CT image correction method and device, computer equipment and storage medium
Through basic material decomposition and density calculation, the incident energy spectrum of the CT system is obtained and the hardening error is calculated to correct the CT image, which solves the problems of low accuracy and low efficiency of the CT image correction method, and achieves higher accuracy and faster image correction.
Patent Information
- Application Number
- CN202311841879.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-28
- Publication Date
- 2025-07-01
AI Technical Summary
The existing CT image correction methods have low accuracy and low correction efficiency. Especially when processing dense substances, there are problems that beam hardening artifacts affect image quality and quantitative accuracy.
By decomposing the base material to be corrected, the base material image is obtained, the base material density is calculated, and the incident energy spectrum of the CT system detector unit in each energy interval is obtained, and the hardening error is calculated based on the incident energy spectrum and the base material density, and the image is then corrected.
Improve the accuracy and efficiency of CT image correction, reduce beam hardening artifacts, improve image quality and quantitative accuracy, and eliminate the need for segmentation of images.
Smart Images
Figure CN120235965A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of CT imaging technology, and particularly to a CT image correction method, apparatus, computer device, and storage medium. Background Art
[0002] The polychromatic spectral characteristics of the X-ray source and the energy-dependent linear attenuation characteristics of substances lead to the emergence of beam hardening effects. When X-rays penetrate an object, generally, low-energy photons are more easily absorbed than high-energy photons. As the depth of the incident object increases, the X-ray energy spectrum gradually shifts towards the high-energy end, which causes the attenuation coefficient of the measured value to be underestimated and beam hardening artifacts such as cupping or streaking to appear in the reconstructed CT image. Beam hardening artifacts are more obvious for substances with high atomic numbers, such as metals, bones, iodine, etc. For image-domain imaging, the presence of hardening artifacts will affect the quality and quantitative accuracy of the energy spectrum image, so it is necessary to correct the hardening artifacts.
[0003] In related technologies, the hardening artifacts caused by dense substances are mainly corrected by segmenting the dense objects in the CT image and estimating the substance density based on the CT value. However, the method of estimating the substance density using the CT value has low accuracy, and it is also necessary to segment the dense objects in the CT image before correction, resulting in relatively low correction efficiency.
[0004] Currently, there is no effective solution to the problem of low accuracy of the CT image correction method in related technologies. Summary of the Invention
[0005] Based on this, it is necessary to provide a CT image correction method, apparatus, computer device, and computer-readable storage medium that can improve the accuracy of CT image correction for the above technical problems.
[0006] In a first aspect, this application provides a CT image correction method. The method includes:
[0007] Perform basis material decomposition on the image to be corrected to obtain basis material images;
[0008] Calculate the basis material density according to the basis material images;
[0009] Obtain the incident energy spectrum of the detector unit of the CT system in each energy interval, and calculate the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density;
[0010] Correct the image to be corrected according to the hardening error.
[0011] In one embodiment, correcting the image to be corrected according to the hardening error includes:
[0012] Reconstruct a hardening error image according to the hardening error;
[0013] Subtract the image to be corrected from the hardening error image to obtain a first corrected image;
[0014] Perform iterative correction on the first corrected image to obtain a second corrected image.
[0015] In one embodiment, obtaining the incident energy spectrum of the detector unit of the CT system includes:
[0016] Using a step phantom with a known thickness to sample the incident data of the detector unit;
[0017] Obtain the projection data of each sampling point;
[0018] According to the projection data, perform iteration on the initial energy spectrum within a preset energy range to obtain the incident energy spectrum.
[0019] In one embodiment, performing basis material decomposition on the image to be corrected to obtain a basis material image includes:
[0020] According to the CT values of the image to be corrected, calculate the attenuation coefficient of each voxel of the image to be corrected in different energy ranges;
[0021] According to the attenuation coefficient of each voxel of the image to be corrected and the effective mass attenuation coefficient of the basis material, calculate the concentration of the basis material in each voxel;
[0022] Construct the basis material image according to the concentration of the basis material in each voxel.
