Methods, devices, and computer equipment for determining the projection center of CT equipment

Abstract

This application relates to a method, apparatus, and computer device for determining the projection center of a CT scanner. The method includes: acquiring multiple fan-beam projection data of a test object at different scanning angles, rearranging the fan-beam projection data to obtain multiple parallel beam projection data, and then determining at least one set of target parallel beam projection data from the multiple parallel beam projection data; each set of target parallel beam projection data includes parallel beam projection data at two opposing scanning angles, thereby determining the coordinates of the projection center of the CT scanner based on at least one set of target parallel beam projection data. This method enables the determination of the projection center of a CT scanner without relying on a ball bearing phantom.

Description

Technical Field

[0001] This application relates to the field of medical imaging technology, and in particular to a method, apparatus and computer device for determining the projection center of a CT device. Background Technology

[0002] The image reconstruction accuracy of medical imaging equipment, such as micro computed tomography (Micro CT), is related to the position of the projection center. That is, the more accurate the coordinates of the determined projection center are, the higher the accuracy of the image reconstruction.

[0003] Currently, in the process of correcting the coordinates of the projection center, maintenance personnel need to carry the steel ball phantom to the site where the Micro CT is located, and use the Micro CT to scan the steel ball phantom around, fit the projection trajectory of the centroid of the steel ball phantom on the detector into an ellipse, and analyze these projection trajectories to calculate the coordinates of the projection center.

[0004] However, current methods for determining the coordinates of the projection center rely excessively on the steel ball phantom. Therefore, proposing a projection center determination method that does not depend on the steel ball phantom is a key research focus for those in this field. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, apparatus, and computer device for determining the projection center of a CT device that does not rely on a steel ball phantom to address the aforementioned technical problems.

[0006] Firstly, this application provides a method for determining the projection center of a CT scanner. The method includes:

[0007] Acquire multiple sector beam projection data of the tested object at different scanning angles;

[0008] The projection data of each sector beam are rearranged to obtain multiple parallel beam projection data;

[0009] At least one set of target parallel beam projection data is determined from the plurality of parallel beam projection data; each set of target parallel beam projection data includes parallel beam projection data of two opposing scanning angles;

[0010] Based on at least one set of target parallel beam projection data, determine the coordinates of the projection center of the CT device.

[0011] In one embodiment, the parallel beam projection data of the two opposing scanning angles includes first parallel beam projection data and second parallel beam projection data; determining the coordinates of the projection center of the CT device based on the at least one set of target parallel beam projection data includes:

[0012] For each set of target parallel beam projection data, the first parallel beam projection data is flipped along the first direction based on the center coordinates of the detector to obtain the corresponding third parallel beam projection data; the first direction is the radial direction of the detector.

[0013] The coordinates of the projection center are determined based on the second parallel beam projection data and the third parallel beam projection data.

[0014] In one embodiment, determining the coordinates of the projection center based on the second parallel beam projection data and the third parallel beam projection data includes:

[0015] According to the preset translation rules, the third parallel beam projection data is translated along the first direction to obtain the fourth parallel beam projection data;

[0016] Determine the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation;

[0017] The coordinates of the projection center are determined based on the similarity score.

[0018] In one embodiment, determining the coordinates of the projection center based on each of the similarities includes:

[0019] The target similarity is determined from all the similarities; the target similarity is the minimum value among all the similarities.

[0020] Determine the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity;

[0021] The coordinates of the projection center are determined based on the translation distance.

[0022] In one embodiment, determining the coordinates of the projection center based on the translation distance includes:

[0023] The coordinates of the projection center are determined based on the center coordinates of the detector and the translation distance.

[0024] In one embodiment, the rearrangement of the sector beam projection data to obtain multiple parallel beam projection data includes:

[0025] Based on the first correspondence between the projection data of each sector beam and the projection data of the parallel beam, interpolation processing is performed on the projection data of each sector beam to obtain the projection data of each intermediate parallel beam.

[0026] The intermediate parallel beam projection data are processed to be evenly spaced to obtain multiple parallel beam projection data.

[0027] In one embodiment, the equal-spacing processing of each of the intermediate parallel beam projection data results in a plurality of parallel beam projection data, including:

[0028] The minimum distance between each intermediate parallel beam projection data and the original channel is taken as the target distance;

[0029] Based on the target distance, interpolation is performed on the projection data of two adjacent intermediate parallel beams to obtain the multiple parallel beam projection data.

[0030] Secondly, this application also provides a projection center determination device for a CT scanner. The device includes:

[0031] The acquisition module is used to acquire multiple fan-beam projection data of the tested object at different scanning angles;

[0032] The rearrangement module is used to rearrange the projection data of each sector beam to obtain multiple parallel beam projection data.

[0033] The first determining module is used to determine at least one set of target parallel beam projection data from the plurality of parallel beam projection data; each set of target parallel beam projection data includes parallel beam projection data of two opposing scanning angles;

[0034] The second determining module is used to determine the coordinates of the projection center of the CT device based on the at least one set of target parallel beam projection data.

[0035] Thirdly, this application also provides a computer device. The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the steps of any of the methods described above.

[0036] Fourthly, this application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0037] Fifthly, this application also provides a computer program product. The computer program product includes a computer program that, when executed by a processor, implements the steps of any of the methods described above.

[0038] Sixthly, this application also provides a CT device, which includes:

[0039] A radiation source, used to emit radiation;

[0040] A detector is used to receive the ray and generate multiple fan-beam projection data of the object under test at different scanning angles based on the ray that penetrates from the object under test.

[0041] A computer device for performing the method described in any one of the above steps.

[0042] The aforementioned method, apparatus, and computer equipment for determining the projection center of a CT scanner acquire multiple sector beam projection data of the tested object at different scanning angles, rearrange these sector beam projection data to obtain multiple parallel beam projection data, and then determine at least one set of target parallel beam projection data from these multiple parallel beam projection data. Each set of target parallel beam projection data includes parallel beam projection data from two opposing scanning angles, thereby determining the coordinates of the CT scanner's projection center based on at least one set of target parallel beam projection data. Currently, the process of determining the projection center coordinates relies too heavily on steel ball phantoms. Since steel ball phantoms must be carried to the CT scanner site by specialized maintenance personnel, the current process of determining the projection center coordinates suffers from poor flexibility and wasted manpower. In this embodiment, since the parallel beam projection data is obtained from multiple sector beam projection data of the tested object at different scanning angles, and each set of target parallel beam projection data includes parallel beam projection data from two opposing scanning angles, the target parallel beam projection data can reflect the deviation of the projection center, thus allowing the determination of the CT scanner's projection center coordinates based on the target parallel beam projection data. The entire determination process only uses the projection data of the CT equipment, without relying on the steel ball phantom, thus avoiding the problems of poor flexibility and wasted manpower in the current process of determining the coordinates of the projection center. Attached Figure Description

[0043] Figure 1 This is an application environment diagram of the projection center determination method for CT equipment in the embodiments of this application;

[0044] Figure 2 This is a flowchart illustrating the method for determining the projection center of a CT device in an embodiment of this application.

