Method and system for calculating the shape of the focal spot light intensity distribution of a ct tube

Abstract

This invention discloses a method and system for calculating the shape of the focal intensity distribution of a CT tube, relating to the field of medical imaging technology. The method includes: scanning a flat panel phantom to obtain corresponding projection data; calculating the position data and dimensions of the phantom based on the projection data; performing a simulated projection on the phantom based on the projection data, position data, and dimensions to obtain the projection result; constructing a focal intensity distribution model; inputting the projection result into the model; iteratively calculating the optimal parameter values ​​of the model using the least squares method with the projection data as the target; and calculating the shape of the focal intensity distribution of the CT tube based on the optimal parameter values. This method helps to solve the problem that existing technologies cannot accurately calculate the shape of the focal intensity distribution of a CT tube.

Description

Technical Field

[0001] This invention relates to the field of medical imaging technology, and in particular to a method and system for calculating the shape of the focal light intensity distribution of a CT tube. Background Technology

[0002] In CT imaging systems, the intensity distribution of the X-ray source has a significant impact on image quality. Ideally, the X-ray source is often assumed to be a point source, with its intensity uniformly distributed and concentrated at a single point. In this case, the imaging system can obtain a clear, distortion-free projected image. However, in practical applications, the focal point of the X-ray source has a certain size and a complex intensity distribution, and is not an ideal point source. This non-ideal focal intensity distribution directly leads to blurring, artifacts, and other issues during imaging, affecting diagnostic accuracy.

[0003] Therefore, there is an urgent need for a method that can accurately calculate the shape of the light intensity distribution at the focal point of a CT tube. Summary of the Invention

[0004] In view of this, the present invention proposes a method and system for calculating the shape of the focal light intensity distribution of a CT tube, which can accurately calculate the shape of the focal light intensity distribution of a CT tube.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for calculating the shape of the light intensity distribution at the focal point of a CT tube includes:

[0007] The flat panel model is scanned to obtain the projection data corresponding to the flat panel model;

[0008] The position data of the flat plate mold is calculated based on the projection data, and the size data of the flat plate mold is calculated based on the position data;

[0009] Based on the projection data, position data, and size data, the flat plate model is simulated and projected to obtain the projection result of the flat plate model.

[0010] The projection results are input into the pre-constructed focal intensity distribution model, and the optimal values ​​of the parameters of the focal intensity distribution model are calculated based on the least squares method iteratively with the projection data as the target.

[0011] The shape of the light intensity distribution at the focal point of the X-ray tube is calculated based on the optimal values ​​of the parameters.

[0012] Based on the above technical solution, the present invention can be further improved as follows:

[0013] Optionally, scanning the flat panel phantom to obtain the projection data corresponding to the flat panel phantom includes:

[0014] The flat plate phantom is scanned to obtain the strength data corresponding to the flat plate phantom;

[0015] The intensity data is preprocessed for the first time to obtain the first preprocessed intensity data;

[0016] The first preprocessed intensity data is subjected to a second preprocessing to obtain the second preprocessed intensity data;

[0017] The projection data corresponding to the flat plate model is obtained based on the second preprocessed intensity data.

[0018] Optionally, calculating the position data of the flat panel phantom based on the projection data includes:

[0019] The position coordinates of the left and right ends of the flat plate mold are calculated using the least squares method, and the position data of the flat plate mold is obtained based on the left and right end position coordinates.

[0020] Optionally, calculating the dimensional data of the flat plate mold based on the position data includes:

[0021] The dimensions of the flat mold are calculated using formula (1);

[0022] Formula (1);

[0023] In the formula, For the dimensional data of the flat mold body, This represents the x-coordinate of the left end position of the flat mold. This represents the ordinate value of the left end position of the flat mold. This represents the x-coordinate of the right end position of the flat mold. This represents the ordinate value of the right end position of the flat mold.

[0024] Optionally, the step of simulating projection of the flat plate model based on the projection data, position data, and size data to obtain the projection result of the flat plate model includes:

[0025] The projection result is calculated using formula (2);

[0026] Formula (2);

[0027] In the formula, The projection result is shown, where c is the pixel number of the detector. For the exposure angle, m represents the number of virtual focal points on one side, where m is the number of the virtual focal points. These are the position coordinates of the virtual focus.

[0028] Optionally, calculating the shape of the light intensity distribution at the X-ray tube focal point based on the optimal value of the parameters includes:

[0029] The shape of the light intensity distribution at the focal point of the X-ray tube is calculated using formula (3);

[0030] Formula (3);

[0031] In the formula, This refers to the shape of the light intensity distribution at the focal point of the X-ray tube. Let be the total number of Gaussian functions. This represents the index of the Gaussian function in the focal intensity distribution model. Let n be the magnitude of the Gaussian function. This is the offset position relative to the center of focus. The location of the center of symmetry for the nth Gaussian function. Let be the standard deviation of the nth Gaussian function.