[0023] In one embodiment, calculating the basis material density according to the basis material image includes:
[0024] Perform forward projection on the basis material image to obtain the forward projection value of the basis material image, where the forward projection value of the basis material image is the line integral of the density of the basis material.
[0025] In one embodiment, calculating the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density includes:
[0026] According to the incident energy spectrum and the basis material density, calculate the ideal projection value and the calculated projection value of the basis material under the incident energy spectrum;
[0027] According to the ideal projection value and the calculated projection value of the basis material under the incident energy spectrum, calculate the hardening error of the image to be corrected.
[0028] In one embodiment, calculating the hardening error of the image to be corrected according to the ideal projection value and the calculated projection value of the base material under the incident energy spectrum includes:
[0029] Performing water hardening correction on the calculated projection value;
[0030] Calculating the hardening error of the image to be corrected according to the difference between the corrected calculated projection value and the ideal projection value.
[0031] In a second aspect, the present application also provides a CT image correction device. The device includes:
[0032] An energy spectrum acquisition module, configured to acquire the incident energy spectrum of the detector unit of the CT system in each energy interval;
[0033] An image acquisition module, configured to perform basis material decomposition on the image to be corrected to obtain a basis material image;
[0034] A density calculation module, configured to calculate the basis material density according to the basis material image;
[0035] An error calculation module, configured to calculate the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density;
[0036] An image correction module, configured to correct the image to be corrected according to the hardening error.
[0037] In a third aspect, the present application also provides a computer device. The computer device includes a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:
[0038] Performing basis material decomposition on the image to be corrected to obtain a basis material image;
[0039] Calculating the basis material density according to the basis material image;
[0040] Acquiring the incident energy spectrum of the detector unit of the CT system in each energy interval, and calculating the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density;
[0041] Correcting the image to be corrected according to the hardening error.
[0042] In a fourth aspect, the present application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, and when the computer program is executed by a processor, the following steps are implemented:
[0043] Performing basis material decomposition on the image to be corrected to obtain a basis material image;
[0044] Calculate the basis material density according to the basis material image;
[0045] Obtain the incident energy spectrum of the detector unit of the CT system in each energy interval, and calculate the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density;
[0046] Correct the image to be corrected according to the hardening error.
[0047] The above CT image correction method, device, computer device and storage medium decompose the image to be corrected into basis material images, obtain the basis material images, calculate the basis material density according to the basis material images, obtain the incident energy spectrum of the detector unit of the CT system in each energy interval, calculate the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density, and correct the image to be corrected according to the hardening error, thereby realizing the correction of CT images using the accurate basis material density calculated from the basis material images, solving the problem of low accuracy of CT image correction methods, improving the accuracy of CT image correction. At the same time, there is no need to segment the basis material image of the image to be corrected during correction, improving the efficiency of CT image correction. Description of the Drawings
[0048] Figure 1 It is a schematic flowchart of a CT image correction method in an embodiment;
[0049] Figure 2 It is a schematic overall flowchart of a CT image correction method in an embodiment;
[0050] Figure 3 It is a schematic diagram of the effect of a CT image correction method in an embodiment;
[0051] Figure 4 It is a structural block diagram of a CT image correction device in an embodiment;
[0052] Figure 5 It is an internal structure diagram of a computer device in an embodiment. Detailed Description of the Embodiments
[0053] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.
[0054] In one embodiment, as Figure 1 shown, a CT image correction method is provided, including the following steps:
[0055] Step S101: Perform basis material decomposition on the image to be corrected to obtain a basis material image.
[0056] Among them, in CT imaging, the X-ray absorption effect of any specific tissue can be equivalently represented by a combination of basis material pairs with corresponding proportions of two substances. Therefore, based on the distribution of basis materials, qualitative and quantitative evaluations of tissue composition and contrast agent distribution can be performed. Clinically, water and iodine or calcium and water are usually used as basis material pairs. The specific process of performing basis material decomposition on the image to be corrected is as follows: After obtaining the image to be corrected, calculate the concentration of the basis material in the voxels of the CT images in different energy intervals according to the CT value of the image and the attenuation coefficient of the basis material in the voxels of the CT images in different energy intervals, and perform calibration according to the basis material concentration to obtain the basis material image.