[0045] Figure 3 This is a schematic diagram of the principle of a CT scanner;

[0046] Figure 4 A schematic diagram of sector beam projection data;

[0047] Figure 5 This is a schematic diagram illustrating the geometric relationship between sector beam projection data and parallel beam projection data;

[0048] Figure 6 This is a schematic diagram showing the case where there is no deviation between the projection center and the detector center;

[0049] Figure 7 This is a schematic diagram showing a deviation between the projection center and the detector center.

[0050] Figure 8 This is a schematic diagram of a process for determining the coordinates of the projection center of a CT device according to an embodiment of this application;

[0051] Figure 9 This is a schematic diagram illustrating another process for determining the coordinates of the projection center in an embodiment of this application;

[0052] Figure 10 This is a schematic diagram illustrating another process for determining the coordinates of the projection center in an embodiment of this application;

[0053] Figure 11 This is a schematic diagram of a process for obtaining multiple parallel beam projection data in an embodiment of this application;

[0054] Figure 12 This is a schematic diagram of another process for obtaining multiple parallel beam projection data in an embodiment of this application;

[0055] Figure 13 This is a schematic diagram illustrating the principle of equal spacing in the embodiments of this application;

[0056] Figure 14 This is a schematic diagram of the overall process of determining the projection center of a CT device in an embodiment of this application;

[0057] Figure 15 This is a structural block diagram of the projection center determination device of the CT equipment in the embodiments of this application;

[0058] Figure 16 This is a diagram showing the internal structure of a computer device in an embodiment of this application. Detailed Implementation

[0059] 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.

[0060] Currently, methods for determining the coordinates of the projection center rely excessively on ball bearing phantoms. On one hand, this method places high demands on the manufacturing processes of both the phantom and the CT equipment's rotation axis, making it suitable only for relatively stable CT devices. Furthermore, any changes to the CT equipment's structure necessitate re-measuring the projection center's coordinates, thus making it unsuitable for small-field-of-view CT devices like MicroCT. On the other hand, the ball bearing phantom must be transported to the CT equipment's location by specialized maintenance personnel, resulting in poor flexibility and wasted manpower in the current process of determining the projection center's coordinates.

[0061] Therefore, it is necessary to provide a method for determining the projection center of a CT device that does not rely on a steel ball phantom to address the above-mentioned technical problems. The following will introduce this method for determining the projection center of a CT device.

[0062] Figure 1This diagram illustrates the application environment of the projection center determination method for a CT scanner in this embodiment. The projection center determination method for a CT scanner provided in this embodiment can be applied to, for example... Figure 1 The computer device shown is configured such that the CT device 102 communicates with the computer device 104 via a network. The computer device 104 can be, but is not limited to, various personal computers, laptops, smartphones, tablets, and portable wearable devices. Portable wearable devices can include smartwatches, smart bracelets, head-mounted devices, etc. Alternatively, the computer device 104 can be implemented using a standalone server or a server cluster consisting of multiple servers. It should be noted that the computer device 104 can also be built into the CT device 102.

[0063] Figure 2 This is a flowchart illustrating the method for determining the projection center of a CT device in an embodiment of this application. This method can be applied to... Figure 1 In one embodiment of the computer device shown, such as Figure 2 As shown, it includes the following steps:

[0064] S201, acquire multiple sector beam projection data of the tested object at different scanning angles.

[0065] In this embodiment, Figure 3 This is a schematic diagram of the principle of a CT scanner. Figure 4 This is a schematic diagram of the sector beam projection data. (Example) Figure 3 As shown, a CT scanner includes a radiation source and a detector. The object being examined is located between the radiation source and the detector, and the object remains stationary. ISO refers to the rotation center of the CT scanner.

[0066] Combination Figure 3 The X-ray source and detector rotate around the rotation center (ISO) of the CT scanner, allowing each channel on the detector to detect the fan-shaped beam projection data corresponding to the X-ray passing through the object being examined. Here, Ciso refers to the detector center. γ c The sector angle represents the angle between detector channel c and the line connecting detector channel c to the X-ray source and ISO to the X-ray source.

[0067] exist Figure 3 Based on this, a coordinate system is established with the rotation center ISO as the coordinate center to obtain... Figure 4 .like Figure 4 As shown, the fan-shaped beam projection data received by the detector can be expressed as F(β,r) cThe diagram shows the projection angle, where β represents the scanning angle, or the current projection angle, which indicates the rotation angle of the X-ray source from its initial rotation position. The fan-beam projection data received by the detector indicates the degree of attenuation of the X-ray as it passes through the object under test, and the imaging of the object can be determined based on the degree of attenuation.

[0068] Combination Figure 4 Ideally, the projection center of a CT scanner coincides with the detector center (Ciso). However, due to various factors during manufacturing, installation, and use, there will be a deviation between the projection center and the detector center (Ciso), resulting in artifacts in the final reconstructed image.

[0069] Therefore, determining the projection center is necessary during the use of CT equipment to improve the accuracy of reconstructed images. In this embodiment, when determining the coordinates of the projection center, the computer device first acquires multiple fan-beam projection data of the object under test at different scanning angles. For example, combining... Figure 4 The computer equipment acquires the fan-beam projection data obtained by each channel on the detector when β = 10°, β = 20°, ..., β = 360°.

[0070] S202, rearrange the projection data of each sector beam to obtain multiple parallel beam projection data.

[0071] Figure 5 This is a schematic diagram illustrating the geometric relationship between sector beam projection data and parallel beam projection data. (Example) Figure 5 As shown, in Figure 4 Based on this, as the X-ray source and detector rotate around the rotation center ISO, their rotational trajectories are as follows: Figure 5 As shown. In this process, since each channel of the detector receives fan-beam projection data at different scanning angles, and the X-ray source and detector rotate at a certain scanning frequency, different fan-beam projection data can be recombined into parallel beam projection data.

[0072] by Figure 5 Taking the two sector beam projection data P(θ,γ1) and P(θ,γ2) corresponding to γ1 and γ2 (shown by dashed lines) as an example, P(θ,θ1) and P(θ,γ2) can be reconstructed into two parallel beam projection data with an included angle θ (shown by solid lines). Here, θ represents the angle between the reconstructed parallel beam projection data and the horizontal axis of the coordinate system.

[0073] according to Figure 5 It can be seen that for any given detector channel c, the corresponding sector beam projection data and parallel beam projection data satisfy the geometric relationship shown in the following equation (1).

[0074] θ=β+γ (1)

[0075] Furthermore, according to equation (1), the sector beam projection data that satisfy the following equation (2) in each sector beam projection data can be combined together to form parallel beam projection data.

[0076] P(θ,γ c )=F(θ-γ c ,γ c (2)

[0077] Where P(θ,γ) c ) represents parallel beam projection data, and equation (2) is used to represent parallel beam projection data on channel c that are from the same channel and have a scanning angle of θ-γ, with an angle of θ-γ between the parallel beam projection data and the horizontal axis of the coordinate system. c The fan-beam projection data.

[0078] Therefore, in this embodiment, after the computer device acquires multiple sector beam projection data of the tested object at different scanning angles, it can rearrange the sector beam projection data based on equation (2) to obtain multiple parallel beam projection data P(θ, γ). c ).

[0079] S203, determine at least one set of target parallel beam projection data from multiple parallel beam projection data, each set of target parallel beam projection data including parallel beam projection data of two opposing scanning angles.

