Geometric parameter correction method, CT system correction method and storage medium

Abstract

The invention relates to a geometric parameter correction method, a CT system correction method and a storage medium, the method is applied to a CT system, the CT system at least comprises a first system and a second system, each of the first system and the second system comprises an X-ray bulb tube and a corresponding detector, and the method comprises the following steps: obtaining first data and second data, the first data and the second data are obtained by scanning a motif by a first system and a second system in the CT system in an axis scanning mode; performing image reconstruction based on the initial geometric parameters of the CT system and the first data to obtain a first image; performing image reconstruction based on the initial geometric parameters and the second data to obtain a second image; determining a first size of the motif in the first image, and determining a second size of the motif in the second image; and determining a correction value of the initial geometric parameter according to the first size, the second size and the first data or the second data. According to the geometric parameter correction method provided by the invention, a more accurate correction value can be obtained.

Description

Technical Field

[0001] The present application relates to the field of imaging technology, and in particular to a correction method for geometric parameters, a correction method for a CT system, and a storage medium. Background Art

[0002] Dual Source Computer Tomography (DSCT) is a CT device that uses two sets of X-ray tubes and two sets of detectors to simultaneously collect images of the imaging object. When using DSCT for dual-energy imaging, the images of the two systems must be registered. However, the geometric parameters of dual-source CT will affect the registration of the images.

[0003] In conventional technology, the geometric parameters of the dual-source CT are measured by scanning two pin needles and utilizing geometric relationships; or by scanning two steel balls and utilizing geometric relationships.

[0004] However, the two methods for measuring the geometric parameters of dual-source CT provided in the conventional technology have the problem that the determined geometric parameters are inaccurate. Summary of the invention

[0005] Based on this, it is necessary to provide a correction method for geometric parameters, a correction method for a CT system and a storage medium that can accurately correct the geometric parameters in order to address the above technical problems.

[0006] In a first aspect, the present application provides a method for correcting geometric parameters, which is applied to a CT system, wherein the CT system includes at least a first system and a second system, wherein both the first system and the second system include an X-ray tube and a corresponding detector, and the method includes:

[0007] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0008] Reconstructing an image based on the initial geometric parameters of the CT system and the first data to obtain a first image; reconstructing an image based on the initial geometric parameters and the second data to obtain a second image;

[0009] determining a first size of the phantom in the first image, and determining a second size of the phantom in the second image;

[0010] A correction value of the initial geometric parameter is determined based on the first size, the second size and the first data or the second data.

[0011] In one embodiment, the phantom includes a first sub-phantom, the initial geometric parameter includes a first geometric parameter, the first geometric parameter is a source wheelbase, and the correction value of the initial geometric parameter is determined according to the first size, the second size and the first data or the second data, including:

[0012] Acquire a plurality of first reference geometric parameters, perform image reconstruction based on each first reference geometric parameter and the first data to obtain a first image to be processed, and determine a size of a first sub-phantom in each first image to be processed;

[0013] Determining a first linear equation based on the size of the first sub-phantom and all first reference geometric parameters in all first images to be processed, as well as the first size and the first geometric parameter;

[0014] Corrected values ​​of the initial geometric parameters are determined based on the parameters of the first linear equation and the second dimension.

[0015] In one embodiment, the parameters of the first linear equation include a first slope and a first intercept, and determining the correction value of the initial geometric parameter according to the parameters of the first linear equation and the second size includes:

[0016] determining a first difference between the second dimension and the first intercept;

[0017] Determining a first correction value according to a ratio of the first difference and the first slope;

[0018] The first geometric parameter is corrected according to the first correction value.

[0019] In one embodiment, the phantom includes a second sub-phantom, the initial geometric parameter includes a second geometric parameter, the second geometric parameter is a source-to-detector distance, and a correction value of the initial geometric parameter is determined according to the first size, the second size, and the first data or the second data, including:

[0020] Acquire a plurality of second reference geometric parameters, perform image reconstruction based on each second reference geometric parameter and the first data to obtain a second image to be processed, and determine a size change curve of the second sub-phantom in the plurality of second images to be processed;

[0021] Determine a size change curve of the second sub-mock in the first image according to the first size, and determine a size change curve of the second sub-mock in the second image according to the second size;

[0022] Determining a slope of a target size difference curve according to a size change curve of the second sub-phantom in the first image, a size change curve of the second sub-phantom in the second image, and size change curves of the second sub-phantom in a plurality of second images to be processed;

[0023] The correction value of the initial geometric parameters is determined according to the slope of the target size difference curve.

[0024] In one embodiment, determining the slope of the target size difference curve according to the size change curve of the second sub-phantom in the first image, the size change curve of the second sub-phantom in the second image, and the size change curves of the second sub-phantom in a plurality of second images to be processed includes:

[0025] Determine a first size difference curve between a size change curve of the second sub-mock in the second image and a size change curve of the second sub-mock in the first image, and fit the first size difference curve to determine a slope of the first size difference curve;

[0026] A second size difference curve between the size change curve of the second sub-mock in each second image to be processed and the size change curve of the second sub-mock in the first image is determined, and each second size difference curve is fitted to determine the slopes of the plurality of second size difference curves.

[0027] In one embodiment, determining the correction value of the initial geometric parameter according to the slope of the target size difference curve includes:

[0028] Determining a second linear equation based on the slopes of the plurality of second size difference curves and the plurality of second reference geometric parameters;

[0029] The correction values ​​of the initial geometric parameters are determined according to the parameters of the second linear equation and the slope of the first size difference curve.

[0030] In one embodiment, the parameters of the second linear equation include a second slope and a second intercept, and determining the correction value of the initial geometric parameter according to the parameters of the second linear equation and the slope of the first size difference curve includes:

[0031] determining a second difference between the slope of the first size difference curve and the second intercept;

[0032] A second correction value is obtained according to the ratio between the second difference and the second slope.

[0033] In one embodiment, the initial geometric parameters include a first geometric parameter, a second geometric parameter and a third geometric parameter, the first geometric parameter is the source axis distance, the third geometric parameter is the imaging plane spacing of the CT system, and the method further includes:

[0034] The third geometric parameter is determined according to the first size difference curve, the first geometric parameter, the second geometric parameter and half of the vertex angle of the second sub-mold.

[0035] In one embodiment, determining the third geometric parameter according to the first size difference curve, the first geometric parameter, the second geometric parameter, and half of the vertex angle of the second sub-mold comprises:

[0036] determining an average value of all dimensions in the first dimension difference curve;

[0037] determining a first ratio of the average value to a tangent of half the vertex angle of the second sub-phantom and a second ratio of the first geometric parameter to the second geometric parameter;

[0038] A third geometric parameter is determined based on the product of the first ratio and the second ratio.

[0039] In a second aspect, an embodiment of the present application provides a calibration method for a CT system, the CT system comprising at least a first system and a second system, the first system and the second system both comprising an X-ray tube and a corresponding detector, the method comprising:

[0040] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0041] Based on a first geometric parameter of the CT system, reconstructing the first data and the second data respectively to obtain a first image and a second image;

[0042] determining a first radius of the phantom in the first image, and determining a second radius of the phantom in the second image;

[0043] Using a traversal method, based on a plurality of first reference geometric parameters and the first data, a plurality of first images to be processed are determined; and a third radius of the phantom in each first image to be processed is obtained;

[0044] A correction value of the first geometric parameter is determined based on the plurality of first reference geometric parameters, the first radius, the second radius, and the plurality of third radii.

[0045] In a third aspect, an embodiment of the present application provides a calibration method for a CT system, the CT system comprising at least a first system and a second system, the first system and the second system both comprising an X-ray tube and a corresponding detector; the method comprising:

[0046] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0047] Based on a second geometric parameter of the CT system, reconstructing the first data and the second data respectively to obtain a first image and a second image;

[0048] determining a first radius of the phantom in the first image, and determining a second radius of the phantom in the second image;

[0049] Using a traversal method, based on the plurality of second reference geometric parameters and the first data, a plurality of second images to be processed are determined, and a fourth radius of the phantom in each second image to be processed is determined;

[0050] Determine a first radius difference curve between a second radius change curve corresponding to the second radius and a first radius change curve corresponding to the first radius, and respectively determine a second radius difference curve between a third radius change curve corresponding to each fourth radius and the first radius change curve;

[0051] A correction value of the second geometric parameter is determined based on the plurality of second reference geometric parameters, the slope of the first radius difference curve, and the slopes of the plurality of second radius difference curves.

[0052] In a fourth aspect, an embodiment of the present application provides a geometric parameter correction device, which is applied to a CT system. The CT system includes at least a first system and a second system. The first system and the second system both include an X-ray tube and a corresponding detector. The device includes:

[0053] An acquisition module, used for acquiring first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0054] A reconstruction module, configured to perform image reconstruction based on the initial geometric parameters of the CT system and the first data to obtain a first image; and perform image reconstruction based on the initial geometric parameters and the second data to obtain a second image;

[0055] a determination module, configured to determine a first size of the phantom in the first image, and to determine a second size of the phantom in the second image;

[0056] The correction module is used to determine the correction value of the initial geometric parameter according to the first size, the second size and the first data or the second data.

[0057] In a fifth aspect, an embodiment of the present application provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the method provided in the first aspect, the second aspect and the third aspect are implemented.

[0058] In a sixth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the methods provided in the first, second and third aspects above.

[0059] In the seventh aspect, an embodiment of the present application further provides a computer program product, including a computer program, which, when executed by a processor, implements the steps of the methods provided in the first, second and third aspects above.

