Positioning adjustment method, device and equipment for homogenizing flat plate mold body and storage medium

Abstract

The application relates to the technical field of CT imaging, and provides a positioning adjustment method, device and equipment of a homogeneous flat plate phantom and a storage medium, which can accurately estimate the inclination angle of the homogeneous flat plate phantom, so that the positioning position of the homogeneous flat plate phantom can be accurately adjusted. The application determines a change relationship of an inclination angle corresponding to a target pixel point on a detector; the change relationship of the inclination angle comprises a change relationship between the inclination angle of the homogeneous flat plate phantom and a ray path length corresponding to the target pixel point; the ray path length is a path length of a ray from a ray source to the target pixel point and passing through the homogeneous flat plate phantom; a measured value of the ray path length is obtained according to a count rate of the target pixel point measured by the detector and a ray attenuation model; an estimated value of the inclination angle corresponding to the target pixel point is obtained based on the change relationship of the inclination angle and the measured value of the ray path length; and the positioning position of the homogeneous flat plate phantom is adjusted based on the estimated value of the inclination angle corresponding to the target pixel point.

Description

Technical Field

[0001] This application relates to the field of CT imaging technology, and in particular to a method, apparatus, computer equipment, storage medium, and computer program product for adjusting the positioning of a homogeneous flat panel phantom. Background Technology

[0002] In CT (Computed Tomography) imaging of small animals, homogeneous flat phantoms can be used to perform correlation correction of the image link. This makes the acquired raw data perform better after correction, so that the reconstructed image is more in line with the expected imaging results.

[0003] CT imaging systems for small animals typically include components such as a gantry, X-ray source, sample stage, and detector. When using a homogeneous flat phantom for calibration, the phantom is often suspended on the sample stage, allowing the X-rays emitted from the X-ray source to pass through the area of ​​the phantom. The detector then collects the signal after it has been attenuated by the phantom.

[0004] Because of the suspension method, it is impossible to precisely maintain the parallelism between the homogeneous plate phantom and the detector during actual measurements. In traditional technical solutions, the symmetry of the response curve based on measured data is usually used to subjectively evaluate whether the homogeneous plate phantom and the detector are parallel. This method cannot accurately estimate the tilt angle of the homogeneous plate phantom, making it difficult to precisely adjust the placement of the homogeneous plate phantom. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, apparatus, computer equipment, storage medium, and computer program product for adjusting the placement of a homogeneous flat plate mold to address the aforementioned technical problems.

[0006] This application provides a method for adjusting the placement of a homogeneous flat plate mold, the method comprising:

[0007] Determine the tilt angle variation relationship corresponding to the target pixel on the detector; the tilt angle variation relationship includes the variation relationship between the tilt angle of the homogeneous plate model and the ray path length corresponding to the target pixel; the ray path length is the path length of the ray from the ray source to the target pixel through the homogeneous plate model;

[0008] The measured value of the ray path length is obtained based on the count rate of the target pixel points measured by the detector and the ray attenuation model.

[0009] Based on the tilt angle variation relationship and the measured value of the ray path length, the estimated value of the tilt angle corresponding to the target pixel is obtained;

[0010] Based on the estimated tilt angle corresponding to the target pixel, the placement position of the homogeneous flat plate mold is adjusted.

[0011] In one embodiment, determining the target pixel on the detector includes:

[0012] Among several pixels of the detector, the pixel located in the plane of the tilt angle is determined to obtain the target pixel.

[0013] In one embodiment, the target pixels include a plurality of first target pixels and a plurality of second target pixels; the first target pixels and the second target pixels are distributed on both sides of the imaging center of the detector; adjusting the placement position of the homogeneous flat plate phantom based on the estimated value of the tilt angle corresponding to the target pixels includes:

[0014] The estimated values ​​of the tilt angle corresponding to a plurality of first target pixels and the estimated values ​​of the tilt angle corresponding to a plurality of second target pixels are statistically analyzed to obtain a comprehensive estimated value of the tilt angle.

[0015] The placement of the homogeneous flat plate mold is adjusted based on the comprehensive estimate of the tilt angle.

[0016] In one embodiment, the estimated values ​​of the tilt angles corresponding to a plurality of first target pixels and the estimated values ​​of the tilt angles corresponding to a plurality of second target pixels are statistically analyzed to obtain a comprehensive estimate of the tilt angle, including:

[0017] The estimated values ​​of the tilt angles corresponding to a plurality of first target pixels and the estimated values ​​of the tilt angles corresponding to a plurality of second target pixels are averaged.

[0018] Based on the results of the averaging process, a comprehensive estimate of the tilt angle is obtained.

[0019] In one embodiment, based on the tilt angle variation relationship and the measured value of the ray path length, an estimated value of the tilt angle corresponding to the target pixel is obtained, including:

[0020] Obtain the standard thickness value of the homogeneous flat plate mold;

[0021] Based on the standard thickness value and the measured value of the ray path length, the input value of the inverse cosine function is determined to obtain the output value of the inverse cosine function;

[0022] The input value of the arctangent function is determined based on the distance of the target pixel relative to the imaging center of the detector and the distance from the ray source to the detector, so as to obtain the output value of the arctangent function;

[0023] Based on the output values ​​of the inverse cosine function and the arctangent function, an estimated value of the tilt angle corresponding to the target pixel is obtained.

