Geometric calibration method and system for equiangular fan-beam industrial CT (Computed Tomography) system

Abstract

The invention relates to the technical field of computer tomography, in particular to a geometric calibration method and system for an equiangular fan-beam industrial CT (computed tomography) system, and the method comprises the following steps: building a geometric model of the equiangular fan-beam industrial CT system comprising turntable center offset, detector lateral offset and radiation source radial offset; projection data are obtained through two times of scanning before and after displacement of the rotary table; performing interpolation processing on the projection data, and calculating a projection address of a ray penetrating through the rotation center of the rotary table; and calibrating geometric parameters of the geometric model based on a projection address of a ray passing through the rotation center of the rotary table and the basic parameters of the equiangular fan-beam industrial CT system. The method is used for correcting the geometric artifacts in the CT reconstructed image and improving the quality of the reconstructed image.

Description

Technical Field

[0001] The present disclosure relates to the field of computed tomography technology, and particularly relates to a geometric calibration method and system for an equiangular fan-beam industrial CT system. Background Art

[0002] Computed Tomography (CT) is an imaging technology that uses the attenuation information of X-rays penetrating an object and obtains the two-dimensional cross-section or three-dimensional structure of the object through a reconstruction algorithm. Due to its ability to intuitively, accurately, and nondestructively characterize the internal structure of an object, it has been widely used in the industrial field. In the CT system configuration, the fan-beam CT system effectively suppresses ray scattering and signal crosstalk by equipping a post-collimator on the detector and adopting an independent pixel design, thereby significantly improving the clarity of the reconstructed image. According to the different arrangements of the detectors, the fan-beam CT system can be divided into two types: equidistant type and equiangular type. Among them, the equiangular fan-beam CT system can obtain higher-quality reconstructed images due to the characteristics that the detector pixels are evenly distributed along an arc.

[0003] In the practical application of an equiangular fan-beam industrial CT system, the system theoretically needs to meet three key geometric conditions: (1) The central fan-beam of the cone beam emitted by the ray source must be coplanar with the detector plane and parallel to the turntable plane, which is the basic condition to ensure the quality of image reconstruction; (2) The ray source, the rotation center of the turntable, and the central pixel of the detector should be strictly collinear, and this collinear relationship ensures that the workpiece is always within the imaging field of view; (3) The ray source should be precisely located at the center of the arc of the detector, and this requirement ensures the ideal incident angle between the fan beam and the detector pixels. However, in an actual fan-beam CT system, due to the limitations of machining accuracy and the cumulative errors during the assembly process, it is difficult to make the system fully meet the above ideal geometric conditions. Among them, the first condition, as a necessary condition for fan-beam CT reconstruction, is relatively easy to achieve through means such as precise leveling. However, the latter two conditions are often difficult to precisely adjust in an actual system, which will lead to three typical geometric deviations: rotation center offset, that is, there is a deviation between the actual rotation center of the turntable and the line connecting the ray source and the central pixel of the detector, resulting in the turntable not being in a collinear position; detector lateral offset, that is, the detector generates a displacement along the tangent direction of the central pixel in its plane, deviating from the ideal position; ray source radial offset, that is, the ray source fails to be strictly located at the geometric center of the arc of the detector, and there is a distance deviation in the normal direction of the central pixel of the detector.

[0004] The above geometric deviations will have a significant impact on the imaging quality of the CT system. Whether compensating through reconstruction algorithms or precisely calibrating the system, the specific values of various deviations need to be calibrated. In 2024, Xu et al. proposed an innovative calibration method for the geometric parameters of an equiangular fan-beam CT based on a pin gauge sinogram. Although this method can comprehensively calibrate all geometric parameters in the system, it requires custom machining of specific support seats and pin gauges for different systems, which is inconvenient in practical applications. If a self-calibration method applicable to an equiangular fan-beam industrial CT system can be developed, the geometric calibration of the system can be achieved without a special phantom, which will greatly improve the application efficiency and practicality of the system. Therefore, exploring a self-calibration method for the parameters of an equiangular fan-beam CT system has important practical significance and urgency. Summary of the Invention