[0057] Step S102: Calculate the basis material density according to the basis material image.
[0058] Among them, since the basis material image contains the concentration information of the basis material in the voxels of the CT images in different energy intervals, the density of the basis material in the voxels of the CT images in different energy intervals can be obtained according to the basis material image.
[0059] Step S103: Obtain the incident energy spectrum of the detector unit of the CT system in each energy interval, and calculate the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density.
[0060] Among them, for each detector unit of the CT system, its incident energy spectrum is unknown. Therefore, it is necessary to calculate the incident energy spectrum of the detector unit in each energy interval. Sample the data of the detector unit, and the effective incident energy spectrum of each detector unit in different energy intervals can be estimated according to the sampled data. After the incident energy spectrum calculation is completed, the ideal projection value and the calculated projection value of the image to be corrected in different energy intervals can be calculated according to the incident energy spectrum and the basis material density, and the hardening error of the image to be corrected can be calculated according to the ideal projection value and the calculated projection value.
[0061] Step S104: Correct the image to be corrected according to the hardening error.
[0062] Among them, according to the hardening error, a hardening error image can be reconstructed, and the image to be corrected can be corrected by subtracting the hardening error image from the image to be corrected.
[0063] In the above CT image correction method, by performing basis material decomposition on the image to be corrected, basis material images are obtained. Based on the basis material images, basis material densities are calculated, and the incident energy spectra of the detector units of the CT system in each energy interval are acquired. According to the incident energy spectra and the basis material densities, the hardening error of the image to be corrected is calculated. According to the hardening error, the image to be corrected is corrected, thereby realizing the correction of the CT image using the accurate basis material density calculated from the basis material image, solving the problem of low accuracy of the CT image correction method, improving the accuracy of CT image correction. At the same time, when correcting, it is not necessary to segment the basis material image of the image to be corrected, improving the efficiency of CT image correction.
[0064] In one embodiment, correcting the image to be corrected according to the hardening error includes:
[0065] According to the hardening error, a hardening error image is reconstructed; the image to be corrected is subtracted from the hardening error image to obtain a first corrected image; the first corrected image is iteratively corrected to obtain a second corrected image.
[0066] Among them, according to the hardening error term Δp, the hardening error image Δμ_((i))^((n)) can be reconstructed. The image to be corrected is subtracted from the hardening error image to obtain the corrected first corrected image. The first corrected image is used to replace the original image to be corrected and repeat the above correction process of hardening error correction based on the basis material density and the effective energy spectrum data until the iteration ends to obtain the second corrected image, that is, the final corrected image.
[0067] Specifically, the calculation method for subtracting the image to be corrected from the hardening error image is:
[0068] μ_((i))^((n + 1)) = μ_((i))^((0)) - Δμ_((i))^((n))
[0069] Among them, μ_((i))^((0)) is the original image to be corrected, Δμ_((i))^((n)) is the hardening error image at the nth iteration, and μ_((i))^((n + 1)) is the corrected image at the (n + 1)th iteration.
[0070] In this embodiment, by reconstructing the error image and directly subtracting the error image from the original image to be corrected, the efficiency of CT image correction is improved; at the same time, the image to be corrected is iteratively corrected, improving the accuracy of CT image correction.
[0071] In one embodiment, acquiring the incident energy spectra of the detector units of the CT system in each energy interval includes:
[0072] Using a step phantom with a known thickness, sample the incident data of the detector unit; obtain the projection data of each sampling point; according to the projection data, iterate the initial energy spectrum within a preset energy range to obtain the incident energy spectrum.
