Parameter optimization method of CL system, CL system and computer equipment

Abstract

The invention relates to a parameter optimization method of a CL system, the CL system and computer equipment. Acquiring a target image acquired by the CL system; determining initial position information of the mark point according to the target image; determining the initial pose of the target, the initial pose of the detector and the initial pose of the radiation source under the space coordinate system according to the position relationship among the target, the detector and the radiation source and the initial position information of the mark point; converting the initial pose of the detector, the initial pose of the radiation source and the initial pose of the target into a world coordinate system to obtain the initial world pose of the detector, the initial world pose of the radiation source and the initial world pose of the target; the projection pose of the target is determined; and optimizing the initial pose of the detector, the initial pose of the ray source and the initial position information of the mark point by taking the minimum function value of the cost function of the initial pose of the target and the projection pose of the target as a target to obtain an optimal CL system. And the imaging accuracy of the flat object is improved.

Description

Technical Field

[0001] The present application relates to the technical field of X-ray imaging, and in particular to a parameter optimization method of a CL system, a CL system and a computer device. Background Art

[0002] Flat objects refer to objects with a large length-to-thickness ratio and a large width-to-thickness ratio, such as printed circuit boards (PCBs). In order to improve the quality and reliability of flat objects, it is necessary to obtain detailed information on the internal structure of the flat objects.

[0003] Traditionally, computed laminography (CL) technology is used to perform non-destructive testing on flat objects, that is, to obtain quality information of the internal structure of the flat object by scanning without damaging the flat object.

[0004] The first step in imaging flat objects using CL technology is to calibrate the parameters of the CL system. Since the CL system in traditional technology has errors in the machining and assembly process, there are errors between the calibration parameters and the actual parameters of the CL system. Using the calibration parameters and actual parameters with errors for image reconstruction may cause geometric artifacts in the reconstructed image, such as ghosting and obvious blunt edges in the reconstructed image, which seriously affects the quality of the reconstructed image of the CL system and reduces the accuracy of imaging flat objects.

[0005] In the existing parameter optimization method, some calibration parameters and actual parameters can be optimized at one time. The optimization result can only improve the problem of non-parallelism and non-concentricity between the detector and the radiation source, but it cannot be applied to different CL system models. Moreover, the optimization result depends on the accuracy of the target data and cannot effectively improve the imaging performance of the CL system. Summary of the invention

[0006] Based on this, it is necessary to provide a parameter optimization method of a CL system, a CL system and a computer device to address the above technical problems, which can improve the accuracy of imaging of flat objects.

[0007] In a first aspect, the present application provides a method for optimizing parameters of a CL system, the method comprising:

[0008] Acquire a target image acquired by a computer tomography CL system;

[0009] Determining initial position information of the marker point according to the target image;

[0010] Determine the initial position of the target, the detector and the ray source in the spatial coordinate system according to the positional relationship between the target, the detector and the ray source and the initial position information of the marker point;

[0011] Based on the conversion parameters between the spatial coordinate system and the world coordinate system, the initial pose of the detector is converted to the world coordinate system to obtain the initial world pose of the detector, the initial pose of the ray source is converted to the world coordinate system to obtain the initial world pose of the ray source, and the initial pose of the target is converted to the world coordinate system to obtain the initial world pose of the target;

[0012] Determining the projection pose of the target in the detector coordinate system according to the initial world pose of the target, the initial world pose of the detector and the initial world pose of the ray source;

[0013] Constructing a cost function between an initial pose of the target and a projected pose of the target;

[0014] With the goal of minimizing the function value of the cost function, the initial pose of the detector, the initial pose of the ray source and the initial position information of the marker point are optimized to obtain the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point.

[0015] In one embodiment, determining the projection pose of the target in the detector coordinate system according to the initial world pose of the target, the initial world pose of the detector and the initial world pose of the ray source includes:

[0016] Determining a first pose difference value according to the initial world pose of the target and the initial world pose of the detector;

[0017] Determining a second posture difference according to the initial world posture of the ray source and the initial world posture of the detector;

[0018] The projection pose of the target in the detector coordinate system is determined according to the first pose difference and the second pose difference.

