CT image reconstruction method, apparatus, and system, and storage medium

Abstract

The present disclosure provides a CT image reconstruction method, apparatus, and system, and a storage medium. The CT image reconstruction method comprises: acquiring coordinate values of N target points on a target object at a specified moment, N being a natural number greater than 1, and the target object being an object undergoing CT scanning in a CT scanning device; by using the coordinate values of the N target points at the specified moment and coordinate values of the center of rotation of the CT scanning device, determining a deflection angle of the target object; by using the deflection angle and the coordinate values of the center of rotation, correcting coordinate values of each point in a current scanning area of the target object, so as to obtain corrected coordinate values of each point; and, by using the corrected coordinate values of each point and projection data acquired at the specified moment, obtaining a reconstructed CT image.

Description

CT image reconstruction method, device and system, and storage medium

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure is based on and claims priority to CN application number 202311572096.4, filed on November 23, 2023, and CN application number 202410353676.2, filed on March 26, 2024. The disclosure content of the CN application is hereby introduced as a whole into this disclosure. Technical Field

[0003] The present disclosure relates to the field of CT detection technology, and in particular to a CT image reconstruction method, device and system, and storage medium. Background Art

[0004] X-ray inspection technology offers clear images, strong readability, high real-time performance, and low labor costs, making it a common method for rapid nondestructive testing. In particular, CT (Computed Tomography)-based tomography and imaging, which reconstructs internal structures by capturing projection images of an object from different angles, excels in detecting structural differences, cavities, looseness, wrinkles, and other defects.

[0005] For large objects, CT scanning is difficult with self-rotation, so a method using a scanner that rotates and translates the object is used. The object is moved within the scanning channel by a movable component, translating the portion to be scanned into the radiation exposure area. The scanner then rotates the radiation source and detector to obtain the image information required for CT reconstruction.

[0006] Summary of the Invention

[0007] According to a first aspect of an embodiment of the present disclosure, a CT image reconstruction method is provided, comprising: acquiring coordinate values ​​of N target points on a target object at a specified time, where N is a natural number greater than 1, wherein the target object is an object undergoing CT scanning in a CT scanning device; determining a deflection angle of the target object using the coordinate values ​​of the N target points at the specified time and a rotation center coordinate value of the CT scanning device; correcting the coordinate value of each point in a current scanning area of ​​the target object using the deflection angle and the rotation center coordinate value to obtain a corrected coordinate value of each point; and obtaining a reconstructed CT image using the corrected coordinate value of each point and projection data acquired at the specified time.

[0008] In some embodiments, determining the deflection angle of the target object includes: when N is equal to 2, using the coordinate values ​​of two target points on the target object at the specified moment and the coordinate value of the rotation center to obtain the deflection angle of the target object.

[0009] In some embodiments, the deflection angle of the target object is the average of a first angle parameter and a second angle parameter, wherein the first angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the first target point among the two target points at the specified time, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value, and the second angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the second target point among the two target points at the specified time, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value.

[0010] In some embodiments, the first angle parameter is the inverse tangent function value of the ratio of the first difference to the second difference, the first difference is the difference between the y-axis coordinate value of the first target point in the coordinate value at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the second difference is the difference between the x-axis coordinate value of the first target point in the coordinate value at the specified time and the x-axis coordinate value of the rotation center coordinate value; the second angle parameter is the inverse tangent function value of the ratio of the third difference to the fourth difference, the third difference is the difference between the y-axis coordinate value of the second target point in the coordinate value at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the fourth difference is the difference between the x-axis coordinate value of the second target point in the coordinate value at the specified time and the x-axis coordinate value of the rotation center coordinate value.

[0011] In some embodiments, determining the deflection angle of the target object includes: when N is greater than 2, using the N target points to generate K different sets, K is a natural number greater than 1, and each set includes two target points from the N target points; using the coordinate values ​​of the two target points in the i-th set at the specified moment and the rotation center coordinate value of the CT scanning device to obtain the i-th deflection angle, 1≤n≤K; and using the obtained K deflection angles to generate the deflection angle of the target object.

[0012] In some embodiments, the i-th deflection angle is the average value of a third angle parameter and a fourth angle parameter, wherein the third angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value of the first target point among the two target points in the i-th set at the specified moment, and the x-axis coordinate value and the y-axis coordinate value of the rotation center coordinate value, and the fourth angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value of the second target point among the two target points in the i-th set at the specified moment, and the x-axis coordinate value and the y-axis coordinate value of the rotation center coordinate value.

[0013] In some embodiments, the third angle parameter is the inverse tangent function value of the ratio of the fifth difference to the sixth difference, the fifth difference is the difference between the y-axis coordinate value of the first target point in the coordinate value at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the sixth difference is the difference between the x-axis coordinate value of the first target point in the coordinate value at the specified time and the x-axis coordinate value of the rotation center coordinate value; the fourth angle parameter is the inverse tangent function value of the ratio of the seventh difference to the eighth difference, the seventh difference is the difference between the y-axis coordinate value of the second target point in the coordinate value at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the eighth difference is the difference between the x-axis coordinate value of the second target point in the coordinate value at the specified time and the x-axis coordinate value of the rotation center coordinate value.

[0014] In some embodiments, the deflection angle of the target object is an average value of the K deflection angles, or a median of the K deflection angles.

[0015] In some embodiments, the x-axis coordinate value in the corrected coordinate value of each point is determined by the difference between the first correction parameter and the second correction parameter, the first correction parameter is determined by the x-axis coordinate value in the coordinate value of each point, the x-axis coordinate value of the rotation center coordinate value and the cosine value of the deflection angle, the second correction parameter is determined by the y-axis coordinate value in the coordinate value of each point, the y-axis coordinate value of the rotation center coordinate value and the sine value of the deflection angle; the y-axis coordinate value in the corrected coordinate value of each point is determined by the sum of the third correction parameter and the fourth correction parameter, the third correction parameter is determined by the x-axis coordinate value in the coordinate value of each point, the x-axis coordinate value of the rotation center coordinate value and the sine value of the deflection angle, and the fourth correction parameter is determined by the y-axis coordinate value in the coordinate value of each point, the y-axis coordinate value of the rotation center coordinate value and the cosine value of the deflection angle.