[0024] In one embodiment, determining the input value of the inverse cosine function based on the standard thickness value and the measured value of the ray path length includes:

[0025] Divide the standard thickness value by the measured value of the ray path length to obtain the first phase division result;

[0026] Use the first division result as the input value of the inverse cosine function.

[0027] In one embodiment, determining the input value of the arctangent function based on the distance of the target pixel relative to the imaging center of the detector and the distance from the ray source to the detector includes:

[0028] The distance of the target pixel relative to the imaging center of the detector is divided by the distance from the ray source to the detector to obtain the second division result;

[0029] Use the result of the second division as the input value of the arctangent function.

[0030] This application provides a positioning and adjustment device for a homogeneous flat plate mold, the device comprising:

[0031] The change relationship determination module is used to determine the tilt angle change relationship corresponding to the target pixel on the detector; the tilt angle change relationship includes the change relationship between the tilt angle of the homogeneous plate model and the ray path length corresponding to the target pixel; the ray path length is the path length of the ray from the ray source to the target pixel through the homogeneous plate model.

[0032] The path length measurement processing module is used to obtain the measured value of the ray path length based on the count rate of the target pixel points measured by the detector and the ray attenuation model.

[0033] The tilt angle estimation processing module is used to obtain an estimated value of the tilt angle corresponding to the target pixel based on the tilt angle change relationship and the measured value of the ray path length;

[0034] The placement adjustment module is used to adjust the placement position of the homogeneous flat plate mold based on the estimated value of the tilt angle corresponding to the target pixel.

[0035] This application provides a computer device, including a memory and a processor, wherein the memory stores a computer program and the processor executes the above-described method.

[0036] This application provides a computer-readable storage medium having a computer program stored thereon, the computer program being executed by a processor using the methods described above.

[0037] This application provides a computer program product having a computer program stored thereon, the computer program being executed by a processor using the above-described method.

[0038] The aforementioned method, apparatus, computer equipment, storage medium, and computer program product for adjusting the placement of a homogeneous flat plate phantom determine the tilt angle variation relationship corresponding to a target pixel on the detector. This tilt angle variation relationship includes the relationship between the tilt angle of the homogeneous flat plate phantom and the ray path length corresponding to the target pixel. The ray path length is the path length of the ray from the ray source to the target pixel through the homogeneous flat plate phantom. Based on the count rate of the target pixel measured by the detector and the ray attenuation model, the measured value of the ray path length is obtained. Based on the tilt angle variation relationship and the measured value of the ray path length, an estimated value of the tilt angle corresponding to the target pixel is obtained. Based on the estimated value of the tilt angle corresponding to the target pixel, the placement position of the homogeneous flat plate phantom is adjusted. Using the scheme provided in this application, the tilt angle of the homogeneous flat plate phantom can be estimated more accurately, thereby precisely adjusting the placement position of the homogeneous flat plate phantom to ensure that the homogeneous flat plate phantom is parallel to the detector, reducing the problem of correction errors caused by the placement error of the homogeneous flat plate phantom. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1(a) is a top view of the detector structure in one embodiment;

[0041] Figure 1(b) is a schematic diagram of the CT imaging system viewed from the gantry direction in one embodiment;

[0042] Figure 2 This is a schematic diagram showing the tilting of a homogeneous flat plate mold in one embodiment;

[0043] Figure 3 This is a flowchart illustrating the method for adjusting the placement of a homogeneous flat plate mold in one embodiment;

[0044] Figure 4(a) is a schematic diagram of the detector and the plane containing the tilt angle in one embodiment from a top-down perspective;

[0045] Figure 4(b) is a schematic diagram showing the relationship between the tilt angle of the homogeneous flat plate model and the length of the ray path corresponding to the target pixel in one embodiment;

[0046] Figure 5(a) is a schematic diagram of the distribution of target pixels in one embodiment;

[0047] Figure 5(b) is a schematic diagram of the distribution of target pixels in another embodiment;

[0048] Figure 5(c) is a schematic diagram of the distribution of target pixels in another embodiment;

[0049] Figure 6 This is a schematic diagram illustrating the geometric relationships between the components of a CT imaging system in one embodiment;

[0050] Figure 7 This is a structural block diagram of the placement adjustment device for a homogeneous flat plate mold in one embodiment;

[0051] Figure 8 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0053] A CT imaging system includes components such as a gantry, X-ray source, sample stage, and detector. The X-ray source and detector rotate as a single unit. The distance from the X-ray source to the detector via the center of rotation is also known as the X-ray source-detector distance, abbreviated as SDD (Source to Detector Distance). The distance from the X-ray source to the center of rotation is abbreviated as SID (Source to Image Distance).

[0054] Viewed from above, the structural diagram of the CT imaging system is shown in Figure 1(a). The detector consists of several detector units arranged in an array. One direction of the array arrangement is called the array direction of the detector, and the other direction is called the channel direction of the detector. The center of the detector can be called the imaging center of the detector.

