Projection parameter correction method and computer equipment

Abstract

The embodiments of the present application provide a projection parameter correction method and a computer device, which relate to the field of medical imaging. The present application obtains the initial projection parameters required for generating digitally reconstructed radiographic images; obtains projection images at different projection angles, and generates digitally reconstructed radiographic images at projection angles corresponding to the planned images according to the initial projection parameters; and corrects the first projection parameter in the initial projection parameters according to the projection images at different projection angles and the digitally reconstructed radiographic images at the corresponding projection angles. The image projection parameters can be corrected according to the projection images at different projection angles and the digitally reconstructed radiographic images at the corresponding projection angles to obtain accurate image projection parameters.

Description

Technical Field

[0001] The present application relates to the field of medical imaging, and more specifically, to a projection parameter correction method and computer equipment. Background Art

[0002] Image-Guided Radiotherapy (IGRT) is an important means of accurately performing radiotherapy on tumors. IGRT uses an imaging device such as a cone beam CT (CBCT) device to collect real-time projection images of the patient's tumor at a target gantry angle (such as projection images generated by a KV-level imaging device, i.e., KV images), and then uses a planned image (such as a CT image) and projection parameters to generate a digitally reconstructed radiograph (DRR) at the target gantry angle. Finally, the patient's tumor position is quasi-precisely located through the registration results of the real-time projection image and the DRR image.

[0003] In the related art, projection parameters are generally obtained by manual measurement, but this method has the problems of poor accuracy and high cost. Summary of the invention

[0004] The purpose of the present application includes, for example, providing a projection parameter correction method and a computer device, which can correct the image projection parameters according to the projection images at different projection angles and the digitally reconstructed radiological images at the corresponding projection angles, and obtain accurate image projection parameters, thereby improving the accuracy of the registration results of the real-time projection images and the digitally reconstructed radiological images, more accurately locating the patient's tumor position, and improving the efficiency of radiotherapy.

[0005] The embodiments of the present application can be implemented as follows:

[0006] In a first aspect, the present application provides a projection parameter correction method, the method comprising:

[0007] obtaining initial projection parameters required to generate digitally reconstructed radiographic images;

[0008] Acquire projection images at different projection angles, and generate digitally reconstructed radiographic images at projection angles corresponding to the planned images according to initial projection parameters;

[0009] According to the projection images at different projection angles and the digitally reconstructed radiological images at the corresponding projection angles, the first projection parameter in the initial projection parameters is corrected.

[0010] In a second aspect, the present application provides a computer device, comprising: a processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, and when the computer device is running, the processor communicates with the storage medium via the bus, and the processor executes the machine-readable instructions to perform the steps of the projection parameter correction method as described in any one of the aforementioned embodiments.

[0011] In a third aspect, the present application provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the projection parameter correction method as described in any one of the aforementioned embodiments are implemented.

[0012] The beneficial effects of the embodiments of the present application include:

[0013] By using the projection parameter correction method and computer equipment provided in the present application, it is possible to automatically, intuitively and accurately correct the image projection parameters according to the projection images at different projection angles and the digitally reconstructed radiological images at the corresponding projection angles, thereby obtaining more accurate image projection parameters without incurring additional costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 A schematic diagram of a scene of a projection parameter correction system provided in an embodiment of the present application;

[0016] Figure 2 A schematic diagram of the structure of an embodiment of an imaging device provided in an embodiment of the present application;

[0017] Figure 3 A schematic diagram of another embodiment of the structure of the imaging device provided in the embodiment of the present application;

[0018] Figure 4 A schematic diagram of another embodiment of the structure of the imaging device provided in the embodiment of the present application;

[0019] Figure 5 A schematic diagram of a flow chart of an embodiment of a projection parameter correction method provided in an embodiment of the present application;

[0020] Figure 6 A schematic diagram illustrating parameter errors of the projection parameter correction method provided in an embodiment of the present application;

[0021] Figure 7 A schematic flow chart of another embodiment of the projection parameter correction method provided in the embodiment of the present application;

[0022] Figure 8 A schematic flow chart of another embodiment of the projection parameter correction method provided in the embodiment of the present application;

[0023] Fig. 9 A schematic diagram of the structure of a computer device according to an embodiment of the present application.

[0024] Icons: 100 - imaging device; 200 - first computer device; 300 - second computer device; 1001a - first X-ray tube; 1002a - first flat panel detector; 1001b - second X-ray tube; 1002b - second flat panel detector; 1003 - rotating rack; 2001 - processor; 2002 - memory. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0027] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0028] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0029] It should be noted that, in the absence of conflict, the features in the embodiments of the present application may be combined with each other.

[0030] With the rapid development of computer and imaging technology, image-guided radiotherapy (IGRT) technology has also achieved rapid development. However, the accuracy of image guidance is directly related to the safety and clinical treatment effect of radiotherapy. Accurate image guidance can achieve accurate tumor radiotherapy and improve the success rate of tumor radiotherapy.

[0031] Image guidance for radiotherapy is to use the registration result of the real-time projection image at the target gantry angle and the digitally reconstructed radiographic image DRR at the target gantry angle to quasi-precisely locate the tumor position. Usually, the DRR at the target gantry angle is generated based on the planned image and projection parameters, and the projection parameters used to generate the DRR consistent with the projection image position need to be obtained based on the position parameters of the installed imaging device using image calibration technology. However, in the related art, the relevant projection parameters are determined by manual measurement and calculation, which not only has low accuracy but also high labor costs. Therefore, there is an urgent need for a method that can replace (or assist) manual labor to obtain more accurate projection parameters, thereby improving the matching degree between the DRR and the projection image, and further improving the accuracy of the image guidance system.

[0032] To this end, the embodiments of the present application propose a projection parameter correction method, a computer device and a storage medium, which can obtain more accurate projection parameters, thereby reducing the position error between the projection image and the DRR, accurately locating the patient's tumor position, and thereby improving the efficiency of radiotherapy.

[0033] The embodiments of the present application provide a projection parameter correction method, a computer device, and a storage medium, which are described in detail below.

[0034] See also Figure 1 , Figure 1 Schematic diagram of a projection parameter correction system provided in an embodiment of the present application. The projection parameter correction system may include an imaging device 100 and a first computer device 200. The imaging device 100 and the first computer device 200 are in communication connection. The imaging device 100 may transmit data to the first computer device 200. Figure 1 The imaging device 100 in the embodiment can collect projection images at different projection angles and output them to the first computer device 200.