[0016] In some embodiments, the first correction parameter is the product of the difference between the x-axis coordinate value in the coordinate value of each point and the x-axis coordinate value of the rotation center coordinate value and the cosine value of the deflection angle; the second correction parameter is the product of the difference between the y-axis coordinate value in the coordinate value of each point and the y-axis coordinate value of the rotation center coordinate value and the sine value of the deflection angle; the third correction parameter is the product of the difference between the x-axis coordinate value in the coordinate value of each point and the x-axis coordinate value of the rotation center coordinate value and the sine value of the deflection angle; the fourth correction parameter is the product of the difference between the y-axis coordinate value in the coordinate value of each point and the y-axis coordinate value of the rotation center coordinate value and the cosine value of the deflection angle.

[0017] In some embodiments, the coordinate value of the nth target point among the N target points at the specified moment is determined by the coordinate value of the nth position monitoring device corresponding to the nth target point, the distance between the nth position monitoring device and the nth target point at the specified moment, and the angle between the line connecting the nth position monitoring device and the nth target point and the y-axis at the specified moment, wherein the N target points and the N position monitoring devices correspond one to one, and 1≤n≤N.

[0018] In some embodiments, the y-axis coordinate value of the coordinate value of the nth target point at the specified moment is the difference between the y-axis coordinate value of the coordinate value of the nth position monitoring device and the first product, where the first product is the product of the distance and the cosine value of the angle.

[0019] In some embodiments, when the x-axis coordinate value in the coordinate value of the nth position monitoring device is less than or equal to 0, the x-coordinate value in the coordinate value of the nth target point at the specified moment is the sum of the x-axis coordinate value in the coordinate value of the nth position monitoring device and a second product, where the second product is the product of the distance and the sine value of the angle.

[0020] In some embodiments, when the x-axis coordinate value in the coordinate value of the nth position monitoring device is greater than or equal to 0, the x-coordinate value in the coordinate value of the nth target point at the specified moment is the difference between the x-axis coordinate value in the coordinate value of the nth position monitoring device and the second product.

[0021] According to a second aspect of an embodiment of the present disclosure, a CT image reconstruction device is provided, comprising: a first processing module configured to obtain coordinate values ​​of N target points on a target object at a specified moment, where N is a natural number greater than 1, wherein the target object is an object undergoing CT scanning in a CT scanning device; a second processing module configured to determine a deflection angle of the target object using the coordinate values ​​of the N target points at the specified moment and a rotation center coordinate value of the CT scanning device; a third processing module configured to correct the coordinate value of each point in a current scanning area of ​​the target object using the deflection angle and the rotation center coordinate value to obtain a corrected coordinate value of each point; and a fourth processing module configured to obtain a reconstructed CT image using the corrected coordinate value of each point and projection data obtained at the specified moment.

[0022] According to a third aspect of an embodiment of the present disclosure, a CT image reconstruction device is provided, comprising: a memory; and a processor coupled to the memory, the processor being configured to execute the method described in any of the above embodiments based on instructions stored in the memory.

[0023] According to a fourth aspect of an embodiment of the present disclosure, a CT image reconstruction system is provided, comprising: a CT image reconstruction apparatus as described in any of the above embodiments; a CT scanning device configured to perform a CT scan on a target object and send acquired projection data to the CT image reconstruction apparatus; N position monitoring devices corresponding one-to-one to N target points on the target object, where N is a natural number greater than 1, and each of the N position monitoring devices is configured to detect the distance between each position monitoring device and the corresponding target point at the specified moment, and the angle between the line connecting each position monitoring device and the corresponding target point and the y-axis.

[0024] According to a fifth aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and when the instructions are executed by a processor, the method described in any of the above embodiments is implemented.

[0025] According to a sixth aspect of an embodiment of the present disclosure, a computer program product is provided, comprising computer instructions, wherein when the computer instructions are executed by a processor, the method described in any of the above embodiments is implemented.

[0026] According to a seventh aspect of an embodiment of the present disclosure, a computer program is provided, comprising computer instructions, wherein when the computer instructions are executed by a processor, the method described in any of the above embodiments is implemented.

[0027] Other features and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0029] FIG1 is a side view of a CT scan of a large object according to an embodiment of the present disclosure;

[0030] FIG2 is a front view of a CT scan of a large object according to an embodiment of the present disclosure;

[0031] FIG3 is a flow chart of a CT image reconstruction method according to an embodiment of the present disclosure;

[0032] FIG4 is a front view of a CT scan of a large object according to another embodiment of the present disclosure;

[0033] FIG5 is a front view of a large object CT scan according to another embodiment of the present disclosure;

[0034] FIG6 is a schematic structural diagram of a CT image reconstruction device according to an embodiment of the present disclosure;

[0035] FIG7 is a schematic structural diagram of a CT image reconstruction device according to another embodiment of the present disclosure;

[0036] FIG8 is a schematic structural diagram of a CT image reconstruction system according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present disclosure and its application or use. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0038] Unless specifically stated otherwise, the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure.

[0039] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0040] Technologies, methods and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods and equipment should be considered part of the authorization specification.

[0041] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0042] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0043] The inventors noticed that large objects may shift in the scanning channel, thus affecting the image quality of the scanned part. For example, wind turbine blades are long (usually 50 meters to hundreds of meters), but have a low overall density (hollow inside, and the shell material is generally a composite material with a density of 2g / cm 3 During the scanning process, the position of the scanned part is easily affected by the jitter of other parts and shifts, resulting in distortion of the CT scan data at certain angles, which seriously affects the image reconstruction and defect judgment of the internal structure of the blade.

[0044] For example, a side view of a large object being scanned using a CT scanning device is shown in FIG1 , and a corresponding front view is shown in FIG2 .

[0045] In Figures 1 and 2, an X-ray source 1 is mounted on a rotating bracket 3, providing X-rays of appropriate energy and dose, enabling the rays to penetrate an object 4 and achieve the required level of recognition for defect detection across different materials. The source can be an X-ray machine or an accelerator.

[0046] Detector 2 is mounted on the opposite side of X-ray source 1 on a rotating bracket 3. It receives X-rays after they pass through object 4 and converts them into digital signals for data processing and image reconstruction. Generally, the fan-shaped radiation plane from X-ray source 1 to detector 2 must completely cover the object being inspected. Detector 2 can be arranged in a single or multiple rows.

[0047] The rotating bracket 3 carries the X-ray source 1 and detector 2, rotating them synchronously to obtain projection data at a sufficient angle. The rotating bracket 3 needs to ensure sufficient end face and radial operation stability so that the scanning trajectory of the ray fan beam is as close to a plane circle as possible.