[0055] When these detection units are calibrated using a homogeneous flat phantom, the homogeneous flat phantom can be suspended by a sample stage. Figure 1(b) is a schematic diagram of the CT imaging system viewed from the gantry direction; the X-ray source and detector can rotate clockwise as a whole; in the example shown in Figure 1(b), the homogeneous flat phantom is ideally positioned, with the plane of the homogeneous flat phantom parallel to the plane of the detector, and the angle θ between the straight line perpendicular to the plane of the homogeneous flat phantom (hereinafter referred to as the first straight line) and the straight line passing through the X-ray source and the center of rotation (hereinafter referred to as the second straight line) is 0.

[0056] During actual calibration, the homogeneous plate phantom may tilt, causing the plane of the homogeneous plate phantom to be non-parallel to the plane of the detector, such as... Figure 2 As shown, at this time, the first line deflects, causing the angle θ between the first line and the second line to be non-zero.

[0057] The angle θ between the first and second straight lines can reflect whether the plane of the homogeneous flat plate model is parallel to the plane of the detector. In this application, the angle θ between the first and second straight lines can be regarded as the tilt angle of the homogeneous flat plate model. Accordingly, in the following description, θ can also represent the tilt angle of the homogeneous flat plate model.

[0058] The method for adjusting the placement of the homogeneous plate phantom provided in this application can accurately estimate the tilt angle θ of the homogeneous plate phantom, thereby precisely adjusting the placement position of the homogeneous plate phantom to ensure that the plane of the homogeneous plate phantom is as parallel as possible to the plane of the detector.

[0059] The methods provided in this application include Figure 3 The steps shown are as follows:

[0060] Step S301: Determine the tilt angle change relationship corresponding to the target pixel on the detector.

[0061] The relationship between the tilt angle and the target pixel includes the relationship between the tilt angle of the homogeneous flat plate and the length of the ray path. The ray path length is the length of the path taken by the ray from the ray source to the target pixel through the homogeneous flat plate.

[0062] The inclination angle θ of the homogeneous flat plate mold is the angle between the first straight line and the second straight line, and the plane containing the first straight line and the second straight line is the plane containing the inclination angle θ.

[0063] The step of determining the target pixel on the detector includes: among a number of pixels on the detector, determining the pixel located on the plane where the tilt angle is located, thus obtaining the target pixel.

[0064] by Figure 2Taking the tilt angle θ as an example, if the detector is viewed from a top-down angle, the projection position of the plane containing the tilt angle θ on the detector is shown in Figure 4(a). Among the several pixels of the detector, the pixels in the same row as the imaging center are located on the plane containing the tilt angle θ. At least one pixel can be identified as the target pixel among the pixels located on the plane containing the tilt angle θ.

[0065] Referring to Figure 4(b), a target pixel is denoted as P1. If the tilt angle θ of the homogeneous plate phantom is 0, meaning the plane of the homogeneous plate phantom is parallel to the plane of the detector, then the path length of the ray from the X-ray source to the target pixel P1 through the homogeneous plate phantom (i.e., the ray path length corresponding to the target pixel P1) is B1D1. If the tilt angle θ of the homogeneous plate phantom is not 0, meaning the plane of the homogeneous plate phantom is not parallel to the plane of the detector, then the path length of the ray from the X-ray source to the target pixel P1 through the homogeneous plate phantom (i.e., the ray path length corresponding to the target pixel P1) is A1C1. Where A1C1 is not equal to B1D1.

[0066] As can be seen from Figure 4(b), the length of the ray path corresponding to the target pixel P1 changes with the change of the tilt angle θ of the homogeneous plate model. Therefore, through geometric analysis, the relationship between the tilt angle θ of the homogeneous plate model and the length of the ray path corresponding to the target pixel P1 can be constructed. This relationship can be called the tilt angle change relationship corresponding to the target pixel P1.

[0067] Step S302: Based on the count rate of the target pixels measured by the detector and the ray attenuation model, the measured value of the ray path length is obtained.

[0068] In actual calibration, a homogeneous flat phantom can be suspended through a sample stage. After the homogeneous flat phantom is suspended, it has a specific placement position. To determine whether the homogeneous flat phantom is parallel to the detector in this placement position, a beam of radiation can be emitted from a radiation source. Part of the radiation beam is exposed to the detector after passing through the homogeneous flat phantom, allowing us to obtain the actual measurement data of the detector.

[0069] The count rate N(P1) of the target pixel P1 can be obtained from the actual measured data of the detector. Based on the count rate N(P1) of the target pixel P1 and the ray attenuation model, the measured value of the ray path length corresponding to the target pixel P1 can be obtained.

[0070] The ray attenuation model can be expressed mathematically as follows: .

[0071] E is the abbreviation for energy; e is an irrational number, approximately equal to 2.71828; D(E) is the detector's response function; For X-ray source spectrum data; represents the linear attenuation coefficient of the homogeneous flat plate model; L represents the measured value of the ray path length corresponding to the target pixel P1.

[0072] In D(E), Given N(P1), the value of L can be solved to obtain the measured value of the ray path length corresponding to the target pixel P1, L(P1).

[0073] Step S303: Based on the measured values ​​of the tilt angle change relationship and the ray path length, the estimated value of the tilt angle corresponding to the target pixel is obtained.

