Projection number acquisition method and device, terminal and computer storage medium

Abstract

The invention provides a projection number obtaining method and device, a terminal and a computer storage medium, and the method comprises the steps: obtaining all single-dimensional projection coordinates and corresponding projection ordinal numbers of a model body in the scanning process of a CBCT system; based on each single-dimensional projection coordinate and the corresponding projection ordinal number, fitting each single-dimensional projection coordinate and the corresponding projection ordinal number by using a preset periodic relationship, and obtaining a position-projection ordinal number curve function of the die body; obtaining a period value of the position-projection ordinal number curve function, and taking the period value as a projection number; wherein the period value is used for representing the relation of cyclic change of the single-dimensional projection coordinate along with the projection ordinal number in the position-projection ordinal number curve function, accurate acquisition of the projection number is realized based on the relation, and improvement of the image quality of the CBCT system is facilitated.

Description

Technical Field

[0001] The present application belongs to the field of radiographic imaging and relates to a CBCT detection imaging technology, and in particular to a projection number acquisition method, device, terminal and computer storage medium. Background Art

[0002] Cone Beam Computed Tomography (CBCT) is a scintigraphic imaging technique that uses a cone-shaped beam of radiation to rotate around the object being examined, capturing images from multiple angles and ultimately achieving three-dimensional images through reconstruction algorithms. The projection count of a CBCT system is a key parameter for image reconstruction, representing the total number of scintigraphic images acquired during one rotation of the system. Its accuracy directly impacts the spatial resolution, contrast, and artifact control of the reconstructed image.

[0003] Existing CBCT systems typically calculate projection counts by multiplying the CBCT system's angular velocity by the time interval between acquisitions, which is then divided by 360° to calculate the projection count. However, due to the often insufficient mechanical control precision of CBCT systems, especially during high-speed rotation or long scanning periods, errors such as rotation axis deviation and mechanical vibration can lead to unstable angular velocity, resulting in inaccurate calculated projection counts. This, in turn, affects image reconstruction, leading to artifacts in the reconstructed image, poor spatial resolution and contrast, and ultimately inferior image quality.

[0004] Therefore, how to accurately obtain the number of CBCT projections is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a projection number acquisition method, device, terminal and computer storage medium, which are used to solve the problem that the projection number calculated by the existing projection number acquisition method is inaccurate, resulting in poor quality of the reconstructed image.

[0006] In a first aspect, the present application provides a projection number acquisition method, comprising: acquiring all one-dimensional projection coordinates and corresponding projection ordinals of a phantom during a scanning process of a CBCT system; based on each of the one-dimensional projection coordinates and the corresponding projection ordinals, fitting each of the one-dimensional projection coordinates and the corresponding projection ordinals using a preset periodic relationship to acquire a position-projection ordinal curve function of the phantom; acquiring a periodic value of the position-projection ordinal curve function, and using the periodic value as the projection number; wherein the periodic value is used to characterize the relationship between the cyclical change of the one-dimensional projection coordinates in the position-projection ordinal curve function and the projection ordinal.

[0007] In one embodiment of the present application, based on each of the one-dimensional projection coordinates and the corresponding projection ordinal, each of the one-dimensional projection coordinates and the corresponding projection ordinal is fitted using a preset periodic relationship to obtain the position-projection ordinal curve function of the model, including: obtaining each simulation period value; taking each of the simulation period values as fitting parameters in turn, fitting each of the one-dimensional projection coordinates and the corresponding projection ordinal to obtain a motion equation; based on each of the motion equations, respectively obtaining an error measure of each of the motion equations, and taking the motion equation with the smallest error measure as the position-projection ordinal curve function; wherein the simulation period value is a preset value used to characterize the period corresponding to the position-projection ordinal curve function.

[0008] In one embodiment of the present application, a method for obtaining each of the simulated cycle values includes: obtaining a projection number range based on a scanning process of the CBCT system; and obtaining each of the simulated cycle values based on the projection number range and a preset cycle value difference.

[0009] In one embodiment of the present application, based on each of the one-dimensional projection coordinates and the corresponding projection ordinal, each of the one-dimensional projection coordinates and the corresponding projection ordinal is fitted using a preset periodic relationship to obtain the position-projection ordinal curve function of the model, including: obtaining the current periodic value based on the periodic value rule; using the current periodic value as a fitting parameter, fitting each of the one-dimensional projection coordinates and the corresponding projection ordinal to obtain a motion equation; obtaining an error measure of the motion equation, if the error measure is less than or equal to a preset error threshold, using the motion equation as the position-projection ordinal curve function; otherwise, based on the periodic value rule, obtaining the next periodic value, and re-solving the new motion equation; wherein, the periodic value rule is that the current periodic value is the sum of the difference between the previous periodic value and the preset periodic value.