[0019] In one embodiment, the initial pose of the detector, the initial pose of the ray source, and the initial position information of the marker are optimized with the goal of minimizing the function value of the cost function to obtain the target world pose of the detector, the target world pose of the ray source, and the target position information of the marker, including:

[0020] Taking the function value of the cost function as the minimum as the goal, the initial pose of the detector, the initial pose of the ray source and the initial position information of the marker point are optimized to obtain the intermediate world pose of the detector, the intermediate world pose of the ray source and the intermediate position information of the marker point;

[0021] Determining whether the function value of the cost function is less than a preset threshold;

[0022] If yes, determining the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point according to the optimized intermediate world pose of the detector and the intermediate world pose of the ray source;

[0023] If not, the intermediate world pose of the detector and the intermediate world pose of the ray source are used as the new initial pose of the detector and the new initial pose of the ray source respectively, and the intermediate position information of the marker point is used as the initial position information of the new marker point, and the execution is returned to convert the initial pose of the detector to the world coordinate system based on the conversion parameters between the spatial coordinate system and the world coordinate system to obtain the initial world pose of the detector, convert the initial pose of the ray source to the world coordinate system to obtain the initial world pose of the ray source, and convert the initial pose of the target to the world coordinate system to obtain the initial world pose of the target.

[0024] In one embodiment, the step of acquiring a target image acquired by a computer tomography (CL) system comprises:

[0025] When the detector and the ray source in the CL system move synchronously around the target, the detector is controlled to collect at least one target image.

[0026] In one of the embodiments, the conversion parameters between the spatial coordinate system and the world coordinate system include at least a rotation vector and a translation vector.

[0027] In one embodiment, the target includes a plurality of spheres of at least two sizes; wherein the larger spheres in the volume are used to identify the direction of the target.

[0028] In a second aspect, the present application further provides a CL system, the system comprising:

[0029] Target;

[0030] A stage, a detector and a radiation source for placing the target; the detector is used to collect a target image of the target and send the target image to a computer device;

[0031] The computer device is used to execute any one of the CL system parameter optimization methods described in the first aspect based on the target image.

[0032] In a third aspect, the present application further provides a computer device, the computer device comprising a memory and a processor, the memory storing a computer program, and the processor implementing the following steps when executing the computer program:

[0033] Acquire the target image acquired by the CL system;

[0034] Determining initial position information of the marker point according to the target image;

[0035] Determine the initial position of the target, the detector and the ray source in the spatial coordinate system according to the positional relationship between the target, the detector and the ray source and the initial position information of the marker point;

[0036] Based on the conversion parameters between the spatial coordinate system and the world coordinate system, the initial pose of the detector is converted to the world coordinate system to obtain the initial world pose of the detector, the initial pose of the ray source is converted to the world coordinate system to obtain the initial world pose of the ray source, and the initial pose of the target is converted to the world coordinate system to obtain the initial world pose of the target;

[0037] Determining the projection pose of the target in the detector coordinate system according to the initial world pose of the target, the initial world pose of the detector and the initial world pose of the ray source;

[0038] Constructing a cost function between an initial pose of the target and a projected pose of the target;

[0039] With the goal of minimizing the function value of the cost function, the initial pose of the detector, the initial pose of the ray source and the initial position information of the marker point are optimized to obtain the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point.

[0040] In a fourth aspect, the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the following steps are implemented:

[0041] Acquire the target image acquired by the CL system;

[0042] Determining initial position information of the marker point according to the target image;

[0043] Determine the initial position of the target, the detector and the ray source in the spatial coordinate system according to the positional relationship between the target, the detector and the ray source and the initial position information of the marker point;

[0044] Based on the conversion parameters between the spatial coordinate system and the world coordinate system, the initial pose of the detector is converted to the world coordinate system to obtain the initial world pose of the detector, the initial pose of the ray source is converted to the world coordinate system to obtain the initial world pose of the ray source, and the initial pose of the target is converted to the world coordinate system to obtain the initial world pose of the target;

[0045] Determining the projection pose of the target in the detector coordinate system according to the initial world pose of the target, the initial world pose of the detector and the initial world pose of the ray source;

[0046] Constructing a cost function between an initial pose of the target and a projected pose of the target;

[0047] With the goal of minimizing the function value of the cost function, the initial pose of the detector, the initial pose of the ray source and the initial position information of the marker point are optimized to obtain the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point.