[0074] Since the change in the tilt angle corresponding to the target pixel P1 describes the relationship between the tilt angle θ of the homogeneous plate mold and the length of the ray path corresponding to the target pixel P1, an estimated value of the tilt angle θ can be obtained based on the change in the tilt angle corresponding to the target pixel P1 and the measured value L(P1) of the ray path length corresponding to the target pixel P1. This estimated value of the tilt angle θ is obtained based on the change in the tilt angle corresponding to the target pixel P1 and the measured value L(P1). Therefore, this estimated value of the tilt angle θ can be called the estimated value of the tilt angle corresponding to the target pixel P1, and is denoted as θt. .

[0075] Step S304: Adjust the placement of the homogeneous flat plate model based on the estimated tilt angle corresponding to the target pixel.

[0076] If the target pixel count is one If the target pixel is P1, then the estimated tilt angle corresponding to the target pixel P1 is obtained. Then, the estimated tilt angle corresponding to the target pixel P1 can be obtained. The inclination angle of the homogeneous flat plate mold is determined.

[0077] If the tilt angle of the homogeneous plate phantom is less than the tilt angle threshold, it means that the homogeneous plate phantom is parallel to the detector, and the placement of the homogeneous plate phantom does not need to be adjusted.

[0078] If the tilt angle of the homogeneous plate phantom is greater than or equal to the tilt angle threshold, it indicates that the homogeneous plate phantom is not parallel to the detector. In this case, the placement position of the homogeneous plate phantom can be adjusted. After the placement position is adjusted, steps S302 to S303 can be executed again to evaluate whether the homogeneous plate phantom is parallel to the detector in the adjusted placement position.

[0079] In the above-described method for adjusting the placement of a homogeneous flat plate phantom, the tilt angle variation relationship corresponding to the target pixel on the detector is determined. This tilt angle variation relationship includes the relationship between the tilt angle of the homogeneous flat plate phantom and the ray path length corresponding to the target pixel. The ray path length is the path length of the ray from the ray source to the target pixel through the homogeneous flat plate phantom. Based on the count rate of the target pixel measured by the detector and the ray attenuation model, the measured value of the ray path length is obtained. Based on the tilt angle variation relationship and the measured value of the ray path length, an estimated value of the tilt angle corresponding to the target pixel is obtained. Based on the estimated value of the tilt angle corresponding to the target pixel, the placement position of the homogeneous flat plate phantom is adjusted. Using the scheme provided in this application, the tilt angle of the homogeneous flat plate phantom can be estimated more accurately, thereby precisely adjusting the placement position of the homogeneous flat plate phantom to ensure that the homogeneous flat plate phantom is parallel to the detector, reducing the problem of correction errors caused by the placement error of the homogeneous flat plate phantom.

[0080] In one embodiment, there can be multiple target pixels, which can be distributed on the same side of the detector's imaging center. In the example shown in Figure 5(a), the target pixels include P1, P3, and P5, which are distributed on the first side of the detector's imaging center. In the example shown in Figure 5(b), the target pixels include P2, P4, and P6, which are distributed on the second side of the detector's imaging center. The target pixels distributed on the first side of the detector's imaging center can be referred to as first target pixels, and the target pixels distributed on the second side of the detector's imaging center can be referred to as second target pixels.

[0081] In one embodiment, the target pixel includes a plurality of first target pixels and a plurality of second target pixels; the first target pixels and the second target pixels are distributed on both sides of the imaging center of the detector. In the example shown in Figure 5(c), the target pixel includes three first target pixels and three second target pixels, wherein the three first target pixels are P1, P3 and P5, and the three second target pixels are P2, P4 and P6.

[0082] In this case, based on the estimated tilt angle corresponding to the target pixel, the placement of the homogeneous flat plate mold is adjusted, including:

[0083] The estimated tilt angles corresponding to several first target pixels and several second target pixels are statistically analyzed to obtain a comprehensive estimate of the tilt angle; the placement position of the homogeneous flat plate mold is adjusted based on the comprehensive estimate of the tilt angle.

[0084] Following the aforementioned method, the following relationships can be constructed: the tilt angle change relationship corresponding to target pixel P1, target pixel P2, target pixel P3, target pixel P4, target pixel P5, and target pixel P6.

[0085] Following the method described above, the measured values ​​of the ray path lengths corresponding to the target pixel P1, P2, PP3, P4, P5, and P6 can also be obtained.

[0086] Based on the relationship between the tilt angle change corresponding to the target pixel P1 and the measured value L(P1) of the ray path length corresponding to the target pixel P1, the estimated value of the tilt angle corresponding to the target pixel P1 can be obtained. .

[0087] Based on the relationship between the tilt angle change corresponding to the target pixel P2 and the measured value L(P2) of the ray path length corresponding to the target pixel P2, the estimated value of the tilt angle corresponding to the target pixel P2 can be obtained. .

[0088] Based on the relationship between the tilt angle change corresponding to the target pixel P3 and the measured value L(P3) of the ray path length corresponding to the target pixel P3, the estimated value of the tilt angle corresponding to the target pixel P3 can be obtained. .

[0089] Based on the relationship between the tilt angle change corresponding to the target pixel P4 and the measured value L(P4) of the ray path length corresponding to the target pixel P4, the estimated value of the tilt angle corresponding to the target pixel P4 can be obtained. .

[0090] Based on the relationship between the tilt angle change corresponding to the target pixel P5 and the measured value L(P5) of the ray path length corresponding to the target pixel P5, the estimated value of the tilt angle corresponding to the target pixel P5 can be obtained. .