[0048] The carrier 5 is used to carry and move an object through the scanning channel. During tomographic or cone-beam CT scanning, the carrier 5 drags the object to a designated position and stops. The rotating bracket 3 drives the X-ray source 1 and detector 2 to rotate synchronously, collecting data from multiple angles within the object's slice. After the current position is acquired, the carrier 5 drags the object to the next position, and the process repeats. During spiral CT scanning, the rotating bracket 3 drives the X-ray source 1 and detector 2 to rotate. Simultaneously, the carrier 5 drags the object to a uniform motion within the scanning channel, collecting spiral projection images of the object.

[0049] CT scanners also include data processing and image reconstruction systems. The data processing system receives data collected by the detector and integrates relevant information required for image reconstruction to generate projection image data. The image reconstruction system processes the projection image to produce a two-dimensional or three-dimensional image of the objects within the scanning area.

[0050] For example, taking slice scanning as an example, when there is no position jitter in the scanned object, the collected projection data is as shown in formula (1).

[0051] Where p is the projection data, β is the projection angle, s is the coordinate of the detector, and μ(x, y) is the linear attenuation coefficient distribution of the object and its internal space, that is, μ(x, y) is used to generate the reconstructed CT image.

[0052] It should be noted that the projection angle β is the angle between the fan beam center line 12mid and the positive direction of the X-axis.

[0053] The inventors noticed that when the scanned object is shaking, the collected projection data is as shown in formulas (2) to (4). x′=x+Δx (3) y′=y+Δy (4)

[0054] Δx and Δy are the displacement components of a point within the object on the x-axis and y-axis, respectively, due to jitter. This jitter can come from wind, machinery, vibration, human effort, and other factors, leading to errors or deviations in the projection data, distorting the reconstructed CT image, and affecting the identification of defects in the object.

[0055] Accordingly, the present disclosure provides a CT image reconstruction solution that can effectively correct the CT image distortion problem caused by object shaking.

[0056] Figure 3 is a flow chart of a CT image reconstruction method according to an embodiment of the present disclosure. In some embodiments, the following CT image reconstruction method is performed by a CT image reconstruction device.

[0057] In step 301 , coordinate values ​​of N target points on a target object at a specified time are obtained, where N is a natural number greater than 1, and the target object is an object to be CT scanned in a CT scanning device.

[0058] In some embodiments, a position monitoring device can be used to obtain the coordinate value of a target point on a target object. For example, the coordinate value of the nth target point among N target points at a specified time can be determined by the coordinate value of the nth position monitoring device corresponding to the nth target point, the distance between the nth position monitoring device and the nth target point at the specified time, and the angle between the line connecting the nth position monitoring device and the nth target point and the y-axis at the specified time, wherein the N target points and the N position monitoring devices correspond one to one, and 1≤n≤N. It should be noted here that the position monitoring device is usually fixedly set in the scanning channel of the CT scanning device. Therefore, for example, when the rotation center of the rotating bracket 3 of the CT scanning device is set as the origin of the coordinate system, the coordinate value of the position monitoring device is known.

[0059] For example, when N is 2, the coordinates of the first target point on the target object are obtained using the first position monitoring device, and the coordinates of the second target point on the target object are obtained using the second position monitoring device. Let the straight line between the first position monitoring device and the first target point be the first straight line, and the straight line between the second position monitoring device and the second target point be the second straight line. A certain angle must exist between the first straight line and the second straight line so that the jitter of the first and second target points can be detected to reconstruct the jitter condition within the entire two-dimensional plane.

[0060] It should be noted that if the first straight line and the second straight line are approximately parallel, it is difficult to reconstruct the two-dimensional coordinates, or the reconstruction result has a large deviation. In some embodiments, the angle between the first straight line and the second straight line is approximately 90°.

[0061] For another example, when N is 3, the coordinate value of the first target point on the target object is obtained using the first position monitoring device, the coordinate value of the second target point on the target object is obtained using the second position monitoring device, and the coordinate value of the third target point on the target object is obtained using the third position monitoring device. Let the straight line between the first position monitoring device and the first target point be the first straight line, the straight line between the second position monitoring device and the second target point be the second straight line, and the straight line between the third position monitoring device and the third target point be the third straight line. To ensure that every two straight lines from the first straight line to the third straight line have a certain angle, the coverage angle of these three position monitoring devices is at least 180°.

[0062] It should also be noted that when N is 1, that is, the coordinate value of one target point on the target object is obtained using one position monitoring device. Since it is impossible to calculate a unique linear transformation based on the coordinate value of one target point, at least two target points are selected on the target object.

[0063] In some embodiments, non-contact distance detection can be performed using methods such as laser ranging, radar ranging, and ultrasonic ranging to obtain the distance between the position monitoring device and the target point at a specified time. Accordingly, the position monitoring device can include a laser rangefinder, radar rangefinder, ultrasonic rangefinder, etc.

[0064] It should also be noted that when multiple position monitoring devices are fixedly installed in the scanning channel of a CT scanner, each position monitoring device should be installed away from the X-ray beam plane, but not too far away. For example, each position monitoring device should be installed within a few centimeters of the X-ray beam plane. This ensures that the measurement of each position monitoring device does not affect X-ray image acquisition, while effectively detecting jitter in the current scanning position.

[0065] In some embodiments, the y-axis coordinate value of the coordinate value of the nth target point at a specified time is the difference between the y-axis coordinate value of the coordinate value of the nth position monitoring device and the first product, where the first product is the product of the distance and the cosine value of the angle.

[0066] In some embodiments, when the x-axis coordinate value in the coordinate value of the nth position monitoring device is less than or equal to 0, the x-coordinate value in the coordinate value of the nth target point at a specified moment is the sum of the x-axis coordinate value in the coordinate value of the nth position monitoring device and the second product, and the second product is the product of the distance and the sine value of the angle.

[0067] In some embodiments, when the x-axis coordinate value in the coordinate value of the nth position monitoring device is greater than or equal to 0, the x-coordinate value in the coordinate value of the nth target point at a specified moment is the difference between the x-axis coordinate value in the coordinate value of the nth position monitoring device and the second product.