[0073] Among them, the step phantom is a material with a known density and thickness. By scanning the phantom, the calibration of the incident energy spectrum of the detector unit can be realized. The projection data of the sampling point includes the projection value of the sampling point and the forward projection value. The projection value is the measured projection value of each sampling point obtained after scanning, and the forward projection value is the equivalent length of the ray passing through in the voxel space of the scanned object, which can reflect the distribution ratio and thickness of the substance in the voxel. The initial energy spectrum is the incident energy spectrum obtained in advance, and its accuracy is relatively low. Therefore, it needs to be iteratively updated according to the actual projection data, and finally the incident energy spectrum of the detector unit in each energy range is obtained. Store the obtained effective energy spectrum data in the form of a file or other forms for subsequent correction or other processing.
[0074] Specifically, set the initial energy spectrum Denote the measured projection value at each sampling point i as p i , and denote the forward projection as L p , and the finally obtained effective incident energy spectrum is S j , j is the energy index, set the energy interval between the energy intervals, and in this embodiment, an energy interval of 1 keV is taken. Use the following formula to iteratively update the incident energy spectrum, and stop when the iteration converges to obtain the incident energy spectrum:
[0075]
[0076]
[0077]
[0078] In this embodiment, calibration is performed through the phantom, which can effectively and accurately calibrate the incident energy spectrum and the effective energy, improving the efficiency and accuracy of the CT image correction method.
[0079] In one embodiment, perform basis material decomposition on the image to be corrected, and the obtained basis material images include:
[0080] According to the CT value of the image to be corrected, calculate the attenuation coefficient of each voxel of the image to be corrected in different energy ranges; according to the attenuation coefficient of each voxel of the image to be corrected and the effective mass attenuation coefficient of the basis material, calculate the concentration of the basis material in each voxel; according to the concentration of the basis material in each voxel, construct the basis material image.
[0081] Among them, the effective mass attenuation coefficient of the basis material can be calibrated according to the linear attenuation coefficient of the basis material and the corresponding basis material concentration in the CT image. Alternatively, when the specific type of the basis material is unknown, the basis material image can also be obtained by decomposing the photoelectric effect term and Compton scattering term of the incident ray as basis functions.
[0082] Specifically, the method for performing basis material decomposition on the image to be corrected is as follows:
[0083]
[0084] Among them, μ j is the linear attenuation coefficient in the voxel of the image to be corrected in the i-th energy interval, λ m is the concentration of the basis material m in the voxel of the image to be corrected. Select M basis materials, and the effective mass attenuation coefficient of the M-th basis material in the i-th energy interval is which can be calibrated by using the linear attenuation coefficient in the Gammex standard image and the corresponding material concentration in the image.
[0085] In this embodiment, the basis material image is obtained by performing basis material decomposition on the original image to be corrected, without the need to segment the image to be corrected, improving the efficiency of image processing. At the same time, the basis material image obtained by basis material decomposition has a high accuracy, thereby improving the accuracy of CT image correction.
[0086] In one embodiment, calculating the basis material density according to the basis material image includes:
[0087] Performing forward projection on the basis material image to obtain the forward projection value of the basis material image. Among them, the forward projection value of the basis material image is the density line integral of the basis material.
[0088] Among them, for the forward projection of the basis material image, according to the forward projection value of the basis material, the density of the basis material in each voxel can be calculated, thereby obtaining the density line integral of the basis material.
[0089] In this embodiment, calculating the density line integral of the basis material according to the projection value of the basis material has higher accuracy compared to estimating the density of the basis material through CT values, thereby improving the accuracy of CT image correction.
[0090] In one embodiment, calculating the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density includes:
[0091] According to the incident energy spectrum and the basis material density, calculate the ideal projection value and the calculated projection value of the basis material under the incident energy spectrum; according to the ideal projection value and the calculated projection value of the basis material under the incident energy spectrum, calculate the hardening error of the image to be corrected.