[0091] Based on the relationship between the tilt angle change corresponding to the target pixel P6 and the measured value L(P6) of the ray path length corresponding to the target pixel P6, the estimated value of the tilt angle corresponding to the target pixel P6 can be obtained. .

[0092] The estimated tilt angle corresponding to the target pixel P1 The estimated value of the tilt angle corresponding to the target pixel P2 The estimated value of the tilt angle corresponding to the target pixel P3 The estimated value of the tilt angle corresponding to the target pixel P4 The estimated value of the tilt angle corresponding to the target pixel P5 And the estimated tilt angle corresponding to the target pixel P6. Statistical processing can yield a comprehensive estimate of the tilt angle θ of the homogeneous flat plate model.

[0093] If the comprehensive estimated value of the tilt angle θ of the homogeneous plate phantom is less than the tilt angle threshold, it indicates that the homogeneous plate phantom is parallel to the detector, and the placement of the homogeneous plate phantom does not need to be adjusted.

[0094] If the comprehensive estimated value of the tilt angle θ of the homogeneous plate phantom is greater than or equal to the tilt angle threshold, it indicates that the homogeneous plate phantom is not parallel to the detector. In this case, the placement position of the homogeneous plate phantom can be adjusted. After the placement position is adjusted, steps S302 to S303 can be executed again to evaluate whether the homogeneous plate phantom is parallel to the detector in the adjusted placement position.

[0095] It is understandable that the number of first target pixels and the number of second target pixels can be the same or different; the distribution of multiple first target pixels on the detector and the distribution of multiple second target pixels on the detector can be symmetrical about the imaging center or not.

[0096] When the number of first target pixels is the same as the number of second target pixels, and the distribution of multiple first target pixels on the detector is symmetrical about the imaging center as the distribution of multiple second target pixels on the detector, the comprehensive estimate of the tilt angle θ of the homogeneous flat plate phantom is more accurate.

[0097] In one embodiment, the estimated tilt angles corresponding to a plurality of first target pixels and the estimated tilt angles corresponding to a plurality of second target pixels are statistically analyzed to obtain a comprehensive estimate of the tilt angle, including:

[0098] The estimated tilt angles corresponding to several first target pixels and several second target pixels are averaged; based on the result of the averaging, a comprehensive estimate of the tilt angle is obtained.

[0099] Specifically, the estimated tilt angles corresponding to several first target pixels can be averaged, and the averaged result can be used as a first comprehensive sub-estimate of the tilt angle. Similarly, the estimated tilt angles corresponding to several second target pixels can be averaged, and the averaged result can be used as a second comprehensive sub-estimate of the tilt angle. Finally, the first and second comprehensive sub-estimates of the tilt angle can be averaged, and the averaged result can be used as a comprehensive estimate of the tilt angle.

[0100] The above process can be represented by the following formula: .

[0101] i is a positive odd number greater than or equal to 1, P i P represents the first target pixel, where j is a positive even number greater than or equal to 2. j Let n1 represent the number of first target pixels and n2 represent the number of second target pixels.

[0102] For example, if an estimated value of the tilt angle corresponding to the target pixel P1 is obtained... The estimated value of the tilt angle corresponding to the target pixel P2 The estimated value of the tilt angle corresponding to the target pixel P3 The estimated value of the tilt angle corresponding to the target pixel P4 The estimated value of the tilt angle corresponding to the target pixel P5 And the estimated tilt angle corresponding to the target pixel P6. Then the following processing can be performed:

[0103] The estimated tilt angle corresponding to the target pixel P1 The estimated value of the tilt angle corresponding to the target pixel P3 And the estimated value of the tilt angle corresponding to the target pixel P5. The average value is then used as the first comprehensive sub-estimate of the tilt angle.

[0104] The estimated tilt angle corresponding to the target pixel P2 The estimated value of the tilt angle corresponding to the target pixel P4 And the estimated tilt angle corresponding to the target pixel P6. The average value is then used as the second comprehensive sub-estimate of the tilt angle.

[0105] The first and second comprehensive sub-estimates of the tilt angle are averaged, and the averaged result is used as the comprehensive estimate of the tilt angle.

[0106] In one embodiment, based on the measured values ​​of the tilt angle variation relationship and the ray path length, an estimated value of the tilt angle corresponding to the target pixel is obtained, including:

[0107] Obtain the standard thickness value of the homogeneous flat plate phantom; determine the input value of the inverse cosine function based on the standard thickness value and the measured value of the ray path length, so as to obtain the output value of the inverse cosine function; determine the input value of the arctangent function based on the distance of the target pixel point relative to the imaging center of the detector and the distance of the ray source to the detector, so as to obtain the output value of the arctangent function; obtain the estimated value of the tilt angle corresponding to the target pixel point based on the output values ​​of the inverse cosine function and the arctangent function.

[0108] Taking target pixel P1 and target pixel P2 as examples, the distance between target pixel P1 and the imaging center of the detector can be denoted as d1, and the distance between target pixel P2 and the imaging center of the detector can be denoted as d2.