[0060] The above-mentioned correction method of geometric parameters, correction method of CT system and storage medium, the method is applied to the CT system, the CT system includes at least a first system and a second system, the first system and the second system both include an X-ray tube and a corresponding detector, the method obtains first data and second data, the first data is obtained by the first system scanning the phantom in an axial scanning mode, and the second data is obtained by the second system scanning the phantom in an axial scanning mode; based on the initial geometric parameters of the CT system and the first data, image reconstruction is performed to obtain a first image; based on the initial geometric parameters and the second data, image reconstruction is performed to obtain a second image; determine the first size of the phantom in the first image, and determine the second size of the phantom in the second image; determine the correction value of the initial geometric parameters according to the first size, the second size and the first data or the second data. In this embodiment, by acquiring the first image and the second image corresponding to the phantom, the correction value of the initial geometric parameter can be determined according to the first size of the phantom in the first image and the second size of the phantom in the second image, as well as the first data or the second data of the phantom, so that there is no high requirement for the manufacturing accuracy of the phantom and the positioning accuracy of the phantom in the CT system, as long as the size of the phantom in the corresponding image can be obtained, the correction value for correcting the initial geometric parameter of the CT system can be obtained, so that the correction method of the geometric parameter has higher practicality. In addition, there will be no problem of inaccurate correction values ​​of the determined geometric parameters due to inaccurate manufacturing accuracy and positioning accuracy of the phantom, so that in the process of imaging using the CT system, the correction value determined by the correction method of the geometric parameter provided by the present application is used to correct the registration of the images scanned by the first system and the second system in the CT system, which can improve the accuracy of the obtained registered image. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 A diagram showing an application environment of a method for correcting geometric parameters in one embodiment;

[0062] Figure 2 A schematic diagram of a step flow of a method for correcting geometric parameters in one embodiment;

[0063] Figure 3 A schematic flow chart of steps of a method for calibrating geometric parameters in another embodiment;

[0064] Figure 4 is a schematic diagram of a straight line corresponding to a first linear equation in an embodiment;

[0065] Figure 5 is a schematic diagram of a straight line corresponding to the first linear equation in another embodiment;

[0066] Figure 6 A schematic flow chart of steps of a method for calibrating geometric parameters in another embodiment;

[0067] Figure 7 A schematic flow chart of steps of a method for calibrating geometric parameters in another embodiment;

[0068] Figure 8 A schematic flow chart of steps of a method for calibrating geometric parameters in another embodiment;

[0069] Fig. 9 A schematic flow chart of steps of a method for calibrating geometric parameters in another embodiment;

[0070] Fig.10 is a schematic diagram of a straight line corresponding to the second linear equation in one embodiment;

[0071] Fig.11 A schematic flow chart of steps of a method for calibrating geometric parameters in another embodiment;

[0072] Fig.12 A schematic flow chart of steps of a method for calibrating geometric parameters in another embodiment;

[0073] Fig.13 A schematic diagram of a flow chart of steps of a calibration method for a CT system in one embodiment;

[0074] Fig.14 A schematic flow chart of steps of a calibration method for a CT system in another embodiment;

[0075] Fig.15 Schematic diagram of the structure of a correction device for geometric parameters in one embodiment. DETAILED DESCRIPTION

[0076] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0077] The serial numbers assigned to the components in this article, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning.

[0078] First, before specifically introducing the technical solutions of the embodiments disclosed in the present application, the background technology or technical evolution context based on the embodiments of the present application is introduced. Computed Tomography (CT) is a technology that uses X-rays to perform tomographic imaging of the human body or an object. Its basic principle is that the X-ray beam passes through the scanned object from multiple directions, and the detector receives the X-ray signal after attenuation by the object. Since different tissues have different attenuation degrees of X-rays (for example, the attenuation degree of bones to X-rays is much higher than that of soft tissues), the signal strength received by the detector is also different. By reconstructing these signals, the ray attenuation information at different angles can be reconstructed into a tomographic image inside the object. The CT system may include dual-source CT (DSCT) and multi-source CT. Dual-source CT is a CT device that simultaneously collects images of the imaging object through two sets of X-ray tubes and corresponding two sets of detectors. The working principle of DSCT is: two sets of X-ray tubes and two sets of detectors are installed on the same plane at a certain angle for synchronous scanning. Multi-source CT is a CT device that includes multiple X-ray tubes and corresponding detectors to collect images of the imaging object. When using DSCT or multi-source CT for imaging, it is required that the images of two or more systems be registered. However, the geometric parameters of the CT system will affect the registration of the image. In the conventional technology, the geometric parameters of the dual-source CT are measured by scanning two pin needles using geometric relationships; or by scanning two steel balls using geometric relationships. However, the two methods for measuring the geometric parameters of the dual-source CT provided in the conventional technology have poor operability, which may result in inaccurate geometric parameters. In this regard, the present application provides a method for correcting geometric parameters.

[0079] The geometric parameter correction method provided in the present application can be applied to a dual-source CT system or a multi-source CT system in a CT system. The CT system includes a computer device, which can be, but is not limited to, an industrial computer, a laptop computer, and a tablet computer. The internal structure of the computer device can be as follows: Figure 1As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a method for correcting a geometric parameter is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0080] Those skilled in the art will understand that Figure 1 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0081] In one embodiment, Figure 2 As shown, a method for correcting geometric parameters is provided. This embodiment uses the method applied to a computer device in a CT system as an example. In this embodiment, the method includes the following steps:

[0082] Step 200 , obtaining first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode.

[0083] A phantom is placed at a designated position of a CT system. The CT system includes at least a first system and a second system. The first system includes an X-ray tube and a corresponding detector, and the second system includes another X-ray tube and a corresponding detector. When the CT system is a multi-source CT system, the first system and the second system can be any two systems in a dual-source CT system that require image registration. The computer device sends a control signal to the CT system to control the CT system to scan the phantom in an axial scanning mode to obtain first data and second data. The first data is obtained by scanning the phantom by the first system in the CT system, and the second data is obtained by scanning the phantom by the second system in the CT system. Both the first data and the second data are original CT data collected. The CT system sends the first data and the second data obtained by scanning to the computer device.

[0084] Among them, the axial scanning mode is also called the non-helical scanning mode. In this scanning mode, the X-ray source and detector rotate around the phantom and scan. After completing a circle of scanning, the scanning bed (carrying the phantom) moves a certain distance, and then performs the next circle of scanning, and repeats this process until the predetermined area is scanned. The data obtained from the scanning is used to reconstruct the tomographic images inside the phantom. These images are parallel layer by layer, just like cutting the phantom into thin slices for observation.

[0085] The first data and the second data can be sent to the computer device in real time after the CT system scans, or can be stored in an image device post-processing workstation or a server such as PACS (Picture Archiving and Communication Systems) after the CT system scans, and the computer device obtains the data from the image device post-processing workstation or PACS when necessary. This embodiment does not limit the specific method of obtaining the first data and the second data, as long as the function can be achieved.

[0086] Step 210: reconstruct an image based on the initial geometric parameters of the CT system and the first data to obtain a first image; and reconstruct an image based on the initial geometric parameters and the second data to obtain a second image.

[0087] The initial geometric parameters of the CT system refer to the geometric parameters of the CT system determined by the user before using the CT system; they may also be the geometric parameters of the CT system provided by the manufacturer. The CT system includes at least two systems, and the initial geometric parameters of the CT system may refer to the geometric parameters of each system, or the geometric parameters of the entire CT system. After acquiring the first data corresponding to the phantom, the computer device performs image reconstruction based on the initial geometric parameters of the CT system and the first data, and can obtain the first image of the phantom. That is, the image reconstruction is performed based on the initial geometric parameters of the first system in the CT system and the first data to obtain the first image. After acquiring the second data corresponding to the phantom, the computer device performs image reconstruction based on the initial geometric parameters of the CT system and the second data, and can obtain the second image of the phantom. That is, the image reconstruction is performed based on the initial geometric parameters and the second data of the second system in the CT system to obtain the second image. Both the first image and the second image are CT images. This embodiment does not limit the specific method for image reconstruction, as long as its function can be achieved.

[0088] Step 220: Determine a first size of the phantom in the first image, and determine a second size of the phantom in the second image.

[0089] After obtaining the first image of the phantom, the computer device determines the first size of the phantom in the first image. After obtaining the second image of the phantom, the computer device determines the second size of the phantom in the second image. Generally, the phantom is a three-dimensional structure, and the cross section in the bed entry direction is a regular shape. The first size of the first image and the second size of the second image can be the size of the cross section in the phantom entry direction. The method of determining the first size of the phantom in the first image and the second size of the phantom in the second image is related to the specific structure of the phantom, and this embodiment does not limit this.

[0090] Step 230: Determine a correction value of the initial geometric parameter according to the first size, the second size and the first data or the second data.

[0091] After obtaining the first size of the phantom in the first image and the second size of the phantom in the second image, the computer device determines the correction value of the initial geometric parameter according to the first size and the second size, and the first data or the second data obtained by the CT system scan. Different initial geometric parameters have different methods for determining the correction value of the initial geometric parameter according to the first size, the second size and the first data or the second data. If the initial geometric parameters of the first system in the CT system are corrected, the correction value of the initial geometric parameter is determined using the first size, the second size and the first data. If the initial geometric parameters of the second system in the CT system are corrected, the correction value of the initial geometric parameter is determined using the first size, the second size and the second data.

[0092] The geometric parameter correction method provided in the embodiment of the present application is applied to a CT system, and the CT system includes at least a first system and a second system, and the first system and the second system both include an X-ray tube and a corresponding detector. The method acquires first data and second data, and the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode; reconstructs an image based on the initial geometric parameters of the CT system and the first data to obtain a first image; reconstructs an image based on the initial geometric parameters and the second data to obtain a second image; determines a first size of the phantom in the first image, and determines a second size of the phantom in the second image; and determines a correction value of the initial geometric parameters according to the first size, the second size, and the first data or the second data. In this embodiment, by acquiring the first image and the second image corresponding to the phantom, the correction value of the initial geometric parameter can be determined according to the first size of the phantom in the first image and the second size of the phantom in the second image, as well as the first data or the second data of the phantom, so that there is no high requirement for the manufacturing accuracy of the phantom and the positioning accuracy of the phantom in the CT system, as long as the size of the phantom in the corresponding image can be obtained, the correction value for correcting the initial geometric parameter of the CT system can be obtained, so that the correction method of the geometric parameter has higher practicality. In addition, there will be no problem of inaccurate correction values ​​of the determined geometric parameters due to inaccurate manufacturing accuracy and positioning accuracy of the phantom, so that in the process of imaging using the CT system, the correction value determined by the correction method of the geometric parameter provided by the present application is used to correct the registration of the images scanned by the first system and the second system in the CT system, which can improve the accuracy of the obtained registered image.