[0035] In the embodiments of the present application, the imaging device 100 is explained as a CBCT device as an example, but the imaging device 100 in the present application can also be a computed tomography (CT), a magnetic resonance (MR), a B-scan ultrasonography or other imaging devices, etc., and the present application is not limited here.

[0036] In addition, if Figure 1 As shown, the projection parameter correction system may further include a second treatment computer device 300 for storing a treatment plan for the patient. The second computer device 300 is communicatively connected to the first computer device 200. The second computer device 300 may transmit the treatment plan for the patient to the first computer device 200. The treatment plan includes a planned image of the patient. The planned image may be at least one of a CT image, an MR image, a PET image, a CBCT image, or a fusion image thereof.

[0037] In the embodiment of the present application, the above-mentioned computer device (including the first computer device 200 and the second computer device 300) can be an independent server, or a server network or server cluster composed of servers. For example, the computer device described in the embodiment of the present application includes but is not limited to a computer, a network host, a single network server, a plurality of network server sets or a cloud server composed of a plurality of servers. The cloud server is composed of a large number of computers or network servers based on cloud computing (Cloud Computing).

[0038] In the embodiment of the present application, the above-mentioned computer device can be a general-purpose computer device or a special-purpose computer device. In a specific implementation, the computer device can be a desktop computer, a portable computer, a network server, a PDA (Personal Digital Assistant), a mobile phone, a tablet computer, a wireless terminal device, a communication device, an embedded device, etc. This embodiment does not limit the type of computer device.

[0039] In the embodiments of the present application, communication between the imaging device 100 and the first computer device 200, and between the second computer device 300 and the first computer device 200 can be achieved through any communication method, including but not limited to mobile communications based on the 3rd Generation Partnership Project (3GPP), Long Term Evolution (LTE), and Worldwide Interoperability for Microwave Access (WiMAX), or computer network communications based on the TCP / IP Protocol Suite (TCP / IP) and User Datagram Protocol (UDP).

[0040] Those skilled in the art will understand that Figure 1The application environment shown in the figure is only one application scenario of the present application solution and does not constitute a limitation on the application scenario of the present application solution. Other application environments may also include Figure 5 More or less computer equipment as shown in Figure 1 Only one computer device is shown in the figure. It can be understood that the medical image processing system can also include one or more other computer devices that can process data, which are not specifically limited here.

[0041] It should be noted that Figure 1 The scene diagram of the medical image processing system shown is only an example. The medical image processing system and scene described in the embodiment of the present application are intended to more clearly illustrate the technical solution of the embodiment of the present application, and do not constitute a limitation on the technical solution provided in the embodiment of the present application. Ordinary technicians in this field can know that with the evolution of medical image processing systems and the emergence of new business scenarios, the technical solution provided in the embodiment of the present application is also applicable to similar technical problems.

[0042] In order to clearly explain the embodiments of the present application, some terms involved in the embodiments of the present application will be explained by taking the imaging device 100 as a CBCT device as an example.

[0043] The imaging device 100 may include at least one set of X-ray tubes and flat panel detectors arranged opposite to each other. Figure 2 As shown, when the imaging device 100 includes a set of first X-ray tubes 1001a and first flat panel detectors 1002a arranged opposite to each other, the first X-ray tubes 1001a can emit KV-level X-ray beams, which pass through the target part of the human body, such as the head or the body, and are emitted to the corresponding first flat panel detectors 1002a. Since X-rays have short wavelengths, high energy, and are penetrating, but there are differences in density and thickness between human tissues, when the X-ray beams emitted by the first X-ray tube 1001a at the target projection angle pass through different tissues of the target part of the human body, the X-ray beams are absorbed to different degrees, and a real-time projection image of the target part of the human body can be obtained after being processed by the first flat panel detector 1002a.

[0044] In order to obtain projection images at different projection angles, in one embodiment, the X-ray tube and the flat panel detector in the imaging device 100 may be multiple groups, such as Figure 2 As shown, the imaging device 100 may further include: a second X-ray tube 1001b and a second flat panel detector 1002b. Here, only the case where the X-ray tube and the flat panel detector are two groups is shown. Of course, the X-ray tube and the flat panel detector may also be three groups, four groups or more groups. In another embodiment, as Figure 3As shown, the first X-ray tube 1001a and the first flat panel detector 1002a are arranged on a rotating frame 1003. The rotating frame 1003 can drive the first X-ray tube 1001a and the first flat panel detector 1002a to rotate around the Y axis. The Y axis passes through the positioning center point or the isocenter O. Here, only one group of X-ray tubes and flat panel detectors are arranged on the rotating frame. Of course, more than two groups of X-ray tubes and flat panel detectors can also be arranged on the rotating frame. In this way, projection images at different projection angles can be obtained more quickly.

[0045] like Figure 2 and Figure 3 As shown, in the three-dimensional space coordinate system, the XOY plane is parallel to the geoid plane, the Z axis is perpendicular to the XOY plane, and the positioning center point or isocenter O coincides with the intersection of the beam center line of the X-ray beam emitted by the X-ray tube at different projection angles. The plane formed by the beam center line (s1, s2) of the X-ray beam emitted by the X-ray tube at different projection angles can be perpendicular to the horizontal plane, that is, the plane formed by the beam center line (s1, s2) of the X-ray beam emitted by the X-ray tube at different projection angles is perpendicular to the XOY plane.

[0046] Of course, the plane formed by the center line of the X-ray beam emitted by the X-ray tube at different projection angles may not be perpendicular to the horizontal plane, that is, there is an angle tilt, such as Figure 4 As shown, the beam center lines AP of the X-ray beams emitted by the two sets of X-ray tubes A and B are A With BP B After crossing, the X-ray beam passes through the center point O and is directed to the corresponding flat panel detector. A With BP B The projection points (P A With P B ) coincides with the center point of the flat-panel detector.

[0047] In the three-dimensional space coordinate system, the beam center line AP of the X-ray beam can be determined by A Whether it is perpendicular to the Y axis, to determine whether the plane formed by the center line of the X-ray beam emitted by the X-ray tube at different projection angles is perpendicular to the horizontal plane. If the center line AP of the X-ray beam A If it is not perpendicular to the Y axis, it means that the plane formed by the center line of the X-ray beam emitted by the X-ray tube at different projection angles is not perpendicular to the horizontal plane or is tilted at an angle. A Perpendicular to the Y-axis, it means that the plane formed by the center line of the X-ray beam emitted by the X-ray tube at different projection angles is perpendicular to the horizontal plane.