[0010] In one embodiment of the present application, the method for obtaining the one-dimensional projection coordinates includes: obtaining each projection image of the phantom during the scanning process of the CBCT system; based on each of the projection images, obtaining the coordinates of the center point corresponding to the phantom in a pre-constructed one-dimensional coordinate system as the one-dimensional projection coordinates of the phantom.

[0011] In one embodiment of the present application, a method for obtaining the coordinates of the center point of the phantom includes: performing a binarization operation on each of the projection images and obtaining edge information of the phantom through edge detection; and calculating the coordinates of the center point based on the edge information.

[0012] In an embodiment of the present application, before binarizing each of the projection images, the method further includes performing air correction on each of the projection images.

[0013] In a second aspect, the present application provides a projection number acquisition device, comprising a coordinate acquisition module, a curve function acquisition module, and a projection number acquisition module; the coordinate acquisition module is used to acquire all one-dimensional projection coordinates and corresponding projection ordinals of a phantom during a scanning process of a CBCT system; the curve function acquisition module is used to acquire a position-projection ordinal curve function of the phantom based on each of the one-dimensional projection coordinates and the corresponding projection ordinal, combined with a pre-constructed periodic function expression; the curve function acquisition module is used to use the periodic value corresponding to the position-projection ordinal curve function as the projection number; wherein the periodic value is used to characterize the relationship between the cyclical change of the one-dimensional projection coordinate in the position-projection ordinal curve function and the projection ordinal.

[0014] In a third aspect, the present application provides a terminal comprising: a processor and a memory, wherein the memory is communicatively connected to the processor; the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the terminal performs the projection number acquisition method as described above.

[0015] In a fourth aspect, the present application provides a computer storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the projection number acquisition method as described above.

[0016] As described above, the present application provides a projection number acquisition method, device, terminal and computer storage medium, which obtains the position-projection ordinal curve function of the phantom through a pre-constructed periodic function expression, and uses the periodic value of the position-projection ordinal curve function as the projection number of the CBCT system, thereby accurately obtaining the projection number of the CBCT system to assist in the image reconstruction of the CBCT system, thereby improving the image quality and detection effect of the CBCT system, and facilitating the practical application of the CBCT system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Shown is a structural schematic diagram of a CBCT system.

[0018] Figure 2 Shown is a flow chart of a projection number acquisition method described in an embodiment of the present application.

[0019] Figure 3 Shown is a flow chart of a method for obtaining single-dimensional projection coordinates according to an embodiment of the present application.

[0020] Figure 4 Shown is a flow chart of a method for obtaining a position-projection ordinal curve function according to an embodiment of the present application.

[0021] Figure 5The image is displayed as a result of image reconstruction based on the number of projections.

[0022] Figure 6 Shown is a flow chart of a method for obtaining each simulation period value according to an embodiment of the present application.

[0023] Figure 7 Shown is a flow chart of another method for obtaining a position-projection ordinal curve function according to an embodiment of the present application.

[0024] Figure 8 Shown is a flow chart of a method for obtaining the coordinates of the center point of a phantom described in an embodiment of the present application.

[0025] Figure 9 Shown is a structural schematic diagram of a projection data acquisition device described in an embodiment of the present application.

[0026] Figure 10 Shown is a structural schematic diagram of a terminal described in an embodiment of the present application.

[0027] Description of Reference Numerals

[0028] 11: ray source; 12: detector; 20: phantom; 41: coordinate acquisition module; 42: curve function acquisition module; 43: projection number acquisition module; 50: terminal; 51: processor; 52: memory; 521: operating system; 522: application; 53: user interface; 54: network interface; 55: bus system. DETAILED DESCRIPTION

[0029] The following describes the embodiments of the present application through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0030] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. Therefore, the illustrations only show components related to the present application and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0031] Existing methods for obtaining projection counts often use the angle of rotation of the CBCT system between two consecutive acquisitions to calculate the number of acquisitions per rotation. However, due to the unstable angular velocity of the CBCT system during scanning, the projection counts obtained using this method are less accurate. Image reconstruction based on this projection count reduces the spatial resolution and contrast of the reconstructed image and is prone to artifacts, resulting in poor reconstructed image quality and, in turn, poor detection performance of the CBCT system.