[0093] In one embodiment, the phantom includes a first sub-phantom, and the corresponding dimensions of the cross sections of the first sub-phantom in the bed entry direction are the same. The first sub-phantom may be a water phantom, and the structure of the water phantom may be a cylinder, or may be other regular three-dimensional structures such as a cuboid or a cube. The first sub-phantom is placed at the rotation center of the CT system, and the CT system is controlled to scan the first sub-phantom in an axial scanning mode, so that first data and second data of the first sub-phantom can be obtained. The correction values ​​of the initial geometric parameters of the determined CT system may be the correction values ​​of the initial geometric parameters of the first system in the CT system, or may be the correction values ​​of the initial geometric parameters of the second system. If the correction values ​​of the initial geometric parameters of the first system in the CT system are determined, the initial geometric parameters include the first geometric parameters, and the first geometric parameters refer to the distance between the focus of the first system in the CT system and the rotation center of the CT system, that is, the source axial distance (Source Isocenter Distance, SID). In the case of determining the correction values ​​of the first geometric parameters of the first system, such as Figure 3As shown, it is related to an implementation method of determining a correction value of an initial geometric parameter according to a first size, a second size and first data or second data, and the steps of the implementation method include:

[0094] Step 300: Acquire a plurality of first reference geometric parameters, perform image reconstruction based on each first reference geometric parameter and the first data to obtain a first image to be processed, and determine the size of the first sub-model in each first image to be processed.

[0095] The multiple first reference geometric parameters may be multiple reference SIDs of the first system pre-set by the user and stored in the computer device. This embodiment does not limit the number of the first reference geometric parameters as long as the function can be achieved.

[0096] For each first reference geometric parameter, the computer device performs image reconstruction based on the first reference geometric parameter and the first data to obtain a first image to be processed, thereby obtaining multiple first images to be processed, and determining the size of the first sub-phantom in each first image to be processed. The size of the first sub-phantom in the first image to be processed refers to the size of the cross section of the first sub-phantom in the bed entry direction. If the first sub-phantom is a cylinder, the size of the first sub-phantom in the first image to be processed may be the diameter or radius of the cross-sectional circle of the cylinder; if the first sub-phantom is a cube, the size of the first sub-phantom in the first image to be processed may be the length of the side length of the square of the cube cross section or half of the length of the side length; if the first sub-phantom is a rectangle, the size of the first sub-phantom in the first image to be processed may be the length of any side length of the rectangle or square of the cross section of the rectangle in the bed entry direction or half of the length of any side length.

[0097] Step 310: Determine a first linear equation according to the size of the first sub-phantom in all first images to be processed and all first reference geometric parameters, as well as the first size and the first geometric parameter.

[0098] After obtaining the size of the first sub-phantom in all the first to-be-processed images of the first sub-phantom, the computer device performs linear fitting on the size of the first sub-phantom in all the first to-be-processed images and all the reference geometric parameters corresponding to all the first to-be-processed images, as well as the first size and the first geometric parameters to obtain a fitting equation, namely, a first linear equation. Specifically, according to the size of the first sub-phantom in all the first to-be-processed images and all the reference geometric parameters corresponding to all the first to-be-processed images, as well as the first size and the first geometric parameters, a straight line is formed in the first coordinate system, such as Figure 4As shown, the equation of the straight line is the first linear equation. The abscissa of the first coordinate system represents the geometric parameter (SID), and the ordinate represents the size. The first linear equation can be expressed as: r = p1*SID+p2, r represents the size of the first sub-mold, SID represents the geometric parameter, and p1 and p2 are the parameters of the first linear equation.

[0099] In an optional embodiment, a size ratio of the first sub-phantom to the first size in each first image to be processed, and a parameter ratio of the reference geometric parameter to the first geometric parameter are determined, and a straight line is formed in the second coordinate system according to all size ratios and all parameter ratios, such as Figure 5 As shown, the equation of the straight line is the first linear equation. The abscissa of the second coordinate system represents the ratio of geometric parameters, and the ordinate represents the ratio of dimensions.

[0100] Step 320: Determine a correction value of the first geometric parameter according to the parameter of the first linear equation and the second dimension.

[0101] After determining the first linear equation, the computer device determines a correction value of a first geometric parameter of the first system according to the parameters in the first linear equation and a second size corresponding to the second image.

[0102] In this embodiment, by acquiring a plurality of first reference geometric parameters, image reconstruction is performed based on each first reference geometric parameter and the first data to obtain a first image to be processed, and the size of the first sub-model in each first image to be processed is determined; a first linear equation is determined according to the size of the first sub-model in all first images to be processed and all first reference geometric parameters, as well as the first size and the first geometric parameter; and a correction value of the first geometric parameter is obtained according to the parameter of the first linear equation and the second size. Such a method for determining the correction value of the first geometric parameter is quick and easy to implement. Moreover, in this embodiment, the correction value of the first geometric parameter of the first system is determined by the second size corresponding to the second image obtained by scanning the second system in the CT system, so that the use of the correction value of the first geometric parameter can improve the accuracy of the registration of the images corresponding to the first system and the second system in the CT system.

[0103] In one embodiment, the parameters of the first linear equation include a first slope p1 and a first intercept p2. In this case, Figure 6 As shown, it is related to an implementation method of determining a correction value of a first geometric parameter according to a parameter of a first linear equation and a second dimension, and the steps of the implementation method include:

[0104] Step 600: Determine a first difference between the second size and the first intercept.

[0105] The computer device obtains the first intercept in the first linear equation and determines the difference between the second dimension and the first intercept, that is, the first difference. In other words, the first difference is obtained by subtracting the first intercept from the second dimension.

[0106] Step 610: Determine a first correction value according to the ratio of the first difference to the first slope.

[0107] The computer device obtains the first slope in the first linear equation, determines the ratio of the first difference to the first slope, that is, the first difference divided by the first slope, and obtains a first correction value, that is, a correction value of the first geometric parameter.

[0108] The first correction value SID_corr may be expressed as: SID_corr=(r_2-p2) / p1, where r_2 represents the second size.

[0109] In this embodiment, the first correction value of the first geometric parameter is obtained by determining the first difference between the second dimension and the first intercept in the first linear equation; and determining the ratio of the first difference to the first slope in the first linear equation. This method of determining the correction value of the first geometric parameter is quick and easy to implement, and can improve the efficiency of determining the correction value of the geometric parameter.

[0110] In one embodiment, the phantom includes a second sub-phantom, and the corresponding dimensions of the cross section of the second sub-phantom in the bed-entry direction are different. Specifically, the second sub-phantom can be any phantom whose dimensions change uniformly along the bed-entry direction, such as a cone or a truncated cone. The initial geometric parameters include second geometric parameters, and the second geometric parameters refer to the distance between the focus of the first system and the corresponding detector, that is, the source-to-detector distance (Source Detector Distance, SDD). The second sub-phantom is placed at the corresponding position (rotation center) in the CT system, and the CT system is controlled to scan the second sub-phantom, so that the first data and the second data of the second sub-phantom can be obtained. When determining the correction value of the initial geometric parameter (SDD) of the first system in the CT system, such as Figure 7 As shown, another implementation method of determining the correction value of the initial geometric parameter according to the first size, the second size and the first data or the second data, the steps of the implementation method include:

[0111] Step 700: Acquire a plurality of second reference geometric parameters, perform image reconstruction based on each second geometric parameter and the first data to obtain a second image to be processed, and determine a size change curve of the second sub-phantom in the plurality of second images to be processed.

[0112] The plurality of second reference geometric parameters may be a plurality of reference SDDs of the first system pre-set by a user and stored in the computer device. This embodiment does not limit the number of the second geometric parameters as long as the function thereof can be achieved.

[0113] For each second reference geometric parameter, the computer device performs image reconstruction based on the second reference geometric parameter and the first data to obtain a second image to be processed, thereby obtaining multiple second images to be processed, and determining the size of the second sub-phantom in each second image to be processed. The size of the second sub-phantom in the second image to be processed refers to the size of the cross section of the second sub-phantom in the bed entry direction. If the second sub-phantom is a cone, the size of the second sub-phantom in each second image to be processed may include the size of the multi-layer cross-sectional circles in the cone; if the second sub-phantom is a truncated cone, the size of the second sub-phantom in each second image to be processed may include the size of the multi-layer cross-sectional circles in the truncated cone. In other words, the size of the second sub-phantom in each second image to be processed includes multiple sizes that vary with the number of layers. For the multiple sizes included in each second image to be processed, a size change curve can be determined, that is, a curve of size change with the number of layers. The size change curve of the second sub-phantom in each second image to be processed may be a size that gradually increases with the number of layers, or a size that gradually decreases with the number of layers.

[0114] Step 710: Determine a size change curve of the second sub-phantom in the first image according to the first size, and determine a size change curve of the second sub-phantom in the second image according to the second size.

[0115] After the computer device scans and reconstructs the second sub-phantom through the CT system to obtain the first image and the second image. The first size of the second sub-phantom in the first image includes multiple sizes of the second sub-phantom that change with the number of layers, and the size change curve of the second sub-phantom in the first image is determined according to the multiple sizes that change with the number of layers. The size change curve of the second sub-phantom in the first image can be that the size gradually increases with the number of layers, or that the size gradually decreases with the number of layers.