[0048] Continue to see Figure 4 , where the distance from the X-ray tube to the isocenter O, such as AO, is SAD; the distance from the X-ray tube to the corresponding flat panel detector is SID, such as AP A ; The gantry tilt angle of the X-ray tube is the gantry angle ∠G, which is the angle between the projection of the beam centerline of the X-ray tube on the XOZ plane and the Z axis; the angle between the projection of the beam centerline of the X-ray tube on the XOZ plane and the beam centerline is the out-of-plane angle ∠θ. In addition, ∠α is the beam centerline AP of the X-ray tube. A The angle with the Z axis, ∠β is the beam centerline AP of the above X-ray beam A The angle between the projection on the horizontal plane and the X-axis.

[0049] It can be understood that the above-mentioned initial projection parameters are explained by taking X-ray tube A and a relatively arranged flat panel detector as an example. The meaning of the initial projection parameters constituted by X-ray tube B and a relatively arranged flat panel detector is the same as the above description, and this application will not repeat them here.

[0050] A projection parameter correction method provided in an embodiment of the present application will be explained below in combination with application examples of multiple embodiments.

[0051] Embodiment 1

[0052] Figure 5 FIG. 1 is a flow chart of an embodiment of a projection parameter correction method provided in an embodiment of the present application. The execution subject of the method may be a computer device with computing processing capabilities, such as the first computer device 200. Figure 5 As shown, the method includes the following steps S101 to S103:

[0053] S101, obtaining initial projection parameters required for generating a digitally reconstructed radiological image.

[0054] In the embodiment of the present application, the initial projection parameters required for generating a digitally reconstructed radiological image (DRR) can be obtained by manual measurement during mechanical installation, or can be obtained after geometric calibration. The initial projection parameters may include: a flat panel offset, a tube offset, a tube-to-isocenter distance or a source axis distance (Source to Axis Distance, referred to as SAD), a tube-to-flat panel detector distance (Source-to-Image receptor Distance, referred to as SID), a gantry angle (∠G), an out-of-plane angle (∠θ), and one or more of an in-plane angle.

[0055] The flat panel offset refers to the position offset of the flat panel detector relative to the reference flat panel position in the three-dimensional space of the flat panel detector, and the position offset is usually expressed in the form of (X, Y, 0) three-dimensional coordinates in the three-dimensional coordinate system of the flat panel detector; the tube offset refers to the position offset of the tube relative to the reference tube position in the three-dimensional space of the tube, and the position offset is usually expressed in the form of (X, Y, 0) three-dimensional coordinates in the three-dimensional coordinate system of the tube. The above-mentioned standard flat panel position and standard tube position are set according to specific requirements and specifications, and this application does not make specific limitations here.

[0056] It should be noted that, due to the differences in the configuration of imaging devices, the initial projection parameters may also include other parameters for generating digitally reconstructed radiological images, which are not limited in the embodiments of the present application.

[0057] S102, acquiring projection images at different projection angles, and generating digitally reconstructed radiological images at projection angles corresponding to the planned images according to initial projection parameters.

[0058] After obtaining the initial projection parameters required for generating the digitally reconstructed radiographic image, the planned image and projection images at different projection angles are obtained, and then the digitally reconstructed radiographic image at the projection angle corresponding to the planned image is generated according to the initial projection parameters.

[0059] Here, the projection angle may be the angle between the center line of the beam in the imaging device and each coordinate axis in the three-dimensional space, and may include: the angle between the center line of the beam in the three-dimensional space and the Z axis (e.g. Figure 4 Mid-beam centerline AP A The angle between the projection of the beam centerline in the horizontal plane and the X-axis in three-dimensional space (such as Figure 4 Mid-beam centerline AP A The angle between the projection AO' on the horizontal plane and the X-axis is ∠β), and the angle between the projection of the beam centerline on the XOZ plane in three-dimensional space and the Z axis (also called the gantry angle, such as Figure 4 Mid-beam centerline AP A The included angle ∠G between the projection A0P0 on the XOZ plane and the Z axis), the included angle between the projection of the beam centerline on the XOZ plane in three-dimensional space and the beam centerline (the size of the included angle is equal to the size of the external angle of the plane, such as Figure 4 In the middle, beam center line AP A At least one of the projection A0P0 on the XOZ plane and the angle ∠θ) between A0P0.

[0060] Exemplarily, when the plane formed by the beam centerline at different projection angles is perpendicular to the horizontal plane, the angle between the beam centerline in the projection angle and the Z axis in three-dimensional space is equal to the angle between the projection of the beam centerline on the XOZ plane in three-dimensional space and the Z axis (angle ∠α is equal to angle ∠G), the angle between the projection of the beam centerline on the horizontal plane in three-dimensional space and the X axis, and the angle between the projection of the beam centerline on the XOZ plane in three-dimensional space and the Z axis are both 0 (angle ∠β and angle ∠θ are both 0).

[0061] It can be understood that the projection angle and the above-mentioned initial projection parameters can be in a one-to-one correspondence, that is, each time the projection angle of the imaging device is adjusted, the initial projection parameters are measured and / or calibrated once, and a corresponding projection image is obtained at the same time. In this way, projection images at different projection angles and corresponding initial projection parameters can be obtained. The projection images at different projection angles can be projection images at two projection angles, or can be projection images at more than two projection angles.

[0062] The projection image may be a KV image, an MV image (i.e., a projection image generated by an MV-level imaging device) or other types of images; the planning image may be at least one of a CT image, an MR image, a PET image, a CBCT image, or a fusion image thereof, etc. When the planning image is a non-CT image, it is usually necessary to generate a pseudo CT image from the planning image, and then generate the DRR at the corresponding projection angle of the pseudo CT image according to the initial projection parameters.

[0063] S103, modifying the first projection parameter in the initial projection parameters according to the projection images at different projection angles and the digitally reconstructed radiological images at the corresponding projection angles.

[0064] In the embodiment of the present application, the first projection may be all parameters of the aforementioned initial projection parameters, or may be part of the aforementioned initial projection parameters, such as one, two, three or four projection parameters, and the present application does not make any specific limitation on this.

[0065] In an embodiment of the present application, the first projection parameter in the initial projection parameters is corrected based on multiple groups of projection images at different angles and digitally reconstructed radiographic images at corresponding projection angles, so as to obtain accurate projection parameters, thereby reducing the error between the projection image and the digitally reconstructed radiographic image, improving the registration accuracy between the digitally reconstructed radiographic image and the projection image, and further improving the efficiency of radiotherapy.