[0032] In response to the technical problems existing in the prior art, the following embodiments of the present application provide a projection number acquisition method, device, terminal, and computer storage medium. Through a pre-constructed periodic function expression, the position-projection ordinal curve function of the phantom is obtained, and the periodic value of the position-projection ordinal curve function is used as the projection number, thereby accurately obtaining the projection number of the CBCT system, which is conducive to improving the image reconstruction effect, obtaining higher-quality detection images, and thus improving the detection effect of the CBCT system.

[0033] like Figure 1 As shown, for ease of understanding, this embodiment exemplifies a CBCT system, including a radiation source 11 and a detector 12. The radiation source 11 is configured to emit a cone-shaped radiation beam, and the detector 12 is configured to receive the cone-shaped radiation beam to generate projection data. Furthermore, when it is necessary to obtain projection data from the CBCT system, a phantom 20 is placed between the radiation source 11 and the detector 12. The radiation source 11 and the detector 12 perform a circular motion around the phantom 20 for scanning, thereby obtaining projection data from the CBCT system. This embodiment provides a method for obtaining projection data based on the scanning process of the CBCT system.

[0034] The technical solutions in the embodiments of the present application will be described in detail below with reference to the accompanying drawings in the embodiments of the present application.

[0035] like Figure 2 As shown, this embodiment provides a method for obtaining projection numbers, including:

[0036] S100 , obtaining all single-dimensional projection coordinates and corresponding projection ordinal numbers of the phantom 20 during the scanning process of the CBCT system.

[0037] The single-dimensional projection coordinates are used to represent the position of the projection of the phantom 20 on the detector 12 during the current acquisition. Specifically, a projection image of the phantom 20 during the current scan acquisition is obtained, and the image coordinates of the phantom 20 in the projection image are used as the corresponding single-dimensional projection coordinates.

[0038] The projection sequence number refers to the number of acquisitions by the CBCT system when acquiring the projection image. For example, the projection images of the phantom 20 during the CBCT system scanning process are stored and sorted in chronological order, and the sequence number of each projection image is used as its corresponding projection sequence number. Based on this, the projection sequence numbers are actually consecutive positive integers.

[0039] Furthermore, based on all the projection images of the phantom 20 during the scanning process of the CBCT system, all the single-dimensional projection coordinates and projection ordinal numbers thereof are obtained.

[0040] In some optional embodiments, such as Figure 3 As shown, the method for obtaining the one-dimensional projection coordinates includes:

[0041] S110 , obtaining projection images of the phantom 20 during the scanning process of the CBCT system.

[0042] Illustratively, during the scanning process of the CBCT system, the rotation angle is greater than 180°, so as to obtain more data for subsequent steps and improve the accuracy of the obtained projection number.

[0043] S120 , based on each of the projection images, obtaining the center point coordinates corresponding to the phantom 20 in a pre-constructed one-dimensional coordinate system as the one-dimensional projection coordinates of the phantom 20 .

[0044] The center point of the phantom 20 is the geometric center of the projection of the phantom 20 on the projection image. The coordinates of the center point represent the position of the phantom 20, thereby preventing the shape or size of the phantom 20 from affecting the accuracy of the single-dimensional projection coordinates, thereby improving the accuracy of the obtained projection number.

[0045] Exemplarily, the phantom 20 is a steel ball, and its projection on the projection image is a circle, and the center coordinates of the projection are used as the corresponding one-dimensional projection coordinates.

[0046] It should be noted that, in order to facilitate the execution of subsequent steps, the one-dimensional coordinate system of each projection image is the same one-dimensional coordinate system to avoid coordinate conversion of each one-dimensional projection coordinate, thereby improving the execution efficiency of the projection number acquisition method.

[0047] For example, a one-dimensional coordinate system is established with the geometric center point of the projection image as the origin and the horizontal direction from left to right along the positive direction of the coordinate axis. The coordinates of the projection center point of the phantom 20 in each projection image are obtained as the corresponding one-dimensional projection coordinates. Of course, those skilled in the art may also construct other coordinate systems based on actual needs to obtain the one-dimensional projection coordinates, as long as the coordinate systems corresponding to the one-dimensional projection coordinates are the same coordinate system. This embodiment does not impose any specific limitations on this.