[0109] Reference Figure 6 In the example shown, target pixels P1 and P2 are symmetrical about the detector's imaging center, meaning d1 equals d2. When the homogeneous plate phantom is parallel to the detector, the ray path length corresponding to target pixel P1 is B1D1, and the ray path length corresponding to target pixel P2 is A2C2. Since target pixels P1 and P2 are symmetrical about the detector's imaging center, B1D1 equals A2C2. When the homogeneous plate phantom rotates clockwise, it is no longer parallel to the detector, and the ray path length corresponding to target pixel P1 is A1C1, while the ray path length corresponding to target pixel P2 is B2D2. In this case, A1C1 is less than B2D2. Therefore, the rotation direction of the homogeneous plate phantom can be determined based on the relative magnitudes of the ray path lengths corresponding to target pixel P1 and P2. When the length of the ray path corresponding to the target pixel P1 is less than the length of the ray path corresponding to the target pixel P2, it can be determined that the rotation direction of the homogeneous plate mold is clockwise; when the length of the ray path corresponding to the target pixel P1 is greater than the length of the ray path corresponding to the target pixel P2, it can be determined that the rotation direction of the homogeneous plate mold is counterclockwise.

[0110] according to Figure 6 The geometric relationships shown hold for the target pixel P1, and the following equation applies:

[0111] ;

[0112] ;

[0113] ;

[0114] ;

[0115] ;

[0116] in, d1 is the angle between the second straight line (i.e., the straight line passing through the ray source and the rotation center) and the ray directed towards the target pixel P1; d1 is the distance between the target pixel P1 and the imaging center of the detector; SDD is the distance from the ray source to the detector via the rotation center. The angle between the second straight line and the plane of the homogeneous flat plate mold; The angle between the ray directed towards the target pixel P1 and the plane of the homogeneous flat plate mold is denoted as T; T is the standard thickness value of the homogeneous flat plate mold.

[0117] According to the above equation, we have Transforming the expression, we get ; that is, .

[0118] L(P1) is the measured value of the ray path length corresponding to the target pixel P1. This is an estimated value of the tilt angle corresponding to the target pixel P1.

[0119] The relationship between the tilt angle change corresponding to the target pixel P1 can be expressed as:

[0120] .

[0121] Based on the measured value L(P1) of the ray path length corresponding to the target pixel P1 and the standard value T of the thickness of the homogeneous plate phantom, the input value of the inverse cosine function is obtained, and then the output value of the inverse cosine function is obtained. Based on the distance d1 of the target pixel P1 relative to the imaging center of the detector and the distance SDD of the ray source from the rotation center to the detector, the input value of the arctangent function is obtained, and then the output value of the arctangent function is obtained. The output values ​​of the inverse cosine function and the arctangent function are added together to obtain the estimated value of the tilt angle corresponding to the target pixel P1. .

[0122] Specifically, the input value of the inverse cosine function is determined based on the standard thickness value and the measured value of the ray path length, including: dividing the standard thickness value by the measured value of the ray path length to obtain the first division result; and using the first division result as the input value of the inverse cosine function.

[0123] Specifically, the input value of the arctangent function is determined based on the distance between the target pixel and the imaging center of the detector and the distance between the ray source and the detector. This includes: dividing the distance between the target pixel and the imaging center of the detector by the distance between the ray source and the detector to obtain a second division result; and using the second division result as the input value of the arctangent function.

[0124] That is, the standard value of the thickness of the homogeneous plate phantom is divided by the measured value L(P1) of the ray path length corresponding to the target pixel P1, resulting in the first division result T / L(P1). T / L(P1) is used as the input value of the inverse cosine function and substituted into the relationship with the tilt angle change corresponding to the target pixel P1. The distance d1 of the target pixel P1 relative to the imaging center of the detector is divided by the distance SDD from the ray source through the rotation center to the detector, resulting in the second division result d1 / SDD. d1 / SDD is used as the input value of the arctangent function and substituted into the relationship with the tilt angle change corresponding to the target pixel P1. In the relationship with the tilt angle change corresponding to the target pixel P1, and The summation yields an estimate of the tilt angle corresponding to the target pixel P1. .

[0125] By processing the target pixel P1 in the same way, the other first target pixels can be processed to obtain the estimated tilt angles of the other first target pixels.

[0126] according to Figure 6 The geometric relationships shown hold for the target pixel P2, and the following equation applies:

[0127] ;

[0128] ;

[0129] ;

[0130] ;

[0131] ;

[0132] in, d2 is the angle between the second straight line (i.e., the straight line passing through the ray source and the rotation center) and the ray directed towards the target pixel P2; d2 is the distance between the target pixel P2 and the imaging center of the detector; SDD is the distance from the ray source to the detector via the rotation center. The angle between the second straight line and the plane of the homogeneous flat plate mold; The angle between the ray directed towards the target pixel P2 and the plane of the homogeneous flat plate mold is denoted as T; T is the standard thickness value of the homogeneous flat plate mold.

[0133] According to the above equation, we have Transforming the expression, we get ; that is, .

[0134] L(P2) is the measured value of the ray path length corresponding to the target pixel P2. This is an estimated value of the tilt angle corresponding to the target pixel P2.

[0135] The relationship between the tilt angle change corresponding to the target pixel P2 can be expressed as:

[0136] .

