Cone beam CT image reconstruction method and device, electronic equipment and storage medium

Abstract

The application provides a cone beam CT image reconstruction method and device, electronic equipment and storage medium. The cone beam CT image reconstruction method comprises the following steps: firstly, reconstructing an initial three-dimensional reconstruction image according to acquired projection data; then, performing bone segmentation on the initial three-dimensional reconstruction image to obtain a first bone tissue three-dimensional image; calculating Radon data of the first bone tissue three-dimensional image, and determining missing Radon data according to the Radon data to obtain reference Radon data; then, reconstructing a second bone tissue three-dimensional image according to the reference Radon data; obtaining a cone beam artifact error three-dimensional image according to the first bone tissue three-dimensional image and the second bone tissue three-dimensional image; and finally, obtaining a target three-dimensional reconstruction image according to the initial three-dimensional reconstruction image and the cone beam artifact error three-dimensional image. The application can not only remove cone beam artifacts well and improve the quality of the reconstruction image when large cone angle projection is performed, but also can significantly improve the reconstruction speed.

Description

Technical Field

[0001] This invention relates to the field of medical imaging technology, and in particular to a cone-beam CT image reconstruction method, apparatus, electronic device, and storage medium. Background Technology

[0002] The advent of cone-beam computed tomography (CBCT) was a major breakthrough in the field of X-ray imaging. The application of planar detectors has brought unique advantages such as high spatial resolution, fast scanning speed, and high radiation utilization. It is now widely used in clinical diagnosis and treatment.

[0003] FDK is the most widely used 3D reconstruction algorithm in cone-beam CT systems, with advantages such as simplicity and efficiency. It can be understood as an approximate derivation of the tomographic filtering back projection algorithm in 3D space. FDK can be used reasonably when the cone angle is small; however, when the cone angle becomes large, the single-circle scanning trajectory deviates from the central layer and insufficient sampling will produce cone-beam artifacts, which manifest as the shape distortion of high-density materials in the reconstructed image.

[0004] Cone-beam CT image reconstruction methods in related technologies mainly fall into two categories. One category utilizes machine learning to fill in missing data at the large cone angle in the edge layers for image reconstruction. The basic principle of this method is to use machine learning to train a predictive model on training data (sample data), and then input the current input data into the trained predictive model to infer the missing data at the large cone angle. The main drawbacks of this method are twofold: First, there are significant individual differences among patients in clinical practice, making it difficult to ensure that the predictive model generated from the training data can adapt to the current input data, leading to inaccurate compensation data. Second, other errors may occur after reconstruction, potentially causing misdiagnosis, thus limiting its widespread clinical application.

[0005] Another method is the iterative reconstruction method that wirelessly approximates the original acquired projection data. While this method can guarantee the accuracy of the reconstructed image, each iteration requires both orthographic and backprojection reconstruction. Orthographic projection requires calculating the line integral of each ray path in the 3D image space, resulting in a huge computational burden. Furthermore, backprojection, which can be understood as the inverse process of orthographic projection, distributes each pixel of the projection data evenly to each pixel of the ray path, also presenting a computationally intensive problem. Moreover, to improve the image quality of the reconstructed image, multiple iterations are required. The total computational burden is equivalent to the product of the number of iterations and (orthographic + backprojection), leading to low image reconstruction efficiency and high demands on computer graphics card performance, thus increasing computational costs.

[0006] It should be noted that the information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to address one or more of the problems existing in the technology, such as some cone-beam CT image reconstruction methods being unsuitable for large cone-angle projections, making them unsuitable for clinical application, or other cone-beam CT image reconstruction methods requiring multiple iterations to remove cone-beam artifacts to achieve a final reconstructed image that meets quality requirements and having low reconstruction efficiency. This invention provides a cone-beam CT image reconstruction method, apparatus, electronic device, and storage medium. This invention not only effectively removes cone-beam artifacts and improves the image quality of reconstructed images under large cone-angle projections, but also requires only a single (no iteration) execution of the entire reconstruction process to obtain the target 3D reconstructed image, significantly improving reconstruction speed.