[0048] S200 , based on each of the one-dimensional projection coordinates and the corresponding projection ordinal, fitting each of the one-dimensional projection coordinates and the corresponding projection ordinal using a preset periodic relationship to obtain a position-projection ordinal curve function of the phantom.

[0049] The position-projection number curve function is used to characterize the change in the position of the phantom 20 on the detector relative to the projection number during the scanning process of the CBCT system, that is, the change relationship between each of the single-dimensional projection coordinates and the projection number.

[0050] It should be noted that, because the radiation source 11 and detector 12 perform periodic reciprocating circular motion during the CBCT system's scanning process, the position-projection ordinal curve function of the phantom 20 also follows a periodic reciprocating trajectory. Therefore, the relationship between the single-dimensional projection coordinates and the projection ordinal in this embodiment is actually periodic, meaning that the position-projection ordinal curve function is a periodic function.

[0051] Furthermore, since the CBCT system's period is actually a 360° rotation, the period of the position-projection number curve function is the projection number corresponding to a 360° rotation of the CBCT system, that is, the number of images acquired during a 360° rotation of the CBCT system. Based on this, the number of projections of the CBCT system can be obtained based on the period of the position-projection number curve function.

[0052] In order to facilitate those skilled in the art to understand the series scheme described in this embodiment, the specific acquisition method and principle of the position-projection ordinal curve function will be explained in detail below.

[0053] In some optional embodiments, such as Figure 4 As shown, the method for obtaining the position-projection ordinal curve function includes:

[0054] S210, obtaining each simulation cycle value.

[0055] S220 , sequentially using each simulation period value as a fitting parameter, fitting each one-dimensional projection coordinate and the corresponding projection ordinal number to obtain a motion equation.

[0056] The simulation cycle value is a preset value used to represent the cycle corresponding to the position-projection ordinal curve function. For example, the projection number range for the CBCT system is estimated based on the experience of those skilled in the art. For example, if the estimated projection number for the CBCT system is 600, then 550 is set as the first simulation cycle value, 650 is set as the last simulation cycle value, and the remaining simulation cycle values are set to values with preset differences between 550 and 650.

[0057] In some optional embodiments, the periodic relationship between the one-dimensional projection coordinates and the projection ordinal is characterized by a Fourier function. Specifically, each simulated periodic value is used as the actual periodic value of the Fourier function, and each one-dimensional projection coordinate and the corresponding projection ordinal are substituted into the Fourier function to solve and fit the corresponding motion equation, thereby obtaining the position-projection ordinal curve function based on each motion equation.

[0058] Specifically, the Fourier function expression is:

[0059]

[0060] Wherein, f(n) is the coordinate value of the one-dimensional projection coordinate, a k and b k is the Fourier coefficient of the motion equation, k is the Fourier level of the motion equation, N is the maximum Fourier level of the motion equation, n is the projection ordinal number, and m is the actual period value of the motion equation.

[0061] Let the value of m be each simulation period value, and construct a linear equation system based on each single-dimensional projection coordinate and the corresponding projection ordinal number, that is, substitute the coordinate value of each single-dimensional projection coordinate and the corresponding projection ordinal number into the Fourier function expression to construct a linear equation system for solving the Fourier coefficient a k and b k The value of the Fourier coefficient a is obtained based on the solution k and b k , and the value of m, to obtain the equation of motion. Since the relative motion of the phantom 20 during the rotation of the CBCT system is actually a smooth physical motion, the high-frequency terms in the Fourier function expression may introduce high-frequency noise and cause errors. Therefore, in this embodiment, the maximum number of Fourier levels does not exceed 3, that is, N ≤ 3.

[0062] It should be noted that those skilled in the art should be aware of the specific steps and principles of constructing a system of linear equations based on the coordinate values of each of the one-dimensional projection coordinates and the corresponding projection ordinal numbers to solve the Fourier coefficients, which will not be specifically explained in this embodiment.

[0063] S230 , based on the motion equations, respectively obtain the error metrics of the motion equations, and use the motion equation with the smallest error metric as the position-projection ordinal curve function.

[0064] The error metric is used to characterize the degree of deviation between the motion equation and each of the single-dimensional projection coordinates. The motion equation with the minimum error metric is the optimal equation describing the relationship between the position of the phantom 20 and the acquisition number. Based on this, a highly accurate position-projection ordinal curve function can be obtained, thereby improving the accuracy of the projection number obtained by the CBCT system.