[0032] Optionally, the optimal value of the parameter is , and .

[0033] A shape calculation system for the focal intensity distribution of a CT tube includes:

[0034] The projection data acquisition module is used to scan the flat panel model and obtain the projection data corresponding to the flat panel model.

[0035] The position calculation module is used to calculate the position data of the flat panel model based on the projection data;

[0036] The size calculation module is used to calculate the size data of the flat plate mold based on the position data;

[0037] The projection result acquisition module is used to simulate projection of the flat plate model based on the projection data, position data and size data, and obtain the projection result of the flat plate model.

[0038] The parameter calculation module is used to input the projection result into the pre-constructed focal light intensity distribution model, and calculate the optimal value of the parameters of the focal light intensity distribution model based on the least squares method iteration with the projection data as the target.

[0039] The shape calculation module is used to calculate the shape of the light intensity distribution at the focal point of the X-ray tube based on the optimal value of the parameters.

[0040] An electronic device includes a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of the method described herein.

[0041] A non-transitory computer-readable storage medium having a computer program stored thereon, the computer program implementing the steps of the method when executed by a processor.

[0042] The present invention has the following advantages:

[0043] The method for calculating the shape of the focal intensity distribution of a CT tube in this invention acquires projection data through scanning a flat phantom, simulates the projection by combining position and size data, constructs a focal intensity distribution model, and iteratively optimizes the parameters using the least squares method to achieve accurate calculation of the shape of the CT tube's focal intensity distribution. Compared with traditional methods, this method effectively eliminates the influence of scanning system errors and phantom positioning deviations, improves the accuracy of focal shape calculation, provides a reliable basis for tube performance evaluation, image quality optimization, and equipment maintenance, reduces image artifacts caused by focal shape errors, and enhances the imaging stability and diagnostic accuracy of the CT system. Attached Figure Description

[0044] For illustrative and not limiting purposes, the present invention will now be described in conjunction with embodiments and accompanying drawings, wherein:

[0045] Figure 1 This is a flowchart illustrating the method for calculating the shape of the focal light intensity distribution of a CT tube in an embodiment of the present invention.

[0046] Figure 2 This is a schematic diagram of the main components of the shape calculation system for the focal light intensity distribution of a CT tube in an embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of the physical structure of the electronic device provided by the present invention. Detailed Implementation

[0048] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0049] It should be noted that the terms "first," "second," etc., in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate for the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0050] It should be noted that, where there is no conflict, the embodiments and features of the present invention can be combined with each other. The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0051] Figure 1 This is a flowchart illustrating the method for calculating the shape of the CT tube focal light intensity distribution in an embodiment of the present invention, as shown below. Figure 1 As shown, the method for calculating the shape of the focal light intensity distribution of a CT tube provided in this embodiment of the invention includes the following steps S101 to S105.

[0052] S101, Scan the flat plate model to obtain the corresponding projection data of the flat plate model.

[0053] A flat plate phantom made of a high-attenuation material was scanned using the same preset conditions to obtain the corresponding strength data of the flat plate phantom. During scanning, the flatbed phantom should be placed as far away from the center of rotation as possible to ensure that its projection covers all channels. The flatbed phantom can be made of high-attenuation materials such as tungsten or molybdenum.

[0054] The intensity data is preprocessed for the first time to obtain the first preprocessed intensity data. Preprocessing mainly involves interpolating and performing atmospheric correction on the data from the bad channels, as well as correcting for exposure differences at each angle. The first preprocessing step involves intensity data. If the value is less than a certain threshold, set it to 0.

[0055] The first preprocessed intensity data is subjected to a second preprocessing to obtain the second preprocessed intensity data. ;

[0056] ;

[0057] Where c is the detector pixel unit number, v is the v-th exposure angle, and T is the threshold, i.e., the threshold for distinguishing the boundary between air and the flat panel phantom.

[0058] The projection data corresponding to the flat plate model is obtained based on the second preprocessed intensity data.

[0059] S102, calculate the position data of the flat plate mold based on the projection data, and calculate the size data of the flat plate mold based on the position data.

[0060] The position coordinates of the left and right ends of the flat plate mold are calculated using the least squares method, and the position data of the flat plate mold is obtained based on the left and right end position coordinates.

[0061] First, let's assume that the coordinates of the left end and the right end of the flat mold are respectively... and Then, the coordinates of the X-ray tube focal center at various exposure angles. Based on the rotation angle, it can be known that; and at each exposure angle, the angle between the focal position and the two vectors formed by the left and right ends of the flat plate mold is respectively;

[0062] The data from each exposure angle constitutes the coordinates of the flat phantom's position. and A series of equations were used to calculate the position coordinates of the left and right ends of the flat plate model using the least squares method. and And the dimensions of the flat mold body.