[0066] Optionally, in the above step S103, each projection parameter in the first projection parameter in the initial projection parameters is corrected according to the projection images at different projection angles and the digitally reconstructed radiological images at the corresponding projection angles, which may include the following steps S201 to S203:

[0067] S201, obtaining error values ​​of first projection parameters at different projection angles according to projection images at different projection angles and digitally reconstructed radiological images at corresponding projection angles.

[0068] As an example, different projection angles can be obtained by rotating a group of X-ray tubes and corresponding flat panel detectors randomly, or by simulating the above process with other equipment. Of course, the present application is not limited to this.

[0069] Generally speaking, the projection image at a certain angle should be consistent with the digitally reconstructed radiographic image at the corresponding projection angle in terms of geometric position. However, due to the error in the first projection parameter in the initial projection parameters, it is difficult for the above projection image to be consistent with the digitally reconstructed radiographic image. In this way, the error value of the first projection parameter at the projection angle can be obtained according to the degree of inconsistency between the two (error value operation).

[0070] By repeating the above error value operation, the error values ​​of multiple first projection parameters at different projection angles can be obtained according to the projection images at multiple different projection angles and the digitally reconstructed radiological images at the corresponding projection angles. It can be understood that the error value of each first projection parameter is used to describe the error of the first projection parameter at the corresponding projection angle.

[0071] S202: Perform statistical analysis on the error values ​​of the first projection parameter at different projection angles to obtain the deviation of the first projection parameter.

[0072] Furthermore, statistical analysis is performed on the error values ​​of the plurality of first projection parameters obtained above. Optionally, the statistical analysis may be performed in at least one of mean value processing, mean square error processing, and mutual information processing.

[0073] In this way, the deviation of the first projection parameter is obtained, which can be interpreted as the deviation of the first projection parameter at each projection angle relative to the accurate projection parameter when the personnel who measure and calibrate the mechanical installation and initial projection parameters have not changed.

[0074] S203: Correct the first projection parameter in the initial projection parameters by using the deviation of the first projection parameter.

[0075] After knowing the current relative accurate projection parameters, the deviation of the first projection parameters and the corresponding items of the first projection parameters of the initial projection parameters can be corrected (or compensated), for example, the deviation of the first projection parameters and the corresponding items of the first projection parameters of the initial projection parameters can be added. It can be understood that the deviation value of the first projection parameter can be a positive deviation value or a negative deviation value.

[0076] Optionally, in this embodiment, the first projection parameter may include at least one parameter of a plate offset or a tube offset, and may also include at least one parameter of a rack angle and an out-of-plane angle. Each parameter may be corrected through steps S201 to S203.

[0077] The first projection parameters may also include other parameters describing the mechanical installation of the imaging device, which are used to correct the mechanical installation error of the imaging device according to the error of the first projection parameters, so as to obtain mutually accurate projection images and digitally reconstructed radiological images at corresponding projection angles.

[0078] In this embodiment, the deviation of the first projection parameter is obtained by statistically analyzing the error values ​​of multiple first projection parameters at different projection angles. This deviation obtained based on a large amount of data avoids the influence of data fluctuation on the result and has higher accuracy.

[0079] Optionally, in the above step S201, obtaining the error value of the first projection parameter at different projection angles according to the projection images at different projection angles and the digitally reconstructed radiological images at the corresponding projection angles may include the following steps S301 to S302:

[0080] S301, comparing the projection images at different projection angles with the digitally reconstructed radiological images at the corresponding projection angles, and obtaining the offset between the projection images at different projection angles and the digitally reconstructed radiological images.

[0081] Since the digitally reconstructed radiographic image DRR is obtained by projecting the planned image according to the initial projection parameters corresponding to different projection angles, and DRR simulates the image obtained by projecting the X-ray beam emitted by the X-ray tube on the flat panel detector under ideal conditions when the projection angle of the imaging device is the initial projection parameter, therefore, if the first projection parameter in the initial projection parameter has an error relative to the accurate projection parameter at the current projection angle, the projection image at this time and the digitally reconstructed radiographic image at the corresponding projection angle cannot be registered.

[0082] Therefore, the image deviation between the projection image and the digitally reconstructed radiographic image at the corresponding projection angle can be compared to determine the image deviation between the two images that can achieve registration, that is, the offset between the projection image and the digitally reconstructed radiographic image (comparison operation). It can be understood that the offset can be a three-dimensional offset or more, for example, when the offset is 6-dimensional, it can include a horizontal offset (including an offset horizontally in the X, Y or Z axis direction) and a rotational offset (including an offset rotated around the X, Y or Z axis).

[0083] As an optional implementation, the offset between the projection image and the digitally reconstructed radiographic image at the above-mentioned different projection angles can be expressed by a horizontal offset. Specifically, it can be expressed by one or more of the offset in the horizontal direction in the X-axis direction, the offset in the Y-axis direction, and the offset in the Z-axis direction.

[0084] Exemplarily, the phantom is arranged between the X-ray tube and the flat panel detector. When there is no error in the projection parameters, the central ray of the X-ray beam emitted by the X-ray tube passes through the center or isocenter O of the phantom, is perpendicular to the corresponding flat panel detector, and the projection point with the flat panel detector is located at the center of the flat panel detector. However, there may be errors in the actual installation, so that the central ray of the X-ray beam emitted by the X-ray tube is not located at the center of the flat panel detector or is not perpendicular to the flat panel, such as Figure 6 As shown in the figure, the solid line shows the central ray, which is perpendicular to the flat panel detector, but the projection point is not at the center of the flat panel detector and does not pass through the isocenter O. The dashed line shows the central ray, which passes through the isocenter O but is not perpendicular to the flat panel detector and the projection point is not at the center of the flat panel detector. This may cause a horizontal offset between the projected image and the digitally reconstructed radiological image at the corresponding projection angle.

[0085] The above comparison operation is repeated for the projection images and the digitally reconstructed radiographic images at different projection angles, thereby obtaining a plurality of offsets between the projection images and the digitally reconstructed radiographic images at different angles.

[0086] S302, determining error values ​​of initial projection parameters at different projection angles according to the offsets between the projection image and the digitally reconstructed radiological image at different projection angles.