[0065] Exemplarily, the error metric is a mean square error, specifically, based on the position-projection ordinal curve function, the position value corresponding to each projection ordinal is obtained, and the difference is made between each actual position value, and the sum of the squares of these differences is divided by the largest projection ordinal as the error metric; or, the error metric is a mean absolute error, specifically, based on the position-projection ordinal curve function, the position value corresponding to each projection ordinal is obtained, and the difference is made between each actual position value, and the sum of the absolute values of these differences is divided by the largest projection ordinal as the error metric; or, the error metric is a residual sum of squares, specifically, based on the position-projection ordinal curve function, the position value corresponding to each projection ordinal is obtained, and the difference is made between each actual position value, and the sum of the squares of these differences is used as the error metric. The above is only an exemplary explanation of the specific method of obtaining the error metric. Those skilled in the art can make specific settings according to actual needs. As long as the error metric can characterize the degree of deviation between the motion equation and each of the one-dimensional projection coordinates, this embodiment does not impose specific restrictions on this.

[0066] Based on this, the motion equation with the minimum error metric is used as the position-projection ordinal curve function, and the projection number of the CBCT system is obtained based on the period value of the position-projection ordinal curve function, so that the accuracy of the projection number is high. Image reconstruction based on the projection number can improve the image quality of the reconstructed image, thereby achieving a better detection effect. For example, Figure 5 The result of image reconstruction based on the projection number is displayed, wherein the image on the left is a reconstructed image reconstructed based on the projection number obtained by the existing method, and the image on the right is a reconstructed image reconstructed based on the projection number obtained by the projection number obtaining method provided in this embodiment. Obviously, since the projection number obtained by this embodiment has a higher accuracy, the obtained reconstructed image has higher spatial resolution and contrast, better clarity, and no artifact problems.

[0067] It should be noted that this embodiment obtains the position-projection ordinal curve function by iterating each of the simulation period values, which is actually to obtain the motion equation with the smallest error among all the motion equations as the position-projection ordinal curve function. Therefore, the simulation period value will affect the accuracy of the obtained position-projection ordinal curve function. In order to obtain a more accurate position-projection ordinal curve function, it is necessary to improve the accuracy of each of the simulation period values. Based on this, this embodiment also exemplarily gives a method for obtaining each of the simulation period values to improve the accuracy of each of the simulation period values obtained. Specifically, Figure 6 As shown, the method for obtaining each of the simulation period values includes:

[0068] S211 : Acquire a projection number range based on a scanning process of the CBCT system.

[0069] Specifically, the CBCT system is rotated one revolution for scanning, and the total number of acquisitions during the process is obtained. Based on the total number of acquisitions, a projection number range is obtained. It should be noted that in actual application scenarios, due to limitations of the CBCT system structure, the CBCT system is often unable to rotate 360° during the scanning process. Therefore, each value in the projection number range is not less than the total number of acquisitions.

[0070] For example, if the CBCT system rotates 270° during the scanning process, when the total number of acquisitions is 600, the projection number range is [750, 850].

[0071] Alternatively, an initial value of the projection number is obtained based on an existing projection number acquisition method, and the projection number range is obtained based on the initial value of the projection number, wherein the minimum value of the projection number range is less than the initial value of the projection number, and the maximum value of the projection number range is greater than the initial value of the projection number.

[0072] S212: Based on the projection number range and in combination with a preset period value difference, obtain each of the simulation period values.

[0073] The period value difference is used to represent the difference between two adjacent simulation period values. For example, the period value difference is 0.1.

[0074] Specifically, based on the minimum value in the projection number range, a new simulation period value is obtained at each interval of the period value difference until the simulation period value is not less than the maximum value in the projection number range.

[0075] Based on this, relatively accurate values of the simulation cycles can be obtained, so as to improve the accuracy of the obtained projection numbers.

[0076] In some other optional implementations, such as Figure 7 As shown, when the periodic function expression is a Fourier function expression, the method for obtaining the position-projection ordinal curve function may also include:

[0077] S210', based on the period value rule, obtain the current period value.

[0078] The period value rule is that the current period value is equal to the sum of the difference between the previous period value and the preset period value. For example, the period value difference is 0.1.

[0079] S220′, using the current period value as a fitting parameter, fitting each of the single-dimensional projection coordinates and the corresponding projection ordinal number to obtain a motion equation;

[0080] Exemplarily, the periodic relationship between the one-dimensional projection coordinates and the projection ordinal is characterized by a Fourier function. Each simulated periodic value is used as the actual periodic value of the Fourier function, and each one-dimensional projection coordinate and the corresponding projection ordinal are substituted into the Fourier function to solve and fit the corresponding equation of motion. Specifically, the specific method and principle for obtaining the equation of motion can be found in the aforementioned step S220, and will not be elaborated upon in this embodiment.

