.

Some exemplary embodiments of the present disclosure also provide an image reconstruction method for a scanning imaging device. Fig. 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.

In step S810, the scanned object 120 is placed in the scan region formed by the rays.

In step S820, rays passing through the scan region are acquired by the detector 30 to acquire actual projection data of the scanned object 120.

In step S830, calibration data is acquired. The calibration data may be calibration data generated by the above method.

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.

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

As shown in fig. 9, an electronic device according to an embodiment of the present disclosure may include a processor 1001 that may 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 section 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 an associated chipset and/or a special purpose microprocessor (e.g., an Application Specific Integrated Circuit (ASIC)), or the like. The processor 1001 may also include on-board memory for caching purposes. The processor 1001 may include a single processing unit or multiple processing units for performing different actions of the method flows according to embodiments of the present disclosure.

In the RAM 1003, various programs and data required for the method are stored. The processor 1001, the ROM 1002, and the RAM 1003 are connected to each other by a bus 1004. The processor 1001 performs various operations of the method flow according to the embodiment of the present disclosure by executing programs in the ROM 1002 and/or the RAM 1003. Note that the program may be stored in one or more memories other than the ROM 1002 and the RAM 1003. The processor 1001 may also perform various operations of the method flow according to the embodiments of the present disclosure by executing programs stored in the one or more memories.

According to embodiments of the present disclosure, the electronic device may further include an input/output (I/O) interface 1005, the input/output (I/O) interface 1005 also being connected to the bus 1004. The electronic device may also include one or more of the following components connected to the I/O interface 1005: an input section 1006 including a keyboard, a mouse, and the like; an output portion 1007 including a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), etc., and a speaker, etc.; a storage portion 1008 including a hard disk or the like; and a communication section 1009 including a network interface card such as a LAN card, a modem, or the like. The communication section 1009 performs communication processing via a network such as the internet. The 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, or the like, is installed as needed in the drive 1010, so that a computer program read out therefrom is installed as needed in the storage section 1008.

The present disclosure also provides a computer-readable storage medium that may be embodied in the apparatus/device/system described in the above embodiments; or may exist alone without being assembled into the apparatus/device/system. The computer-readable storage medium carries one or more programs which, when executed, implement methods in accordance with embodiments of the present disclosure.

According to embodiments of the present disclosure, the computer-readable storage medium may be a non-volatile computer-readable storage medium, which may include, for example, but is not limited to: a portable computer diskette, 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 disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this disclosure, a computer-readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. For example, according to embodiments of the present disclosure, the computer-readable storage medium may include ROM 1002 and/or RAM 1003 and/or one or more memories other than ROM 1002 and RAM 1003 described above.

According to embodiments of the present disclosure, program code for performing computer programs provided by embodiments of the present disclosure may be written in any combination of one or more programming languages, and in particular, such computer programs may be implemented in high-level procedural and/or object-oriented programming languages, and/or assembly/machine languages. Programming languages include, but are not limited to, such as Java, c++, python, "C" or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, partly on a remote computing device, or entirely on the remote computing device or server. In the case of remote computing devices, the remote computing device may be connected to the user computing device through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., connected via the Internet using an Internet service provider).

The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams or flowchart illustration, and combinations of blocks in the block diagrams or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present disclosure have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined by the claims and their equivalents. Those skilled in the art will appreciate that the features recited in the various embodiments of the disclosure and/or in the claims may be provided in a variety of combinations and/or combinations, even if such combinations or combinations are not explicitly recited in the disclosure. In particular, the features recited in the various embodiments of the present disclosure and/or the claims may be variously combined and/or combined without departing from the spirit and teachings of the present disclosure. All such combinations and/or combinations fall within the scope of the present disclosure.

Claims

1. A method of generating calibration data for correction of image reconstruction of a scanning imaging device comprising a source for emitting radiation and a detector for receiving radiation, during which calibration a calibration phantom is located in a scanning area formed by the radiation, characterized in that the method comprises:

2. The method of claim 1, wherein the generating calibration data based on the M physical property theoretical values and the M physical property measured values comprises performing a loop process until i equals M; the cyclic process includes:

3. The method of claim 1 or 2, wherein at least one of the following physical properties of any two of the M materials are different: density, atomic number.

4. The method of claim 1 or 2, wherein the acquiring, by the detector, radiation passing through the scan region to acquire actual projection data comprises:

Scanning the calibration die body for a plurality of times; and

5. The method of claim 1 or 2, wherein after generating the calibration data, the method further comprises:

6. The method of claim 1 or 2, wherein the scanning imaging device comprises a scanning channel between the radiation source and the detector; and

The calibration phantom includes a calibration rod disposed within the scan channel in a direction substantially parallel to the scan channel during the calibration process.

7. An image reconstruction method for a scanning imaging device comprising a radiation source for emitting radiation and a detector for receiving radiation, wherein the method comprises:

Placing a scanned object in a scanning area formed by the rays;

Acquiring calibration data generated by the method of any one of claims 1-5;

8. The calibration die body is characterized by comprising M parts which are respectively formed by M materials, wherein the M materials respectively have M physical attribute values, M is a positive integer greater than or equal to 2, and any two of the M physical attribute values are different; and

The calibration phantom also includes a base shaped to resist rolling of the calibration phantom about its own axis.

9. The calibration phantom of claim 8, wherein the calibration phantom is a calibration rod, the M sections including a first section and a second section, the base being located between the first section and the second section in an extension direction of the calibration rod.

10. The calibration phantom of claim 8 or 9, wherein each of the M portions has a mass of not less than 50 grams; and/or the number of the groups of groups,

Each of the M portions has a diameter of no more than 15 cm.