[0080] In this embodiment, the computer device determines at least one set of target parallel beam projection data from multiple sets of parallel beam projection data. Each set of target parallel beam projection data includes parallel beam projection data at two opposing scanning angles.

[0081] Please continue to refer to this. Figure 5 Assuming the computer device determines 100 parallel beam projection data, the computer device can determine a set of target parallel beam projection data based on equation (2), where the parallel beam projection data with a scanning angle β of 0° and the parallel beam projection data with a scanning angle β of 180° are used as a set of target parallel beam projection data, thereby determining at least one set of target parallel beam projection data.

[0082] S204, Determine the coordinates of the projection center of the CT device based on at least one set of target parallel beam projection data.

[0083] In this embodiment, the target parallel beam projection data includes parallel beam projection data with a scanning angle β of 0° and parallel beam projection data with a scanning angle β of 180° as an example. Figure 6 This is a schematic diagram showing the case where there is no deviation between the projection center and the detector center. Figure 7This diagram illustrates a situation where the projection center deviates from the detector center. The dashed lines represent rays emitted from the X-ray source towards the detector, the elliptical shape represents the object being measured, and 1 and N represent different channels on the detector, i.e., different pixels on the detector, where N is an integer greater than 1.

[0084] like Figure 6 As shown, Figure 6 (a) is a schematic diagram when the scanning angle is 0°. Figure 6 (b) is a schematic diagram when the scanning angle is 180°. (Combined with...) Figure 6 (a) and Figure 6 (b) When there is no deviation between the projection center and the detector center Ciso, the ray direction is parallel to the line connecting the rotation center ISO and the detector center Ciso. Therefore, in this case, the projection data generated by the object under test at scanning angles of 0° and 180° are mirror-symmetrical and can be mirror-overlapped.

[0085] like Figure 7 As shown, Figure 7 (a) is a schematic diagram when the scanning angle is 0°. Figure 7 (b) is a schematic diagram when the scanning angle is 180°. (Combined with...) Figure 7 (a) and Figure 7 (b) When there is a deviation between the projection center ISO and the detector center Ciso, the ray direction is not parallel to the line connecting the rotation center ISO and the detector center Ciso. Therefore, in this case, the projection data generated by the object under test at scanning angles of 0° and 180° also have deviations.

[0086] In this embodiment, the target parallel beam projection data includes parallel beam projection data at two opposing scanning angles. The target parallel beam projection data can be used to indicate the deviation between the projection center and the detector center Ciso.

[0087] Furthermore, the computer equipment can determine the coordinates of the projection center of the CT equipment based on at least one set of target parallel beam projection data.

[0088] Optionally, the computer device can determine the projection center coordinates of the CT device onto the same plane based on the detector's center coordinates, i.e., based on Ciso, and determine the projection center coordinates of the CT device based on the differences between the two parallel beam projection data on the same plane.

[0089] Of course, the computer device can also determine the coordinates of the projection center of the CT device based on at least one set of target parallel beam projection data in other ways, and this embodiment is not limited to this.

[0090] The projection center determination method for a CT scanner provided in this embodiment acquires multiple sector beam projection data of the tested object at different scanning angles, rearranges these sector beam projection data to obtain multiple parallel beam projection data, and then determines at least one set of target parallel beam projection data from these multiple parallel beam projection data. Each set of target parallel beam projection data includes parallel beam projection data from two opposing scanning angles. Based on this at least one set of target parallel beam projection data, the coordinates of the CT scanner's projection center are determined. Currently, determining the projection center coordinates relies heavily on steel ball phantoms. Since these phantoms must be carried to the CT scanner site by specialized maintenance personnel, the current method suffers from poor flexibility and wasted manpower. In this embodiment, however, because the parallel beam projection data is obtained from multiple sector beam projection data of the tested object at different scanning angles, and each set of target parallel beam projection data includes parallel beam projection data from two opposing scanning angles, the target parallel beam projection data can reflect the deviation of the projection center. Therefore, the coordinates of the CT scanner's projection center can be determined based on the target parallel beam projection data. The entire determination process only uses the projection data of the CT equipment, without relying on the steel ball phantom, thus avoiding the problems of poor flexibility and wasted manpower in the current process of determining the coordinates of the projection center.

[0091] Furthermore, the steel ball phantom has high technological requirements for both the phantom itself and the rotation axis of the CT equipment, making it suitable only for relatively stable CT equipment. When the structure of the CT equipment system is changed, the coordinates of the projection center need to be remeasured, thus making it unsuitable for small-field-of-view CT equipment such as Micro CT. This embodiment, however, does not rely on a steel ball phantom, and therefore can be applied to small-field-of-view CT equipment such as Micro CT, expanding the application scope of the projection center determination process.

[0092] Figure 8 This is a flowchart illustrating a method for determining the coordinates of the projection center of a CT scanner, as described in an embodiment of this application. Figure 8 This embodiment relates to an optional implementation of how to determine the coordinates of the projection center of a CT scanner. Based on the above embodiment, the parallel beam projection data of the two opposing scanning angles includes first parallel beam projection data and second parallel beam projection data. Step S204 above, determining the coordinates of the projection center of the CT scanner based on at least one set of target parallel beam projection data, includes the following steps:

[0093] S801, for each group of target parallel beam projection data, the first parallel beam projection data is flipped along the first direction based on the center coordinates of the detector to obtain the corresponding third parallel beam projection data; the first direction is the radial direction of the detector.

[0094] In this embodiment, continuing the example of S203 above, it is assumed that the computer device determines that the first parallel beam projection data is parallel beam projection data with a scanning angle β of 0°, denoted as P1(i,j), and determines that the second parallel beam projection data is parallel beam projection data with a scanning angle β of 180°, denoted as P2(i,j). Here, i and j represent the abscissa and ordinate of the parallel beam projection data, respectively, and both i and j are numbers greater than or equal to 0.

[0095] based on Figure 7 The computer equipment flips the first parallel beam projection data P1(i,j) along the coordinates of the detector's center Ciso towards the radial direction of the detector to obtain the third parallel beam projection data, denoted as... The radial direction of the detector is also the direction of its detection surface. The detection surface refers to the part of the detector that receives rays and generates fan-shaped beam projection data based on the rays. For example, combining... Figure 6 and Figure 7 The radial direction of the detector refers to the horizontal direction, which can be horizontal to the right or horizontal to the left.

[0096] Figure 7 (c) is a schematic diagram of the result obtained by flipping, combined with Figure 7 (c) The computer device will flip P1(i,j) based on the center coordinates of the detector in the radial direction of the detector, that is, it will horizontally flip P1(i,j) based on Ciso to obtain

[0097] Since the first and second parallel beam projection data are obtained at two opposing scanning angles, respectively, for the same fixed object under test, the first parallel beam projection data P1(i,j) can be understood as the data obtained by projecting the object from top to bottom, and the second parallel beam projection data P2(i,j) can be understood as the data obtained by projecting the object from bottom to top. Therefore, the first and second parallel beam projection data are mirror images, meaning their directions are opposite. Thus, flipping the first parallel beam projection data along the first direction based on the detector's center coordinates is actually to make the third parallel beam projection data and the second parallel beam projection data have the same direction, thereby enabling a better comparison of the differences between the third and second parallel beam projection data to determine the deviation of the projection center.