[0068] As shown in Figure 4, in order to detect the shaking of the object, a position monitoring device I and a position monitoring device II are fixedly installed in the CT scanning channel. For the convenience of description, in Figure 4, the rotation center of the rotating bracket 3 of the CT scanning device is set as the origin of the coordinate system, and the x-axis coordinate value of the coordinate value of the position monitoring device I is set as x I , the y-axis coordinate value in the coordinate value of the position monitoring device 1 is set to y I , set the x-axis coordinate value in the coordinate value of the position monitoring device II to x II , set the y-axis coordinate value of the position monitoring device II to y IIThe distance between the position monitoring device I and the target point A at the specified time is d I (t), the angle between the line connecting the position monitoring device I and the target point A and the y-axis at the specified time is γ I (t). The distance between the position monitoring device II and the target point B at the specified time is d II (t), the angle between the line connecting the position monitoring device II and the target point B and the y-axis at the specified time is γ II (t). Thus, the coordinate value of target point A at the specified time is shown in formula (5), and the coordinate value of target point B at the specified time is shown in formula (6). (x A (t),y A (t))=(x I +d I (t)·sin(γ I (t)),y I -d I (t)·cos(γ I (t))) (5) (x B (t),y B (t))=(x II -d II (t)·sin(γ II (t)),y II -d II (t)·cos(γ II (t))) (6)

[0069] Among them, (x I ,y I ) is the coordinate of the position monitoring device I, (x II ,y II ) are the coordinates of the position monitoring device II.

[0070] In some embodiments, as shown in FIG4 , for a first straight line between position monitoring device I and target point A and a second straight line between position monitoring device II and target point B, the angle between the first straight line and the second straight line is about 90°.

[0071] In step 302, the deflection angle of the target object is determined using the coordinate values ​​of the N target points at a specified time and the coordinate value of the rotation center of the CT scanning device.

[0072] For example, as shown in FIG. 4 , since the target object 4 is deflected, the target object 4 is deflected from the black area to the gray area.

[0073] In some embodiments, when N is equal to 2, the deflection angle of the target object is obtained using the coordinate values ​​of two target points on the target object at a specified time and the coordinate value of the rotation center.

[0074] In some embodiments, the deflection angle of the target object is the average of a first angle parameter and a second angle parameter, wherein the first angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the first target point of the two target points at a specified time, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value, and the second angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the second target point of the two target points at a specified time, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value.

[0075] In some embodiments, the first angle parameter is an inverse tangent function value of the ratio of the first difference to the second difference, where the first difference is the difference between the y-axis coordinate value of the coordinate value of the first target point at a specified time and the y-axis coordinate value of the rotation center coordinate value, and the second difference is the difference between the x-axis coordinate value of the coordinate value of the first target point at a specified time and the x-axis coordinate value of the rotation center coordinate value. The second angle parameter is an inverse tangent function value of the ratio of the third difference to the fourth difference, where the third difference is the difference between the y-axis coordinate value of the coordinate value of the second target point at a specified time and the y-axis coordinate value of the rotation center coordinate value, and the fourth difference is the difference between the x-axis coordinate value of the coordinate value of the second target point at a specified time and the x-axis coordinate value of the rotation center coordinate value.

[0076] For example, as shown in FIG4 , there are two target points on the target object, namely, target point A and target point B. Then the deflection angle Δθ of the target object is as shown in formula (7).

[0077] Among them, (x A (t),y A (t)) is the coordinate of the target point A at the specified time, (x B (t),y B (t)) is the coordinate of target point B at the specified time, and (x0, y0) is the coordinate value of the rotation center.

[0078] In some embodiments, when N is greater than 2, K distinct sets are generated using the N target points, where K is a natural number greater than 1, and each set includes two target points from the N target points. The i-th deflection angle is obtained using the coordinate values ​​of the two target points in the i-th set at a specified time and the coordinate value of the rotation center of the CT scanner, where 1 ≤ i ≤ K. Next, the deflection angle of the target object is generated using the obtained K deflection angles.

[0079] In some embodiments, the deflection angle of the target object is an average of K deflection angles, or a median of K deflection angles.

[0080] In some embodiments, the i-th deflection angle is the average of a third angle parameter and a fourth angle parameter, wherein the third angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the first target point of the two target points in the i-th set at a specified moment, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value, and the fourth angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the second target point of the two target points in the i-th set at a specified moment, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value.

[0081] In some embodiments, the third angle parameter is the inverse tangent function value of the ratio of the fifth difference to the sixth difference, the fifth difference being the difference between the y-axis coordinate value of the coordinate value of the first target point at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the sixth difference being the difference between the x-axis coordinate value of the coordinate value of the first target point at the specified time and the x-axis coordinate value of the rotation center coordinate value. The fourth angle parameter is the inverse tangent function value of the ratio of the seventh difference to the eighth difference, the seventh difference being the difference between the y-axis coordinate value of the coordinate value of the second target point at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the eighth difference being the difference between the x-axis coordinate value of the coordinate value of the second target point at the specified time and the x-axis coordinate value of the rotation center coordinate value.

[0082] As shown in Figure 5, there are three target points on the target object, namely, target point A, target point B, and target point C. In this case, multiple different sets are generated using the three target points. For example, the first set includes target point A and target point B, the second set includes target point A and target point C, and the third set includes target point B and target point C.

[0083] First, using the first set, we get the first deflection angle Δθ AB As shown in formula (8).

[0084] Among them, (x A (t),y A (t)) is the coordinate of the target point A at the specified time, (x B (t),y B (t)) is the coordinate of target point B at the specified time, and (x0, y0) is the coordinate value of the rotation center.

[0085] Using the second set, the second deflection angle Δθ is obtained AC As shown in formula (9).

[0086] Among them, (x C (t),y C (t)) is the coordinate of the target point C at the specified time.

[0087] Using the third set, we get the third deflection angle Δθ BC As shown in formula (10).

[0088] It should be noted that since the object is rigidly rotating, theoretically Δθ AB =Δθ AC =Δθ BC In this case, using Δθ AB , Δθ AC , Δθ BC The average or median of the deflection angle is used to represent the overall deflection angle of the object.

[0089] In some embodiments, in order to save computational cost, when there are target points A, B, and C on the target object, only Δθ AB , Δθ AC and Δθ BC For example, using only Δθ AB and Δθ AC Calculate the overall deflection angle of the object. In some embodiments, as shown in FIG5 , the line between position monitoring device I and target point A is defined as a first line, the line between position monitoring device II and target point B is defined as a second line, and the line between position monitoring device III and target point C is defined as a third line. To ensure that every two lines from the first to the third lines have a certain angle, the coverage angle of position monitoring devices I, II, and III is at least 180°.