[0087] It is understandable that different projection parameters have a one-to-one correspondence with the projection image and the digitally reconstructed radiographic image, so that the error values ​​of the initial projection parameters at different projection angles can be determined according to the offset between the projection image and the digitally reconstructed radiographic image at different projection angles. Exemplarily, the error values ​​of the X-ray tube and the flat panel detector in the horizontal direction and / or the rotational direction at different projection angles can be determined according to the offset of the positions of the X-ray tube and the flat panel detector at different projection angles relative to the positions of the X-ray tube and the flat panel detector at the initial projection parameters in the horizontal direction and / or the rotational direction.

[0088] In this embodiment, by comparing the projection images at different projection angles and the digitally reconstructed radiological images at the corresponding projection angles, the offset between the two is determined, and the error values ​​of the initial projection parameters at different projection angles are further inferred. The projection parameter error is reversely inferred based on the alignment result, so that the error value of the initial projection parameters can be determined more accurately.

[0089] The above embodiment illustrates the process of correcting the initial projection parameters by correcting the first projection parameters. In the specific implementation process, on the basis of completing the correction of the above first projection parameters, the correction of the second projection parameters described below can be further implemented through the following embodiment 2. Alternatively, the correction of the second projection parameters can also be implemented through a separate embodiment of the following embodiment 2 in the present application. Alternatively, after the correction of the second projection parameters described below is implemented through the following embodiment 2, the correction of the first projection parameters can be further implemented through the embodiment 1.

[0090] The following is a detailed description of the correction process of the second projection parameters.

[0091] Embodiment 2

[0092] like Figure 7 As shown, another embodiment of the projection parameter correction method provided in the embodiment of the present application is a flow chart of another embodiment. The execution subject of the method may be a computer device with computing processing capabilities, such as the first computer device 200, and may include the following steps S401 to S402:

[0093] S401: Obtain angle measurement parameters at a first projection angle.

[0094] Optionally, a projection angle formed by any group of X-ray tubes and a flat panel detector of the imaging device may be selected as a first projection angle, and the first projection angle may be measured and calibrated to obtain an angle measurement parameter.

[0095] It should be noted that the angle measurement parameters may be parameters used to describe the X-ray tube, the X-ray beam emitted by the X-ray tube, and the rotation angle of the flat panel detector, and are not specifically limited here.

[0096] S402: Correct the second projection parameter in the initial projection parameter at the first projection angle according to the angle measurement parameter.

[0097] The second projection parameters may be all the parameters of the initial projection parameters of the aforementioned embodiment 1, or may be part of the parameters of the initial projection parameters of the aforementioned embodiment 1, and this application does not make any specific limitation on this.

[0098] It should be noted that when the imaging device is under a certain projection parameter, the angle measurement parameters used to describe the angles of the X-ray tube and the flat panel detector in the initial projection parameters are associated with the second projection parameters, and the second projection parameters can be corrected based on this association.

[0099] It is understandable that if the imaging device includes multiple sets of X-ray tubes and flat panel detectors, the method of steps S401 to S402 can be used to modify the second projection parameters of each set in turn.

[0100] In addition, in the embodiment of the present application, the process of correcting the second projection parameters used to describe the angle of the imaging device is implemented separately, that is, it may not be performed synchronously or sequentially with the process of correcting the first projection parameters in the above embodiment.

[0101] In this embodiment, the second projection parameters are corrected according to the correlation between the measured and calibrated angle measurement parameters and the second projection parameters. In this way, more accurate second projection parameters can be obtained, and the flexibility of the method is improved.

[0102] Optionally, the angle measurement parameters include: a first measurement angle and a second measurement angle, and the second projection parameter includes: a gantry angle and an out-of-plane angle.

[0103] For example, see Figure 4 The first measurement angle may be the beam centerline AP of the X-ray beam emitted by the X-ray tube. A The angle ∠α with the Z axis, the second measurement angle can be the beam centerline AP of the X-ray beam A The angle ∠β between the projection AO' on the horizontal plane and the X-axis may also be other parameters used to describe the angle of the X-ray tube and flat panel detector of the imaging device, which is not specifically limited here. In this embodiment, the first measurement angle is ∠α and the second measurement angle is ∠β.

[0104] The specific definitions of the frame angle ∠G and the out-of-plane angle ∠θ have been explained in the aforementioned embodiments and will not be repeated here.

[0105] It is worth noting that the out-of-plane angle ∠θ cannot be obtained through actual measurement. Therefore, when measuring the angle measurement parameters, the initial value of the out-of-plane angle ∠θ can be first set to a preset value, such as 0, and the out-of-plane angle ∠θ can be calculated and corrected according to other parameters in the following processing process.

[0106] In the above step S402, the second projection parameter in the initial projection parameter at the first projection angle is corrected according to the angle measurement parameter, which may include:

[0107] The surface outer angle and the frame angle are corrected according to the first measurement angle, the second measurement angle and the frame angle.

[0108] As described in the above-mentioned embodiment, ∠α and ∠β in the first measurement angle are correlated with the rack angle ∠G and the out-of-plane angle ∠θ of the second measurement angle at the same projection angle. In this way, the errors of ∠G and ∠θ can be corrected according to ∠α and ∠β so that the KV image and the DRR can correspond to each other.

[0109] Optional, if Figure 4 X-ray beam AP shownA With BP B When the plane formed needs to be perpendicular to the horizontal plane, the X-ray beam AP can also be verified based on ∠α and ∠β A With BP B Whether the formed plane is perpendicular to the horizontal plane, and then correct ∠G and ∠θ to make the above two planes perpendicular.

[0110] In this embodiment, the gantry angle and the out-of-plane angle are corrected by using the first measurement angle. This self-correction method can make the obtained gantry angle and out-of-plane angle more accurate.

[0111] Optionally, in the above steps, correcting the external angle and the rack angle according to the first measurement angle, the second measurement angle and the rack angle may include the following steps S501 to S504:

[0112] S501, obtaining a plurality of estimated out-of-plane angles according to a first measured angle, a second measured angle, and a rack angle.

[0113] According to the description in the above embodiments, the first measurement angle ∠α, the second measurement angle ∠β, the gantry angle ∠G, and the out-of-plane angle ∠θ of the imaging device at the same projection angle are correlated, and the out-of-plane angle ∠θ cannot be directly obtained through measurement and calibration. Therefore, the initial value of ∠θ can be set to zero, and a plurality of estimated out-of-plane angles can be obtained by inferring the first measurement angle ∠α, the second measurement angle ∠β, and the gantry angle ∠G.