[0092] Among them, the calculation method of the ideal projection value is as follows:
[0093]
[0094] The calculation method of the calculated projection value is as follows:
[0095]
[0096] Among them, n is the number of iterations performed, is the calculated projection value of the reference material in the i-th energy interval, is the ideal projection value of the reference material in the i-th energy interval, S is the calibrated normalized energy spectrum under each actually measured energy interval, j is the energy index, is the effective energy under different energy intervals.
[0097] After obtaining the ideal projection value and the calculated projection value of the reference material in different energy intervals, according to the difference between the ideal projection value and the calculated projection value, the hardening error Δp of the image to be corrected can be calculated. The specific calculation method is as follows:
[0098]
[0099] In this embodiment, calculating the hardening error of the image to be corrected according to the ideal projection value and the calculated projection value of the reference material in different energy intervals has higher accuracy in calculating the hardening error compared with the method of estimating based on CT values.
[0100] In one embodiment, calculating the hardening error of the image to be corrected according to the ideal projection value and the calculated projection value of the reference material under the incident energy spectrum includes:
[0101] Performing water hardening correction on the calculated projection value; calculating the hardening error of the image to be corrected according to the difference between the corrected calculated projection value and the ideal projection value.
[0102] Among them, after calculating the calculated projection value, perform water hardening correction on the calculated projection value to ensure that the calculated calculated projection value is relatively accurate. The specific calculation method is as follows:
[0103]
[0104] Among them, n is the number of iterations performed, (·) wcorr is the water hardening correction process, and coeff is the water hardening correction coefficient.
[0105] In this embodiment, performing water error hardening correction on the calculated projection value before the hardening error makes the calculated projection value more accurate, thereby improving the accuracy of CT image correction.
[0106] In one embodiment,Figure 2 It is a schematic diagram of the overall process of the CT image correction method. As Figure 2 shown, the effective energy spectrum data is calculated by collecting the projection data of a phantom with a known thickness. The original image to be corrected is reconstructed and basis material decomposition based on the image domain is performed on it to obtain the basis material image. According to the effective energy spectrum data and the basis material image, the calculated projection value and the ideal projection value are generated. To ensure the accuracy of the calculated projection value, water hardening correction is performed on the calculated projection value. The hardening correction error is calculated based on the ideal projection value and the corrected calculated projection value, and the error image is reconstructed according to the hardening correction error. The original image to be corrected is subtracted from the error image, and the above steps are repeated for iteration. When the iteration condition is met, the corrected image is output as the final correction result.
[0107] In one embodiment, Figure 3 It is a schematic diagram of the effect of the CT image correction method according to an embodiment of the present application. As Figure 3 shown, image correction is performed on the head phantom image. The left image is the image effect of the traditional water hardening correction method under bin1 and bin2 (chip 1 and chip 2), and the right image is the image effect of the CT image correction method according to the embodiment of the present application under bin1 and bin2. It can be seen from the figure that compared with the traditional water hardening correction method, the image obtained by the error correction method according to the embodiment of the present application has less hardening artifacts and higher image accuracy.
[0108] It should be understood that although the steps in the flowcharts involved in the above-mentioned embodiments are sequentially shown according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least a part of other steps or steps or stages in other steps.
[0109] Based on the same inventive concept, an embodiment of the present application also provides a CT image correction device for implementing the above-mentioned CT image correction method. The solution provided by this device to solve the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the CT image correction device provided below can refer to the limitations on the CT image correction method in the above text, and will not be repeated here.
[0110] In one embodiment, as Figure 4As shown in the figure, a CT image correction device is provided, including: an energy spectrum acquisition module 41, an image acquisition module 42, a density calculation module 43, an error calculation module 44, and an image correction module 45, where:
[0111] The energy spectrum acquisition module 41 is configured to acquire the incident energy spectrum of the detector unit of the CT system in each energy interval;
[0112] The image acquisition module 42 is configured to perform basis material decomposition on the image to be corrected to obtain a basis material image;
[0113] The density calculation module 43 is configured to calculate the basis material density according to the basis material image;
[0114] The error calculation module 44 is configured to calculate the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density;
[0115] The image correction module 45 is configured to correct the image to be corrected according to the hardening error.