[0116] Similarly, the second size of the second sub-phantom in the second image includes a plurality of sizes that change with the number of layers in the second sub-phantom, and a size change curve of the second sub-phantom in the second image can be determined based on the plurality of sizes that change with the number of layers. The size change curve of the second sub-phantom in the second image can be a size that gradually increases with the number of layers, or a size that gradually decreases with the number of layers. The size change curve of the second sub-phantom in the first image, the size change curve of the second sub-phantom in the second image, and the size change curve of the second sub-phantom in the second image to be processed have the same change trends.

[0117] Step 720: Determine the slope of the target size difference curve according to the size change curve of the second sub-phantom in the first image, the size change curve of the second sub-phantom in the second image, and the size change curves of the second sub-phantom in a plurality of second images to be processed.

[0118] The computer device determines a target size difference curve according to the determined size change curve of the second sub-mock in the first image, the size change curve of the second sub-mock in the second image, and the size change curves of the second sub-mock in a plurality of second images to be processed, and determines the slope of the target size difference curve. The target size difference curve includes the first size difference curve and the second size difference curve, and the slope of the target size curve includes the slope of the first size difference curve and the slope of the second size difference curve.

[0119] For determining the slope of the target size difference curve, in one embodiment, as Figure 8 As shown, it is related to an implementation method of determining the slope of the target size difference curve according to the size change curve of the second sub-mock in the first image, the size change curve of the second sub-mock in the second image, and the size change curves of the second sub-mock in multiple second images to be processed. The steps of the implementation method include:

[0120] Step 800: determine a first size difference curve between the size change curve of the second sub-phantom in the second image and the size change curve of the second sub-phantom in the first image, and fit the first size difference curve to determine the slope of the first size difference curve.

[0121] The computer device determines a first size difference curve between the size change curve of the second sub-mock in the second image and the size change curve of the second sub-mock in the first image. That is, the first size difference curve can be obtained by calculating the difference between the size change curve of the second sub-mock in the second image and the size change curve of the second sub-mock in the first image, that is, calculating the difference between each dimension in the size change curve of the second sub-mock in the second image and the corresponding dimension in the size change curve of the second sub-mock in the first image.

[0122] After obtaining the first size difference curve, the computer device performs linear fitting on the first size difference curve to determine the slope of the first size difference curve. Specifically, the computer device forms the first size difference curve in the third coordinate system, fits the first size difference curve into a straight line, and determines the slope of the straight line, which is the slope of the first size difference curve. The abscissa of the third coordinate system represents the second geometric parameter (SDD), and the ordinate represents the size difference.

[0123] Step 810: determine a second size difference curve between the size change curve of the second sub-mock in each second image to be processed and the size change curve of the second sub-mock in the first image, and fit each second size difference curve to determine the slopes of the plurality of second size difference curves.

[0124] For each size change curve of the second sub-phantom in the second image to be processed, the computer device determines a second size difference curve between the size change curve of the second sub-phantom in the second image to be processed and the size change curve of the second sub-phantom in the first image. That is, the computer device calculates the difference between the size change curve of the second sub-phantom in the second image to be processed and the size change curve of the second sub-phantom in the first image, that is, calculates the difference between each dimension in the size change curve of the second sub-phantom in the second image to be processed and the corresponding dimension in the size change curve of the second sub-phantom in the first image, and the second size difference curve can be obtained, so that a plurality of second size difference curves can be obtained.

[0125] For each second size difference curve, the computer device performs linear fitting on the second size difference curve to determine the slope of the second size difference curve, thereby obtaining the slopes of multiple second size difference curves. Specifically, the computer device forms the second size difference curve in the third coordinate system, fits the second size difference curve into a straight line, and determines the slope of the straight line, which is the slope of the second size difference curve.

[0126] The method provided in this embodiment for determining the slope of the first size difference curve and the slope of the second size difference curve in the slope of the target size difference curve is quick and easy to implement, and can improve the efficiency and practicality of determining the correction value of the geometric parameter.

[0127] Step 730: Determine a correction value of the second geometric parameter according to the slope of the target size difference curve.

[0128] After determining the slope of the target size difference curve, the computer device determines the correction value of the second geometric parameter of the first system according to the slope of the target size difference.

[0129] In this embodiment, image reconstruction is performed for each acquired second reference geometric parameter and first data to obtain a second image to be processed, and a size change curve of the second sub-phantom in a plurality of second images to be processed is determined; the size change curve of the first image is determined according to the first size, and the size change curve of the second image is determined according to the second size; the slope of the target size difference curve is determined according to the size change curve of the second sub-phantom in the first image, the size change curve of the second sub-phantom in the second image, and the size change curve of the second sub-phantom in a plurality of second images to be processed; and the correction value of the second geometric parameter is determined according to the slope of the target size difference curve. Such a method for determining the correction value of the second geometric parameter is quick and easy to implement. Moreover, in this embodiment, the determination of the slope of the target size difference curve is related to the second image obtained by scanning the second system in the CT system, and the correction value of the second geometric parameter is determined by using the slope of the target size difference curve. Using the correction value of the second geometric parameter can improve the accuracy of registering the images corresponding to the first system and the second system in the CT system.

[0130] In one embodiment, Fig. 9 As shown, it is related to an implementation method of determining the correction value of the second geometric parameter according to the slope of the target size difference curve, and the steps of the implementation method include:

[0131] Step 900: Determine a second linear equation according to the slopes of a plurality of second size difference curves and a plurality of second reference geometric parameters.

[0132] After determining the slopes of the plurality of second size difference curves, the computer device performs linear fitting according to the slopes of the plurality of second size difference curves and the corresponding plurality of second reference geometric parameters to obtain a fitting equation, namely, a second linear equation. Specifically, a straight line can be formed in the fourth coordinate system according to the slopes of the plurality of second size difference curves and the corresponding plurality of second reference geometric parameters, such as Fig.10 As shown, the equation of the straight line is the second linear equation. The abscissa of the fourth coordinate system represents the second reference geometric parameter (SDD), and the ordinate represents the slope of the size difference curve. The second linear equation can be expressed as: Slope = q1*SDD+q2, where Slope represents the slope of the size difference curve, SDD represents the geometric parameter, and q1 and q2 are the parameters of the second linear equation.

[0133] Step 910: Determine a correction value of a second geometric parameter according to the parameter of the second linear equation and the slope of the first size difference curve.

[0134] After determining the second linear equation, the computer device determines the correction value of the second geometric parameter according to the parameters in the second linear equation and the slope of the first size difference curve.

[0135] In this embodiment, the correction value of the second geometric parameter is determined by the second linear equation determined by the slope of multiple second dimension difference curves and multiple second reference geometric parameters, and the slope of the first dimension difference curve. This method of determining the correction value of the second geometric parameter is quick and easy to implement, and can improve the efficiency of determining the correction value of the second geometric parameter.

[0136] In one embodiment, the parameters of the second linear equation include a second slope q1 and a second intercept q2, such as Fig.11 As shown, it is related to an implementation method of determining the correction value of the second geometric parameter according to the parameters of the second linear equation and the slope of the first size difference curve, and the steps of the implementation method include:

[0137] Step 111: Determine a second difference between the slope of the first size difference curve and the second intercept.

[0138] The computer device obtains the second intercept in the second linear equation and determines the difference between the slope of the first size difference curve and the second intercept, that is, the second difference. In other words, the second difference is obtained by subtracting the second intercept from the slope of the first size difference curve.

[0139] Step 112: Obtain a second correction value according to the ratio between the second difference and the second slope.

[0140] The computer device obtains the second slope of the second linear equation, determines the ratio of the second difference to the second slope, that is, the second difference divided by the second slope, to obtain a second correction value. The second correction value is used to correct the second geometric parameter.

[0141] The second correction value SDD_corr can be expressed as SDD_corr=(Slope_2-q2) / q1, where Slope_2 represents the slope of the first size difference curve.

[0142] In this embodiment, by determining the second difference between the slope of the first size difference curve and the second intercept; according to the ratio between the second difference and the second slope, a second correction value, that is, a correction value of the second geometric parameter, is obtained. This method for determining the correction value of the second geometric parameter is quick and easy to implement, and can improve the efficiency of determining the correction value of the second geometric parameter. In addition, using the correction value of the second geometric parameter can improve the accuracy of registering the images corresponding to the first system and the second system in the CT system.

[0143] In an optional embodiment, the specific method for correcting the initial geometric parameters of the second system may refer to the above-mentioned method for correcting the initial geometric parameters of the first system, which will not be described in detail here.

[0144] In one embodiment, the initial geometric parameters include a first geometric parameter, a second geometric parameter and a third geometric parameter, wherein the first geometric parameter is a source axis data and the third geometric parameter is an imaging plane spacing of the CT system.

[0145] The third geometric parameter refers to the imaging plane distance (IPD) of the CT system. The imaging plane distance of the CT system refers to the distance between the midpoint between the focus of the first system and the corresponding detector and the midpoint between the focus of the second system and the corresponding detector in the CT system in the Z-axis direction, wherein the Z-axis direction is the moving direction of the bed used to carry the object to be imaged. The description of the first geometric parameter and the second geometric parameter can refer to the specific description in the above embodiment, and will not be repeated here.

[0146] In the case where the initial geometric parameters include a third geometric parameter and the second sub-mock is a cone, the method for correcting the geometric parameters may also determine the third geometric parameter, and the method may further include:

[0147] The third geometric parameter is determined according to the first size difference curve, the first geometric parameter, the second geometric parameter and half of the vertex angle of the second sub-mold.

[0148] The first geometric parameter and the second geometric parameter of the CT system are both geometric parameters that are not CT-corrected. The vertex angle of the second sub-phantom may be pre-stored in the computer device.

[0149] The computer device determines the third geometric parameter according to the determined first size difference curve, the second geometric parameter, the second geometric parameter and half of the vertex angle of the second sub-mold.

[0150] In one embodiment, Fig.12 As shown, it involves an implementation method of determining the third geometric parameter according to the first size difference curve, the first geometric parameter, the second geometric parameter and half of the vertex angle of the second sub-mold, and the steps of the implementation method include:

[0151] Step 121: Determine the average value of all dimensions in the first dimension difference curve.