[0114] Furthermore, multiple estimated out-of-plane angles can be inferred through any two of the first measured angle ∠α, the second measured angle ∠β and the frame angle ∠G.

[0115] Exemplarily, the first estimated external surface angle ∠θ1, the second estimated external surface angle ∠θ2 and the third estimated external surface angle ∠θ3 may be inferred by the following formula:

[0116]

[0117] Specifically, the first estimated external surface angle ∠θ1 can be calculated according to ∠α and ∠G, the second estimated external surface angle ∠θ2 can be calculated according to ∠α and ∠β, and finally, the third estimated external surface angle ∠θ3 can be calculated according to ∠G and ∠β.

[0118] It can be understood that, in this embodiment, the number of estimated out-of-plane angles is 3 as an example for description, and in a specific embodiment, the number of estimated out-of-plane angles can be determined as needed.

[0119] S502: Correct the first measured angle, the second measured angle, and the rack angle according to the multiple estimated external surface angles.

[0120] Next, assuming that ∠α and ∠G are accurate values, the first estimated external surface angle ∠θ1 is also accurate. Based on the relative error between the first estimated external surface angle ∠θ1 and the second estimated external surface angle ∠θ2, ∠β is corrected, and the corrected second estimated external surface angle ∠θ2 is obtained based on ∠α and the corrected ∠β.

[0121] Then, ∠G can be corrected according to the relative error between the corrected second estimated external surface angle ∠θ2 and the third estimated external surface angle ∠θ3, and the corrected third estimated external surface angle ∠θ3 can be obtained according to ∠β and the corrected ∠G.

[0122] Finally, ∠α can be corrected according to the relative error between the corrected third estimated external surface angle ∠θ3 and the first estimated external surface angle ∠θ1, and the corrected first estimated external surface angle ∠θ1 is obtained according to ∠G and the corrected ∠α.

[0123] Therefore, according to the differences between ∠θ1, ∠θ2 and ∠θ3, the first measured angle ∠α, the second measured angle ∠β and the rack angle ∠G are corrected, and the first estimated external surface angle ∠θ1, the second estimated external surface angle ∠θ2 and the third estimated external surface angle ∠θ3 are corrected.

[0124] S503, repeat the above steps until the multiple estimated external angles of the surface satisfy a first preset relationship.

[0125] Optionally, the first preset condition may include, for example: all or part of the differences between the multiple estimated external surface angles are smaller than a preset difference, and / or each of the multiple estimated external surface angles is smaller than a preset threshold.

[0126] Exemplarily, if the differences between ∠θ1, ∠θ2 and ∠θ3 are very small, or ∠θ1, ∠θ2 and ∠θ3 are all less than a preset threshold, it can be considered that the multiple out-of-plane angles satisfy the first preset relationship, and the loop ends; otherwise, the first measurement angle ∠α, the second measurement angle ∠β and the rack angle ∠G after this correction are continued to be used as the first measurement angle ∠α, the second measurement angle ∠β and the rack angle ∠G, and the process returns to step S501.

[0127] S504: Determine a corrected out-of-plane angle according to the multiple estimated out-of-plane angles.

[0128] Optionally, one of ∠θ1, ∠θ2 and ∠θ3 that meets the first preset condition can be used as the corrected out-of-plane angle ∠θ, or ∠θ1, ∠θ2 and ∠θ3 can be statistically analyzed and processed, and the processed result is used as the corrected out-of-plane angle ∠θ. The specific statistical analysis processing method is not specifically limited here.

[0129] In this embodiment, the first measured angle, the second measured angle and the rack angle are used as known angles, and the out-of-plane angle is obtained by cyclic correction. In this way, not only can an accurate out-of-plane angle be obtained, but also ∠α, ∠β and ∠G can be corrected through the estimated relationship between multiple angles, thereby maintaining the data consistency between the angles and making the out-of-plane angle more accurate.

[0130] The above describes the implementation method of correcting the second projection parameters. In the specific implementation process, the first measurement angle, the second measurement angle and the gantry angle can also be corrected by the following embodiment 3 before the above implementation method of correcting the second projection parameters. Of course, the following embodiment 3 of correcting the first measurement angle, the second measurement angle and the gantry angle can also be implemented separately, and the result of the separate implementation can be used in a specific scene. For example, when the plane formed by the beam centerline is perpendicular to the horizontal plane, the gantry angle can be corrected by the result of the separate implementation without correcting the out-of-plane angle.

[0131] The process of correcting the first measurement angle, the second measurement angle, and the rack angle is described in detail below.

[0132] Embodiment 3

[0133] Another embodiment of the projection parameter correction method provided in the embodiments of the present application, the execution subject of the method may be a computer device with computing processing capabilities, such as the first computer device 200, and may include:

[0134] The first measurement angle, the second measurement angle and the rack angle are corrected according to the correlation between the first measurement angle, the second measurement angle and the rack angle, wherein the correlation may be a mutual derivation relationship satisfied between ∠α, ∠β and ∠G at the same projection angle.

[0135] When the center line AP of the X-ray beam A With BP B When the angle between the plane formed and the horizontal plane is inclined, the second projection parameters can be corrected by the above steps S501 to S504. A With BP B When the formed plane is perpendicular to the horizontal plane, the external angle ∠θ is zero. The rack angle ∠G can be corrected according to the correlation between the first measurement angle ∠α, the second measurement angle ∠β and the rack angle ∠G. The specific correction process is described in detail in the third embodiment.

[0136] It can be understood that the method provided in this embodiment can be independent of the embodiment after the above steps S401 to S402, and can be executed before or in parallel. Of course, this is not limited to this in the present application.

[0137] Optionally, in the above steps, the first measurement angle, the second measurement angle, and the rack angle are corrected according to the first measurement angle, the second measurement angle, and the rack angle, and the correlation between the first measurement angle, the second measurement angle, and the rack angle, which may include the following steps S601 to S603:

[0138] S601: Perform a first correction on the first measurement angle, the second measurement angle, and the rack angle according to the first measurement angle, the second measurement angle, and the rack angle, and a correlation relationship between the first measurement angle, the second measurement angle, and the rack angle.

[0139] Optionally, since the first measurement angle ∠α, the second measurement angle ∠β, and the rack angle ∠G have a mutually derivable correlation relationship, the third angle can be inferred from any two of them, so that the angle with deviation among the above three angles can be corrected.