[0005] Embodiments of the present disclosure provide a geometric calibration method and system for an equiangular fan-beam industrial CT system to solve the problems existing in the related art. The technical solutions are as follows: In a first aspect, embodiments of the present disclosure provide a geometric calibration method for an equiangular fan-beam industrial CT system, including the following steps: Establish a geometric model of an equiangular fan-beam industrial CT system including the offset of the turntable center, the lateral offset of the detector, and the radial offset of the radiation source; Obtain projection data through two scans before and after the displacement of the turntable; Calculate the projection address of the ray passing through the rotation center of the turntable after interpolating the projection data; Calibrate the geometric parameters of the geometric model based on the projection address of the ray passing through the rotation center of the turntable and the basic parameters of the equiangular fan-beam industrial CT system.

[0006] Optionally, both the turntable and the detector for obtaining projection data can move along the tangential and normal directions of the central pixel of the detector.

[0007] Optionally, obtaining projection data through two scans before and after the displacement of the turntable includes: Place any workpiece on the turntable for scanning. After the scanning is completed, move the turntable along the normal direction of the central pixel of the detector by a preset distance, and then scan the workpiece again to obtain the projection data for both times.

[0008] Optionally, the interpolation processing of the projection data further includes: Performing E times of interpolation between each pixel of the detector, so that the width of the projection data becomes E times the original, and the pixel size of the detector is reduced to of the original.

[0009] Optionally, the projection address of the ray passing through the rotation center of the turntable is calculated using the following formula: , where is the projection address of the ray passing through the rotation center of the turntable, is the central angle corresponding to the arc detector, M is the total number of projection images collected during one full rotation of the turntable, is the current rotation angle of the turntable, , , is the projection data collected by the system.

[0010] Optionally, the geometric parameters of the geometric model are calibrated, including: , , , , where , and are the projection addresses of the rotation center of the turntable calculated before and after the turntable displacement respectively, is the distance that the turntable moves in the normal direction of the detector center pixel before and after two scans, and are the offset distances of the turntable center calculated before and after the turntable displacement; is the distance between the ray source and the turntable in the normal direction of the detector center pixel, is the distance between the ray source and the detector center pixel, is the arc radius of the arc detector, is the equal angular interval between the detector pixels of the arc detector.

[0011] Optionally, when the workpiece is scanned again, the geometric positions of the detector and the ray source are kept unchanged.

[0012] In a second aspect, an embodiment of the present disclosure further provides a geometric calibration system for an equiangular fan-beam industrial CT system, including: A geometric model establishment unit that establishes a geometric model of an equiangular fan-beam industrial CT system including turntable center offset, detector lateral offset, and ray source radial offset; A projection data acquisition unit that acquires projection data through two scans before and after turntable displacement; A projection address calculation unit that calculates the projection address of the ray passing through the rotation center of the turntable after interpolating the projection data; The geometric parameter calibration unit calibrates the geometric parameters of the geometric model based on the projection addresses of the rays passing through the rotation center of the turntable and the basic parameters of the isometric fan-beam industrial CT system.

[0013] In a third aspect, an embodiment of the present disclosure also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the geometric calibration method of the isometric fan-beam industrial CT system is implemented.

[0014] In a third aspect, an embodiment of the present disclosure also provides a computer-readable storage medium, on which a computer program is stored. The program is characterized in that when it is executed by a processor, the geometric calibration method of the isometric fan-beam industrial CT system is implemented.

[0015] The advantages or beneficial effects in the above technical solutions at least include: The present disclosure does not require processing a specific phantom. By calculating the projection center address through multiple displacements of the turntable, two geometric deviations, namely, center offset and detector offset, existing in the isometric fan-beam industrial CT system are calibrated. The embodiments of the present disclosure can be used to correct geometric artifacts in CT reconstructed images and improve the quality of the reconstructed images.

[0016] The above summary is only for the purpose of the specification and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present disclosure will be readily apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In the drawings, unless otherwise specified, the same reference numerals throughout the several views denote the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments in accordance with the present disclosure and should not be regarded as limiting the scope of the present disclosure.