[0098] This embodiment uses the flipping of the first parallel beam projection data as an example for illustration. It can be understood that the second parallel beam projection data can also be flipped.

[0099] S802, determine the coordinates of the projection center based on the second parallel beam projection data and the third parallel beam projection data.

[0100] In this embodiment, after obtaining the corresponding third parallel beam projection data, the computer device can determine the coordinates of the projection center based on the second and third parallel beam projection data.

[0101] Optionally, the computer device can translate the third parallel beam projection data along the first direction according to a preset translation rule to obtain the fourth parallel beam projection data, and determine the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation, until the translation distance corresponding to the similarity being less than a preset threshold is determined, thereby determining the coordinates of the projection center based on the translation distance corresponding to the similarity being less than the preset threshold. The preset threshold can be set according to actual conditions, for example, the preset threshold can be zero.

[0102] The computer device may also determine the coordinates of the projection center based on the second parallel beam projection data and the third parallel beam projection data in other ways, and this embodiment is not limited thereto.

[0103] In this embodiment, for each set of target parallel beam projection data, the first parallel beam projection data is flipped along a first direction based on the detector's center coordinates to obtain the corresponding third parallel beam projection data. The coordinates of the projection center are then determined based on the second and third parallel beam projection data. Since the first direction is the detector's radial direction, when the original directions of the first and second parallel beam projection data are opposite, the direction of the third parallel beam projection data obtained after flipping the first parallel beam projection data is the same as that of the second parallel beam projection data. Therefore, the coordinates of the projection center can be determined based on the second and third parallel beam projection data. Furthermore, since the process of determining the projection center in this embodiment is directly related to the projection data of the CT equipment, it can be further integrated with the reconstruction algorithm to improve the accuracy of the projection center.

[0104] Figure 9 This is a schematic diagram illustrating another process for determining the coordinates of the projection center in an embodiment of this application. (Refer to...) Figure 9 This embodiment relates to an optional implementation of how to determine the coordinates of the projection center. Based on the above embodiment, step S802, which determines the coordinates of the projection center according to the second parallel beam projection data and the third parallel beam projection data, includes the following steps:

[0105] S901, according to the preset translation rules, the third parallel beam projection data is translated along the first direction to obtain the fourth parallel beam projection data.

[0106] In this embodiment, when determining the coordinates of the projection center using the second and third parallel beam projection data, the computer device will translate the third parallel beam projection data along the first direction according to a preset translation rule to obtain the fourth parallel beam projection data.

[0107] The preset translation rules include the computer equipment traversing the translation distance within a preset range according to a certain step size, and translating the third parallel beam projection data according to the translation distance each time.

[0108] For example, suppose a computer device moves the third parallel beam projection data by n pixels in steps of 1 pixel, where n ranges from -10 to 10. That is, based on... Figure 7 and Figure 9 The computer device starts execution from n=-10. First, it shifts the third parallel beam projection data 10 pixels to the left to obtain the fourth parallel beam projection data 1. Then, it shifts the third parallel beam projection data 9 pixels to the left to obtain the fourth parallel beam projection data 2, and so on. Excluding cases where n=0, the computer device finally shifts the third parallel beam projection data 10 pixels to the right to obtain the fourth parallel beam projection data 20. It should be noted that, based on... Figure 9 Here, we take the first direction as horizontal to the right as an example. The first direction can also be horizontal to the left. This embodiment does not limit it.

[0109] S902, determine the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation.

[0110] In this embodiment, the computer device determines the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation. The similarity value indicates the degree of similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation, and the magnitude of the similarity value can be positively or negatively correlated with the degree of similarity.

[0111] Continuing with the example above, after obtaining the fourth parallel beam projection data 1, the computer device will determine the similarity between the second parallel beam projection data and the fourth parallel beam projection data 1 as 1. After obtaining the fourth parallel beam projection data 2, it will determine the similarity between the second parallel beam projection data and the fourth parallel beam projection data 2 as 2. And so on, the computer device will determine 20 similarities.

[0112] Optionally, the computer device can use the sum of squared errors to determine the similarity SSD, as shown in the following formula (3).

[0113]

[0114] Where nChannel represents the total number of channels of the detector, that is... Figure 7 N in the SSD value typically ranges from -10 to 10. The smaller the SSD value, the greater the similarity.

[0115] S903, determine the coordinates of the projection center based on each similarity.

[0116] In this embodiment, after the computer device determines 20 similarity scores (similarity 1, similarity 2...similarity 20, etc.) between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation, it can determine the coordinates of the projection center based on each similarity score.

[0117] Optionally, based on equation (3) above, the computer device can determine the minimum value among the similarities and determine the coordinates of the projection center based on the translation distance corresponding to the minimum similarity. Alternatively, the computer device can calculate the average of the translation distances corresponding to similarities less than a preset threshold and then determine the coordinates of the projection center. This embodiment does not impose any limitations.

[0118] In this embodiment, the third parallel beam projection data is translated along the first direction according to a preset translation rule to obtain the fourth parallel beam projection data. The similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation is determined, and the coordinates of the projection center are determined based on these similarities. Since the similarity is determined for both the fourth and second parallel beam projection data obtained after each translation according to the preset translation rule, the differences between the second and fourth parallel beam projection data at each translation distance can be determined using the translation distance and similarity. This allows for the determination of cases where the differences between the second and fourth parallel beam projection data are small, thus providing the coordinates of the projection center.

[0119] Figure 10 This is a schematic diagram illustrating another process for determining the coordinates of the projection center in an embodiment of this application. (Refer to...) Figure 10 This embodiment relates to an optional implementation of how to determine the coordinates of the projection center. Based on the above embodiment, step S903, which determines the coordinates of the projection center according to each similarity, includes the following steps:

[0120] S1001, determine the target similarity from all similarities; the target similarity is the minimum value among all similarities.

[0121] In this embodiment, when determining the coordinates of the projection center based on each similarity score, the computer device first determines the target similarity score, which is the minimum value among all similarity scores. For example, if the computer device determines similarity scores from 1 to 20, and the value of similarity score 19 is the smallest among the above 20 similarity scores, then the computer device determines similarity score 19 as the target similarity score.

[0122] S1002, determine the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity.

[0123] In this embodiment, based on S1001, the computer device determines the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity. For example, the similarity 19 is determined based on the fourth parallel beam projection data 19, which is obtained by shifting the third parallel beam projection data to the right by 9 pixels, i.e., n=9. Therefore, the computer device determines that the translation distance corresponding to the target similarity is 9.

[0124] S1003, determine the coordinates of the projection center based on the translation distance.

[0125] In this embodiment, please continue to refer to Figure 7 and Figure 9 After translating the third parallel beam projection data by the translation distance corresponding to the target similarity, the third and fourth parallel beam projection data should be identical. In other words, the translation distance indicates the distance between the projection center and the detector center. Ideally, half the distance between the projection center and the detector center should equal the translation distance corresponding to the target similarity. Therefore, after determining the translation distance corresponding to the fourth parallel beam projection data for the target similarity, the computer can determine the coordinates of the projection center based on this translation distance.