[0152] After determining the first size difference curve, the computer device obtains all sizes corresponding to the first size difference curve and calculates the average value of all sizes.

[0153] Step 122: Determine a first ratio of the average value to the tangent value of half the vertex angle of the second sub-mold, and a second ratio of the first geometric parameter to the second geometric parameter.

[0154] The computer device determines the tangent value of half of the vertex angle of the second submold. After determining the average value of all dimensions in the first dimension difference curve, the computer device determines a first ratio of the average value to the determined tangent value, that is, the average value divided by the tangent value; and determines a second ratio of the first geometric parameter to the second geometric parameter, that is, the second geometric parameter divided by the first geometric parameter.

[0155] Step 123: Determine a third geometric parameter according to the product of the first ratio and the second ratio.

[0156] After determining the first ratio and the second ratio, the computer device calculates the product between the first ratio and the second ratio to obtain a third geometric parameter. The third geometric parameter can be expressed as: Wherein, IPD represents the third geometric parameter, r_diff_mean represents the average value of all sizes in the first size difference curve, tan(alpha) represents the tangent value of half the vertex angle of the second sub-mold, SDD represents the second geometric parameter, and SID represents the first geometric parameter.

[0157] In this embodiment, the third geometric parameter is determined by determining the average value of each dimension in the first dimension difference curve; determining the first ratio of the average value to the tangent value of half the vertex angle of the second sub-mold, and the second ratio of the first geometric parameter to the second geometric parameter; and determining the third geometric parameter according to the product of the first ratio and the second ratio. In this way, not only the correction value of the second geometric parameter in the CT system can be determined, but also the third geometric parameter of the CT system can be obtained. In addition, the method for determining the third geometric parameter is fast and easy to implement.

[0158] In one embodiment, the present application provides a method for calibrating geometric parameters, the method comprising the steps of:

[0159] S1. Scanning a water phantom placed at a rotation center of the dual-source CT using an axial scanning mode using a dual-source CT to obtain first water phantom data and second water phantom data;

[0160] S2. Reconstruct an image according to the initial SID and the first water phantom data of the first system in the dual-source CT to obtain a first water phantom image, and determine a first size of the water phantom in the first water phantom image; reconstruct an image according to the initial S1D and the second water phantom data of the second system in the dual-source CT to obtain a second water phantom image, and determine a second size of the water phantom in the second water phantom image.

[0161] S3, acquiring multiple first reference SIDs of the first system, performing image reconstruction based on each first reference SID and the first water phantom data to obtain a first image to be processed, and determining the size of the water phantom in each first image to be processed;

[0162] S4, determining a first linear equation according to the sizes of the water phantoms in all the first images to be processed and all the first reference SIDs, as well as the first sizes and the initial SIDs;

[0163] S5. Determine a first difference between the second size and the first intercept of the first linear equation; and determine a first correction value of the initial SID according to a ratio of the first difference to the first slope of the first linear equation.

[0164] S6. Scanning a cone placed at the rotation center of the dual-source CT using an axial scanning mode using the dual-source CT to obtain first cone data and second cone data;

[0165] S7. Perform image reconstruction based on the initial SDD and the first cone data of the first system in the dual-source CT to obtain a first cone image, and determine the radius of the cross-sectional circle of each layer of the cone in the first cone image; perform image reconstruction based on the initial SDD and the second cone data of the second system in the dual-source CT to obtain a second cone image, and determine the radius of the cross-sectional circle of each layer of the cone in the second cone image.

[0166] S8, acquiring multiple second reference SDDs of the first system, performing image reconstruction based on each second reference SDD and the first cone data to obtain a second image to be processed, and determining the radius of each layer of the cone cross-section circle in each second image to be processed;

[0167] S9, determining a first radius variation curve according to the radius of each layer of the cone cross-section circle in the first cone image; determining a second radius variation curve according to the radius of each layer of the cone cross-section circle in the second cone image; determining a radius variation curve of the cone in each second image to be processed according to the radius of each layer of the cone cross-section circle in each second image to be processed;

[0168] S10, determining the difference between the second radius change curve and the first radius change curve to obtain a first radius difference curve, and fitting the first radius difference curve to determine the slope of the first radius difference curve;

[0169] S11, determining the difference between the radius change curve of the cone in each second image to be processed and the first radius change curve to obtain a second radius difference curve, and fitting each second radius difference curve to determine the slopes of multiple second radius difference curves;

[0170] S12. Determine a second linear equation according to the slopes of the plurality of second radius difference curves and the plurality of second reference SDDs.

[0171] S13, determining a second difference between the slope of the first radius difference curve and the second intercept in the second linear equation; and obtaining a second correction value of the initial SDD according to a ratio between the second difference and the second slope in the second linear equation;

[0172] S14, determining the average value of all radii in the first radius difference curve; determining a first ratio of the average value to the tangent value of half the apex angle of the cone, and a second ratio of the initial SDD to the initial SID; determining the IPD of the dual-source CT according to the product of the first ratio and the second ratio.

[0173] In one embodiment, Fig.13 As shown, a correction method for a CT system is provided, the CT system includes at least a first system and a second system, the first system and the second system both include an X-ray tube and a corresponding detector. This embodiment is illustrated by applying the correction method to a computer device in the CT system. The steps of the correction method include:

[0174] Step 131 , obtaining first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode.

[0175] For the specific description of obtaining the first data and the second data, reference may be made to the specific description of the above embodiment, which will not be repeated here.

[0176] Step 132: Based on the first geometric parameter of the CT system, reconstruct the first data and the second data respectively to obtain a first image and a second image.

[0177] The first geometric parameter is the SID. The computer device reconstructs the first data based on the SID of the first system in the CT system to obtain a first image. The computer device reconstructs the second data based on the SID of the second system in the CT system to obtain a second image. Both the first image and the second image are CT images. This embodiment does not limit the specific method for image reconstruction, as long as its function can be achieved.

[0178] Step 133: Determine a first radius of the phantom in the first image, and determine a second radius of the phantom in the second image.

[0179] When calibrating the first geometric parameter of the CT system, the phantom may be a first sub-phantom, and the corresponding dimensions of the cross-section of the first sub-phantom in the bed entry direction are the same. The description of the first sub-phantom can refer to the specific description of the above embodiment, and will not be repeated here.

[0180] After obtaining the first image and the second image, the computer device determines a first radius of the phantom in the first image and a second radius of the phantom in the second image. The description of determining the first radius and the second radius can refer to the specific description of the above embodiment, which will not be repeated here.

[0181] Step 134: using a traversal method, based on the plurality of first reference geometric parameters and the first data, determine a plurality of first images to be processed; and obtain a third radius of the phantom in each first image to be processed;

[0182] The plurality of first reference geometric parameters may be a plurality of reference SIDs of the first system that are preset by a user and stored in the computer device.

[0183] For each first reference geometric parameter, the computer device reconstructs the first data based on the first reference geometric parameter to obtain a first image to be processed, thereby obtaining multiple first images to be processed. For each first image to be processed, the third radius of the phantom in the first image to be processed is determined.

[0184] Step 135 : Determine a correction value of the first geometric parameter according to the plurality of first reference geometric parameters, the first radius, the second radius, and the plurality of third radii.

[0185] After determining the first radius, the second radius, and the plurality of third radii, the computer device determines the correction value of the first geometric parameter according to the first radius, the second radius, and the plurality of third radii. Optionally, the computer device fits the first radius, the first geometric parameter, the plurality of third radii, and the plurality of first reference geometric parameters into a straight line, and determines the equation of the straight line, i.e., the first linear equation. The correction value of the first geometric parameter is determined according to the first slope and the first intercept of the first linear equation, and the second radius. The specific determination process can refer to the specific description of the above embodiment.

[0186] In this embodiment, by acquiring the first image, the second image and the first image to be processed corresponding to the phantom, the correction value of the first geometric parameter can be determined according to the first radius of the phantom in the first image, the second radius of the phantom in the second image, the third radius of the phantom in each first image to be processed, and the first reference geometric parameter corresponding to the first image to be processed, so that there is no high requirement for the manufacturing accuracy of the phantom and the positioning accuracy of the phantom in the CT system, as long as the radius of the phantom in the corresponding image can be obtained, the correction value for correcting the first geometric parameter of the CT system can be obtained, so that the correction method of the CT system has higher practicality. In addition, there will be no problem of inaccurate correction value of the determined first geometric parameter due to inaccurate manufacturing accuracy and positioning accuracy of the phantom, so that in the process of imaging using the CT system, the correction value determined by the correction method of the CT system provided by the present application is used to correct the registration of the images scanned by the first system and the second system in the CT system, which can improve the accuracy of the obtained registered image.

[0187] In one embodiment, Fig.14 As shown, a correction method for a CT system is provided, the CT system includes at least a first system and a second system, the first system and the second system both include an X-ray tube and a corresponding detector. This embodiment is illustrated by applying the correction method to a computer device in the CT system. The steps of the correction method include:

[0188] Step 141 , obtaining first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode.

[0189] For the specific description of obtaining the first data and the second data, reference may be made to the specific description of the above embodiment, which will not be repeated here.

[0190] Step 142: Based on the second geometric parameters of the CT system, reconstruct the first data and the second data respectively to obtain a first image and a second image.

[0191] The second geometric parameter is SDD. The computer device reconstructs the first data based on the SDD of the first system in the CT system to obtain a first image. The computer device reconstructs the second data based on the SDD of the second system in the CT system to obtain a second image. Both the first image and the second image are CT images. This embodiment does not limit the specific method for image reconstruction, as long as its function can be achieved.

[0192] Step 143: Determine a first radius of the phantom in the first image, and determine a second radius of the phantom in the second image.

[0193] When calibrating the second geometric parameter of the CT system, the phantom may be a second sub-phantom, and the corresponding size of the cross section of the first sub-phantom in the bed entry direction is different. The description of the first sub-phantom can refer to the specific description of the above embodiment, which will not be repeated here.