[0018] Figure 1 is a flowchart of the geometric calibration method of the isometric fan-beam industrial CT system in an embodiment of the present disclosure; Figure 2 is a schematic diagram of the ideal geometric configuration of the system in an embodiment of the present disclosure; Figure 3 is a geometric schematic diagram of the system before and after the turntable displacement in an embodiment of the present disclosure; Figure 4 is a reconstructed result diagram before and after calibration in the simulation experiment in an embodiment of the present disclosure; Figure 5 is a block diagram of the geometric calibration system of the isometric fan-beam industrial CT system in an embodiment of the present disclosure. Detailed Implementation Modes

[0019] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present disclosure. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0020] The execution subject of the geometric calibration method for an equiangular fan-beam industrial CT system can be a computer or other control systems or control devices capable of implementing the geometric calibration of the equiangular fan-beam industrial CT system. For example, the method can be executed by a terminal device, a server, or other processing devices. Among them, the terminal device can be a user equipment (UE), a mobile device, a terminal, a server, a personal digital assistant (PDA), a handheld device, a computing device, a vehicle-mounted device, a wearable device, etc. In some possible implementation manners, the geometric calibration method for the equiangular fan-beam industrial CT system can be implemented by a processor calling computer-readable instructions stored in a memory.

[0021] Embodiment 1

[0022] The embodiments of the present disclosure provide a geometric calibration method for an equiangular fan-beam industrial CT system, as Figure 1 shown, including the following steps: S10. Establish a geometric model of an equiangular fan-beam industrial CT system including the offset of the turntable center, the lateral offset of the detector, and the radial offset of the radiation source; S20. Obtain projection data through two scans before and after the turntable displacement; S30. Calculate the projection address of the ray passing through the turntable rotation center after interpolating the projection data; S40. Calibrate the geometric parameters of the geometric model based on the projection address of the ray passing through the turntable rotation center and the basic parameters of the equiangular fan-beam industrial CT system.

[0023] The above steps of the embodiments of the present disclosure do not require machining a specific phantom. By calculating the projection center address through multiple displacements of the turntable, two geometric deviations, namely the center offset and the detector offset, existing in the equiangular fan-beam industrial CT system are calibrated. To correct the geometric artifacts in the CT reconstructed image and improve the quality of the reconstructed image. The following is a detailed description of each step: S10. Establish a geometric model of an equiangular fan-beam industrial CT system including the offset of the turntable center, the lateral offset of the detector, and the radial offset of the radiation source; As an alternative embodiment, the equiangular fan-beam industrial CT system includes a radiation source, a turntable, and an arc detector. According to the geometric position relationship among the radiation source, the turntable, and the arc detector, a geometric model of the equiangular fan-beam industrial CT system is established. The geometric model of the equiangular fan-beam industrial CT system should include all geometric deviations. For example, it is necessary to include the offset of the turntable center, the lateral offset of the detector, and the radial offset of the radiation source.

[0024] The ideal geometric configuration of the system is shown in the subfigure (a) of Figure 2 , where O is the ideal position of the rotation center of the stage, D is the preset distance from the radiation source to the rotation center in the TX direction, R is the radius of the arc of the arc detector, is the rotation angle of the turntable. Both the stage and the arc detector of this system are set to be movable along the TX direction and the TY direction. In actual applications, it is usually difficult to maintain the ideal geometric state for the built system. The geometric model of the equiangular fan-beam industrial CT system in the actual working state is shown in the subfigure (b) of Figure 2 . The radiation source is not accurately positioned at the center of the circle of the arc detector, and the turntable also deviates from the ideal position. Figure 2 In the subfigure (b) of SDD , represents the actual distance from the radiation source to the central pixel of the detector. The actual rotation center of the stage has an offset relative to the ideal position, the center of the detector has a lateral offset relative to the ideal position, and the radiation source has a radial offset

[0025] S20. Obtain projection data through two scans before and after the displacement of the turntable;