[0063] The dimensions of the flat mold are calculated using formula (1);

[0064] Formula (1);

[0065] In the formula, For the dimensional data of the flat mold body, This represents the x-coordinate of the left end position of the flat mold. This represents the ordinate value of the left end position of the flat mold. This represents the x-coordinate of the right end position of the flat mold. This represents the ordinate value of the right end position of the flat mold.

[0066] S103, based on the projection data, position data and size data, simulate the projection of the flat plate model to obtain the projection result of the flat plate model.

[0067] The constructed X-ray tube focal intensity distribution model can calculate the focal intensity at any point on the focal plane. Assuming we take... With a total of 2M+1 virtual focal points, the light intensity of 2M+1 virtual focal points can be obtained. ;

[0068] in, .

[0069] The projection of the simulated flat panel phantom onto the focal intensity distribution model constructed using a Gaussian function is first calculated. The line connecting the position of the m-th virtual focal point and the c-th detector pixel at each projection angle v is then checked to see if it intersects with the flat panel phantom. If they intersect, it means that the ray passes through the flat panel phantom, i.e., the light intensity of the focal point is attenuated by the high-density flat panel phantom, and the light intensity of the focal point does not contribute to the detector pixel. Otherwise, if they do not intersect, it means that the light intensity of the virtual focal point shines on the detector, and the detector receives the light intensity of the virtual focal point.

[0070] ;

[0071] The projection result is calculated using formula (2);

[0072] Formula (2);

[0073] In the formula, The projection result is shown, where c is the pixel number of the detector. For the exposure angle, m represents the number of virtual focal points on one side, where m is the number of the virtual focal points. These are the position coordinates of the virtual focus.

[0074] S104. Input the projection result into the pre-built focal intensity distribution model, and calculate the optimal value of the parameters of the focal intensity distribution model based on the least squares method iterative calculation with the projection data as the target.

[0075] The optimal value of the parameter is , and .

[0076] S105, calculates the shape of the light intensity distribution at the focal point of the X-ray tube based on the optimal parameter values.

[0077] The shape of the light intensity distribution at the focal point of the X-ray tube is calculated using formula (3);

[0078] Formula (3);

[0079] In the formula, This refers to the shape of the light intensity distribution at the focal point of the X-ray tube. Let be the total number of Gaussian functions. This represents the index of the Gaussian function in the focal intensity distribution model. Let n be the magnitude of the Gaussian function. This is the offset position relative to the center of focus. The location of the center of symmetry for the nth Gaussian function. Let be the standard deviation of the nth Gaussian function.

[0080] The method for calculating the shape of the focal intensity distribution of a CT tube supports selecting a portion of the detector pixels to test the shape model of the focal intensity distribution. It can detect the shape of the focal intensity distribution from a portion of the detector channels and analyze the differences in focal intensity distribution observed in different detector channels, providing a basis for more accurate correction of these differences.

[0081] Figure 2 This is a schematic diagram of the main components of the shape calculation system for the focal intensity distribution of a CT tube in an embodiment of the present invention. Figure 2 As shown, the shape calculation system 1 for the focal light intensity distribution of a CT tube provided in this embodiment of the invention includes a projection data acquisition module 10, a position calculation module 20, a size calculation module 30, a projection result acquisition module 40, a parameter calculation module 50, and a shape calculation module 60.

[0082] The projection data acquisition module 10 is used to scan the flat panel model and obtain the projection data corresponding to the flat panel model.

[0083] Position calculation module 20 is used to calculate the position data of the flat panel model based on the projection data;

[0084] Size calculation module 30 is used to calculate the size data of the flat plate mold based on the position data;

[0085] The projection result acquisition module 40 is used to simulate projection of the flat plate model based on the projection data, position data and size data, and obtain the projection result of the flat plate model.

[0086] The parameter calculation module 50 is used to input the projection result into the pre-constructed focal light intensity distribution model, and calculate the optimal value of the parameters of the focal light intensity distribution model based on the least squares method iteration with the projection data as the target.

[0087] The shape calculation module 60 is used to calculate the shape of the light intensity distribution at the focal point of the X-ray tube based on the optimal value of the parameters.

[0088] Figure 3 This is a schematic diagram of the physical structure of an electronic device provided in an embodiment of the present invention, such as... Figure 3 As shown, the electronic device 70 includes: a processor 701, a memory 702, and a bus 703;

[0089] The processor 701 and the memory 702 communicate with each other via the bus 703.

[0090] The processor 701 is used to call program instructions in the memory 702 to execute the methods provided in the above-described method embodiments, and to execute the methods provided in the embodiments of the present invention.