[0048] In a fifth aspect, the present application further provides a computer program product, the computer program product comprising a computer program, which implements the following steps when executed by a processor:

[0049] Acquire the target image acquired by the CL system;

[0050] Determining initial position information of the marker point according to the target image;

[0051] Determine the initial position of the target, the detector and the ray source in the spatial coordinate system according to the positional relationship between the target, the detector and the ray source and the initial position information of the marker point;

[0052] Based on the conversion parameters between the spatial coordinate system and the world coordinate system, the initial pose of the detector is converted to the world coordinate system to obtain the initial world pose of the detector, the initial pose of the ray source is converted to the world coordinate system to obtain the initial world pose of the ray source, and the initial pose of the target is converted to the world coordinate system to obtain the initial world pose of the target;

[0053] Determining the projection pose of the target in the detector coordinate system according to the initial world pose of the target, the initial world pose of the detector and the initial world pose of the ray source;

[0054] Constructing a cost function between an initial pose of the target and a projected pose of the target;

[0055] With the goal of minimizing the function value of the cost function, the initial pose of the detector, the initial pose of the ray source and the initial position information of the marker point are optimized to obtain the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point.

[0056] The parameter optimization method, system, computer device and storage medium obtain a target image collected by a CL system; determine the initial position information of the marker point according to the target image; and then determine the initial pose of the target, the initial pose of the detector and the initial pose of the ray source in the spatial coordinate system according to the positional relationship between the target, the detector and the ray source and the initial position information of the marker point; and based on the conversion parameters between the spatial coordinate system and the world coordinate system, the initial pose of the detector is converted to the world coordinate system to obtain the initial world pose of the detector, and the initial pose of the ray source is converted to the world coordinate system to obtain the ray source. The initial world pose of the line source and the initial pose of the target are converted to the world coordinate system to obtain the initial world pose of the target; according to the initial world pose of the target, the initial world pose of the detector and the initial world pose of the ray source, the projection pose of the target in the detector coordinate system is determined; then a cost function between the initial pose of the target and the projection pose is constructed; and with the minimum function value of the cost function as the goal, the initial pose of the detector, the initial pose of the ray source and the initial position information of the marker are optimized to obtain the target world pose of the detector, the target world pose of the ray source and the target position information of the marker. The above scheme realizes the optimization of the pose of the detector and the pose of the ray source in the CL system, thereby improving the accuracy of imaging of flat objects. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A diagram showing an application environment of a parameter optimization method in an embodiment;

[0058] Figure 2 A schematic diagram of a flow chart of a parameter optimization method in one embodiment;

[0059] Figure 3 A schematic diagram of the relative positions of the detector and the radiation source when acquiring a target image in one embodiment;

[0060] Figure 4 is a schematic diagram of a target image in one embodiment;

[0061] Figure 5 A schematic diagram of a process for determining target projection coordinates in one embodiment;

[0062] Figure 6 A schematic diagram of a process for obtaining target posture parameters of the CL system in one embodiment;

[0063] Figure 7 A schematic flow chart of another parameter optimization method in one embodiment;

[0064] Figure 8 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0065] 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.

[0066] The parameter optimization method provided in the embodiment of the present application can be applied to Figure 1 In the application scenarios shown (not limited to Figure 1 scene, and other modes of plane scanning can be used).

[0067] The computer device can mechanically control the ray source and detector in the CL system. When performing three-dimensional imaging of the object to be measured, the object to be measured is placed on the stage, and the ray source passes through the object to be measured and is received by the detector; the detector sends the output signal generated based on the received ray source to the computer device, and the computer device generates a three-dimensional image of the object to be measured based on the output signal. The relative position of the detector and the ray source in the CL system will affect the accuracy of imaging the object to be measured in the CL system. Therefore, the embodiment of the present application optimizes the relative position of the detector and the ray source in the CL system to improve the accuracy of imaging flat objects.

[0068] In the existing parameter optimization method, some calibration parameters and actual parameters can be optimized at one time. The optimization result can only improve the problem of non-parallelism and non-concentricity between the detector and the radiation source, but it cannot be applied to different CL system models. Moreover, the optimization result depends on the accuracy of the target data and cannot effectively improve the imaging performance of the CL system.

[0069] The method provided in the embodiment of the present application can be executed by a computer device. The computer device can be, but is not limited to, various personal computers, laptops, smart phones, tablet computers, Internet of Things devices and portable wearable devices. The Internet of Things devices can be smart speakers, smart TVs, smart air conditioners, smart car devices, etc. The portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc.

[0070] In one embodiment, Figure 2 As shown, a parameter optimization method is provided, which is applied to Figure 1 The computer device in the example is used to illustrate, including the following steps:

[0071] S201, acquiring a target image acquired by a computer tomography (CL) system.