[0194] After obtaining the first image and the second image, the computer device determines a first radius of the phantom in the first image and a second radius of the phantom in the second image. The description of determining the first radius and the second radius can refer to the specific description of the above embodiment, which will not be repeated here.

[0195] Step 144 : using a traversal method, based on the plurality of second reference geometric parameters and the first data, determine a plurality of second images to be processed, and determine a fourth radius of the phantom in each second image to be processed.

[0196] The plurality of second reference geometric parameters may be a plurality of reference SDDs of the first system that are preset by a user and stored in the computer device.

[0197] For each second reference geometric parameter, the computer device reconstructs the first data based on the second reference geometric parameter to obtain a second image to be processed, thereby obtaining multiple second images to be processed. For each second image to be processed, a fourth radius of the phantom in the second image to be processed is determined.

[0198] Step 145, determining a first radius difference curve between a second radius change curve corresponding to the second radius and a first radius change curve corresponding to the first radius, and respectively determining a second radius difference curve between a third radius change curve corresponding to each fourth radius and the first radius change curve.

[0199] The first radius of the phantom in the first image includes multiple radii of the phantom that change with the number of layers, and the first radius change curve corresponding to the first radius can be determined based on the multiple radii that change with the number of layers. Similarly, the second radius of the phantom in the second image includes multiple radii of the phantom that change with the number of layers, and the second radius change curve corresponding to the second radius can be determined based on the multiple radii that change with the number of layers. The fourth radius of the phantom in each second to-be-processed image includes multiple radii of the phantom that change with the number of layers, and the third radius change curve corresponding to the fourth radius can be determined based on the multiple radii that change with the number of layers, so that multiple third radius change curves can be obtained.

[0200] The difference between the second radius change curve and the first radius change curve is determined to obtain a first radius difference curve, and the difference between each third change curve and the first radius change curve is determined to obtain a second radius difference curve, thereby obtaining multiple second radius difference curves.

[0201] Step 146: Determine a correction value of the second geometric parameter according to the plurality of second reference geometric parameters, the slope of the first radius difference curve, and the slopes of the plurality of second radius difference curves.

[0202] After determining the first radius difference curve, the computer device performs linear fitting on the first radius difference curve to determine the slope of the first radius difference curve. After determining multiple second radius difference curves, the computer device performs linear fitting on each second radius difference curve to determine the slope of the second radius difference curve. According to the slopes of the multiple second radius difference curves and the multiple second reference geometric parameters, a fitting equation, i.e., the second linear equation, is obtained by performing linear fitting. According to the second slope and the second intercept of the second linear equation, and the slope of the first radius difference curve, the correction value of the second geometric parameter is determined. The determination process of the body can refer to the specific description of the above embodiment.

[0203] In this embodiment, by acquiring the first image, the second image, and the second image to be processed corresponding to the phantom, the correction value of the second geometric parameter can be determined according to the first radius of the phantom in the first image, the second radius of the phantom in the second image, the fourth radius of the phantom in each second image to be processed, and the second reference geometric parameter corresponding to the second image to be processed. In this way, there is no high requirement for the manufacturing accuracy of the phantom and the positioning accuracy of the phantom in the CT system. As long as the radius of the phantom in the corresponding image can be obtained, the correction value for correcting the second geometric parameter of the CT system can be obtained, so that the correction method of the CT system has higher practicality. In addition, there will be no problem of inaccurate correction value of the determined second geometric parameter due to inaccurate manufacturing accuracy and positioning accuracy of the phantom, so that in the process of imaging using the CT system, the correction value determined by the correction method of the CT system provided by the present application is used to correct the registration of the images scanned by the first system and the second system in the CT system, which can improve the accuracy of the obtained registered image.

[0204] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0205] Based on the same inventive concept, the embodiment of the present application also provides a device for correcting geometric parameters for implementing the method for correcting geometric parameters involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific definition in the embodiment of the device for correcting one or more geometric parameters provided below can refer to the definition of the method for correcting geometric parameters above, and will not be repeated here.

[0206] In one embodiment, Fig.15 As shown, a geometric parameter correction device 10 is provided, which is applied to a CT system. The CT system includes at least a first system and a second system. The first system and the second system both include an X-ray tube and a corresponding detector. The device includes: an acquisition module 11, a reconstruction module 12, a determination module 13 and a correction module 14, wherein:

[0207] The acquisition module 11 is used to acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode.

[0208] The reconstruction module 12 is used to perform image reconstruction based on the initial geometric parameters of the CT system and the first data to obtain a first image; and to perform image reconstruction based on the initial geometric parameters and the second data to obtain a second image.

[0209] The determination module 13 is configured to determine a first size of the phantom in the first image and a second size of the phantom in the second image.

[0210] The correction module 14 is used to determine the correction value of the initial geometric parameter according to the first size, the second size and the first data or the second data.

[0211] In one embodiment, the phantom includes a first sub-phantom, and the initial geometric parameters include a first geometric parameter, and the first geometric parameter is a source wheelbase. The correction module 14 includes a first acquisition unit, a first determination unit, and a first correction unit. The first acquisition unit is used to acquire a plurality of first reference geometric parameters, perform image reconstruction based on each first reference geometric parameter and the first data, obtain a first image to be processed, and determine the size of the first sub-phantom in each first image to be processed. The first determination unit is used to determine a first linear equation based on the size of the second sub-phantom in all first images to be processed and all first reference geometric parameters, as well as the first size and the first geometric parameter. The first correction unit is used to determine a correction value of the first geometric parameter based on the parameters of the first linear equation and the second size.

[0212] In one embodiment, the parameters of the first linear equation include a first slope and a first intercept, and the first correction unit is specifically used to determine a first difference between the second size and the first intercept; and determine a first correction value according to a ratio of the first difference and the first slope.

[0213] In one embodiment, the phantom includes a second sub-phantom, the initial geometric parameters include a second geometric parameter, and the second geometric parameter is a source-to-detector distance. The correction module 14 also includes a second acquisition unit, a second determination unit, a third determination unit, and a second correction unit. The second acquisition unit is used to acquire a plurality of second reference geometric parameters, perform image reconstruction based on each second reference geometric parameter and the first data, obtain a second image to be processed, and determine a size change curve of the second sub-phantom in a plurality of second images to be processed. The second determination unit is used to determine a size change curve of the second sub-phantom in the first image according to the first size, and determine a size change curve of the second sub-phantom in the second image according to the second size. The third determination unit is used to determine the slope of the target size difference curve according to the size change curve of the second sub-phantom in the first image, the size change curve of the second sub-phantom in the second image, and the size change curve of the second sub-phantom in a plurality of second images to be processed. The second correction unit is used to determine the correction value of the second geometric parameter according to the slope of the target size difference curve.

[0214] In one embodiment, the third determination unit is specifically used to determine a first size difference curve between a size change curve of the second sub-model in the second image and a size change curve of the second sub-model in the first image, and to fit the first size difference curve to determine the slope of the first size difference curve; determine a second size difference curve between the size change curve of each second image to be processed and the size change curve of the first image, and to fit each second size difference curve to determine the slopes of multiple second size difference curves.

[0215] In one embodiment, the second correction unit is specifically used to determine the second linear equation based on the slopes of multiple second size difference curves and multiple second reference geometric parameters; and determine the correction value of the second geometric parameter based on the parameters of the second linear equation and the slope of the first size difference curve.

[0216] In one embodiment, the parameters of the second linear equation include a second slope and a second intercept, and the second correction unit is specifically used to determine a second difference between the slope and the second intercept of the first size difference curve; and obtain a second correction value based on the ratio between the second difference and the second slope.

[0217] In one embodiment, the determination module 13 includes a fourth determination unit. The fourth determination unit is used to determine the third geometric parameter according to the first size difference curve, the first geometric parameter, the second geometric parameter and half of the vertex angle of the second sub-mold.

[0218] In one embodiment, the fourth determination unit is specifically used to determine the average value of all dimensions in the first dimension difference curve; determine a first ratio of the average value to the tangent value of half the vertex angle of the second sub-mold, and a second ratio of the first geometric parameter to the second geometric parameter; and determine the third geometric parameter based on the product of the first ratio and the second ratio.

[0219] In one embodiment, a correction device for a CT system is provided, the CT system includes at least a first system and a second system, the first system and the second system both include an X-ray tube and a corresponding detector, the device includes: a data acquisition module, an image reconstruction module, a radius determination module, a traversal module, and a correction value determination module. Wherein;

[0220] A data acquisition module, used to acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0221] An image reconstruction module, used for reconstructing the first data and the second data based on the first geometric parameter of the CT system to obtain a first image and a second image;

[0222] a radius determination module, configured to determine a first radius of the phantom in the first image, and to determine a second radius of the phantom in the second image;

[0223] A traversal module, configured to determine a plurality of first images to be processed based on a plurality of first reference geometric parameters and the first data by adopting a traversal method; and to obtain a third radius of the phantom in each of the first images to be processed;

[0224] The correction value determination module is used to determine the correction value of the first geometric parameter according to a plurality of first reference geometric parameters, a first radius, a second radius and a plurality of third radii.

[0225] In one embodiment, a correction device for a CT system is provided, the CT system includes at least a first system and a second system, the first system and the second system both include an X-ray tube and a corresponding detector, the device includes: a data acquisition module, an image reconstruction module, a radius determination module, a traversal module, a radius difference curve determination module, and a correction value determination module. Wherein;

[0226] A data acquisition module, used to acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0227] An image reconstruction module, used for reconstructing the first data and the second data based on a second geometric parameter of the CT system to obtain a first image and a second image;

[0228] a radius determination module, configured to determine a first radius of the phantom in the first image and a second radius of the phantom in the second image;

[0229] A traversal module, configured to determine a plurality of second images to be processed and determine a fourth radius of the phantom in each second image to be processed based on a plurality of second reference geometric parameters and the first data by adopting a traversal method;

[0230] a radius difference curve determination module, used to determine a first radius difference curve between a second radius change curve corresponding to the second radius and a first radius change curve corresponding to the first radius, and to respectively determine a second radius difference curve between a third radius change curve corresponding to each fourth radius and the first radius change curve;

[0231] The correction value determination module is used to determine the correction value of the second geometric parameter according to a plurality of second reference geometric parameters, the slope of the first radius difference curve and the slopes of a plurality of second radius difference curves.