[0126] Optionally, the above-mentioned S1003, which determines the coordinates of the projection center based on the translation distance, can also be implemented as follows:

[0127] The coordinates of the projection center are determined based on the center coordinates of the detector and the translation distance.

[0128] In this embodiment, after the computer device determines the translation distance n* corresponding to the fourth parallel beam projection data corresponding to the target similarity, it can use |n* / 2| as the distance between the detector center Ciso and the projection center. Since the coordinates of the detector center Ciso are known, the coordinates of the projection center can be determined by using the center coordinates of the detector, i.e., the coordinates of Ciso, and the translation distance n*.

[0129] In some embodiments, optionally, to further improve the accuracy of the projection center coordinates, the computer device can further adjust the step size to update the target similarity. For example, based on S1001, the computer device further adjusts the compensation to 0.1 pixels / step, and based on the update n value range of (8, 10), continues to translate the third parallel beam projection data along the first direction to obtain the fourth parallel beam projection data, and determines the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation, and then determines the minimum value from each similarity to update the target similarity. Finally, the computer device determines the distance between the projection center and the detector center according to the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity, thereby determining the coordinates of the projection center.

[0130] Alternatively, taking into account the influence of the cone angle during CT projection, the computer device may determine the coordinates of the projection center using only the projection data when it is close to the detector channel.

[0131] This embodiment determines the target similarity from among various similarity scores, and then determines the translation distance corresponding to the fourth parallel beam projection data of the target similarity score. Based on this translation distance, the coordinates of the projection center are determined. Since the target similarity score is the minimum value among all similarity scores, the coordinates of the projection center can be calculated using the translation distance corresponding to the target similarity score. The determination process only utilizes the projection data of the CT equipment and does not rely on the steel ball phantom. Furthermore, since the coordinates of the projection center are determined based on the center coordinates of the detector and the translation distance, and because the process of determining the projection center is directly related to the projection data of the CT equipment, it can be further integrated with the reconstruction algorithm to improve the accuracy of the projection center.

[0132] Figure 11 This is a schematic diagram illustrating a process for obtaining multiple parallel beam projection data in an embodiment of this application. (Refer to...) Figure 11 This embodiment relates to an optional implementation of how to obtain multiple parallel beam projection data. Based on the above embodiment, step S202, which rearranges the sector beam projection data to obtain multiple parallel beam projection data, includes the following steps:

[0133] S1101, based on the first correspondence between the projection data of each sector beam and the projection data of the parallel beam, interpolation processing is performed on the projection data of each sector beam to obtain the projection data of each intermediate parallel beam.

[0134] In this embodiment, when rearranging the projection data of each sector beam, the computer device first performs interpolation processing on the projection data of each sector beam according to the first correspondence between the projection data of each sector beam and the projection data of the parallel beam, so as to obtain the projection data of each intermediate parallel beam.

[0135] The first correspondence between the projection data of each sector beam and the projection data of the parallel beam is used to indicate the conversion relationship between the projection data of each sector beam and the projection data of the parallel beam. Specifically, the computer device determines the first correspondence between the projection data of each sector beam and the projection data of the parallel beam according to equation (2). That is to say, for the same detector channel, the computer device can determine the first correspondence according to equation (2).

[0136] Furthermore, in practice, since the scanning angles are discrete, the fan-beam angle θ-γ corresponding to the parallel beam... c The actual scanning angle β does not correspond strictly to the actual angle β. Therefore, in order to improve the accuracy of the determined parallel beam projection data and make the parallel beam projection data completely parallel, the computer device will interpolate the projection data of each sector beam according to the first correspondence to obtain the projection data of each intermediate parallel beam.

[0137] Optionally, the computer device can interpolate the sector beam projection data according to the following formulas (4) to (7).

[0138]

[0139]

[0140]

[0141] a = jj * (7)

[0142] in, This indicates that detector channel c is at the scanning angle The following sector beam projection data, This indicates that detector channel c is at the scanning angle The fan-beam projection data, P(θ) k ,γ c ) indicates to and After interpolation, the angle between the detector channel c and the horizontal axis of the coordinate system is θ. k The intermediate parallel beam projection data. k and j * These are labels representing the scanning angle. For example, the X-ray source and detector rotate within 360° at a scanning frequency of once per 1° rotation, where k and j represent the scanning angle. * The value range of θ is 1 to 360. k This represents the angle between the k-th parallel beam projection data and the horizontal axis of the coordinate system. Then it means that the j-th * The scanning angle of the sector beam projection data. Wherein, θ k and The value increases with the number of digits, and Δβ represents the interval between the scanning angles of two adjacent fan beam projection data.

[0143] S1102, the projection data of each intermediate parallel beam is processed to equalize the spacing, resulting in multiple parallel beam projection data.

[0144] In this embodiment, ideally, the spacing between adjacent intermediate parallel beam projection data should be the same. However, due to factors such as interpolation errors, the intermediate parallel beam projection data obtained by the actual computer device will also have errors, resulting in uneven spacing between adjacent intermediate parallel beam projection data.

[0145] Therefore, to improve the accuracy of the final parallel beam projection data bundle, the computer equipment also performs equal-spacing processing on each intermediate parallel beam projection data bundle to obtain multiple parallel beam projection data bundles. Equal-spacing means ensuring that the interval between each intermediate parallel beam projection data bundle is equal.

[0146] Optionally, the computer equipment may further interpolate the projection data of each intermediate parallel beam according to a preset interval to obtain the equally spaced projection data of each parallel beam. The preset interval can be set according to requirements and is a number greater than 0.

[0147] In this embodiment, based on the first correspondence between the projection data of each sector beam and the projection data of the parallel beam, interpolation processing is performed on the projection data of each sector beam to obtain the projection data of each intermediate parallel beam. Then, the intermediate parallel beam projection data are processed to achieve equal spacing, resulting in multiple parallel beam projection data sets. Thus, the parallel beam projection data determined by the computer device is more accurate, thereby improving the accuracy of the coordinates of the finally determined projection center.

[0148] Figure 12 This is a schematic diagram illustrating another process for obtaining multiple parallel beam projection data in an embodiment of this application. (Refer to...) Figure 12 This embodiment relates to an optional implementation of how to obtain multiple parallel beam projection data. Based on the above embodiment, S1102 above involves equalizing the spacing of each intermediate parallel beam projection data to obtain multiple parallel beam projection data, including the following steps:

[0149] S1201, take the minimum distance between each intermediate parallel beam projection data and the original channel as the target distance.

[0150] In this embodiment, Figure 13 This is a schematic diagram illustrating the principle of equal spacing in the embodiments of this application, such as... Figure 13 As shown, the computer device uses the minimum distance among the distances between each intermediate parallel beam projection data and the original channel as the target distance. Optionally, the computer device determines the target distance Δc according to the following formula (8).

[0151] Δc=SID*min (abs(γ c (8)

[0152] Where SID represents the distance from the X-ray source to the rotation center ISO, c represents the coordinates of the original channel in the detector, c = 1, 2, 3…N, γ c abs(γ) represents the sector angle of detector channel c. c ) represents the absolute value of the sector angle of detector channel c, min(abs(γ) c )) indicates taking the minimum absolute value of the sector angle of detector channel c.