[0140] Specifically, the correction process can be expressed by the following formula:

[0141]

[0142] First, assuming that ∠α and ∠β are accurate values, a relatively accurate ∠G can be derived. Then, based on the ∠G obtained in the previous step and the accurate ∠α, a relatively accurate ∠β can be derived. Finally, based on the ∠β obtained in the previous step and the ∠G obtained in the first step, a relatively accurate ∠α can be derived. In this way, the first correction is completed, and the corrected ∠α, ∠β, and ∠G are obtained.

[0143] S602: Perform a second correction on the first measured angle, the second measured angle, and the rack angle after the first correction according to the first measured angle, the second measured angle, and the rack angle after the first correction, and a correlation relationship among the first measured angle, the second measured angle, and the rack angle.

[0144] It should be noted that the first correction mentioned above may be the Nth correction, and the second correction may be the N+1th correction, where N is an integer greater than or equal to 1, and the initial value of N is 1.

[0145] That is to say, based on the above-mentioned corrected ∠α, ∠β, ∠G, the same process as the first correction in the above steps can be adopted, and the corrected ∠α, ∠β, ∠G can be corrected again according to the correlation relationship that can be derived from each other among ∠α, ∠β, ∠G, thus completing the second correction and obtaining the second corrected ∠α, ∠β, ∠G.

[0146] S603, repeating the above steps until the first corrected first measurement angle, the second measurement angle, and the rack angle and the second corrected first measurement angle, the second measurement angle, and the rack angle satisfy a second preset relationship.

[0147] The above-mentioned first correction and second correction processes can be executed in a loop until, in a certain loop, after the first correction and the second correction are executed consecutively, the difference between the corresponding angles of ∠α, ∠β, ∠G after the first correction and the ∠α, ∠β, ∠G after the second correction is less than the preset threshold, that is, the second preset relationship is satisfied, then it is considered that ∠α, ∠β, ∠G are already accurate values, and the loop is stopped.

[0148] Afterwards, the ∠α, ∠β, and ∠G obtained after the first correction and the second correction in the last cycle can be statistically analyzed. For example, the average can be taken, and finally the ∠α, ∠β, and ∠G after the statistical analysis can be used as the final result; or the ∠α, ∠β, and ∠G obtained after the second correction in the last cycle can be used as the final result.

[0149] In this embodiment, according to the correlation relationship between ∠α, ∠β, and ∠G, cyclic correction is performed to obtain accurate ∠α, ∠β, and ∠G, thereby ensuring the data consistency between ∠α, ∠β, and ∠G and improving the accuracy of angle parameter estimation.

[0150] As an optional implementation manner, based on at least one of the above-mentioned embodiments 1, 2 and 3, the projection parameters may be compensated and corrected by the following embodiment 4.

[0151] Embodiment 4

[0152] like Figure 8 As shown, another embodiment of the projection parameter correction method provided in the embodiment of the present application may include the following steps S701 to S703:

[0153] S701, acquiring a projection image at a second projection angle, and generating a digitally reconstructed radiological image at the second projection angle corresponding to the planned image according to the corrected initial projection parameters.

[0154] After the initial projection parameters are corrected, the projection angle of a set of X-ray tubes and flat panel detectors can be used as the second projection angle. It is understandable that the second projection angle can be the same as or different from the first projection angle, and this application does not limit this.

[0155] At the second projection angle, the planned image is projected according to the corrected initial projection parameters corrected in the aforementioned embodiment to generate a digitally reconstructed radiological image DRR at the second projection angle.

[0156] At the same time, at the second projection angle, a projection image, such as a KV image, is obtained.

[0157] S702: Compare the projection image at the second projection angle with the digitally reconstructed radiological image at the second projection angle to obtain an offset between the projection image at the second projection angle and the digitally reconstructed radiological image.

[0158] The projection image at the second projection angle obtained above is compared with the DRR at the second projection angle to obtain the offset between the projection image at the second projection angle and the DRR. It can be understood that the offset can be a three-dimensional offset or more, for example, when the offset is 6-dimensional, it can include a horizontal offset (including an offset horizontally in the X, Y or Z axis direction) and a rotation offset (including an offset rotated around the X, Y or Z axis).

[0159] S703, when it is determined that the offset between the projection image and the digitally reconstructed radiographic image at the second projection angle is not within a preset threshold range, the corrected initial projection parameters are corrected according to the offset between the projection image and the digitally reconstructed radiographic image at the second projection angle.

[0160] It is understandable that since there is a one-to-one correspondence between the projection parameters and the DRR, that is, the offset between the projection image and the DRR can also reflect the error between the projection parameters. Therefore, the corrected initial projection parameters can be corrected again according to the offset between the projection image and the DRR.

[0161] For example, if the KV image and DRR are registered and the horizontal offset of the DRR relative to the KV image is 1 mm in one of the X, Y or Z axes, the initial projection parameters can be compensated according to the positive and negative direction and size of the offset.

[0162] In this embodiment, the revised initial projection parameters DRR are registered with the projection image at the corresponding projection angle, and the revised initial projection parameters are further revised, so as to ensure that accurate DRR and KV images can be obtained and more accurate projection parameters can be obtained.

[0163] Optionally, the projection parameter correction method provided in the embodiment of the present application may further include: when it is determined that the offset between the projection image and the digitally reconstructed radiological image at the second projection angle is within a preset threshold range, saving the corrected initial projection parameters.

[0164] Optionally, the offset between the projected image and the DRR at the second projection angle may include: a horizontal offset and a rotational offset. Correspondingly, the preset threshold range may also include a horizontal threshold range and a rotational threshold range.

[0165] When the horizontal offset between the projected image and the DRR is not within the horizontal threshold range, the projection parameter correction method in the aforementioned embodiment 1 can be executed to correct the first projection parameter, and the projection parameter correction method in the aforementioned embodiment 2 can be continued to be executed to correct the first projection parameter and the second projection parameter in turn.

[0166] When the rotation offset between the KV image and the DRR is not within the rotation threshold range, the projection parameter correction method in the aforementioned embodiment 2 can be executed to correct only the second projection parameter, or the projection parameter correction method in the aforementioned embodiment 1 and embodiment 2 can be executed to correct the first projection parameter and the second projection parameter in turn.

[0167] If the horizontal offset between the KV image and the DRR is within the horizontal threshold range and the rotational offset is within the rotational threshold range, it can be considered that the current initial projection parameters have been corrected and are accurate projection parameters, and the correction can be stopped and saved.