[0232] Each module in the correction device for geometric parameters and the correction device for CT system can be implemented in whole or in part by software, hardware and their combination. Each module can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory in the computer device in the form of software, so that the processor can call and execute the corresponding operations of each module.

[0233] In one embodiment, a computer device is provided, whose internal structure diagram can be as follows: Figure 1 In one embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the following steps are implemented:

[0234] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0235] Reconstructing an image based on the initial geometric parameters of the CT system and the first data to obtain a first image; reconstructing an image based on the initial geometric parameters and the second data to obtain a second image;

[0236] determining a first size of the phantom in the first image, and determining a second size of the phantom in the second image;

[0237] A correction value of the initial geometric parameter is determined based on the first size, the second size and the first data or the second data.

[0238] In one embodiment, when the processor executes the computer program, the following steps are also implemented: obtaining multiple first reference geometric parameters, reconstructing the image based on each first reference geometric parameter and the first data to obtain a first image to be processed, and determining the size of the first sub-model in each first image to be processed; determining a first linear equation based on the size of the first sub-model in all first images to be processed and all first reference geometric parameters, as well as the first size and the first geometric parameter; determining a correction value of the first geometric parameter based on the parameters of the first linear equation and the second size.

[0239] In one embodiment, when the processor executes the computer program, the following steps are further implemented: determining a first difference between the second size and the first intercept; and determining a first correction value according to a ratio of the first difference to the first slope.

[0240] In one embodiment, when the processor executes the computer program, the following steps are also implemented: obtaining multiple second reference geometric parameters, reconstructing the image based on each second reference geometric parameter and the first data to obtain a second image to be processed, and determining the size change curve of the second sub-model in the multiple second images to be processed; determining the size change curve of the second sub-model in the first image according to the first size, and determining the size change curve of the second sub-model in the second image according to the second size; determining the slope of the target size difference curve according to the size change curve of the second sub-model in the first image, the size change curve of the second sub-model in the second image, and the size change curve of the second sub-model in the multiple second images to be processed; determining the correction value of the second geometric parameter according to the slope of the target size difference curve.

[0241] In one embodiment, when the processor executes the computer program, the following steps are also implemented: determining a first size difference curve between the size change curve of the second sub-mock in the second image and the size change curve of the second sub-mock in the first image, and fitting the first size difference curve to determine the slope of the first size difference curve; determining a second size difference curve between the size change curve of the second sub-mock in each second image to be processed and the size change curve of the second sub-mock in the first image, and fitting each second size difference curve to determine the slopes of multiple second size difference curves.

[0242] In one embodiment, when the processor executes the computer program, the following steps are also implemented: determining a second linear equation based on the slopes of multiple second size difference curves and multiple second reference geometric parameters; determining a correction value of the second geometric parameter based on the parameters of the second linear equation and the slope of the first size difference curve.

[0243] In one embodiment, when the processor executes the computer program, the following steps are also implemented: determining a second difference between the slope of the first size difference curve and the second intercept; and obtaining a second correction value based on a ratio between the second difference and the second slope.

[0244] In one embodiment, when the processor executes the computer program, the following steps are further implemented: determining a third geometric parameter based on the first size difference curve, the first geometric parameter, the second geometric parameter and half of the vertex angle of the second sub-mold.

[0245] In one embodiment, when the processor executes the computer program, the following steps are also implemented: determining the average value of all dimensions in the first dimension difference curve; determining a first ratio of the average value to the tangent value of half the vertex angle of the second sub-mold, and a second ratio of the first geometric parameter to the second geometric parameter; determining a third geometric parameter based on the product of the first ratio and the second ratio.

[0246] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0247] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0248] Based on a first geometric parameter of the CT system, reconstructing the first data and the second data respectively to obtain a first image and a second image;

[0249] determining a first radius of the phantom in the first image, and determining a second radius of the phantom in the second image;

[0250] Using a traversal method, based on a plurality of first reference geometric parameters and the first data, a plurality of first images to be processed are determined; and a third radius of the phantom in each first image to be processed is obtained;

[0251] A correction value of the first geometric parameter is determined based on the plurality of first reference geometric parameters, the first radius, the second radius, and the plurality of third radii.

[0252] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0253] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0254] Based on a second geometric parameter of the CT system, reconstructing the first data and the second data respectively to obtain a first image and a second image;

[0255] determining a first radius of the phantom in the first image, and determining a second radius of the phantom in the second image;

[0256] Using a traversal method, based on the plurality of second reference geometric parameters and the first data, a plurality of second images to be processed are determined, and a fourth radius of the phantom in each second image to be processed is determined;

[0257] Determine a first radius difference curve between a second radius change curve corresponding to the second radius and a first radius change curve corresponding to the first radius, and respectively determine a second radius difference curve between a third radius change curve corresponding to each fourth radius and the first radius change curve;

[0258] A correction value of the second geometric parameter is determined based on the plurality of second reference geometric parameters, the slope of the first radius difference curve, and the slopes of the plurality of second radius difference curves.

[0259] In one embodiment, a computer readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

[0260] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0261] Reconstructing an image based on the initial geometric parameters of the CT system and the first data to obtain a first image; reconstructing an image based on the initial geometric parameters and the second data to obtain a second image;

[0262] determining a first size of the phantom in the first image, and determining a second size of the phantom in the second image;

[0263] A correction value of the initial geometric parameter is determined based on the first size, the second size and the first data or the second data.

[0264] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: obtaining multiple first reference geometric parameters, reconstructing the image based on each first reference geometric parameter and the first data to obtain a first image to be processed, and determining the size of the first sub-model in each first image to be processed; determining a first linear equation based on the size of the first sub-model in all first images to be processed and all first reference geometric parameters, as well as the first size and the first geometric parameter; determining a correction value of the first geometric parameter based on the parameters of the first linear equation and the second size.

[0265] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: determining a first difference between the second size and the first intercept; and determining a first correction value according to a ratio of the first difference to the first slope.

[0266] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: obtaining multiple second reference geometric parameters, reconstructing the image based on each second reference geometric parameter and the first data to obtain a second image to be processed, and determining the size change curve of the second sub-model in the multiple second images to be processed; determining the size change curve of the second sub-model in the first image according to the first size, and determining the size change curve of the second sub-model in the second image according to the second size; determining the slope of the target size difference curve according to the size change curve of the second sub-model in the first image, the size change curve of the second sub-model in the second image, and the size change curve of the second sub-model in the multiple second images to be processed; determining the correction value of the second geometric parameter according to the slope of the target size difference curve.

[0267] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: determining a first size difference curve between the size change curve of the second sub-mock in the second image and the size change curve of the second sub-mock in the first image, and fitting the first size difference curve to determine the slope of the first size difference curve; determining a second size difference curve between the size change curve of the second sub-mock in each second image to be processed and the size change curve of the second sub-mock in the first image, and fitting each second size difference curve to determine the slopes of multiple second size difference curves.

[0268] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented: determining a second linear equation based on the slopes of multiple second size difference curves and multiple second reference geometric parameters; determining a correction value of the second geometric parameter based on the parameters of the second linear equation and the slope of the first size difference curve.

[0269] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: determining a second difference between the slope of the first size difference curve and the second intercept; and obtaining a second correction value based on a ratio between the second difference and the second slope.

[0270] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: determining a third geometric parameter based on the first size difference curve, the first geometric parameter, the second geometric parameter and half of the vertex angle of the second sub-mold.

[0271] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented: determining the average value of all dimensions in the first dimension difference curve; determining a first ratio of the average value to the tangent value of half the vertex angle of the second sub-mold, and a second ratio of the first geometric parameter to the second geometric parameter; determining a third geometric parameter based on the product of the first ratio and the second ratio.

[0272] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0273] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0274] Based on a first geometric parameter of the CT system, reconstructing the first data and the second data respectively to obtain a first image and a second image;

[0275] determining a first radius of the phantom in the first image, and determining a second radius of the phantom in the second image;

[0276] Using a traversal method, based on a plurality of first reference geometric parameters and the first data, a plurality of first images to be processed are determined; and a third radius of the phantom in each first image to be processed is obtained;

[0277] A correction value of the first geometric parameter is determined based on the plurality of first reference geometric parameters, the first radius, the second radius, and the plurality of third radii.

[0278] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0279] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0280] Based on a second geometric parameter of the CT system, reconstructing the first data and the second data respectively to obtain a first image and a second image;

[0281] determining a first radius of the phantom in the first image, and determining a second radius of the phantom in the second image;

[0282] Using a traversal method, based on the plurality of second reference geometric parameters and the first data, a plurality of second images to be processed are determined, and a fourth radius of the phantom in each second image to be processed is determined;

[0283] Determine a first radius difference curve between a second radius change curve corresponding to the second radius and a first radius change curve corresponding to the first radius, and respectively determine a second radius difference curve between a third radius change curve corresponding to each fourth radius and the first radius change curve;

[0284] A correction value of the second geometric parameter is determined based on the plurality of second reference geometric parameters, the slope of the first radius difference curve, and the slopes of the plurality of second radius difference curves.

[0285] In one embodiment, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the following steps:

[0286] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0287] Reconstructing an image based on the initial geometric parameters of the CT system and the first data to obtain a first image; reconstructing an image based on the initial geometric parameters and the second data to obtain a second image;

[0288] determining a first size of the phantom in the first image, and determining a second size of the phantom in the second image;

[0289] A correction value of the initial geometric parameter is determined based on the first size, the second size and the first data or the second data.