[0153] S1202, based on the target distance, interpolate the projection data of two adjacent intermediate parallel beams to obtain multiple parallel beam projection data.

[0154] In this embodiment, after determining the target distance Δc, the computer device can interpolate the projection data of two adjacent intermediate parallel beams based on the target distance Δc to obtain multiple equally spaced parallel beam projection data.

[0155] Please continue to combine Figure 13 The equidistant parallel beam projection data is obtained by interpolating two adjacent original parallel beam projection data.

[0156] Optionally, the computer device first finds two original channels adjacent to the channel to be interpolated, then records the relevant linear interpolation coefficients between the two original channels and the interpolation channel, and performs linear interpolation based on the linear coefficients. The linear interpolation coefficient b can be determined according to the following equations (9) to (12).

[0157]

[0158] c = SID × sin(γ) (10)

[0159] c M =SID×sin (γ) M (11)

[0160] c M+1 =SID×sin (γ) M+1 (12)

[0161] Where c represents the interpolated channels with equal spacing, c M and c M+1 These are the physical coordinates of the two adjacent original channels. M is an integer greater than 0 and less than N.

[0162] Furthermore, using the linear interpolation coefficient b, the computer device can perform interpolation processing on the intermediate parallel beam projection data corresponding to two adjacent original channels of the interpolation channel according to the following equation (13) to obtain multiple parallel beam projection data P(θ,γ). c ).

[0163]

[0164] In other words, for detector channels 1 to N, at the same included angle θ, the computer device obtains 100 intermediate parallel beam projection data after projecting the sector beam data based on the above formula (4). The computer device will then further perform equal spacing on these 100 intermediate parallel beam projection data according to the above formula (13) to obtain rearranged parallel beam projection data. For example, when c = 10, the computer device rearranges the intermediate parallel beam projection data corresponding to c = 9 and the intermediate parallel beam projection data corresponding to c = 11 using the above formula (13) to obtain the parallel beam projection data corresponding to c = 10.

[0165] In this embodiment, the minimum distance between each intermediate parallel beam projection data and the original channel is taken as the target distance. Based on the target distance, interpolation processing is performed on two adjacent intermediate parallel beam projection data to obtain multiple parallel beam projection data. This improves the accuracy of the parallel beam projection data, thereby improving the accuracy of the projection center coordinates.

[0166] In summary, after the CT scanner begins scanning, the computer device first acquires multiple sector beam projection data of the subject at different scanning angles. Then, it rearranges these sector beam projection data to obtain multiple parallel beam projection data. Finally, it registers these multiple parallel beam projection data to determine the coordinates of the CT scanner's projection center. To more clearly illustrate the method for determining the projection center of the CT scanner in this embodiment, the following is combined with... Figure 14 illustrate, Figure 14 This is a schematic diagram of the overall process of determining the projection center of a CT device in an embodiment of this application.

[0167] like Figure 14 As shown, the computer equipment executes the projection center determination method of the CT equipment according to the following procedure.

[0168] S1401, acquire multiple sector beam projection data of the tested object at different scanning angles.

[0169] S1402, based on the first correspondence between the projection data of each sector beam and the projection data of the parallel beam, interpolation processing is performed on the projection data of each sector beam to obtain the projection data of each intermediate parallel beam.

[0170] S1403, the minimum distance among the distances between each intermediate parallel beam projection data and the original channel is taken as the target distance.

[0171] S1404, based on the target distance, interpolate the projection data of two adjacent intermediate parallel beams to obtain multiple parallel beam projection data.

[0172] S1405, determine at least one set of target parallel beam projection data from multiple parallel beam projection data; each set of target parallel beam projection data includes first parallel beam projection data and second parallel beam projection data at two opposing scanning angles.

[0173] S1406, for each group of target parallel beam projection data, the first parallel beam projection data is flipped along the first direction based on the center coordinates of the detector to obtain the corresponding third parallel beam projection data; the first direction is the radial direction of the detector.

[0174] S1407, according to the preset translation rules, the third parallel beam projection data is translated along the first direction to obtain the fourth parallel beam projection data.

[0175] S1408, determine the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation.

[0176] S1409, determine the target similarity from all similarities; the target similarity is the minimum value among all similarities.

[0177] S1410, determine the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity.

[0178] S1411, determine the coordinates of the projection center based on the center coordinates of the detector and the translation distance.

[0179] The principles of steps S1401 to S1411 can be found in the description of the above embodiments, and will not be repeated here.

[0180] 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.

[0181] Based on the same inventive concept, this application also provides a projection center determination device for CT equipment to implement the projection center determination method of the CT equipment described above. 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 projection center determination device for CT equipment provided below can be found in the limitations of the projection center determination method for CT equipment above, and will not be repeated here.

[0182] Figure 15 This is a structural block diagram of the projection center determination device of the CT equipment in the embodiments of this application, such as... Figure 15 As shown, this application provides a projection center determination device 1500 for a CT scanner, including: an acquisition module 1501, a rearrangement module 1502, a first determination module 1503, and a second determination module 1504, wherein:

[0183] The acquisition module 1501 is used to acquire multiple sector beam projection data of the tested object at different scanning angles.

[0184] The rearrangement module 1502 is used to rearrange the projection data of each sector beam to obtain multiple parallel beam projection data.

[0185] The first determining module 1503 is used to determine at least one set of target parallel beam projection data from multiple parallel beam projection data; each set of target parallel beam projection data includes parallel beam projection data of two opposing scanning angles.

[0186] The second determining module 1504 is used to determine the coordinates of the projection center of the CT device based on at least one set of target parallel beam projection data.

[0187] The projection center determination device for a CT scanner provided in this embodiment acquires multiple sector beam projection data of the tested object at different scanning angles, rearranges each sector beam projection data to obtain multiple parallel beam projection data, and then determines at least one set of target parallel beam projection data from the multiple parallel beam projection data. Each set of target parallel beam projection data includes parallel beam projection data from two opposing scanning angles, thereby determining the coordinates of the projection center of the CT scanner based on at least one set of target parallel beam projection data. Currently, the process of determining the coordinates of the projection center relies too heavily on steel ball phantoms. Since steel ball phantoms must be carried to the CT scanner site by specialized maintenance personnel, the current process of determining the coordinates of the projection center suffers from poor flexibility and waste of manpower. In this embodiment, since the parallel beam projection data is obtained from multiple sector beam projection data of the tested object at different scanning angles, and each set of target parallel beam projection data includes parallel beam projection data from two opposing scanning angles, the target parallel beam projection data can reflect the deviation of the projection center, thus allowing the coordinates of the projection center of the CT scanner to be determined based on the target parallel beam projection data. The entire determination process only uses the projection data of the CT equipment, without relying on the steel ball phantom, thus avoiding the problems of poor flexibility and wasted manpower in the current process of determining the coordinates of the projection center.

[0188] Optionally, the parallel beam projection data for the two opposing scanning angles includes first parallel beam projection data and second parallel beam projection data; the second determining module 1504 includes:

[0189] The flipping unit is used to flip the first parallel beam projection data along the first direction based on the center coordinates of the detector for each group of target parallel beam projection data to obtain the corresponding third parallel beam projection data; the first direction is the radial direction of the detector.