[0137] Based on the measured value L(P2) of the ray path length corresponding to the target pixel P2 and the standard value T of the homogeneous plate phantom thickness, the input value of the inverse cosine function is obtained, and then the output value of the inverse cosine function is obtained. Based on the distance d2 of the target pixel P2 relative to the imaging center of the detector and the distance SDD of the ray source from the rotation center to the detector, the input value of the arctangent function is obtained, and then the output value of the arctangent function is obtained. Subtracting the output value of the inverse cosine function from the output value of the arctangent function yields the estimated value of the tilt angle corresponding to the target pixel P2. .

[0138] Specifically, the input value of the inverse cosine function is determined based on the standard thickness value and the measured value of the ray path length, including: dividing the standard thickness value by the measured value of the ray path length to obtain the first division result; and using the first division result as the input value of the inverse cosine function.

[0139] Specifically, the input value of the arctangent function is determined based on the distance between the target pixel and the imaging center of the detector and the distance between the ray source and the detector. This includes: dividing the distance between the target pixel and the imaging center of the detector by the distance between the ray source and the detector to obtain a second division result; and using the second division result as the input value of the arctangent function.

[0140] That is, the standard value of the thickness of the homogeneous plate phantom is divided by the measured value L(P2) of the ray path length corresponding to the target pixel P2, resulting in the first division result T / L(P2). T / L(P2) is used as the input value of the inverse cosine function and substituted into the relationship with the tilt angle change corresponding to the target pixel P2. The distance d2 of the target pixel P2 relative to the imaging center of the detector is divided by the distance SDD from the ray source through the rotation center to the detector, resulting in the second division result d2 / SDD. d2 / SDD is used as the input value of the arctangent function and substituted into the relationship with the tilt angle change corresponding to the target pixel P2. In the relationship with the tilt angle change corresponding to the target pixel P2, and Subtracting the two values ​​yields an estimate of the tilt angle corresponding to the target pixel P2. .

[0141] By processing the target pixel P2 in the same way, we can process the other second target pixels and obtain the estimated values ​​of the tilt angles corresponding to the other second target pixels.

[0142] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0143] Based on the same inventive concept, this application also provides a homogeneous flat plate mold positioning adjustment device for implementing the above-described homogeneous flat plate mold positioning adjustment method. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more embodiments of the homogeneous flat plate mold positioning adjustment device provided below can be found in the limitations of the homogeneous flat plate mold positioning adjustment method described above, and will not be repeated here.

[0144] In one embodiment, such as Figure 7 As shown, a device for adjusting the placement of a homogeneous flat plate mold is provided, comprising:

[0145] The change relationship determination module 701 is used to determine the tilt angle change relationship corresponding to the target pixel on the detector; the tilt angle change relationship includes the change relationship between the tilt angle of the homogeneous plate model and the ray path length corresponding to the target pixel; the ray path length is the path length of the ray from the ray source to the target pixel through the homogeneous plate model.

[0146] The path length measurement processing module 702 is used to obtain the measured value of the ray path length based on the count rate of the target pixel points measured by the detector and the ray attenuation model.

[0147] The tilt angle estimation processing module 703 is used to obtain an estimated value of the tilt angle corresponding to the target pixel based on the tilt angle change relationship and the measured value of the ray path length.

[0148] The placement adjustment module 704 is used to adjust the placement position of the homogeneous flat plate mold based on the estimated value of the tilt angle corresponding to the target pixel.

[0149] In one embodiment, the apparatus further includes a target pixel determination module, configured to:

[0150] Among several pixels of the detector, the pixel located in the plane of the tilt angle is determined to obtain the target pixel.

[0151] In one embodiment, the target pixels include a plurality of first target pixels and a plurality of second target pixels; the first target pixels and the second target pixels are distributed on both sides of the imaging center of the detector; the positioning adjustment module 704 is further configured to:

[0152] The estimated values ​​of the tilt angles corresponding to a number of first target pixels and the estimated values ​​of the tilt angles corresponding to a number of second target pixels are statistically analyzed to obtain a comprehensive estimate of the tilt angles; the placement position of the homogeneous flat plate mold is adjusted according to the comprehensive estimate of the tilt angles.

[0153] In one embodiment, the positioning adjustment module 704 is further configured to:

[0154] The estimated values ​​of the tilt angle corresponding to a plurality of first target pixels and the estimated values ​​of the tilt angle corresponding to a plurality of second target pixels are averaged; based on the result of the averaging process, a comprehensive estimated value of the tilt angle is obtained.

[0155] In one embodiment, the tilt angle estimation processing module 703 is further configured to:

[0156] Obtain the standard thickness value of the homogeneous flat plate phantom; determine the input value of the inverse cosine function based on the standard thickness value and the measured value of the ray path length, so as to obtain the output value of the inverse cosine function; determine the input value of the arctangent function based on the distance of the target pixel point relative to the imaging center of the detector and the distance from the ray source to the detector, so as to obtain the output value of the arctangent function; obtain the estimated value of the tilt angle corresponding to the target pixel point based on the output value of the inverse cosine function and the output value of the arctangent function.

[0157] In one embodiment, the tilt angle estimation processing module 703 is further configured to:

[0158] Divide the standard thickness value by the measured value of the ray path length to obtain the first division result; use the first division result as the input value of the inverse cosine function.