[0072] For example, when the CL system collects the target image, the detector and the radiation source are kept synchronized, and both move synchronously around the rotation axis (not limited to circular motion, such as rectangular, elliptical, etc.), and the target remains stationary, wherein the rotation axis can be an axis passing through the target. Figure 3 As shown. During the synchronous movement of the detector and the radiation source in the CL system around the target, the detector is controlled to collect at least one target image. Specifically, the imaging object (target) can be placed on the stage in the CL system to collect one or more target images.

[0073] S202: Determine initial position information of the marker point according to the target image.

[0074] Exemplarily, the target is composed of multiple marker points, and the target image includes each marker point, so that the initial position information of the marker point can be determined according to the target image, wherein the initial position information can reflect the relative position relationship of each marker point in the target. It should be noted that the initial position information of the marker point here may not be accurate position information, but may be an estimated initial value.

[0075] When acquiring the target image, the positional relationship between the target, the detector and the radiation source can also be recorded, wherein the positional relationship between the target, the detector and the radiation source can reflect the relative positions between the target, the detector and the radiation source. The positional relationship between the target, the detector and the radiation source can be obtained from the three-dimensional drawings corresponding to the target, the detector and the radiation source; the three-dimensional drawings corresponding to the target, the detector and the radiation source are established according to the positional relationship between the target, the detector and the radiation source.

[0076] For example, the target may include a plurality of spheres of two sizes; wherein the larger spheres in the volume are used to identify the direction of the target. Figure 4 , Figure 4 A schematic diagram of a target image is provided. Exemplarily, the target may include three large balls and multiple small balls. Each target image may include three large balls, and the three large balls are used to identify the direction of the target.

[0077] S203, determining the initial position of the target, the detector and the ray source in the spatial coordinate system according to the positional relationship among the target, the detector and the ray source and the initial position information of the marker point.

[0078] For example, the relative position of the marker point can be determined according to the initial position information X_K of the target, and the initial position X_K of the target in the spatial coordinate system can be obtained according to the inclination angle of the target. target Among them, the initial position of the target X target Including the initial position information X_K (3D pose) and attitude (tilt angle) of the target. The spatial coordinate system can be a spatial coordinate system corresponding to the CL system established with a certain position of the CL system as the origin.

[0079] Furthermore, the initial position and posture of the detector and the initial position and posture of the ray source in the spatial coordinate system may be determined according to the positional relationship among the target, the detector and the ray source.

[0080] S204, based on the conversion parameters between the spatial coordinate system and the world coordinate system, the initial pose of the detector is converted to the world coordinate system to obtain the initial world pose of the detector, the initial pose of the ray source is converted to the world coordinate system to obtain the initial world pose of the ray source, and the initial pose of the target is converted to the world coordinate system to obtain the initial world pose of the target.

[0081] Exemplarily, the conversion parameters between the spatial coordinate system and the world coordinate system may include a rotation vector and a translation vector, and specifically may include a rotation vector om of the detector. detector and the translation vector T detector , the rotation vector om of the ray source source and the translation vector T source , and the target's rotation vector om target and the translation vector T target .

[0082] Specifically, it can be based on the rotation vector om of the detector detector and the translation vector T detector , convert the initial pose of the detector to the world coordinate system to obtain the initial world pose of the detector. The specific conversion relationship is as follows:

[0083]

[0084] Among them, W detector is the initial world pose of the detector, is the initial pose of the detector.

[0085] Specifically, it can be based on the rotation vector om of the ray source source and the translation vector T source , convert the initial pose of the ray source to the world coordinate system to obtain the initial world pose of the ray source. The specific conversion relationship is as follows:

[0086]

[0087] Among them, W source is the initial world pose of the ray source, is the initial position of the ray source.

[0088] Specifically, it can be based on the rotation vector om of the target target and the translation vector T target , convert the initial pose of the target to the world coordinate system to obtain the initial world pose of the target. The specific conversion relationship is as follows:

[0089]

[0090] Among them, W target is the initial world pose of the target.

[0091] S205 , determining the projection pose of the target in the detector coordinate system according to the initial world pose of the target, the initial world pose of the detector and the initial world pose of the ray source.

[0092] Exemplarily, the projection pose of the target in the detector coordinate system may be determined according to the initial world pose of the target, the initial world pose of the detector, and the initial world pose of the ray source. For example, the initial world pose of the target and the initial world pose of the ray source may be first unified to the detector plane, and then the projection pose of the target in the detector coordinate system may be further determined according to the poses unified to the detector plane.

[0093] S206, constructing a cost function between the initial pose and the projected pose of the target.