[0190] The determining unit is used to determine the coordinates of the projection center based on the second parallel beam projection data and the third parallel beam projection data.

[0191] Optionally, the determining unit includes:

[0192] The translation subunit is used to translate the third parallel beam projection data along the first direction according to a preset translation rule to obtain the fourth parallel beam projection data.

[0193] The first determining sub-unit is used to determine the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation.

[0194] The second determining sub-unit is used to determine the coordinates of the projection center based on each similarity.

[0195] Optionally, a second determining subunit is used to determine the target similarity from each similarity; the target similarity is the minimum value among all similarities; the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity is determined; and the coordinates of the projection center are determined based on the translation distance.

[0196] Optionally, the second determining subunit is also used to determine the coordinates of the projection center based on the center coordinates of the detector and the translation distance.

[0197] Optionally, the rearrangement module 1502 includes:

[0198] The interpolation unit is used to interpolate the projection data of each sector beam according to the first correspondence between the projection data of each sector beam and the projection data of the parallel beam, so as to obtain the projection data of each intermediate parallel beam.

[0199] The equal-spacing unit is used to equalize the spacing of the projection data of each intermediate parallel beam to obtain multiple parallel beam projection data.

[0200] Optionally, the equidistant units include:

[0201] The third determining sub-unit is used to take the minimum distance between the projection data of each intermediate parallel beam and the original channel as the target distance.

[0202] The interpolation subunit is used to interpolate the projection data of two adjacent intermediate parallel beams based on the target distance, so as to obtain multiple parallel beam projection data.

[0203] The various modules in the projection center determination device of the aforementioned CT equipment can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of the computer device in hardware form or independent of it, or stored in the memory of the computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0204] Figure 16 This is an internal structure diagram of a computer device in an embodiment of this application. This application provides a computer device, which may be a server, and its internal structure diagram can be as follows. Figure 16As shown, the computer device includes a processor, memory, and a network interface connected via a system bus. The processor provides computing 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 in the non-volatile storage media. The database stores relevant data. The network interface communicates with external terminals via a network connection. When executed by the processor, the computer program implements a method for determining the projection center of a CT scanner.

[0205] Those skilled in the art will understand that Figure 16 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.

[0206] This embodiment illustrates the application of this method to a server. It is understood that this method can also be applied to terminals, and to systems that include both terminals and servers, and is implemented through interaction between the terminal and the server. The terminal can be, but is not limited to, various personal computers, laptops, smartphones, and tablets. The server can be a standalone server or a server cluster consisting of multiple servers.

[0207] In one embodiment, a CT device is provided, which includes an X-ray source, a detector, and a computer device. The computer device can be a personal computer, laptop, smartphone, tablet, or portable wearable device located outside the detector, or a CPU, DSP, FPGA, or other programmable logic device located inside the photon counting detector.

[0208] The object under test is located between the X-ray source and the detector. After the X-ray source emits X-rays, the detector receives the X-rays that penetrate through the object under test and generates multiple fan-beam projection data of the object under test at different scanning angles based on the X-rays that penetrate through the object under test.

[0209] Furthermore, the CT scanner rotates around its rotation center ISO, allowing the computer to acquire multiple sector beam projection data of the subject at different scanning angles. These sector beam projection data are then rearranged to obtain multiple parallel beam projection data. From these parallel beam projection data, at least one set of target parallel beam projection data is determined, and based on this set, the coordinates of the CT scanner's projection center are determined. Each set of target parallel beam projection data includes parallel beam projection data from two opposing scanning angles.

[0210] Optionally, when determining the coordinates of the projection center of the CT device, the computer device can, for each group of target parallel beam projection data, flip the first parallel beam projection data along the first direction based on the center coordinates of the detector to obtain the corresponding third parallel beam projection data; the first direction is the radial direction of the detector; and determine the coordinates of the projection center based on the second and third parallel beam projection data.

[0211] Optionally, the computer device can also translate the third parallel beam projection data along the first direction according to a preset translation rule to obtain the fourth parallel beam projection data; determine the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation; and determine the coordinates of the projection center based on each similarity.

[0212] Optionally, when determining the coordinates of the projection center based on each similarity, the computer device can determine the target similarity from each similarity; the target similarity is the minimum value among all similarities; determine the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity; and determine the coordinates of the projection center based on the translation distance.

[0213] Optionally, the computer equipment can determine the coordinates of the projection center based on the center coordinates of the detector and the translation distance.

[0214] Optionally, when rearranging the projection data of each sector beam, the computer device can perform interpolation processing on each sector beam projection data according to the first correspondence between each sector beam projection data and the parallel beam projection data to obtain each intermediate parallel beam projection data; and perform equal spacing processing on each intermediate parallel beam projection data to obtain multiple parallel beam projection data.

[0215] Optionally, when the computer device obtains multiple parallel beam projection data, it can take the minimum distance between each intermediate parallel beam projection data and the original channel as the target distance; based on the target distance, it can perform interpolation processing on two adjacent intermediate parallel beam projection data to obtain multiple parallel beam projection data.

[0216] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0217] Acquire multiple sector beam projection data of the tested object at different scanning angles;

[0218] The projected data of each sector beam are rearranged to obtain multiple parallel beam projected data;

[0219] At least one set of target parallel beam projection data is determined from the plurality of parallel beam projection data; each set of target parallel beam projection data includes parallel beam projection data of two opposing scanning angles;

[0220] The coordinates of the projection center of the CT device are determined based on the at least one set of target parallel beam projection data.

[0221] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0222] For each set of target parallel beam projection data, the first parallel beam projection data is flipped along the first direction based on the center coordinates of the detector to obtain the corresponding third parallel beam projection data; the first direction is the radial direction of the detector; the coordinates of the projection center are determined according to the second parallel beam projection data and the third parallel beam projection data.

[0223] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0224] According to a preset translation rule, the third parallel beam projection data is translated along the first direction to obtain the fourth parallel beam projection data; the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation is determined; and the coordinates of the projection center are determined based on the similarity scores.

[0225] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0226] A target similarity is determined from the aforementioned similarities; the target similarity is the minimum value among the aforementioned similarities; the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity is determined; the coordinates of the projection center are determined based on the translation distance.

[0227] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0228] The coordinates of the projection center are determined based on the center coordinates of the detector and the translation distance.

[0229] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0230] Based on the first correspondence between the sector beam projection data and the parallel beam projection data, interpolation processing is performed on the sector beam projection data to obtain the intermediate parallel beam projection data; the intermediate parallel beam projection data is then processed to equalize the spacing to obtain multiple parallel beam projection data.

[0231] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0232] The minimum distance among the distances between each of the intermediate parallel beam projection data and the original channel is taken as the target distance; based on the target distance, interpolation processing is performed on two adjacent intermediate parallel beam projection data to obtain the plurality of parallel beam projection data.

[0233] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0234] Acquire multiple sector beam projection data of the tested object at different scanning angles;

[0235] The projected data of each sector beam are rearranged to obtain multiple parallel beam projected data;

[0236] At least one set of target parallel beam projection data is determined from the plurality of parallel beam projection data; each set of target parallel beam projection data includes parallel beam projection data of two opposing scanning angles;

[0237] The coordinates of the projection center of the CT device are determined based on the at least one set of target parallel beam projection data.