[0008] To achieve the above objectives, the present invention provides a cone-beam CT image reconstruction method, comprising:

[0009] An initial three-dimensional reconstructed image is obtained based on the acquired projection data; wherein, the projection data is acquired by a cone-beam CT system;

[0010] Bone segmentation is performed on the initial three-dimensional reconstructed image to obtain a first three-dimensional image of bone tissue; the Radiant data corresponding to the first three-dimensional image of bone tissue is calculated, and the missing Radiant data is determined based on the Radiant data to obtain reference Radiant data;

[0011] Based on the reference Leiden data, a second three-dimensional image of bone tissue is reconstructed; and based on the first three-dimensional image of bone tissue and the second three-dimensional image of bone tissue, a cone-beam artifact error three-dimensional image is obtained.

[0012] The target three-dimensional reconstructed image is obtained based on the initial three-dimensional reconstructed image and the cone-beam artifact error three-dimensional image.

[0013] Optionally, the cone-beam CT image reconstruction method includes: acquiring the projection data by using a single-circle scanning trajectory or a spiral scanning trajectory.

[0014] Optionally, the Raydon data corresponding to the first three-dimensional image of bone tissue is calculated through the following steps:

[0015] Perform a three-dimensional Fourier transform on the first three-dimensional image of bone tissue to obtain a third three-dimensional image of bone tissue;

[0016] Three-dimensional linear interpolation is performed on the three-dimensional image of the third bone tissue to obtain a three-dimensional image of the fourth bone tissue;

[0017] A one-dimensional inverse Fourier transform along the polar radius direction is performed on the three-dimensional image of the fourth bone tissue to obtain the Raydon data corresponding to the three-dimensional image of the first bone tissue.

[0018] Optionally, cone-beam CT image reconstruction methods include:

[0019] The size of the shadow region in the Radiant space is set to |ρ|>SO|sinθ|, and the values ​​at the corresponding positions in the shadow region are filled with 0 to determine the missing Radiant data; and the derivative of ρ is taken to obtain the reference Radiant data; where ρ is the polar radius of the data point in the Radiant space, θ represents the polar angle, and SO is the distance from the X-ray tube focal point of the cone-beam CT system to the rotation center of the C-arm.

[0020] Optionally, the step of reconstructing a second three-dimensional image of bone tissue based on the reference Raydon data includes:

[0021] A radial one-dimensional Fourier transform is performed on the reference Radiant data in the vertical plane of Radiant space to obtain the first frequency domain result in a two-dimensional polar coordinate system; the first frequency domain result is then interpolated to a two-dimensional Cartesian coordinate system, and a two-dimensional inverse Fourier transform is used to obtain the reconstruction result of the vertical plane;

[0022] The reconstruction result of the vertical plane is subjected to a one-dimensional Fourier transform in the horizontal plane to obtain a second frequency domain result in a two-dimensional polar coordinate system; the second frequency domain result is then interpolated to the two-dimensional Cartesian coordinate system, and the two-dimensional inverse Fourier transform is used to obtain the three-dimensional image of the second bone tissue.

[0023] Optionally, the cone-beam CT image reconstruction method further includes: performing Gaussian filtering on the cone-beam artifact error three-dimensional image to obtain a target three-dimensional reconstructed image based on the initial three-dimensional reconstructed image and the Gaussian-filtered cone-beam artifact error three-dimensional image.

[0024] Optionally, the cone-beam CT image reconstruction method includes: segmenting the initial three-dimensional reconstructed image using a threshold segmentation method based on the CT value range corresponding to the bone tissue to obtain the first three-dimensional image of the bone tissue.

[0025] To achieve the above objectives, the present invention also provides a cone-beam CT image reconstruction apparatus, the cone-beam CT image reconstruction apparatus comprising:

[0026] The initial image acquisition unit is configured to reconstruct an initial three-dimensional reconstructed image based on the acquired projection data; wherein the projection data is acquired by a cone-beam CT system.

[0027] The Radiant missing data acquisition unit is configured to perform bone segmentation on the initial three-dimensional reconstructed image to obtain a first three-dimensional image of bone tissue; calculate the Radiant data corresponding to the first three-dimensional image of bone tissue; and determine the Radiant missing data based on the Radiant data to obtain reference Radiant data.

[0028] The cone-beam artifact error acquisition unit is configured to reconstruct a second three-dimensional image of bone tissue based on the reference Raydon data; and to obtain a three-dimensional image of cone-beam artifact error based on the first three-dimensional image of bone tissue and the second three-dimensional image of bone tissue.

[0029] The target image acquisition unit is configured to obtain a target three-dimensional reconstructed image based on the initial three-dimensional reconstructed image and the cone-beam artifact error three-dimensional image.