[0168] In this embodiment, whether the initial projection parameters need to be corrected again is determined based on whether the offset between the KV image and the DRR is within a preset range, thereby ensuring the accuracy of the corrected initial projection parameters and reducing the error of image registration.

[0169] like Fig. 9 As shown, an embodiment of the present application further provides a computer device, which includes: a processor 2001, a memory 2002 and a bus, the memory 2002 stores machine-readable instructions executable by the processor 2001, and when the computer device is running, the above-mentioned machine-readable instructions are executed, the processor 2001 communicates with the memory 2002 through the bus, and the processor 2001 is used to execute the steps in any one of the projection parameter correction methods provided in the embodiments of the present application.

[0170] The memory 2002, the processor 2001 and the bus components are electrically connected to each other directly or indirectly to realize data transmission or interaction. For example, these components can be electrically connected to each other through one or more communication buses or signal lines. The data processing device of the projection parameter correction system includes at least one software function module that can be stored in the memory 2002 in the form of software or firmware or solidified in the operating system (OS) of the computer device. The processor 2001 is used to execute the executable module stored in the memory 2002, such as the software function module and computer program included in the data processing device of the projection parameter correction system.

[0171] Among them, the memory 2002 can be, but is not limited to, random access memory (Random Access Memory, RAM), read only memory (Read Only Memory, ROM), programmable read-only memory (Programmable Read-Only Memory, PROM), erasable programmable read-only memory (Erasable Programmable Read-Only Memory, EPROM), electrically erasable read-only memory (Electric Erasable Programmable Read-Only Memory, EEPROM), etc.

[0172] The present application also provides a non-volatile storage medium, which may include: a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk, etc. A computer program is stored thereon, and the computer program is loaded by a processor to execute the steps of any projection parameter correction method provided in the embodiments of the present application. The specific implementation method and technical effect are similar and will not be repeated here.

[0173] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the method embodiment, and will not be repeated in this application. In the several embodiments provided in this application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0174] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

[0175] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A projection parameter correction method, It is characterized in that The projection parameters are applied in the process of generating a digitally reconstructed radiological image from a planning image, and the method comprises: obtaining initial projection parameters required to generate digitally reconstructed radiographic images; Acquire the planned image and projection images at different projection angles, and project the planned image according to the initial projection parameters to generate a digitally reconstructed radiological image at the projection angle corresponding to the planned image; Modifying a first projection parameter in the initial projection parameters according to the projection images at different projection angles and the digitally reconstructed radiological images at the corresponding projection angles; The step of modifying the first projection parameter in the initial projection parameters according to the projection images at different projection angles and the digitally reconstructed radiological images at the corresponding projection angles includes: Obtaining error values ​​of the first projection parameters at different projection angles according to the projection images at different projection angles and the digitally reconstructed radiological images at the corresponding projection angles; Performing statistical analysis on the error values ​​of the first projection parameter at the different projection angles to obtain a deviation of the first projection parameter; The first projection parameter in the initial projection parameters is corrected using the deviation of the first projection parameter.

2. The projection parameter correction method according to claim 1, It is characterized in that The method further comprises: Obtaining angle measurement parameters at a first projection angle; According to the angle measurement parameter, a second projection parameter in the initial projection parameter at the first projection angle is corrected.

3. The projection parameter correction method according to claim 2, It is characterized in that The angle measurement parameters include: a first measurement angle and a second measurement angle, and the second projection parameters include: a gantry angle and an out-of-plane angle; The step of correcting the second projection parameter in the initial projection parameter at the first projection angle according to the angle measurement parameter comprises: The out-of-plane angle and the rack angle are corrected according to the first measured angle, the second measured angle and the rack angle.

4. The projection parameter correction method according to claim 3, It is characterized in that The correcting the external angle and the rack angle according to the first measurement angle, the second measurement angle and the rack angle comprises: Obtaining a plurality of estimated out-of-plane angles according to the first measured angle, the second measured angle, and the gantry angle; Correcting the first measured angle, the second measured angle, and the gantry angle according to the multiple estimated external surface angles; Repeat the above steps until the multiple estimated surface external angles satisfy a first preset relationship; A corrected out-of-plane angle is determined based on the plurality of estimated out-of-plane angles.

5. The projection parameter correction method according to claim 3, It is characterized in that The method further comprises: The first measurement angle, the second measurement angle, and the rack angle are corrected according to the first measurement angle, the second measurement angle, and the rack angle, and a correlation relationship between the first measurement angle, the second measurement angle, and the rack angle.

6. The projection parameter correction method according to claim 5, It is characterized in that Correcting the first measurement angle, the second measurement angle, and the rack angle according to the first measurement angle, the second measurement angle, and the rack angle, and a correlation relationship between the first measurement angle, the second measurement angle, and the rack angle, includes: performing a first correction on the first measurement angle, the second measurement angle, and the rack angle according to the first measurement angle, the second measurement angle, and the rack angle, and a correlation relationship between the first measurement angle, the second measurement angle, and the rack angle; According to the first corrected first measurement angle, the second measurement angle, and the rack angle, and the correlation between the first measurement angle, the second measurement angle, and the rack angle, performing a second correction on the first corrected first measurement angle, the second measurement angle, and the rack angle; The above steps are repeated until the first corrected first measurement angle, the second measurement angle, and the rack angle and the second corrected first measurement angle, the second measurement angle, and the rack angle satisfy a second preset relationship.

7. The projection parameter correction method according to claim 1 or 2, It is characterized in that The method further comprises: Acquire a projection image at a second projection angle, and generate a digitally reconstructed radiological image corresponding to the second projection angle of the planned image according to the corrected initial projection parameters; comparing the projection image at the second projection angle and the digitally reconstructed radiological image at the second projection angle to obtain an offset between the projection image at the second projection angle and the digitally reconstructed radiological image; When it is determined that the offset between the projection image and the digitally reconstructed radiographic image at the second projection angle is not within a preset threshold range, the corrected initial projection parameters are corrected according to the offset between the projection image and the digitally reconstructed radiographic image at the second projection angle.

8. The projection parameter correction method according to claim 7, It is characterized in that The method further comprises: When it is determined that the offset between the projection image and the digitally reconstructed radiological image at the second projection angle is within a preset threshold range, the corrected initial projection parameters are saved.

9. A computer device, It is characterized in that The computer device comprises: a processor and a memory, wherein the memory stores machine-readable instructions executable by the processor, and when the computer device is running, the processor executes the machine-readable instructions to execute the steps of the projection parameter correction method as described in any one of claims 1 to 8.

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