[0238] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0239] For each set of target parallel beam projection data, the first parallel beam projection data is flipped along the first direction based on the center coordinates of the detector to obtain the corresponding third parallel beam projection data; the first direction is the radial direction of the detector; the coordinates of the projection center are determined according to the second parallel beam projection data and the third parallel beam projection data.

[0240] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0241] According to a preset translation rule, the third parallel beam projection data is translated along the first direction to obtain the fourth parallel beam projection data; the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation is determined; and the coordinates of the projection center are determined based on the similarity scores.

[0242] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0243] A target similarity is determined from the aforementioned similarities; the target similarity is the minimum value among the aforementioned similarities; the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity is determined; the coordinates of the projection center are determined based on the translation distance.

[0244] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0245] The coordinates of the projection center are determined based on the center coordinates of the detector and the translation distance.

[0246] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0247] Based on the first correspondence between the sector beam projection data and the parallel beam projection data, interpolation processing is performed on the sector beam projection data to obtain the intermediate parallel beam projection data; the intermediate parallel beam projection data is then processed to equalize the spacing to obtain multiple parallel beam projection data.

[0248] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0249] The minimum distance among the distances between each of the intermediate parallel beam projection data and the original channel is taken as the target distance; based on the target distance, interpolation processing is performed on two adjacent intermediate parallel beam projection data to obtain the plurality of parallel beam projection data.

[0250] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, performs the following steps:

[0251] Acquire multiple sector beam projection data of the tested object at different scanning angles;

[0252] The projected data of each sector beam are rearranged to obtain multiple parallel beam projected data;

[0253] At least one set of target parallel beam projection data is determined from the plurality of parallel beam projection data; each set of target parallel beam projection data includes parallel beam projection data of two opposing scanning angles;

[0254] The coordinates of the projection center of the CT device are determined based on the at least one set of target parallel beam projection data.

[0255] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0256] For each set of target parallel beam projection data, the first parallel beam projection data is flipped along the first direction based on the center coordinates of the detector to obtain the corresponding third parallel beam projection data; the first direction is the radial direction of the detector; the coordinates of the projection center are determined according to the second parallel beam projection data and the third parallel beam projection data.

[0257] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0258] According to a preset translation rule, the third parallel beam projection data is translated along the first direction to obtain the fourth parallel beam projection data; the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation is determined; and the coordinates of the projection center are determined based on the similarity scores.

[0259] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0260] A target similarity is determined from the aforementioned similarities; the target similarity is the minimum value among the aforementioned similarities; the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity is determined; the coordinates of the projection center are determined based on the translation distance.

[0261] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0262] The coordinates of the projection center are determined based on the center coordinates of the detector and the translation distance.

[0263] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0264] Based on the first correspondence between the sector beam projection data and the parallel beam projection data, interpolation processing is performed on the sector beam projection data to obtain the intermediate parallel beam projection data; the intermediate parallel beam projection data is then processed to equalize the spacing to obtain multiple parallel beam projection data.

[0265] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0266] The minimum distance among the distances between each of the intermediate parallel beam projection data and the original channel is taken as the target distance; based on the target distance, interpolation processing is performed on two adjacent intermediate parallel beam projection data to obtain the plurality of parallel beam projection data.

[0267] 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 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, etc., and are not limited to these.

[0268] 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 specification.

[0269] 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 determining the projection center of a CT scanner, characterized in that, The method includes: Acquire multiple sector beam projection data of the tested object at different scanning angles; The projected data of each sector beam are rearranged to obtain multiple parallel beam projected data; At least one set of target parallel beam projection data is determined from the plurality of parallel beam projection data; each set of target parallel beam projection data includes parallel beam projection data at two opposing scanning angles; the parallel beam projection data at the two opposing scanning angles includes first parallel beam projection data and second parallel beam projection data; For each set of target parallel beam projection data, the first parallel beam projection data is flipped along the first direction based on the center coordinates of the detector to obtain the corresponding third parallel beam projection data; the first direction is the radial direction of the detector; According to the preset translation rules, the third parallel beam projection data is translated along the first direction to obtain the fourth parallel beam projection data; Determine the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation; The coordinates of the projection center are determined based on the aforementioned similarity.

2. The method according to claim 1, characterized in that, Determining the coordinates of the projection center based on each similarity score includes: The target similarity is determined from the aforementioned similarities; the target similarity is the minimum value among the aforementioned similarities. Determine the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity; The coordinates of the projection center are determined based on the translation distance.

3. The method according to claim 2, characterized in that, Determining the coordinates of the projection center based on the translation distance includes: The coordinates of the projection center are determined based on the center coordinates of the detector and the translation distance.

4. The method according to any one of claims 1-3, characterized in that, The rearrangement of the projection data of each sector beam to obtain multiple parallel beam projection data includes: Based on the first correspondence between each of the sector beam projection data and the parallel beam projection data, interpolation processing is performed on each of the sector beam projection data to obtain each intermediate parallel beam projection data. The intermediate parallel beam projection data are processed to be equally spaced to obtain multiple parallel beam projection data.

5. The method according to claim 4, characterized in that, The process of equalizing the spacing of each intermediate parallel beam projection data results in multiple parallel beam projection data, including: The minimum distance among the distances between each intermediate parallel beam projection data and the original channel is taken as the target distance; Based on the target distance, interpolation processing is performed on the projection data of two adjacent intermediate parallel beams to obtain the multiple parallel beam projection data.

6. A projection center determination device for a CT scanner, characterized in that, The device includes: The acquisition module is used to acquire multiple fan-beam projection data of the tested object at different scanning angles; The rearrangement module is used to rearrange the projected data of each sector beam to obtain multiple parallel beam projected data. The first determining module is used to determine at least one set of target parallel beam projection data from the plurality of parallel beam projection data; each set of target parallel beam projection data includes parallel beam projection data at two opposing scanning angles; the parallel beam projection data at the two opposing scanning angles includes first parallel beam projection data and second parallel beam projection data. The second determining module is used to, for each group of target parallel beam projection data, flip the first parallel beam projection data along a first direction based on the center coordinates of the detector to obtain the corresponding third parallel beam projection data; the first direction is the radial direction of the detector; translate the third parallel beam projection data along the first direction according to a preset translation rule to obtain fourth parallel beam projection data; determine the similarity between the second parallel beam projection data and the fourth parallel beam projection data obtained after each translation; and determine the coordinates of the projection center based on each similarity.

7. The apparatus according to claim 6, characterized in that, The second determining module is further configured to determine a target similarity from each of the aforementioned similarities; the target similarity is the minimum value among the aforementioned similarities; determine the translation distance corresponding to the fourth parallel beam projection data corresponding to the target similarity; and determine the coordinates of the projection center based on the translation distance.

8. The apparatus according to claim 7, characterized in that, The second determining module is further configured to determine the coordinates of the projection center based on the center coordinates of the detector and the translation distance.

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 steps of the method according to any one of claims 1 to 5.

10. A CT scanner, characterized in that, The CT device includes: A radiation source, used to emit radiation; A detector is used to receive the rays and generate multiple fan-beam projection data of the object under test at different scanning angles based on the rays penetrating from the object under test. A computer device for performing the method according to any one of claims 1-5.

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