[0094] For example, a bundle adjustment (BA) model can be constructed, and a cost function of the BA model can be constructed, and the cost function of the BA model can be used as the cost function between the initial pose and the projection pose of the target. The goal of the BA model is to optimize the pose of the ray source and the detector, as well as the pose of the target by minimizing the reprojection error; the reprojection error refers to the difference between the feature points actually observed and the projection points calculated by the pose of the detector, the pose of the ray source, and the pose of the target in the CL system.

[0095] S207, with the goal of minimizing the function value of the cost function, optimize the initial pose of the detector, the initial pose of the ray source, and the initial position information of the marker point to obtain the target world pose of the detector, the target world pose of the ray source, and the target position information of the marker point.

[0096] Furthermore, the initial pose of the detector, the initial pose of the ray source, and the initial position information of the marker points can be optimized with the goal of minimizing the function value of the cost function. When the iteration stopping condition is met, the optimization of the initial pose of the detector, the initial pose of the ray source, and the initial position information of the marker points is stopped, and the optimal CL system is determined based on the initial pose of the detector, the initial pose of the ray source, and the initial position information of the marker points corresponding to this iteration.

[0097] The above parameter optimization method obtains the target image collected by the CL system; and determines the initial position information of the marker point according to the target image; and then determines the initial pose of the target, the initial pose of the detector and the initial pose of the ray source in the spatial coordinate system according to the positional relationship between the target, the detector and the ray source and the initial position information of the marker point; and based on the conversion parameters between the spatial coordinate system and the world coordinate system, the initial pose of the detector is converted to the world coordinate system to obtain the initial world pose of the detector, and the initial pose of the ray source is converted to the world coordinate system to obtain the initial world pose of the ray source. The initial pose of the target is converted into the world coordinate system to obtain the initial world pose of the target; according to the initial world pose of the target, the initial world pose of the detector and the initial world pose of the ray source, the projection pose of the target in the detector coordinate system is determined; then a cost function between the initial pose of the target and the projection pose is constructed; and with the minimum function value of the cost function as the goal, the initial pose of the detector, the initial pose of the ray source and the initial position information of the marker point are optimized to obtain the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point. The above scheme realizes the optimization of the pose of the detector and the pose of the ray source in the CL system, thereby improving the accuracy of imaging of flat objects.

[0098] In some optional embodiments, see Figure 5 , Figure 5 A schematic diagram of a process for determining the projection pose of a target is provided, which specifically includes the following steps:

[0099] S501, determining a first pose difference according to the initial world pose of the target and the initial world pose of the detector.

[0100] For example, the first pose difference can be determined according to the initial world pose of the target and the initial world pose of the detector, which can be understood as mapping the initial world pose of the target to the detector plane. The specific first pose difference can be determined according to the following relationship:

[0101]

[0102] Among them, W_X is the first pose difference, W target is the initial world pose of the target, Wdetector is the initial world pose of the detector.

[0103] S502, determining a second pose difference according to the initial world pose of the ray source and the initial world pose of the detector.

[0104] Exemplarily, the second pose difference can be determined according to the initial world pose of the ray source and the initial world pose of the detector, that is, it can be understood as mapping the initial world pose of the ray source to the detector plane. The specific second pose difference can be determined according to the following relationship:

[0105]

[0106] Among them, W_S is the second pose difference, W source is the initial world pose of the ray source.

[0107] S503, determining the projection pose of the target in the detector coordinate system according to the first pose difference and the second pose difference.

[0108] For example, the projection pose of the target in the detector coordinate system can be determined according to the first pose difference and the second pose difference, which can be determined according to the following relationship:

[0109]

[0110] It can be understood that the projection pose in the detector coordinate system can be understood as the coordinate of the target in the detector coordinate system. Among them, w_td(x) is the horizontal coordinate of the target in the detector coordinate system, w_td(y) is the vertical coordinate of the target in the detector coordinate system, W_X(x) is the x-axis coordinate of the target in the first pose difference, W_X(y) is the y-axis coordinate of the target in the first pose difference, W_X(z) is the z-axis coordinate of the target in the first pose difference, W_S(x) is the x-axis coordinate of the ray source in the second pose difference, W_S(y) is the y-axis coordinate of the ray source in the second pose difference, and W_S(z) is the z-axis coordinate of the ray source in the second pose difference.

[0111] In an embodiment of the present application, the initial world pose of the target and the initial world pose of the ray source are first unified to the detector plane to facilitate further determination of the projection pose of the target, and a feasible method for determining the projection pose of the target is provided to facilitate further acquisition of the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point.