[0081] S230', obtaining an error metric of the motion equation. If the error metric is less than or equal to a preset error threshold, the motion equation is used as the position-projection ordinal curve function; otherwise, based on the periodic value rule, the next periodic value is obtained and a new motion equation is solved again.

[0082] Among them, the error metric is used to characterize the degree of deviation between the motion equation and each of the one-dimensional projection coordinates. Exemplarily, the error metric is any one of the mean square error, mean absolute error, residual sum of squares or other physical quantities that can characterize the degree of deviation between the motion equation and each of the one-dimensional projection coordinates. This embodiment does not impose any specific restrictions on this.

[0083] The error threshold represents the minimum error metric between the motion equation and each of the single-dimensional projection coordinates when the accuracy of the projection number meets the requirements of the CBCT system for image reconstruction. Based on this, when the error metric of the motion equation is less than or equal to the error threshold, the motion equation is used as a function of the position-projection ordinal curve to obtain the projection number with higher accuracy.

[0084] Furthermore, when the error metric of the motion equation is greater than the error threshold, a new period value is obtained to obtain the corresponding motion equation based on the new period value and determine whether it can be used as the position-projection ordinal curve function. Specifically, the new period value is the sum of the current period value and the difference between the period values.

[0085] Based on this, this embodiment obtains a motion equation with an error metric less than or equal to the error threshold as the position-projection ordinal curve function, thereby ensuring that the position-projection ordinal curve function has high accuracy, thereby making the obtained projection number more accurate, which is beneficial for assisting the CBCT system in obtaining better image reconstruction effects.

[0086] S300: Obtain a period value of the position-projection ordinal curve function, and use the period value as the projection number.

[0087] The period value is used to characterize the relationship between the cyclic change of the single-dimensional projection coordinate and the projection ordinal number in the position-projection ordinal number curve function.

[0088] Exemplarily, the period value is the projection ordinal value corresponding to one period of the position-projection ordinal curve function. Specifically, since the CBCT system actually completes one period of motion for one rotation, the number of projections of the CBCT system is actually the total number of images acquired when the CBCT system completes one period of motion, i.e., the projection ordinal value corresponding to one period of the position-projection ordinal curve function, i.e., the simulated period value or period value corresponding to the position-projection ordinal curve function.

[0089] Based on this, by obtaining the period value corresponding to the position-projection ordinal curve function, the projection number of the CBCT system can be obtained. Since the position-projection ordinal curve function has a high accuracy, the accuracy of the projection number is also high, which is beneficial for the CBCT system to improve its image reconstruction effect.

[0090] It should be noted that, in order to further improve the accuracy of the projection number, this embodiment obtains the coordinates of the center point corresponding to the phantom 20 as the single-dimensional projection coordinates of the phantom 20, thereby avoiding the shape or size of the phantom 20 affecting the accuracy of the single-dimensional projection coordinates, thereby improving the accuracy of the obtained projection number. In some optional embodiments, such as Figure 8 As shown, this embodiment also provides a method for obtaining the coordinates of the center point of the phantom 20, including:

[0091] S121 , performing a binarization operation on each of the projection images to obtain corresponding binarized images.

[0092] Specifically, each of the projection images is binarized using a global threshold method or an adaptive threshold method, so as to distinguish the background in the projection image from the projection pattern of the phantom 20 .

[0093] S122: Calculate the coordinates of each center point corresponding to each projection image based on each of the binarized images.

[0094] It should be noted that the center point is actually the geometric center of the projection pattern of the phantom 20, that is, the geometric center coordinates of the projection pattern of the phantom 20 in each of the binary images serve as the one-dimensional projection coordinates of the phantom 20 in the corresponding projection image.

[0095] It should be noted that those skilled in the art should be aware of the specific execution method and principle of obtaining the geometric center coordinates of the projection pattern based on the binarized image, which will not be specifically explained in this embodiment.

[0096] In some optional embodiments, in order to further improve the accuracy of the one-dimensional projection coordinates, thereby improving the accuracy of the obtained projection number, before binarizing each projection image, it is also necessary to perform air correction on each projection image to eliminate errors caused by environmental factors such as air.