[0090] In some embodiments, as shown in FIG5 , if target points A, B, and C are located in the same plane, the above processing can be used to obtain the deflection angle in a two-dimensional scene. If target points A, B, and C are located in different planes, the above processing can be used to obtain the deflection angle in a three-dimensional scene.

[0091] In step 303 , the coordinate value of each point in the current scanning area of ​​the target object is corrected using the deflection angle and the rotation center coordinate value to obtain a corrected coordinate value of each point.

[0092] In some embodiments, the x-axis coordinate value in the corrected coordinate value of each point is determined by the difference between the first correction parameter and the second correction parameter, the first correction parameter is determined by the x-axis coordinate value in the coordinate value of each point, the x-axis coordinate value of the rotation center coordinate value, and the cosine value of the deflection angle, and the second correction parameter is determined by the y-axis coordinate value in the coordinate value of each point, the y-axis coordinate value of the rotation center coordinate value, and the sine value of the deflection angle.

[0093] The y-axis coordinate value in the corrected coordinate value of each point is determined by the sum of the third correction parameter and the fourth correction parameter, the third correction parameter is determined by the x-axis coordinate value in the coordinate value of each point, the x-axis coordinate value of the rotation center coordinate value, and the sine value of the deflection angle, and the fourth correction parameter is determined by the y-axis coordinate value in the coordinate value of each point, the y-axis coordinate value of the rotation center coordinate value, and the cosine value of the deflection angle.

[0094] In some embodiments, the first correction parameter is the product of the difference between the x-axis coordinate value of each point in the coordinate value and the x-axis coordinate value of the rotation center coordinate value and the cosine value of the deflection angle. The second correction parameter is the product of the difference between the y-axis coordinate value of each point in the coordinate value and the y-axis coordinate value of the rotation center coordinate value and the sine value of the deflection angle. The third correction parameter is the product of the difference between the x-axis coordinate value of each point in the coordinate value and the x-axis coordinate value of the rotation center coordinate value and the sine value of the deflection angle. The fourth correction parameter is the product of the difference between the y-axis coordinate value of each point in the coordinate value and the y-axis coordinate value of the rotation center coordinate value and the cosine value of the deflection angle.

[0095] For example, the coordinate value of each point in the current scanning area of ​​the target object is (x, y), and the corrected coordinate value (X, Y) of each point is obtained using formula (11) and formula (12). O )cos(Δθ)-(yy O )sin(Δθ) (11) Y=(xx O )sin(Δθ)+(yy O )cos(Δθ) (12)

[0096] In step 304, a reconstructed CT image is obtained using the corrected coordinate value of each point and the projection data acquired at a specified time.

[0097] For example, the reconstructed CT image is obtained using the corrected coordinate values ​​(X, Y) and the obtained projection data, as shown in formula (13).

[0098] In some embodiments, CT image reconstruction can be performed using analytical methods such as FBP (Filtered Backprojection) or FDK (Feldkamp-Davis-Kress), algebraic iterative methods such as ART (Algebra Reconstruction Techniqu) or SIRT (Simultaneous Iterative Reconstruction Technique), and regularization methods such as TV (Total Variation).

[0099] In the CT image reconstruction method provided in the above embodiment of the present disclosure, the position jitter of the object is corrected, thereby effectively solving the problem of CT image distortion caused by the jitter of the object.

[0100] FIG6 is a schematic diagram of the structure of a CT image reconstruction device according to an embodiment of the present disclosure. As shown in FIG6 , the CT image reconstruction device includes a first processing module 61 , a second processing module 62 , a third processing module 63 and a fourth processing module 64 .

[0101] The first processing module 61 is configured to obtain coordinate values ​​of N target points on a target object at a specified time, where N is a natural number greater than 1, wherein the target object is an object to be CT scanned in a CT scanning device.

[0102] In some embodiments, the coordinate value of the nth target point among N target points at a specified moment can be determined by the coordinate value of the nth position monitoring device corresponding to the nth target point, the distance between the nth position monitoring device and the nth target point at the specified moment, and the angle between the line connecting the nth position monitoring device and the nth target point and the y-axis at the specified moment, where the N target points correspond to the N position monitoring devices, and 1≤n≤N. It should be noted that the position monitoring device is typically fixedly disposed in the scanning channel of the CT scanning device. Therefore, for example, when the rotation center of the rotating support 3 of the CT scanning device is set as the origin of the coordinate system, the coordinate value of the position monitoring device is known.

[0103] It should be noted that non-contact distance detection can be performed using methods such as laser ranging, radar ranging, and ultrasonic ranging to obtain the distance between the position monitoring device and the target point at a specified time. Accordingly, the position monitoring device can include a laser rangefinder, radar rangefinder, ultrasonic rangefinder, etc.

[0104] It should also be noted that when multiple position monitoring devices are fixedly installed in the scanning channel of a CT scanner, each position monitoring device should be installed away from the X-ray beam plane, but not too far away. For example, each position monitoring device should be installed within a few centimeters of the X-ray beam plane. This ensures that the measurement of each position monitoring device does not affect X-ray image acquisition, while effectively detecting jitter in the current scanning position.

[0105] In some embodiments, the y-axis coordinate value of the coordinate value of the nth target point at a specified time is the difference between the y-axis coordinate value of the coordinate value of the nth position monitoring device and the first product, where the first product is the product of the distance and the cosine value of the angle.

[0106] In some embodiments, when the x-axis coordinate value in the coordinate value of the nth position monitoring device is less than or equal to 0, the x-coordinate value in the coordinate value of the nth target point at a specified moment is the sum of the x-axis coordinate value in the coordinate value of the nth position monitoring device and the second product, and the second product is the product of the distance and the sine value of the angle.

[0107] In some embodiments, when the x-axis coordinate value in the coordinate value of the nth position monitoring device is greater than or equal to 0, the x-coordinate value in the coordinate value of the nth target point at a specified moment is the difference between the x-axis coordinate value in the coordinate value of the nth position monitoring device and the second product.