[0030] To achieve the above objectives, the present invention also provides an electronic device, which includes a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, it implements the cone-beam CT image reconstruction method described in any of the above claims.

[0031] To achieve the above objectives, the present invention also provides a readable storage medium storing a computer program, which, when executed by a processor, implements the cone-beam CT image reconstruction method described in any of the preceding claims.

[0032] Compared with existing technologies, the cone-beam CT image reconstruction method, apparatus, electronic device, and storage medium provided by this invention have the following advantages:

[0033] The cone-beam CT image reconstruction method provided by this invention first reconstructs an initial three-dimensional reconstructed image based on acquired projection data, wherein the projection data is acquired by a cone-beam CT system; then, bone segmentation is performed on the initial three-dimensional reconstructed image to obtain a first three-dimensional image of bone tissue; the Raydon data corresponding to the first three-dimensional image of bone tissue is calculated, and Raydon missing data is determined based on the Raydon data to obtain reference Raydon data; next, a second three-dimensional image of bone tissue is reconstructed based on the reference Raydon data; and a cone-beam artifact error three-dimensional image is obtained based on the first three-dimensional image of bone tissue and the second three-dimensional image of bone tissue; finally, a target three-dimensional reconstructed image is obtained based on the initial three-dimensional reconstructed image and the cone-beam artifact error three-dimensional image. Therefore, the cone-beam CT image reconstruction method provided by this invention first obtains an initial three-dimensional reconstructed image (i.e., a three-dimensional reconstructed image containing cone-beam artifacts) through a single three-dimensional reconstruction; then, it obtains a first three-dimensional bone tissue image (a bone tissue image without cone-beam artifacts) by performing bone segmentation on the initial three-dimensional reconstructed image; and calculates (e.g., through three-dimensional Fourier transform) the Raydon data corresponding to the first three-dimensional bone tissue image, and further determines the missing Raydon data (e.g., filling the region corresponding to the missing Raydon data with 0s, the larger the cone angle, the larger the region corresponding to the missing Raydon data) to obtain reference Raydon data, thereby providing a basis for reconstructing CT images through two-dimensional reconstruction. The second three-dimensional image of bone tissue (containing cone-beam artifacts) is obtained through secondary three-dimensional reconstruction, laying the foundation for this. Then, based on the first three-dimensional image of bone tissue (without cone-beam artifacts) and the second three-dimensional image of bone tissue (containing cone-beam artifacts), the cone-beam artifact error image can be obtained. Finally, based on the initial three-dimensional reconstructed image and the cone-beam artifact error image (since cone-beam artifacts are mainly caused by bone tissue, the artifact error image corresponding to the bone tissue can be used as the cone-beam artifact error image contained in the initial three-dimensional reconstructed image), the target three-dimensional reconstructed image with removed cone-beam artifacts is obtained. Therefore, the cone-beam CT image reconstruction method provided by this invention, since the acquisition of cone-beam artifact error is essentially based on the region corresponding to the missing Raydon data, does not limit the size of the cone angle. It is applicable to both large and small cone-angle projections, thus effectively removing cone-beam artifacts and improving the quality of the reconstructed image in large cone-angle projections. Furthermore, the entire reconstruction process not only eliminates the time-consuming orthographic projection step, but also requires only two image reconstructions, and the target 3D reconstructed image can be obtained in a single execution (without iteration), which can significantly improve the reconstruction speed.

[0034] Since the cone-beam CT image reconstruction device, electronic device and storage medium provided by the present invention belong to the same inventive concept as the cone-beam CT image reconstruction method provided by the present invention, the cone-beam CT image reconstruction device, electronic device and storage medium provided by the present invention have at least all the advantages of the cone-beam CT image reconstruction method provided by the present invention. For details, please refer to the relevant description of the cone-beam CT image reconstruction method above, which will not be repeated here. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the overall process of the cone-beam CT image reconstruction method provided in Embodiment 1 of the present invention;

[0036] Figure 2 This is a schematic diagram illustrating the specific process of the cone-beam CT image reconstruction method provided in one embodiment of the present invention;

[0037] Figure 3 A schematic diagram illustrating the process of converting a first three-dimensional image of bone tissue obtained by applying the cone-beam CT image reconstruction method provided in Embodiment 1 of the present invention into reference Raydon data;

[0038] Figure 4 This is a schematic diagram of the cone-beam CT image reconstruction device provided in Embodiment 2 of the present invention;

[0039] Figure 5 This is a block diagram of the electronic device provided in Embodiment 3 of the present invention.