[0116] Each module in the above CT image correction device can be implemented in whole or in part by software, hardware, and their combination. Each of the above modules can be embedded in the processor of the computer device in hardware form or independent of it, or stored in the memory of the computer device in software form, so as to facilitate the processor to call and execute the operations corresponding to each of the above modules.
[0117] In one embodiment, a computer device is provided. The computer device can be a server, and its internal structure diagram can be as Figure 5 shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store incident energy spectrum data and basis material image data. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements a CT image correction method.
[0118] Those skilled in the art can understand, Figure 5The structure shown is only a block diagram of some structures related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have a different component layout.
[0119] In one embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, the following steps are implemented:
[0120] Perform basis material decomposition on the image to be corrected to obtain a basis material image; calculate the basis material density according to the basis material image; obtain the incident energy spectrum of the detector unit of the CT system in each energy interval, and calculate the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density; correct the image to be corrected according to the hardening error.
[0121] In one embodiment, when the processor executes the computer program, the following steps are also implemented:
[0122] Use a phantom with a known thickness to sample the incident data of the detector unit; obtain the projection data of each sampling point; iterate the initial energy spectrum in a preset energy interval according to the projection data to obtain the incident energy spectrum.
[0123] In one embodiment, when the processor executes the computer program, the following steps are also implemented:
[0124] Calculate the attenuation coefficient of each voxel of the image to be corrected in different energy intervals according to the CT value of the image to be corrected; calculate the concentration of the basis material in each voxel according to the attenuation coefficient of each voxel of the image to be corrected and the effective mass attenuation coefficient of the basis material; construct the basis material image according to the concentration of the basis material in each voxel.
[0125] In one embodiment, when the processor executes the computer program, the following steps are also implemented:
[0126] Perform forward projection on the basis material image to obtain the forward projection value of the basis material image; calculate the density line integral of the basis material according to the forward projection value.
[0127] In one embodiment, when the processor executes the computer program, the following steps are also implemented:
[0128] Calculate the ideal projection value and the actual projection value of the basis material under the incident energy spectrum according to the incident energy spectrum and the basis material density; calculate the hardening error of the image to be corrected according to the ideal projection value and the actual projection value of the basis material under the incident energy spectrum.
[0129] In one embodiment, when the processor executes the computer program, the following steps are further implemented:
[0130] Perform water hardening correction on the calculated projection value; calculate the hardening error of the image to be corrected according to the difference between the corrected calculated projection value and the ideal projection value.
[0131] In one embodiment, when the processor executes the computer program, the following steps are further implemented:
[0132] Reconstruct the hardening error image according to the hardening error; subtract the hardening error image from the image to be corrected to obtain a first corrected image; perform iterative correction on the first corrected image to obtain a second corrected image.
[0133] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:
[0134] Perform basis material decomposition on the image to be corrected to obtain a basis material image; calculate the basis material density according to the basis material image; obtain the incident energy spectrum of the detector unit of the CT system in each energy interval, and calculate the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density; correct the image to be corrected according to the hardening error.
[0135] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented:
[0136] Sample the incident data of the detector unit by using a phantom with a known thickness; obtain the projection data of each sampling point; perform iteration on the initial energy spectrum within a preset energy interval according to the projection data to obtain the incident energy spectrum.
[0137] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented:
[0138] Calculate the attenuation coefficient of each voxel of the image to be corrected in different energy intervals according to the CT value of the image to be corrected; calculate the concentration of the basis material in each voxel according to the attenuation coefficient of each voxel of the image to be corrected and the effective mass attenuation coefficient of the basis material; construct the basis material image according to the concentration of the basis material in each voxel.
[0139] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented:
[0140] Perform forward projection on the basis material image to obtain the forward projection value of the basis material image; calculate the density line integral of the basis material according to the forward projection value.