[0159] In one embodiment, the tilt angle estimation processing module 703 is further configured to:

[0160] The distance of the target pixel relative to the imaging center of the detector is divided by the distance from the ray source to the detector to obtain a second division result; the second division result is used as the input value of the arctangent function.

[0161] Each module in the aforementioned homogeneous flat plate mold positioning and adjustment device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0162] In one exemplary embodiment, a computer device is provided, the internal structure of which can be as shown in the figure. Figure 8 As shown, the computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores the data involved in the aforementioned methods. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communicating with external terminals via a network connection. When the computer program is executed by the processor, it implements a method for adjusting the placement of a homogeneous flat plate phantom.

[0163] Those skilled in the art will understand that Figure 8 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0164] In one embodiment, a computer device is provided, including a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the steps in the various method embodiments described above.

[0165] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the various method embodiments described above.

[0166] In one embodiment, a computer program product is provided having a computer program stored thereon, the computer program being executed by a processor of the steps described in the various method embodiments above.

[0167] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0168] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory 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), magnetic 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. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0169] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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 application.

[0170] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for adjusting the placement of a homogeneous flat plate mold, characterized in that, The method includes: Determine the tilt angle variation relationship corresponding to the target pixel on the detector; the tilt angle variation relationship includes the variation relationship between the tilt angle of the homogeneous plate model and the ray path length corresponding to the target pixel; the ray path length is the path length of the ray from the ray source to the target pixel through the homogeneous plate model; The measured value of the ray path length is obtained based on the count rate of the target pixel points measured by the detector and the ray attenuation model. Based on the tilt angle variation relationship and the measured value of the ray path length, the estimated value of the tilt angle corresponding to the target pixel is obtained; Based on the estimated tilt angle corresponding to the target pixel, the placement position of the homogeneous flat plate mold is adjusted.

2. The method according to claim 1, characterized in that, Determining the target pixel on the detector includes: Among several pixels of the detector, the pixel located in the plane of the tilt angle is determined to obtain the target pixel.

3. The method according to claim 1, characterized in that, The target pixels include a plurality of first target pixels and a plurality of second target pixels; the first target pixels and the second target pixels are distributed on both sides of the imaging center of the detector; Based on the estimated tilt angle corresponding to the target pixel, the placement position of the homogeneous flat plate mold is adjusted, including: The estimated values ​​of the tilt angle corresponding to a plurality of first target pixels and the estimated values ​​of the tilt angle corresponding to a plurality of second target pixels are statistically analyzed to obtain a comprehensive estimated value of the tilt angle. The placement of the homogeneous flat plate mold is adjusted based on the comprehensive estimate of the tilt angle.

4. The method according to claim 3, characterized in that, The estimated tilt angles corresponding to a plurality of first target pixels and a plurality of second target pixels are statistically analyzed to obtain a comprehensive estimate of the tilt angle, including: The estimated values ​​of the tilt angles corresponding to a plurality of first target pixels and the estimated values ​​of the tilt angles corresponding to a plurality of second target pixels are averaged. Based on the results of the averaging process, a comprehensive estimate of the tilt angle is obtained.

5. The method according to any one of claims 1 to 4, characterized in that, Based on the measured values ​​of the tilt angle variation and the ray path length, an estimated value of the tilt angle corresponding to the target pixel is obtained, including: Obtain the standard thickness value of the homogeneous flat plate mold; Based on the standard thickness value and the measured value of the ray path length, the input value of the inverse cosine function is determined to obtain the output value of the inverse cosine function; The input value of the arctangent function is determined based on the distance of the target pixel relative to the imaging center of the detector and the distance from the ray source to the detector, so as to obtain the output value of the arctangent function; Based on the output values ​​of the inverse cosine function and the arctangent function, an estimated value of the tilt angle corresponding to the target pixel is obtained.

6. The method according to claim 5, characterized in that, Based on the standard thickness value and the measured value of the ray path length, the input value of the inverse cosine function is determined, including: Divide the standard thickness value by the measured value of the ray path length to obtain the first phase division result; Use the first division result as the input value of the inverse cosine function.

7. The method according to claim 5, characterized in that, The input value of the arctangent function is determined based on the distance of the target pixel relative to the imaging center of the detector and the distance from the ray source to the detector, including: The distance of the target pixel relative to the imaging center of the detector is divided by the distance from the ray source to the detector to obtain the second division result; Use the result of the second division as the input value of the arctangent function.

8. A device for adjusting the placement of a homogeneous flat plate mold, characterized in that, The device includes: The change relationship determination module is used to determine the tilt angle change relationship corresponding to the target pixel on the detector; the tilt angle change relationship includes the change relationship between the tilt angle of the homogeneous plate model and the ray path length corresponding to the target pixel; the ray path length is the path length of the ray from the ray source to the target pixel through the homogeneous plate model. The path length measurement processing module is used to obtain the measured value of the ray path length based on the count rate of the target pixel points measured by the detector and the ray attenuation model. The tilt angle estimation processing module is used to obtain an estimated value of the tilt angle corresponding to the target pixel based on the tilt angle change relationship and the measured value of the ray path length; The placement adjustment module is used to adjust the placement position of the homogeneous flat plate mold based on the estimated value of the tilt angle corresponding to the target pixel.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the method of any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1 to 7.

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