[0040] The accompanying figure is labeled as follows:

[0041] Three-dimensional image of the first bone tissue - f bone 3D image of the third bone tissue - F bone (u,v,w), three-dimensional image of the fourth bone tissue - Raydon data for three-dimensional images of first bone tissue - Reference to Leiden Data-F 3D_radon ;

[0042] Initial image acquisition unit-101, Leiden missing data acquisition unit-102, cone-beam artifact error acquisition unit-103, target image acquisition unit-104;

[0043] 201 - Processor, 202 - Communication interface, 203 - Memory, 204 - Communication bus. Detailed Implementation

[0044] The cone-beam CT image reconstruction method, apparatus, electronic device, and storage medium proposed in this invention will be further described in detail below with reference to the accompanying drawings. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, used only to facilitate and clarify the illustration of the embodiments of this invention. Please refer to the drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this invention. Any modifications to the structure, changes in proportions, or adjustments to the size, provided that the effects and objectives achieved by this invention are the same or similar, should still fall within the scope of the technical content disclosed in this invention. Specific design features of the invention disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the specific application and usage environment. Furthermore, in the embodiments described below, the same reference numerals are sometimes used across different drawings to denote the same parts or parts having the same function, omitting repeated descriptions. In this specification, similar reference numerals and letters are used to denote similar items; therefore, once an item is defined in one figure, it need not be discussed further in subsequent figures. Furthermore, if the methods described herein involve a series of steps, and the order of these steps presented herein is not necessarily the only possible order in which they can be performed, some of the described steps may be omitted and / or other steps not described herein may be added to the method.

[0045] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The singular forms “a,” “an,” and “the” include plural objects. The term “or” is generally used to mean “and / or,” the term “several” is generally used to mean “at least one,” and the term “at least two” is generally used to mean “two or more.” Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0046] To facilitate understanding and explanation of this invention, before detailing the specific embodiments provided, the causes of cone-beam artifacts and the necessity of artifact removal are briefly explained below: As those skilled in the art will understand, with the increase in the number of detector rows, the angle between the light source and the detector along the z-direction also increases. This increased angle results in the loss of voxel attenuation information in the imaging area. This information loss cannot be compensated for in CT circular trajectory scanning mode. Due to incomplete information, cone-beam artifacts are generated in the reconstructed image. Therefore, due to the influence of cone-beam CT geometry, the projection data obtained from the scan is incomplete, resulting in artifacts during reconstruction. In other words, cone-beam artifacts are unavoidable. To better improve the quality of the reconstructed image and more effectively assist doctors in diagnosis and treatment, removing cone-beam artifacts during image reconstruction is essential.

[0047] Based on this, the core idea of ​​the present invention is to provide a cone-beam CT image reconstruction method, apparatus, electronic device and storage medium, so as to effectively remove cone-beam artifacts when projecting at a large cone angle, thereby improving the image quality of the reconstructed image and increasing the reconstruction speed.

[0048] It should be noted that the cone-beam CT image reconstruction method provided by this invention can be applied to the cone-beam CT image reconstruction device and / or electronic device provided by this invention. The electronic device can be a personal computer, mobile terminal, etc., and the mobile terminal can be a mobile phone, tablet computer, or other hardware device with various operating systems. Furthermore, the cone-beam CT image reconstruction device provided by this invention can be arranged on a cone-beam CT system, and this invention does not limit the specific implementation of the cone-beam CT image reconstruction device. The cone-beam CT image reconstruction device provided by this invention can be implemented in software, in hardware, or in a combination of software and hardware; this invention does not limit this. Even further, the cone-beam CT image reconstruction method and cone-beam CT image reconstruction device provided by this invention can be applied to a cone-beam CT system.