[0112] In some optional implementations, see Figure 6 , Figure 6 A schematic flow chart of obtaining the target pose parameters of the CL system is provided, which specifically includes the following steps:

[0113] S601, with the goal of minimizing the function value of the cost function, optimize the initial pose of the detector, the initial pose of the ray source and the initial position information of the marker point to obtain the intermediate world pose of the detector, the intermediate world pose of the ray source and the intermediate position information of the marker point.

[0114] For example, the goal may be to minimize the function value of the cost function, that is, to find the minimum value of the cost function:

[0115]

[0116] in, is the minimum value of the cost function, is the projection pose of the target. The cost function can be specifically to solve the initial position information X_K corresponding to the initial pose of the target and the projection pose of the target The function value of the cost function will be affected by the initial position of the detector, the initial position of the ray source and the initial position information of the marker point.

[0117] Based on this, the LM (Levenberg-Marquardt) algorithm can be used to iteratively adjust the initial pose of the detector, the initial pose of the ray source, and the initial position information of the marker point, so that the cost function is gradually reduced. Among them, the LM algorithm can be understood as a nonlinear least squares optimization algorithm that combines the Gauss-Newton method and the gradient descent method. By optimizing the initial pose of the detector, the initial pose of the ray source, and the initial position information of the marker point, the optimized intermediate world pose of the detector, the intermediate world pose of the ray source, and the intermediate position information of the marker point are obtained.

[0118] S602, determine whether the function value of the cost function is less than a preset threshold; if so, execute S603, if not, execute S604.

[0119] Exemplarily, a stop condition for iteration may be set, for example, a maximum number of iterations may be set, or a preset threshold of error may be set, and iteration may be stopped when the number of iterations reaches the maximum number, or when the function value is less than the preset threshold.

[0120] Based on this, it can be determined whether the function value of the cost function is less than a preset threshold; if it is less than the preset threshold, it is considered that the iteration stop condition is met and S603 can be executed; if it is not less than the preset threshold, it is considered that the iteration stop condition is not met and it is necessary to continue iterating, that is, execute S604.

[0121] S603, determining the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point according to the optimized intermediate world pose of the detector and the intermediate world pose of the ray source.

[0122] For example, when the iteration stop condition is met, the optimized intermediate world pose of the detector, the intermediate world pose of the ray source, and the intermediate position information of the marker point can be used as the target world pose of the detector, the target world pose of the ray source, and the target position information of the marker point. And the left and right CL systems can be constructed based on the target world pose of the detector, the target world pose of the ray source, and the target position information of the marker point.

[0123] S604, taking the intermediate world pose of the detector and the intermediate world pose of the ray source as the new initial pose of the detector and the new initial pose of the ray source respectively, and taking the intermediate position information of the marker point as the initial position information of the new marker point, and returning to execute based on the conversion parameters between the spatial coordinate system and the world coordinate system, converting the initial pose of the detector to the world coordinate system to obtain the initial world pose of the detector, converting the initial pose of the ray source to the world coordinate system to obtain the initial world pose of the ray source, and converting the initial pose of the target to the world coordinate system to obtain the initial world pose of the target.

[0124] Exemplarily, when the iteration stop condition is not met, the intermediate world pose of the detector and the intermediate world pose of the ray source can be used as the new initial pose of the detector and the new initial pose of the ray source, respectively, and the intermediate position information of the marker point can be used as the initial position information of the new marker point, and the execution is returned to convert the initial pose of the detector to the world coordinate system based on the conversion parameters between the spatial coordinate system and the world coordinate system to obtain the initial world pose of the detector, the initial pose of the ray source to the world coordinate system to obtain the initial world pose of the ray source, and the initial pose of the target to the world coordinate system to obtain the initial world pose of the target; a new round of iteration is performed until the function value of the cost function is less than a preset threshold, and the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point are obtained, and based on the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point, the optimal CL system is constructed.

[0125] Furthermore, in order to improve the reliability of the optimization result, in a new round of iterations, after the intermediate world pose of the detector and the intermediate world pose of the ray source are used as the initial pose of the new detector and the initial pose of the new ray source, and the intermediate position information of the marker point is used as the initial position information of the new marker point, the marker points with large deviation values ​​between the initial pose of the target and the projection pose of the target can be first eliminated, and the cost function between the initial pose of the target and the projection pose of the target can be reconstructed by using the remaining initial pose of the target and the projection pose of the target; return to execute S601 until the function value corresponding to the optimized cost function is less than the preset threshold, and the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point are obtained, and the optimal CL system is constructed based on the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point. In this way, the accuracy of the CL system in imaging flat objects can be improved.