[0097] Specifically, each detection image of the CBCT system is acquired when the phantom 20 is not in place, wherein the detection images correspond one-to-one to the projection images. The corresponding projection images are corrected based on the detection images to eliminate the effects of detector dark current, gain inconsistency, and system noise on the projection images, thereby improving the image quality of the projection images and thereby improving the accuracy of the ultimately acquired projection data. It should be noted that those skilled in the art should be aware of the specific steps and principles for correcting the projection images based on the detection images, and this embodiment will not be specifically explained here.

[0098] like Figure 9 As shown, this embodiment further provides a projection number acquisition device, which includes a coordinate acquisition module 41 , a curve function acquisition module 42 and a projection number acquisition module 43 .

[0099] The coordinate acquisition module 41 is used to acquire all single-dimensional projection coordinates and corresponding projection numbers of the phantom during the scanning process of the CBCT system.

[0100] The curve function acquisition module 42 is used to acquire the position-projection ordinal curve function of the phantom based on each of the single-dimensional projection coordinates and the corresponding projection ordinal, in combination with a pre-constructed periodic function expression.

[0101] The projection number acquisition module 43 is configured to use the period value corresponding to the position-projection ordinal number curve function as the projection number.

[0102] Based on the same technical concept, the projection number acquisition method provided in the embodiment of the present invention can be implemented on the terminal side or the server side.

[0103] like Figure 10 FIG2 shows an optional hardware structure diagram of a terminal provided in an embodiment of the present invention. The terminal 50 can be a mobile phone, a computer, a tablet device, a personal digital assistant, a factory backend processing device, or the like. The terminal 50 includes at least one processor 51, a memory 52, at least one network interface 54, and a user interface 53. The various components in the device are coupled together via a bus system 54. It will be appreciated that the bus system 54 is used to enable communication between these components. In addition to a data bus, the bus system 54 also includes a power bus, a control bus, and a status signal bus.

[0104] The user interface 53 may include a display, a keyboard, a mouse, a trackball, a click gun, keys, buttons, a touch pad or a touch screen.

[0105] It will be appreciated that the memory 52 may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. The non-volatile memory may be a read-only memory (ROM) or a programmable read-only memory (PROM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM) and synchronous static random access memory (SSRAM). The memories represented by the embodiments of the present invention are intended to include, but are not limited to, these and any other suitable types of memories.

[0106] The memory 52 in the embodiment of the present invention is used to store various categories of data to support the operation of the terminal. Examples of these data include: any executable program for operating on the terminal 50, such as an operating system 521 and an application 522; the operating system 521 includes various system programs, such as a framework layer, a core library layer, a driver layer, etc., for implementing various basic services and processing hardware-based tasks. The application 522 can include various applications, such as a media player (MediaPlayer), a browser (Browser), etc., for implementing various application services. The projection number acquisition method provided in the embodiment of the present invention can be included in the application 522.

[0107] The method disclosed in the above embodiment of the present invention can be applied to the processor 51 or implemented by the processor 51. The processor 51 may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method can be completed by the hardware integrated logic circuit in the processor 51 or by instructions in the form of software. The above processor may be a general-purpose processor, a digital signal processor (DSP), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor 51 can implement or execute the various methods, steps and logic block diagrams disclosed in the embodiment of the present invention. The processor 51 may be a microprocessor or any conventional processor, etc. The steps of the accessory optimization method provided in the embodiment of the present invention can be directly embodied as being executed by a hardware decoding processor, or can be executed by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium, which is located in a memory. The processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0108] In an exemplary embodiment, the terminal 50 may be configured to execute the aforementioned method using one or more application specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), or complex programmable logic devices (CPLDs).

[0109] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when called by a processor, implements the projection number acquisition method provided by the present invention.

[0110] Among them, a computer-readable storage medium can be a tangible device that can hold and store instructions used by an instruction execution device. The computer-readable storage medium can be, for example, (but not limited to) an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, and a mechanical encoding device.

[0111] The computer-readable program characterized herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in a computer-readable storage medium in each computing / processing device.

[0112] In summary, the present application obtains the position-projection ordinal curve function of the phantom through a pre-constructed periodic function expression, and obtains its periodic value based on the position-projection ordinal curve function, thereby obtaining the projection number of the CBCT system, so that the obtained projection number is highly accurate and used for image reconstruction of the CBCT system, which can effectively improve the image quality of the reconstructed image, is beneficial to improving the detection effect of the CBCT system, and has high industrial application value.