[0108] As shown in Figure 4, in order to detect the shaking of the object, a position monitoring device I and a position monitoring device II are fixedly installed in the CT scanning channel. For the convenience of description, in Figure 4, the rotation center of the rotating bracket 3 of the CT scanning device is set as the origin of the coordinate system, and the x-axis coordinate value of the coordinate value of the position monitoring device I is set as x I , the y-axis coordinate value in the coordinate value of the position monitoring device 1 is set to y I , set the x-axis coordinate value in the coordinate value of the position monitoring device II to x II , set the y-axis coordinate value of the position monitoring device II to y II The distance between the position monitoring device I and the target point A at the specified time is d I (t), the angle between the line connecting the position monitoring device I and the target point A and the y-axis at the specified time is γ I (t). The distance between the position monitoring device II and the target point B at the specified time is d II (t), the angle between the line connecting the position monitoring device II and the target point B and the y-axis at the specified time is γ II (t). Therefore, the coordinate value of target point A at the specified time is shown in formula (5), and the coordinate value of target point B at the specified time is shown in formula (6).

[0109] The second processing module 62 is configured to determine the deflection angle of the target object by using the coordinate values ​​of the N target points at a specified time and the coordinate value of the rotation center of the CT scanning device.

[0110] For example, as shown in FIG. 4 , since the target object 4 is deflected, the target object 4 is deflected from the black area to the gray area.

[0111] In some embodiments, when N is equal to 2, the deflection angle of the target object is obtained using the coordinate values ​​of two target points on the target object at a specified time and the coordinate value of the rotation center.

[0112] In some embodiments, the deflection angle of the target object is the average of a first angle parameter and a second angle parameter, wherein the first angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the first target point of the two target points at a specified time, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value, and the second angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the second target point of the two target points at a specified time, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value.

[0113] In some embodiments, the first angle parameter is the inverse tangent function value of the ratio of the first difference to the second difference, where the first difference is the difference between the y-axis coordinate value of the coordinate value of the first target point at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the second difference is the difference between the x-axis coordinate value of the coordinate value of the first target point at the specified time and the x-axis coordinate value of the rotation center coordinate value. The second angle parameter is the inverse tangent function value of the ratio of the third difference to the fourth difference, where the third difference is the difference between the y-axis coordinate value of the coordinate value of the second target point at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the fourth difference is the difference between the x-axis coordinate value of the coordinate value of the second target point at the specified time and the x-axis coordinate value of the rotation center coordinate value.

[0114] For example, as shown in FIG4 , there are two target points on the target object, namely, target point A and target point B. Then the deflection angle Δθ of the target object is as shown in formula (7).

[0115] In some embodiments, when N is greater than 2, K distinct sets are generated using the N target points, where K is a natural number greater than 1, and each set includes two target points from the N target points. The i-th deflection angle is obtained using the coordinate values ​​of the two target points in the i-th set at a specified time and the coordinate value of the rotation center of the CT scanner, where 1 ≤ n ≤ K. Next, the deflection angle of the target object is generated using the obtained K deflection angles.

[0116] In some embodiments, the deflection angle of the target object is an average of K deflection angles, or a median of K deflection angles.

[0117] In some embodiments, the i-th deflection angle is the average of a third angle parameter and a fourth angle parameter, wherein the third angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the first target point of the two target points in the i-th set at a specified moment, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value, and the fourth angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the second target point of the two target points in the i-th set at a specified moment, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value.

[0118] In some embodiments, the third angle parameter is the inverse tangent function value of the ratio of the fifth difference to the sixth difference, the fifth difference being the difference between the y-axis coordinate value of the coordinate value of the first target point at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the sixth difference being the difference between the x-axis coordinate value of the coordinate value of the first target point at the specified time and the x-axis coordinate value of the rotation center coordinate value. The fourth angle parameter is the inverse tangent function value of the ratio of the seventh difference to the eighth difference, the seventh difference being the difference between the y-axis coordinate value of the coordinate value of the second target point at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the eighth difference being the difference between the x-axis coordinate value of the coordinate value of the second target point at the specified time and the x-axis coordinate value of the rotation center coordinate value.

[0119] As shown in Figure 5, there are three target points on the target object, namely, target point A, target point B, and target point C. In this case, multiple different sets are generated using the three target points. For example, the first set includes target point A and target point B, the second set includes target point A and target point C, and the third set includes target point B and target point C.

[0120] First, using the first set, we get the first deflection angle Δθ AB As shown in formula (8).

[0121] Using the second set, the second deflection angle Δθ is obtained AC As shown in formula (9).

[0122] Using the third set, we get the third deflection angle Δθ BC As shown in formula (10).

[0123] It should be noted that since the object is rigidly rotating, theoretically Δθ AB =Δθ AC =Δθ BC In this case, using Δθ AB , Δθ AC , Δθ BC The average or median of the deflection angle is used to represent the overall deflection angle of the object.

[0124] In some embodiments, in order to save computational cost, when there are target points A, B, and C on the target object, only Δθ AB , Δθ AC and Δθ BC For example, using only Δθ AB and Δθ AC Calculate the overall deflection angle of the object.

[0125] The third processing module 63 is configured to correct the coordinate value of each point in the current scanning area of ​​the target object by using the deflection angle and the rotation center coordinate value to obtain a corrected coordinate value of each point.

[0126] In some embodiments, the x-axis coordinate value in the corrected coordinate value of each point is determined by the difference between the first correction parameter and the second correction parameter, the first correction parameter is determined by the x-axis coordinate value in the coordinate value of each point, the x-axis coordinate value of the rotation center coordinate value, and the cosine value of the deflection angle, and the second correction parameter is determined by the y-axis coordinate value in the coordinate value of each point, the y-axis coordinate value of the rotation center coordinate value, and the sine value of the deflection angle.

[0127] The y-axis coordinate value in the corrected coordinate value of each point is determined by the sum of the third correction parameter and the fourth correction parameter, the third correction parameter is determined by the x-axis coordinate value in the coordinate value of each point, the x-axis coordinate value of the rotation center coordinate value, and the sine value of the deflection angle, and the fourth correction parameter is determined by the y-axis coordinate value in the coordinate value of each point, the y-axis coordinate value of the rotation center coordinate value, and the cosine value of the deflection angle.