[0126] In an embodiment of the present application, a feasible method for using the LM algorithm to optimize the initial posture of the detector, the initial posture of the ray source, and the initial position information of the marker point to solve the minimum value of the cost function is provided, which can more efficiently construct an optimal CL system, thereby improving the accuracy of the CL system in imaging flat objects.

[0127] In some optional implementations, the reliability of the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point in the CL system obtained in the above embodiments can be tested. For example, a standard pin gauge is used as a target, the standard pin gauge is scanned, and a three-dimensional image of the standard pin gauge is reconstructed based on the projection image obtained by the scan. The specific experimental data are as follows:

[0128] The standard value of the needle gauge data is set to 250μm±1μm, and the results are collected as 1mm thickness in the z direction, 200 slices, and the diameter is 249.4μm. The measurement error is ≤1μm. Some test data are shown in Table 1:

[0129] Table 1

[0130]

[0131] It can be seen that the errors of the above measurement results are all smaller than the standard deviation, which shows that the reliability of the target world posture of the detector of the CL system, the target world posture of the ray source and the target position information of the marker point obtained in the above embodiment meets the requirements, thereby making the accuracy of imaging of flat objects higher.

[0132] In addition, the calibration algorithm designed in the embodiment of the present application does not require target true value data. It only needs to arrange the spheres in the target according to certain rules to optimize the target pose parameters, detector pose parameters and ray source pose parameters in the CL system. And if there is a mechanical structure error in the equipment, for example, the detector X-axis and Y-axis are not perpendicular, the detector X-axis and Y-axis can be corrected according to the target world pose of the detector of the CL system, the target world pose of the ray source and the target position information of the marker point; the embodiment of the present application can reconstruct the model under different motion trajectories by obtaining the relative position relationship between the detector and the ray source, eliminating the problem of mechanical motion interpolation accuracy.

[0133] In some optional implementations, see Figure 7 , Figure 7 A flow chart of another parameter optimization method is provided, which specifically includes the following steps:

[0134] S701, acquiring a target image acquired by a CL system.

[0135] S702, determining the initial position information of the marker point according to the target image.

[0136] S703, determining the initial position of the target, the detector and the ray source in the spatial coordinate system according to the positional relationship among the target, the detector and the ray source and the initial position information of the marker point.

[0137] S704, based on the conversion parameters between the spatial coordinate system and the world coordinate system, the initial pose of the detector is converted to the world coordinate system to obtain the initial world pose of the detector, the initial pose of the ray source is converted to the world coordinate system to obtain the initial world pose of the ray source, and the initial pose of the target is converted to the world coordinate system to obtain the initial world pose of the target.

[0138] S705, determining a first pose difference according to the initial world pose of the target and the initial world pose of the detector.

[0139] S706, determining a second pose difference according to the initial world pose of the ray source and the initial world pose of the detector.

[0140] S707, determining the projection pose of the target in the detector coordinate system according to the first pose difference and the second pose difference.

[0141] S708, constructing a cost function between the initial pose of the target and the projected pose of the target.

[0142] S709, with the goal of minimizing the function value of the cost function, optimizing the initial position of the detector, the initial position of the ray source, and the initial position information of the marker point.

[0143] S710, determining whether the function value of the cost function is less than a preset threshold, if so, executing S711; if not, executing S712.

[0144] S711, determining the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point according to the optimized intermediate world pose of the detector and the intermediate world pose of the ray source.

[0145] S712, taking the intermediate world pose of the detector and the intermediate world pose of the ray source as the new initial pose of the detector and the new initial pose of the ray source respectively, and taking the intermediate position information of the marker point as the new initial position information of the marker point, and returning to execute S704.

[0146] The specific process of S701 to S712 can refer to the description of the above method embodiment, and its implementation principle and technical effect are similar, which will not be repeated here.

[0147] 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.

[0148] Based on the same inventive concept, the embodiment of the present application also provides a CL system for implementing the parameter optimization method involved above. The implementation scheme for solving the problem provided by the system is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more CL system embodiments provided below can refer to the limitations of the parameter optimization method of the CL system above, and will not be repeated here.

[0149] In one embodiment, the present application provides a CL system, including:

[0150] Target;

[0151] A stage, a detector and a radiation source for placing a target; the detector is used to collect a target image of the target and send the target image to a computer device;

[0152] A computer device is used to execute the parameter optimization method of the CL system described in any one of the above embodiments based on the target image.