[0026] Specifically, install the workpiece to be detected on the stage, start the stage to drive the workpiece to perform a complete one-week scan, and obtain the first set of projection data; then displace the stage along the normal direction of the central pixel of the detector by a preset distance, and perform another one-week scan to obtain the second set of projection data. Further, when the workpiece is scanned for a complete one-week by the equiangular fan-beam industrial CT system, the obtained projection data should be non-sparse. After the stage is displaced along the normal direction of the central pixel of the detector and then scanned again, the geometric positions of the detector and the radiation source should remain unchanged. Among them, two sets of projection data before and after the displacement of the stage are obtained through two scans. The projection data can be truncated, that is, the workpiece can exceed the imaging field of view of the system, but the collected projection data should be non-sparse, and the displacement amount of the stage between the two scans should have a high accuracy.

[0026] S30. Calculate the projection address of the ray passing through the rotation center of the turntable after interpolating the projection data.

[0027] Specifically, perform interpolation processing on the two sets of acquired projection data, and calculate the projection addresses of the rotation center on the detector during the first and second scans of the stage according to the interpolated projection data. Further, the interpolation method used for interpolating the projection data obtained from the two scans is linear interpolation, which is specifically manifested as performing E interpolation times between each pixel of the detector, so that the width of the projection data becomes E times the original, and the pixel size of the detector is reduced to of the original. Increasing the interpolation times can improve the accuracy of system parameter calibration. Usually, E= 10 interpolation times can already meet the calibration accuracy.

[0028] Further, calculate the projection address of the ray passing through the rotation center of the turntable, which is implemented using the following formula: , (1) where is the projection address of the ray passing through the rotation center of the turntable, is the central angle corresponding to the arc detector, M is the total number of projection images collected during one full rotation of the turntable, is the current rotation angle of the turntable, , , is the projection data collected by the system.

[0029] Specifically, the geometric schematic diagrams of the system before and after the turntable displacement are shown in Figure 3 . The offset of the turntable center and the lateral offset of the detector in the system are calibrated through the projection address passing through the rotation center and the basic parameters of the equiangular fan-beam industrial CT system. The offset of the turntable center and the lateral offset of the detector in the system are calibrated through the following formulas: S40. Based on the projection address of the ray passing through the rotation center of the turntable and the basic parameters of the equiangular fan-beam industrial CT system, calibrate the geometric parameters of the geometric model.

[0030] Calibrating the geometric parameters of the geometric model includes: , (2) , (3) , (4) , where , and They are the projection addresses of the turntable rotation center calculated before and after the turntable displacement, is the distance that the turntable moves in the normal direction of the detector central pixel before and after two scans, and is the offset distance of the turntable center calculated before and after the turntable displacement; is the distance between the radiation source and the turntable in the normal direction of the detector central pixel, is the distance between the radiation source and the detector central pixel, is the arc radius of the arc detector, is the equal-angle interval between the detector pixels of the arc detector.

[0031] In a preferred embodiment, the displaceable turntable performs multiple calibrations of steps S10 - S40, and taking the average of the calibrated geometric parameters can usually obtain higher calibration accuracy.

[0032] The applicant also designed simulation experiments for each step in the method of this embodiment. The scanning parameters of the equal-angle fan-beam industrial CT system are specifically shown in Table 1. The size of the phantom is 256×256. After the scanning is completed, the projection data collected in Experiments I and II are respectively interpolated 10 times.

[0033] Table 1 Simulation experiment system parameters

[0034] For the interpolated projection data of Experiments I and II, the projection address of the turntable rotation center in the projection data is calculated through Equation (1), and then the geometric deviations in the system are calculated through Equations (2), (3), and (4). The finally calibrated center offset and detector offset are shown in Table 2. Using the system parameters before and after calibration to reconstruct the scanned projection data, the reconstruction results are shown in Figure 4 As shown, it can be seen that directly using the parameters of the ideal system for reconstruction without system calibration, the reconstructed image is severely distorted and there are obvious geometric artifacts. However, using the calibrated parameters for reconstruction, the reconstruction results are clear without geometric artifacts.