[0290] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: obtaining multiple first reference geometric parameters, reconstructing the image based on each first reference geometric parameter and the first data to obtain a first image to be processed, and determining the size of the first sub-model in each first image to be processed; determining a first linear equation based on the size of the first sub-model in all first images to be processed and all first reference geometric parameters, as well as the first size and the first geometric parameter; determining a correction value of the first geometric parameter based on the parameters of the first linear equation and the second size.

[0291] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: determining a first difference between the second size and the first intercept; and determining a first correction value according to a ratio of the first difference to the first slope.

[0292] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: obtaining multiple second reference geometric parameters, reconstructing the image based on each second reference geometric parameter and the first data to obtain a second image to be processed, and determining the size change curve of the second sub-model in the multiple second images to be processed; determining the size change curve of the second sub-model in the first image according to the first size, and determining the size change curve of the second sub-model in the second image according to the second size; determining the slope of the target size difference curve according to the size change curve of the second sub-model in the first image, the size change curve of the second sub-model in the second image, and the size change curve of the second sub-model in the multiple second images to be processed; determining the correction value of the second geometric parameter according to the slope of the target size difference curve.

[0293] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: determining a first size difference curve between the size change curve of the second sub-mock in the second image and the size change curve of the second sub-mock in the first image, and fitting the first size difference curve to determine the slope of the first size difference curve; determining a second size difference curve between the size change curve of the second sub-mock in each second image to be processed and the size change curve of the second sub-mock in the first image, and fitting each second size difference curve to determine the slopes of multiple second size difference curves.

[0294] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented: determining a second linear equation based on the slopes of multiple second size difference curves and multiple second reference geometric parameters; determining a correction value of the second geometric parameter based on the parameters of the second linear equation and the slope of the first size difference curve.

[0295] In one embodiment, when the computer program is executed by the processor, the following steps are also implemented: determining a second difference between the slope of the first size difference curve and the second intercept; and obtaining a second correction value based on a ratio between the second difference and the second slope.

[0296] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: determining a third geometric parameter based on the first size difference curve, the first geometric parameter, the second geometric parameter and half of the vertex angle of the second sub-mold.

[0297] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented: determining the average value of all dimensions in the first dimension difference curve; determining a first ratio of the average value to the tangent value of half the vertex angle of the second sub-mold, and a second ratio of the first geometric parameter to the second geometric parameter; determining a third geometric parameter based on the product of the first ratio and the second ratio.

[0298] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0299] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0300] Based on a first geometric parameter of the CT system, reconstructing the first data and the second data respectively to obtain a first image and a second image;

[0301] determining a first radius of the phantom in the first image, and determining a second radius of the phantom in the second image;

[0302] Using a traversal method, based on a plurality of first reference geometric parameters and the first data, a plurality of first images to be processed are determined; and a third radius of the phantom in each first image to be processed is obtained;

[0303] A correction value of the first geometric parameter is determined based on the plurality of first reference geometric parameters, the first radius, the second radius, and the plurality of third radii.

[0304] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0305] Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in an axial scanning mode;

[0306] Based on a second geometric parameter of the CT system, reconstructing the first data and the second data respectively to obtain a first image and a second image;

[0307] determining a first radius of the phantom in the first image, and determining a second radius of the phantom in the second image;

[0308] Using a traversal method, based on the plurality of second reference geometric parameters and the first data, a plurality of second images to be processed are determined, and a fourth radius of the phantom in each second image to be processed is determined;

[0309] Determine a first radius difference curve between a second radius change curve corresponding to the second radius and a first radius change curve corresponding to the first radius, and respectively determine a second radius difference curve between a third radius change curve corresponding to each fourth radius and the first radius change curve;

[0310] A correction value of the second geometric parameter is determined based on the plurality of second reference geometric parameters, the slope of the first radius difference curve, and the slopes of the plurality of second radius difference curves.

[0311] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0312] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0313] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for correcting geometric parameters, characterized in that: Applied to a CT system, the CT system includes at least a first system and a second system, the first system and the second system both include an X-ray tube and a corresponding detector, the method includes: Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in the axial scanning mode; Performing image reconstruction based on the initial geometric parameters of the CT system and the first data to obtain a first image; performing image reconstruction based on the initial geometric parameters and the second data to obtain a second image; determining a first size of the phantom in the first image, and determining a second size of the phantom in the second image; A correction value of the initial geometric parameter is determined according to the first size, the second size and the first data or the second data.

2. The method according to claim 1, characterized in that The phantom includes a first sub-phantom, the initial geometric parameter includes a first geometric parameter, the first geometric parameter is a source wheelbase, and determining a correction value of the initial geometric parameter according to the first size, the second size and the first data or the second data includes: Acquire a plurality of first reference geometric parameters, perform image reconstruction based on each of the first reference geometric parameters and the first data to obtain a first image to be processed, and determine a size of a first sub-phantom in each of the first images to be processed; Determining a first linear equation according to the sizes of the first sub-phantom in all the first images to be processed and all the first reference geometric parameters, as well as the first size and the first geometric parameter; A correction value of the first geometric parameter is determined according to the parameters of the first linear equation and the second dimension.

3. The method according to claim 2, characterized in that The parameters of the first linear equation include a first slope and a first intercept, and determining the correction value of the first geometric parameter according to the parameters of the first linear equation and the second size includes: determining a first difference between the second dimension and the first intercept; A first correction value is determined according to a ratio of the first difference to the first slope.

4. The method according to claim 1, characterized in that: The phantom includes a second sub-phantom, the initial geometric parameter includes a second geometric parameter, the second geometric parameter is a source-to-detector distance, and determining a correction value of the initial geometric parameter according to the first size, the second size, and the first data or the second data includes: Acquire a plurality of second reference geometric parameters, perform image reconstruction based on each of the second reference geometric parameters and the first data to obtain a second image to be processed, and determine a size change curve of the second sub-phantom in the plurality of the second images to be processed; Determine a size change curve of the second sub-mock in the first image according to the first size, and determine a size change curve of the second sub-mock in the second image according to the second size; Determining a slope of a target size difference curve according to a size change curve of the second sub-phantom in the first image, a size change curve of the second sub-phantom in the second image, and size change curves of the second sub-phantom in a plurality of second images to be processed; The correction value of the second geometric parameter is determined according to the slope of the target size difference curve.

5. The method according to claim 4, characterized in that Determining the slope of the target size difference curve according to the size change curve of the second sub-phantom in the first image, the size change curve of the second sub-phantom in the second image, and the size change curves of the second sub-phantom in a plurality of the second images to be processed includes: Determine a first size difference curve between a size change curve of the second sub-phantom in the second image and a size change curve of the second sub-phantom in the first image, and fit the first size difference curve to determine a slope of the first size difference curve; Determine a second size difference curve between the size change curve of the second sub-mock in each of the second to-be-processed images and the size change curve of the second sub-mock in the first image, fit each of the second size difference curves, and determine the slopes of a plurality of second size difference curves.

6. The method according to claim 5, characterized in that Determining the correction value of the second geometric parameter according to the slope of the target size difference curve includes: determining a second linear equation according to a plurality of slopes of the second size difference curves and a plurality of the second reference geometric parameters; Determining a correction value of the second geometric parameter according to a parameter of the second linear equation and a slope of the first size difference curve; The parameters of the second linear equation include a second slope and a second intercept, and determining the correction value of the second geometric parameter according to the parameters of the second linear equation and the slope of the first size difference curve includes: determining a second difference between the slope of the first size difference curve and the second intercept; A second correction value is obtained according to a ratio between the second difference and the second slope.

7. The method according to claim 5, characterized in that The initial geometric parameters include a first geometric parameter, a second geometric parameter and a third geometric parameter, the first geometric parameter is the source axis distance, the third geometric parameter is the imaging plane spacing of the CT system, and the method further includes: determining the third geometric parameter according to the first size difference curve, the first geometric parameter, the second geometric parameter and half of the vertex angle of the second sub-mold; Wherein, determining the third geometric parameter according to the first size difference curve, the first geometric parameter, the second geometric parameter and half of the vertex angle of the second sub-mold comprises: determining an average value of all dimensions in the first dimension difference curve; determining a first ratio of the average value to a tangent of half a vertex angle of the second sub-mold, and a second ratio of the first geometric parameter to the second geometric parameter; The third geometric parameter is determined according to the product of the first ratio and the second ratio.

8. A method for calibrating a CT system, characterized in that: The CT system comprises at least a first system and a second system, wherein the first system and the second system both comprise an X-ray tube and a corresponding detector; the method comprises: Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in the axial scanning mode; Based on the first geometric parameter of the CT system, reconstruct the first data and the second data respectively to obtain a first image and a second image; determining a first radius of the phantom in the first image, and determining a second radius of the phantom in the second image; Using a traversal method, based on a plurality of first reference geometric parameters and the first data, a plurality of first images to be processed are determined; and a third radius of the phantom in each of the first images to be processed is obtained; A correction value of the first geometric parameter is determined based on the first reference geometric parameters, the first radius, the second radius, and the third radii.

9. A method for calibrating a CT system, characterized in that: The CT system comprises at least a first system and a second system, wherein the first system and the second system both comprise an X-ray tube and a corresponding detector; the method comprises: Acquire first data and second data, wherein the first data is obtained by scanning the phantom by the first system in an axial scanning mode, and the second data is obtained by scanning the phantom by the second system in the axial scanning mode; Based on a second geometric parameter of the CT system, reconstruct the first data and the second data respectively to obtain a first image and a second image; determining a first radius of the phantom in the first image, and determining a second radius of the phantom in the second image; Using a traversal method, based on a plurality of second reference geometric parameters and the first data, a plurality of second images to be processed are determined, and a fourth radius of the phantom in each of the second images to be processed is determined; Determine a first radius difference curve between a second radius change curve corresponding to the second radius and a first radius change curve corresponding to the first radius, and respectively determine a second radius difference curve between a third radius change curve corresponding to each of the fourth radii and the first radius change curve; A correction value of the second geometric parameter is determined according to a plurality of the second reference geometric parameters, a slope of the first radius difference curve, and a plurality of slopes of the second radius difference curves.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are implemented.

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