[0113] The descriptions of the processes or structures corresponding to the above figures have different emphases. For parts that are not described in detail in a certain process or structure, please refer to the relevant descriptions of other processes or structures.

[0114] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed in this application shall be covered by the claims of this application.

Claims

1. A method for obtaining projection numbers, comprising: Obtain all single-dimensional projection coordinates and corresponding projection numbers of the phantom during the scanning process of the CBCT system; Based on each of the one-dimensional projection coordinates and the corresponding projection ordinal number, each of the one-dimensional projection coordinates and the corresponding projection ordinal number is fitted using a preset periodic relationship to obtain a position-projection ordinal curve function of the phantom; Obtaining a period value of the position-projection ordinal curve function, and using the period value as the projection number; The period value is used to characterize the relationship between the cyclic change of the single-dimensional projection coordinate and the projection ordinal number in the position-projection ordinal number curve function.

2. The projection number acquisition method according to claim 1, characterized in that: The step of fitting each of the one-dimensional projection coordinates and the corresponding projection ordinal number using a preset periodic relationship based on each of the one-dimensional projection coordinates and the corresponding projection ordinal number to obtain a position-projection ordinal curve function of the phantom includes: Get the value of each simulation cycle; Using each simulation period value as a fitting parameter in turn, fitting each one-dimensional projection coordinate and the corresponding projection ordinal number to obtain a motion equation; Based on the motion equations, respectively obtaining error metrics for the motion equations, and using the motion equation with the smallest error metric as the position-projection ordinal curve function; The simulation period value is a preset value used to characterize the period corresponding to the position-projection ordinal curve function.

3. The projection number acquisition method according to claim 2, characterized in that: Methods for obtaining each of the simulation period values include: Obtaining a projection number range based on a scanning process of the CBCT system; Based on the projection number range and in combination with the preset period value difference, each of the simulation period values is obtained.

4. The projection number acquisition method according to claim 1, characterized in that: The step of fitting each of the one-dimensional projection coordinates and the corresponding projection ordinal number using a preset periodic relationship based on each of the one-dimensional projection coordinates and the corresponding projection ordinal number to obtain a position-projection ordinal curve function of the phantom includes: Based on the period value rule, obtain the current period value; Using the current period value as a fitting parameter, fitting each of the single-dimensional projection coordinates and the corresponding projection ordinal number to obtain a motion equation; Obtaining an error metric of the motion equation; if the error metric is less than or equal to a preset error threshold, using the motion equation as the position-projection ordinal curve function; otherwise, obtaining the next periodic value based on the periodic value rule and resolving a new motion equation; The period value rule is that the current period value is the sum of the difference between the previous period value and the preset period value.

5. The projection number acquisition method according to claim 1, characterized in that: The method for obtaining the one-dimensional projection coordinates includes: Acquiring projection images of the phantom during a scanning process of the CBCT system; Based on each of the projection images, the coordinates of the center point corresponding to the phantom are obtained in a pre-constructed one-dimensional coordinate system as the one-dimensional projection coordinates of the phantom.

6. The projection number acquisition method according to claim 5, characterized in that: The method for obtaining the coordinates of the center point of the phantom includes: performing a binarization operation on each of the projection images, and obtaining edge information of the phantom through edge detection; Based on the edge information, the coordinates of the center point are calculated.

7. The projection number acquisition method according to claim 6, characterized in that: Before binarizing each of the projection images, the method further includes: performing air correction on each of the projection images.

8. A projection number acquisition device, characterized in that: It includes a coordinate acquisition module, a curve function acquisition module and a projection number acquisition module; The coordinate acquisition module is used to obtain all single-dimensional projection coordinates and corresponding projection ordinal numbers of the phantom during the scanning process of the CBCT system; The curve function acquisition module is used to acquire the position-projection ordinal curve function of the phantom based on each of the single-dimensional projection coordinates and the corresponding projection ordinal, in combination with a pre-constructed periodic function expression; The curve function acquisition module is used to use the period value corresponding to the position-projection ordinal curve function as the projection number; The period value is used to characterize the relationship between the cyclic change of the single-dimensional projection coordinate and the projection ordinal number in the position-projection ordinal number curve function.

9. A terminal, characterized in that: include: A processor and a memory, wherein the memory is communicatively connected to the processor; The memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the terminal performs the projection number acquisition method according to any one of claims 1 to 7.

10. A computer storage medium storing a computer program, wherein: When the computer program is executed by a processor, the projection number acquisition method according to any one of claims 1 to 7 is implemented.

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