[0035] Reconstruct the scanned circuit board through the obtained trajectory, and the results are shown in Figure 5 . It can be seen that when reconstructing through the trajectory set by the system, due to the difficulty in correcting the radiation source and the detector to the ideal positions in the actual system, the image will generate severe geometric artifacts. However, the trajectory calibrated by the proposed algorithm can reconstruct better results, once again proving the effectiveness and accuracy of the method.

[0036] Embodiment 2

[0037] As another aspect of the embodiments of the present disclosure, a geometric calibration system 100 for an equal-angle fan-beam industrial CT system is further provided, asFigure 5 As shown in the figure, it is a block diagram of the geometric calibration system of an equiangular fan-beam industrial CT system, including: A geometric model establishment unit 1 that establishes a geometric model of an equiangular fan-beam industrial CT system including the offset of the turntable center, the lateral offset of the detector, and the radial offset of the ray source; A projection data acquisition unit 2 that acquires projection data through two scans before and after the turntable displacement; A projection address calculation unit 3 that calculates the projection address of the ray passing through the turntable rotation center after interpolating the projection data; A geometric parameter calibration unit 4 that calibrates the geometric parameters of the geometric model based on the projection address of the ray passing through the turntable rotation center and the basic parameters of the equiangular fan-beam industrial CT system.

[0038] Without contradiction, the above modules in the system of the embodiments of the present disclosure can implement any implementation manner of the above method.

[0039] Embodiment 3

[0040] The embodiments of the present disclosure further provide an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the geometric calibration method of the equiangular fan-beam industrial CT system in Embodiment 1.

[0041] Embodiment 3 of the present disclosure is merely an example and should not bring any limitations to the functions and usage scopes of the embodiments of the present disclosure.

[0042] The electronic device can be presented in the form of a general computing device. For example, it can be a server device. The components of the electronic device may include, but are not limited to: at least one processor, at least one memory, and a bus connecting different system components (including the memory and the processor).

[0043] The bus includes a data bus, an address bus, and a control bus.

[0044] The memory may include volatile memory, such as random access memory (RAM) and / or cache memory, and may further include read-only memory (ROM).

[0045] The memory may further include a program tool having a set (at least one) of program modules. Such program modules include, but are not limited to: an operating system, one or more application programs, other program modules, and program data. The implementation of a network environment may be included in each or some combination of these examples.

[0046] The processor executes various functional applications and data processing by running the computer program stored in the memory.

[0047] The electronic device can also communicate with one or more external devices (such as a keyboard, a pointing device, etc.). Such communication can be carried out through an input / output (I / O) interface. Moreover, the electronic device can also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through a network adapter. The network adapter communicates with other modules of the electronic device through a bus. It should be understood that, although not shown in the figures, other hardware and / or software modules can be used in combination with the electronic device, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID (redundant array of independent disks) systems, tape drives, and data backup storage systems, etc.

[0048] It should be noted that, although several units / modules or sub-units / modules of the electronic device are mentioned in the above detailed description, such a division is merely exemplary and not mandatory. In fact, according to the embodiments of the present application, the features and functions of two or more units / modules described above can be embodied in one unit / modules. Conversely, the features and functions of one unit / modules described above can be further divided and embodied by multiple units / modules.

[0049] Embodiment 4

[0050] The embodiments of the present disclosure also provide a computer-readable storage medium, where the readable storage medium stores a computer program, and when the program is executed by a processor, the steps of the geometric calibration method of the equiangular fan-beam industrial CT system in Embodiment 1 are implemented.

[0051] Among them, the more specific types that the readable storage medium can adopt can include but are not limited to: portable disks, hard disks, random access memories, read-only memories, erasable programmable read-only memories, optical storage devices, magnetic storage devices, or any suitable combination of the above.

[0052] In a possible implementation manner, the present disclosure can also be implemented in the form of a program product, which includes program code. When the program product runs on a terminal device, the program code is used to cause the terminal device to execute the steps of implementing the geometric calibration method of the equiangular fan-beam industrial CT system described in Embodiment 1.