[0128] In some embodiments, the first correction parameter is the product of the difference between the x-axis coordinate value of each point in the coordinate value and the x-axis coordinate value of the rotation center coordinate value and the cosine value of the deflection angle. The second correction parameter is the product of the difference between the y-axis coordinate value of each point in the coordinate value and the y-axis coordinate value of the rotation center coordinate value and the sine value of the deflection angle. The third correction parameter is the product of the difference between the x-axis coordinate value of each point in the coordinate value and the x-axis coordinate value of the rotation center coordinate value and the sine value of the deflection angle. The fourth correction parameter is the product of the difference between the y-axis coordinate value of each point in the coordinate value and the y-axis coordinate value of the rotation center coordinate value and the cosine value of the deflection angle.

[0129] For example, the coordinate value of each point in the current scanning area of ​​the target object is (x, y), and the corrected coordinate value (X, Y) of each point is obtained using formula (11) and formula (12).

[0130] The fourth processing module 64 is configured to obtain a reconstructed CT image using the corrected coordinate value of each point and the projection data acquired at a specified time.

[0131] For example, the reconstructed CT image is obtained using the corrected coordinate values ​​(X, Y) and the obtained projection data, as shown in formula (13).

[0132] FIG7 is a schematic diagram of the structure of a CT image reconstruction device according to another embodiment of the present disclosure. As shown in FIG7 , the CT image reconstruction device includes a memory 71 and a processor 72 .

[0133] The memory 71 is used to store instructions. The processor 72 is coupled to the memory 71 . The processor 72 is configured to execute the method involved in any embodiment in FIG. 3 based on the instructions stored in the memory.

[0134] As shown in FIG7 , the CT image reconstruction apparatus further includes a communication interface 73 for exchanging information with other devices and a bus 74 through which the processor 72 , the communication interface 73 , and the memory 71 communicate with each other.

[0135] Memory 71 may include high-speed RAM memory or non-volatile memory, such as at least one disk storage device. Memory 71 may also be a memory array. Memory 71 may also be divided into blocks, and the blocks may be combined into virtual volumes according to certain rules.

[0136] Furthermore, the processor 72 may be a central processing unit (CPU), or may be an application-specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present disclosure.

[0137] The present disclosure also relates to a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and when the instructions are executed by a processor, the method involved in any embodiment of FIG. 3 is implemented.

[0138] The present disclosure further provides a computer program product, comprising computer instructions, wherein when the computer instructions are executed by a processor, the method involved in any one of the embodiments in FIG. 3 is implemented.

[0139] Figure 8 is a schematic diagram of the structure of a CT image reconstruction system according to one embodiment of the present disclosure. As shown in Figure 8 , the CT image reconstruction system includes a CT image reconstruction device 81, a CT scanning device 82, and N position monitoring devices 83 corresponding one-to-one to N target points on a target object, where N is a natural number greater than 1. CT image reconstruction device 81 is the CT image reconstruction device described in either of the embodiments of Figures 6 or 7.

[0140] The CT scanning device 82 is configured to perform a CT scan on the target object and send the acquired projection data to the CT image reconstruction apparatus 81 .

[0141] Each of the N position monitoring devices 83 is configured to detect the distance between each position monitoring device and the corresponding target point at a specified time, and the angle between the line connecting each position monitoring device and the corresponding target point and the y-axis.

[0142] For example, N position monitoring devices 83 are fixedly installed in the CT scanning channel.

[0143] By implementing the above-mentioned embodiments of the present disclosure, the problem of CT image distortion caused by object shaking can be effectively corrected.

[0144] In some embodiments, the functional units described above may be implemented as general-purpose processors, programmable logic controllers (PLC), digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or any appropriate combination thereof, for performing the functions described in the present disclosure.

[0145] Those skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware, or by a program to instruct the relevant hardware, and the program may be stored in a computer-readable storage medium, which may be a read-only memory, a disk, or an optical disk, etc.

[0146] The description of the present disclosure is provided for purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the disclosed form. Many modifications and variations will be apparent to those skilled in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present disclosure and to enable those skilled in the art to understand the present disclosure and design various embodiments with various modifications suitable for specific applications.

Claims

1. A CT image reconstruction method, comprising: Obtaining coordinate values ​​of N target points on a target object at a specified time, where N is a natural number greater than 1, wherein the target object is an object to be CT scanned in a CT scanning device; Determine the deflection angle of the target object by using the coordinate values ​​of the N target points at the specified time and the coordinate value of the rotation center of the CT scanning device; Correcting the coordinate value of each point in the current scanning area of ​​the target object by using the deflection angle and the rotation center coordinate value to obtain a corrected coordinate value of each point; A reconstructed CT image is obtained by using the corrected coordinate value of each point and the projection data acquired at the specified time.

2. The CT image reconstruction method according to claim 1, wherein: Determining the deflection angle of the target object includes: When N is equal to 2, the deflection angle of the target object is obtained by using the coordinate values ​​of the two target points on the target object at the specified time and the coordinate value of the rotation center.

3. The CT image reconstruction method according to claim 2, wherein: The deflection angle of the target object is the average value of a first angle parameter and a second angle parameter, wherein the first angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the first target point among the two target points at the specified time, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value, and the second angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value in the coordinate value of the second target point among the two target points at the specified time, and the x-axis coordinate value and the y-axis coordinate value in the rotation center coordinate value.

4. The CT image reconstruction method according to claim 3, wherein: The first angle parameter is an inverse tangent function value of the ratio of the first difference to the second difference, the first difference is the difference between the y-axis coordinate value of the first target point in the coordinate value at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the second difference is the difference between the x-axis coordinate value of the first target point in the coordinate value at the specified time and the x-axis coordinate value of the rotation center coordinate value; The second angle parameter is the inverse tangent function value of the ratio of the third difference to the fourth difference, and the third difference The fourth difference is the difference between the y-axis coordinate value of the second target point in the coordinate value at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the fourth difference is the difference between the x-axis coordinate value of the second target point in the coordinate value at the specified time and the x-axis coordinate value of the rotation center coordinate value.

5. The CT image reconstruction method according to claim 1, wherein: Determining the deflection angle of the target object includes: When N is greater than 2, using the N target points to generate K sets that are different from each other, K is a natural number greater than 1, wherein each set includes two target points among the N target points; Using the coordinate values ​​of the two target points in the i-th set at the specified time and the coordinate value of the rotation center of the CT scanning device, the i-th deflection angle is obtained, 1≤i≤K; The obtained K deflection angles are used to generate the deflection angle of the target object.