[0091] This embodiment provides a non-transitory computer-readable storage medium that stores computer instructions, which cause a computer to execute the method provided in this embodiment of the invention.

[0092] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various storage media capable of storing program code, such as ROM, RAM, magnetic disk, or optical disk.

[0093] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for calculating the shape of the light intensity distribution at the focal point of a CT tube, characterized in that, include: The flat panel model is scanned to obtain the projection data corresponding to the flat panel model; The position data of the flat plate mold is calculated based on the projection data, and the size data of the flat plate mold is calculated based on the position data; Based on the projection data, position data, and size data, the flat plate model is simulated and projected to obtain the projection result of the flat plate model. The projection result is calculated using formula (2); Formula (2); In the formula, The projection result is shown, where c is the pixel number of the detector. For the exposure angle, Let m be the number of virtual focal points on one side, and m be the number of the virtual focal points. The position coordinates of the virtual focus. The light intensity at the virtual focal point; The projection results are input into a pre-constructed focal intensity distribution model, and the optimal values ​​of the parameters of the focal intensity distribution model are calculated based on the least squares method iteratively with the projection data as the target. The shape of the light intensity distribution at the X-ray tube focal spot is calculated based on the optimal values ​​of the parameters. The shape of the light intensity distribution at the focal point of the X-ray tube is calculated using formula (3); Formula (3); In the formula, This refers to the shape of the light intensity distribution at the focal point of the X-ray tube. The total number of Gaussian functions. This represents the index of the Gaussian function in the focal intensity distribution model. Let n be the magnitude of the Gaussian function. This is the offset position relative to the center of focus. The location of the center of symmetry for the nth Gaussian function. Let n be the standard deviation of the nth Gaussian function; The optimal value of the parameter is , and .

2. The method for calculating the shape of the focal intensity distribution of a CT tube according to claim 1, characterized in that, The step of scanning the flat panel phantom to obtain the projection data corresponding to the flat panel phantom includes: The flat plate phantom is scanned to obtain the strength data corresponding to the flat plate phantom; The intensity data is preprocessed for the first time to obtain the first preprocessed intensity data; The first preprocessed intensity data is subjected to a second preprocessing to obtain the second preprocessed intensity data; The projection data corresponding to the flat plate model is obtained based on the second preprocessed intensity data.

3. The method for calculating the shape of the focal intensity distribution of a CT tube according to claim 1, characterized in that, The calculation of the position data of the flat panel model based on the projection data includes: The position coordinates of the left and right ends of the flat plate mold are calculated using the least squares method, and the position data of the flat plate mold is obtained based on the left and right end position coordinates.

4. The method for calculating the shape of the focal intensity distribution of a CT tube according to claim 3, characterized in that, The calculation of the dimensions of the flat plate mold based on the position data includes: The dimensions of the flat mold are calculated using formula (1); Formula (1); In the formula, For the dimensional data of the flat mold body, This represents the x-coordinate of the left end position of the flat mold. This represents the ordinate value of the left end position of the flat mold. This represents the x-coordinate of the right end position of the flat mold. This represents the ordinate value of the right end position of the flat mold.

5. A shape calculation system for the focal intensity distribution of a CT tube, characterized in that, include: The projection data acquisition module is used to scan the flat panel model and obtain the projection data corresponding to the flat panel model. The position calculation module is used to calculate the position data of the flat panel model based on the projection data; The size calculation module is used to calculate the size data of the flat plate mold based on the position data; The projection result acquisition module is used to simulate projection of the flat plate model based on the projection data, position data and size data, and obtain the projection result of the flat plate model. The projection result acquisition module is also used for: The projection result is calculated using formula (2); Formula (2); In the formula, The projection result is shown, where c is the pixel number of the detector. For the exposure angle, Let m be the number of virtual focal points on one side, and m be the number of the virtual focal points. The position coordinates of the virtual focus. The light intensity at the virtual focal point; The parameter calculation module is used to input the projection result into a pre-constructed focal intensity distribution model, and calculate the optimal value of the parameters of the focal intensity distribution model based on the least squares method iteration with the projection data as the target. The shape calculation module is used to calculate the shape of the light intensity distribution at the X-ray tube focal spot based on the optimal value of the parameters; The shape of the light intensity distribution at the focal point of the X-ray tube is calculated using formula (3); Formula (3); In the formula, This refers to the shape of the light intensity distribution at the focal point of the X-ray tube. The total number of Gaussian functions. This represents the index of the Gaussian function in the focal intensity distribution model. Let n be the magnitude of the Gaussian function. This is the offset position relative to the center of focus. The location of the center of symmetry for the nth Gaussian function. Let n be the standard deviation of the nth Gaussian function; The optimal value of the parameter is , and .

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 4.

7. A non-transitory computer-readable medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 4.

Images