[0053] Among them, the program code for executing the present disclosure can be written in any combination of one or more programming languages. The program code can be executed entirely on the user device, partially on the user device, executed as an independent software package, partially on the user device and partially on a remote device, or executed entirely on a remote device.

[0054] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0055] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present disclosure, "a plurality" means two or more unless otherwise specifically defined.

[0056] The above is only the specific implementation manner of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art can easily think of various changes or substitutions within the technical scope disclosed by the present disclosure, and these should all be covered by the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims

1. Geometric calibration method for an isometric fan-beam industrial CT system, characterized in that, The method includes the following steps: Establish a geometric model of an equiangular fan-beam industrial CT system including the offset of the turntable center, the lateral offset of the detector, and the radial offset of the radiation source; Obtain projection data through two scans before and after the turntable displacement; Calculate the projection address of the ray passing through the rotation center of the turntable after interpolating the projection data; Calibrate the geometric parameters of the geometric model based on the projection address of the ray passing through the rotation center of the turntable and the basic parameters of the equiangular fan-beam industrial CT system.

2. The geometric calibration method of the isometric fan-beam industrial CT system according to claim 1, wherein, Both the turntable and the detector for obtaining projection data can move along the tangential and normal directions of the central pixel of the detector.

3. The geometric calibration method of the isometric fan-beam industrial CT system according to claim 1 or 2, characterized in that, Obtaining projection data through two scans before and after the turntable displacement includes: Place any workpiece on the turntable for scanning. After the scanning is completed, move the turntable a preset distance along the normal direction of the central pixel of the detector, and then scan the workpiece again to obtain the projection data for two times.

4. The geometric calibration method of the isometric fan-beam industrial CT system according to claim 1 or 2, characterized in that, Interpolating the projection data further includes: Perform E times of interpolation between each pixel of the detector, so that the width of the projection data becomes E times of the original, and the pixel size of the detector is reduced to of the original.

5. The geometric calibration method of the isometric fan-beam industrial CT system according to claim 1 or 2, characterized in that, Calculating the projection address of the ray passing through the rotation center of the turntable, which is implemented by the following formula: ， Among them, is the projection address of the ray passing through the rotation center of the turntable, is the central angle corresponding to the arc detector, M is the total number of projection images collected in one full rotation of the turntable, is the current rotation angle of the turntable, , , is the projection data collected by the system.

6. The geometric calibration method of the isometric fan-beam industrial CT system according to claim 1 or 2, characterized in that, Calibrating the geometric parameters of the geometric model includes: ， ， ， ， Among them, , and are the projection addresses of the rotation center of the turntable calculated before and after the turntable displacement respectively, is the distance that the turntable moves in the normal direction of the detector center pixel before and after two scans, and are the offset distances of the turntable center calculated before and after the turntable displacement; is the distance between the radiation source and the turntable in the normal direction of the detector center pixel, is the distance between the radiation source and the detector center pixel, is the arc radius of the arc detector, is the equal angular interval between the detector pixels of the arc detector.

7. The geometric calibration method of the isometric fan-beam industrial CT system according to claim 3, wherein When scanning the workpiece again, keep the geometric positions of the detector and the radiation source unchanged.

8. Geometric calibration system of an isometric fan-beam industrial CT system, characterized in that, It includes: A geometric model establishment unit for establishing a geometric model of an equiangular fan-beam industrial CT system including the offset of the turntable center, the lateral offset of the detector, and the radial offset of the radiation source; A projection data acquisition unit for obtaining projection data through two scans before and after the turntable displacement; A projection address calculation unit for calculating the projection address of the ray passing through the rotation center of the turntable after interpolating the projection data; A geometric parameter calibration unit for calibrating the geometric parameters of the geometric model based on the projection address of the ray passing through the rotation center of the turntable and the basic parameters of the equiangular fan-beam industrial CT system.

9. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the geometric calibration method of the equiangular fan-beam industrial CT system according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the geometric calibration method of the equiangular fan-beam industrial CT system according to any one of claims 1 to 7.

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