[0153] In one embodiment, a computer device is provided. The computer device may be a computer device, and its internal structure diagram may be as shown in FIG. Figure 8 As shown. The computer device includes a processor, a memory and a network interface 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, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store target images and CL system posture data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a parameter optimization method is implemented.

[0154] Those skilled in the art will understand that Figure 8 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.

[0155] In one embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program. When the processor executes the computer program, the parameter optimization method of the CL system described in any one of the above embodiments is implemented.

[0156] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the parameter optimization method of the CL system described in any of the above embodiments is implemented.

[0157] In one embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the parameter optimization method of the CL system described in any one of the above embodiments is implemented.

[0158] 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 this 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.

[0159] 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.

[0160] 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 parameter optimization method for a CL system, characterized in that: The method comprises: Acquire a target image acquired by a computer tomography CL system; Determining initial position information of the marker point according to the target image; Determine the initial position of the target, the detector and the ray source in the spatial coordinate system according to the positional relationship between the target, the detector and the ray source and the initial position information of the marker point; Based on the conversion parameters between the spatial coordinate system and the world coordinate system, the initial pose of the detector is converted to the world coordinate system to obtain the initial world pose of the detector, the initial pose of the ray source is converted to the world coordinate system to obtain the initial world pose of the ray source, and the initial pose of the target is converted to the world coordinate system to obtain the initial world pose of the target; Determining the projection pose of the target in the detector coordinate system according to the initial world pose of the target, the initial world pose of the detector and the initial world pose of the ray source; Constructing a cost function between an initial pose of the target and a projected pose of the target; With the goal of minimizing the function value of the cost function, the initial pose of the detector, the initial pose of the ray source and the initial position information of the marker point are optimized to obtain the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point.

2. The method according to claim 1, characterized in that: The step of determining the projection pose of the target in the detector coordinate system according to the initial world pose of the target, the initial world pose of the detector and the initial world pose of the ray source comprises: Determining a first pose difference value according to the initial world pose of the target and the initial world pose of the detector; Determining a second posture difference according to the initial world posture of the ray source and the initial world posture of the detector; The projection pose of the target in the detector coordinate system is determined according to the first pose difference and the second pose difference.

3. The method according to claim 1, characterized in that Taking the function value of the cost function as the minimum as the goal, the initial pose of the detector, the initial pose of the ray source and the initial position information of the marker point are optimized to obtain the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point, including: Taking the function value of the cost function as the minimum as the goal, the initial pose of the detector, the initial pose of the ray source and the initial position information of the marker point are optimized to obtain the intermediate world pose of the detector, the intermediate world pose of the ray source and the intermediate position information of the marker point; Determining whether the function value of the cost function is less than a preset threshold; If yes, determining the target world pose of the detector, the target world pose of the ray source and the target position information of the marker point according to the optimized intermediate world pose of the detector and the intermediate world pose of the ray source; If not, the intermediate world pose of the detector and the intermediate world pose of the ray source are used as the new initial pose of the detector and the new initial pose of the ray source respectively, and the intermediate position information of the marker point is used as the initial position information of the new marker point, and the execution is returned to convert the initial pose of the detector to the world coordinate system based on the conversion parameters between the spatial coordinate system and the world coordinate system to obtain the initial world pose of the detector, convert the initial pose of the ray source to the world coordinate system to obtain the initial world pose of the ray source, and convert the initial pose of the target to the world coordinate system to obtain the initial world pose of the target.

4. The method according to claim 1, characterized in that: The step of acquiring a target image collected by a computer tomography (CL) system comprises: When the detector and the ray source in the CL system move synchronously around the target, the detector is controlled to collect at least one target image.

5. The method according to any one of claims 1 to 4, characterized in that: The conversion parameters between the space coordinate system and the world coordinate system include at least a rotation vector and a translation vector.

6. The method according to any one of claims 1 to 4, characterized in that The target includes a plurality of spheres of at least two sizes; wherein the larger spheres in the volume are used to identify the direction of the target.

7. A CL system, characterized in that: The system comprises: Target; A stage, a detector and a radiation source for placing the target; the detector is used to collect a target image of the target and send the target image to a computer device; The computer device is used to execute the parameter optimization method of the CL system according to any one of claims 1 to 6 based on the target image.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. 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 6 are implemented.

10. A computer program product, comprising a computer program, 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 6 are implemented.

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