[0141] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented:
[0142] Calculate the ideal projection value and the actual projection value of the basis material under the incident energy spectrum according to the incident energy spectrum and the basis material density; calculate the hardening error of the image to be corrected according to the ideal projection value and the actual projection value of the basis material under the incident energy spectrum.
[0143] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented:
[0144] Perform water hardening correction on the calculated projection value; calculate the hardening error of the image to be corrected according to the difference between the corrected calculated projection value and the ideal projection value.
[0145] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented:
[0146] Reconstruct a hardening error image according to the hardening error; subtract the image to be corrected from the hardening error image to obtain a first corrected image; perform iterative correction on the first corrected image to obtain a second corrected image.
[0147] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use, and processing of relevant data need to comply with the relevant laws, regulations, and standards of relevant countries and regions.
[0148] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memories. Non-volatile memory can include Read-Only Memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in the present application can be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., without limitation.
[0149] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.
[0150] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.
Claims
1. A CT image correction method, characterized in that, The method includes: Performing basis material decomposition on the image to be corrected to obtain a basis material image; Calculating the basis material density according to the basis material image; Obtaining the incident energy spectrum of the detector unit of the CT system in each energy interval, and calculating the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density; Correcting the image to be corrected according to the hardening error.
2. The CT image correction method according to claim 1, wherein Correcting the image to be corrected according to the hardening error includes: Reconstructing a hardening error image according to the hardening error; Subtracting the hardening error image from the image to be corrected to obtain a first corrected image; Performing iterative correction on the first corrected image to obtain a second corrected image.
3. The CT image correction method according to claim 1, wherein Obtaining the incident energy spectrum of the detector unit of the CT system in each energy interval includes: Sampling the incident data of the detector unit by using a phantom with a known thickness; Obtaining the projection data of each sampling point; Iterating the initial energy spectrum within a preset energy interval according to the projection data to obtain the incident energy spectrum.
4. The CT image correction method according to claim 1, wherein, Performing basis material decomposition on the image to be corrected to obtain a basis material image includes: Calculating the attenuation coefficient of each voxel of the image to be corrected in different energy intervals according to the CT value of the image to be corrected; Calculating the concentration of the basis material in each voxel according to the attenuation coefficient of each voxel of the image to be corrected and the effective mass attenuation coefficient of the basis material; Constructing the basis material image according to the concentration of the basis material in each voxel.
5. The CT image correction method according to claim 1, characterized in that Calculating the basis material density according to the basis material image includes: Performing forward projection on the basis material image to obtain the forward projection value of the basis material image, where the forward projection value of the basis material image is the density line integral of the basis material.
6. The CT image correction method according to claim 1, wherein Calculating the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density includes: Calculating the ideal projection value and the calculated projection value of the basis material under the incident energy spectrum according to the incident energy spectrum and the basis material density; Calculating the hardening error of the image to be corrected according to the ideal projection value and the calculated projection value of the basis material under the incident energy spectrum.
7. The CT image correction method according to claim 6, wherein Calculating the hardening error of the image to be corrected according to the ideal projection value and the calculated projection value of the basis material under the incident energy spectrum includes: Performing water hardening correction on the calculated projection value; Calculating the hardening error of the image to be corrected according to the difference between the corrected calculated projection value and the ideal projection value.
8. A CT image correction device, characterized in that, Includes: An energy spectrum acquisition module for obtaining the incident energy spectrum of the detector unit of the CT system in each energy interval; An image acquisition module for performing basis material decomposition on the image to be corrected to obtain a basis material image; A density calculation module for calculating the basis material density according to the basis material image; An error calculation module for calculating the hardening error of the image to be corrected according to the incident energy spectrum and the basis material density; An image correction module for correcting the image to be corrected according to the hardening error.
9. A computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, the steps of the CT image correction method according to any one of claims 1 to 7 are implemented.
10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by a processor, it implements the steps of the CT image correction method according to any one of claims 1 to 7.