6. The CT image reconstruction method according to claim 5, wherein: The i-th deflection angle is the average value of the third angle parameter and the fourth angle parameter, wherein the third angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value of the coordinate value of the first target point among the two target points in the i-th set at the specified time, and the x-axis coordinate value and the y-axis coordinate value of the rotation center coordinate value, and the fourth angle parameter is determined by the x-axis coordinate value and the y-axis coordinate value of the coordinate value of the second target point among the two target points in the i-th set at the specified time, and the x-axis coordinate value and the y-axis coordinate value of the rotation center coordinate value.

7. The CT image reconstruction method according to claim 6, wherein: The third angle parameter is an inverse tangent function value of the ratio of the fifth difference to the sixth difference, the fifth difference is the difference between the y-axis coordinate value of the first target point in the coordinate value at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the sixth difference is the difference between the x-axis coordinate value of the first target point in the coordinate value at the specified time and the x-axis coordinate value of the rotation center coordinate value; The fourth angle parameter is the inverse tangent function value of the ratio of the seventh difference to the eighth difference, the seventh difference is the difference between the y-axis coordinate value of the second target point in the coordinate value at the specified time and the y-axis coordinate value of the rotation center coordinate value, and the eighth difference is the difference between the x-axis coordinate value of the second target point in the coordinate value at the specified time and the x-axis coordinate value of the rotation center coordinate value.

8. The CT image reconstruction method according to claim 5, wherein: The deflection angle of the target object is an average value of the K deflection angles, or a median of the K deflection angles.

9. The CT image reconstruction method according to claim 1, wherein: The x-axis coordinate value in the corrected coordinate value of each point is determined by the difference between the first correction parameter and the second correction parameter, the first correction parameter is determined by the x-axis coordinate value in the coordinate value of each point, the x-axis coordinate value of the rotation center coordinate value, and the cosine value of the deflection angle, and the second correction parameter is determined by the y-axis coordinate value in the coordinate value of each point, the y-axis coordinate value of the rotation center coordinate value, and the sine value of the deflection angle; The y-axis coordinate value in the corrected coordinate value of each point is determined by the sum of the third correction parameter and the fourth correction parameter, the third correction parameter is determined by the x-axis coordinate value in the coordinate value of each point, the x-axis coordinate value of the rotation center coordinate value and the sine value of the deflection angle, and the fourth correction parameter is determined by the y-axis coordinate value in the coordinate value of each point, the y-axis coordinate value of the rotation center coordinate value and the cosine value of the deflection angle.

10. The CT image reconstruction method according to claim 9, wherein: The first correction parameter is the product of the difference between the x-axis coordinate value of each point and the x-axis coordinate value of the rotation center coordinate value and the cosine value of the deflection angle; The second correction parameter is the product of the difference between the y-axis coordinate value of each point and the y-axis coordinate value of the rotation center coordinate value and the sine value of the deflection angle; The third correction parameter is the product of the difference between the x-axis coordinate value of each point and the x-axis coordinate value of the rotation center coordinate value and the sine value of the deflection angle; The fourth correction parameter is the product of the difference between the y-axis coordinate value of each point and the y-axis coordinate value of the rotation center coordinate value and the cosine value of the deflection angle.

11. The CT image reconstruction method according to any one of claims 1 to 10, wherein: The coordinate value of the nth target point among the N target points at the specified time is determined by the coordinate value of the nth position monitoring device corresponding to the nth target point, the distance between the nth position monitoring device and the nth target point at the specified time, and the distance between the nth position monitoring device and the nth target point at the specified time. The angle between the designated time and the y-axis is determined, wherein N target points correspond to N position monitoring devices one by one, 1≤n≤N.

12. The CT image reconstruction method according to claim 11, wherein: The y-axis coordinate value of the coordinate value of the n-th target point at the specified time is the difference between the y-axis coordinate value of the coordinate value of the n-th position monitoring device and the first product, and the first product is the product of the distance and the cosine value of the angle.

13. The CT image reconstruction method according to claim 12, wherein: When the x-axis coordinate value in the coordinate value of the nth position monitoring device is less than or equal to 0, the x-coordinate value of the coordinate value of the nth target point at the specified moment is the sum of the x-axis coordinate value in the coordinate value of the nth position monitoring device and the second product, wherein the second product is the product of the distance and the sine value of the angle.

14. The CT image reconstruction method according to claim 13, wherein: When the x-axis coordinate value in the coordinate value of the nth position monitoring device is greater than or equal to 0, the x-axis coordinate value in the coordinate value of the nth target point at the specified time is the difference between the x-axis coordinate value in the coordinate value of the nth position monitoring device and the second product.

15. A CT image reconstruction device, comprising: A first processing module is configured to obtain coordinate values ​​of N target points on a target object at a specified time, where N is a natural number greater than 1, wherein the target object is an object to be CT scanned in a CT scanning device; A second processing module is configured to determine a deflection angle of the target object by using the coordinate values ​​of the N target points at the specified time and the coordinate value of the rotation center of the CT scanning device; A third processing module is configured to correct the coordinate value of each point in the current scanning area of ​​the target object by using the deflection angle and the rotation center coordinate value to obtain a corrected coordinate value of each point; The fourth processing module is configured to obtain a reconstructed CT image using the corrected coordinate value of each point and the projection data acquired at the specified time.

16. A CT image reconstruction device, comprising: Memory; A processor is coupled to the memory, and the processor is configured to execute the CT image reconstruction method according to any one of claims 1 to 14 based on instructions stored in the memory.

17. A CT image reconstruction system comprising The CT image reconstruction device according to any one of claims 15-16; A CT scanning device, configured to perform a CT scan on the target object and send the acquired projection data to the CT image reconstruction device; N position monitoring devices correspond one-to-one to N target points on the target object, N is a natural number greater than 1, and each of the N position monitoring devices is configured to detect the distance between each position monitoring device and the corresponding target point at the specified moment, and the angle between the line connecting each position monitoring device and the corresponding target point and the y-axis.

18. A computer-readable storage medium, wherein: The computer-readable storage medium stores computer instructions, and when the instructions are executed by a processor, the CT image reconstruction method according to any one of claims 1 to 14 is implemented.

19. A computer program product, comprising computer instructions, wherein when the computer instructions are executed by a processor, the CT image reconstruction method according to any one of claims 1 to 14 is implemented.

20. A computer program, comprising computer instructions, wherein when the computer instructions are executed by a processor, the CT image reconstruction method according to any one of claims 1 to 14 is implemented.

Images