[0049] Example 1

[0050] This embodiment provides a cone-beam CT image reconstruction method. For details, please refer to [link to relevant documentation]. Figure 1 This diagram schematically illustrates the overall process of the cone-beam CT image reconstruction method provided in this embodiment. From Figure 1 As can be seen, the cone-beam CT image reconstruction method provided in this embodiment includes:

[0051] S100: Based on the acquired projection data, an initial three-dimensional reconstructed image is obtained; wherein, the projection data is acquired by a cone-beam CT system;

[0052] S200: Perform bone segmentation on the initial three-dimensional reconstructed image to obtain a first three-dimensional image of bone tissue; calculate the Radiant data corresponding to the first three-dimensional image of bone tissue, and determine the missing Radiant data based on the Radiant data to obtain reference Radiant data;

[0053] S300: Based on the reference Raydon data, a second three-dimensional image of bone tissue is reconstructed; and based on the first three-dimensional image of bone tissue and the second three-dimensional image of bone tissue, a cone-beam artifact error three-dimensional image is obtained;

[0054] S400: Obtain the target three-dimensional reconstruction image based on the initial three-dimensional reconstruction image and the cone-beam artifact error three-dimensional image.

[0055] Therefore, the cone-beam CT image reconstruction method provided in this embodiment first obtains an initial 3D reconstructed image (i.e., a 3D reconstructed image containing cone-beam artifacts) through a single 3D reconstruction; then, it obtains a first 3D bone tissue image (a bone tissue image containing cone-beam artifacts) by performing bone segmentation on the initial 3D reconstructed image; and calculates (e.g., through 3D Fourier transform) the Raydon data corresponding to the first 3D bone tissue image, and further determines the missing Raydon data (e.g., filling the region corresponding to the missing Raydon data with 0s, the larger the cone angle, the larger the region corresponding to the missing Raydon data) to obtain reference Raydon data, thereby providing a basis for the reconstruction of CT images. The second three-dimensional image of bone tissue (containing cone-beam artifacts) is obtained through secondary three-dimensional reconstruction, laying the foundation. Then, based on the first three-dimensional image of bone tissue (containing cone-beam artifacts) and the second three-dimensional image of bone tissue (containing cone-beam artifacts), the cone-beam artifact error image can be obtained. Finally, based on the initial three-dimensional reconstructed image and the cone-beam artifact error three-dimensional image (since cone-beam artifacts are mainly caused by bone tissue, the artifact error image corresponding to the bone tissue can be used as the cone-beam artifact error image contained in the initial three-dimensional reconstructed image), the target three-dimensional reconstructed image with cone-beam artifacts removed is obtained. Therefore, the cone-beam CT image reconstruction method provided in this embodiment, since the acquisition of cone-beam artifact error is essentially based on the region corresponding to the missing Raydon data, does not limit the size of the cone angle. It is applicable to both large and small cone-angle projections. Therefore, it can effectively remove cone-beam artifacts and improve the quality of the reconstructed image in large cone-angle projections. Furthermore, the entire reconstruction process not only eliminates the time-consuming orthographic projection step, but also requires only two image reconstructions, and the target 3D reconstructed image can be obtained in a single execution (without iteration), which can significantly improve the reconstruction speed.

[0056] It should be noted that, as those skilled in the art will understand, for two-dimensional image reconstruction, the Radiden transform is the line integral of the ray over the irradiated object, and the data received by each detector unit is a Radiden data point; for three-dimensional image reconstruction, the Radiden transform is the surface integral of the ray irradiating the object, and each Radiden data point corresponds to the line integral of the detector. The Radiden data mentioned in this invention refers to the three-dimensional reconstruction case.

[0057] Specifically, please see Figure 1 and Figure 2 ,in, Figure 2 This is a schematic diagram illustrating the specific process of a cone-beam CT image reconstruction method provided in one embodiment of the present invention. Figure 1 and Figure 2As can be seen, preferredly, step S100 specifically includes: acquiring the projection data using a single-circle scanning trajectory. Therefore, the cone-beam CT image reconstruction method provided in this embodiment, using a single-circle scanning trajectory, not only facilitates scanning the scanned areas of the subject (e.g., the human body), but also allows for the acquisition of projection data of the scanned areas of the subject at various angles. It should be noted that this is not a limitation of the invention. As those skilled in the art will understand, during scanning, the C-arm of a cone-beam CT system typically moves around a pre-defined spherical region, thus the scanning trajectory is a fixed circle. In other embodiments, the size of the spherical region can be reset according to the shape of the scanned area to adapt to the shape of the area to be scanned and reduce unnecessary radiation. Furthermore, it should be noted that the invention does not limit the scanned area of ​​the subject; it can be the head, chest, etc. Further, in other embodiments, a spiral scanning trajectory can also be used to acquire the projection data. It should be noted that the present invention does not specifically limit the scanning method for acquiring projection data. Any scanning trajectory that does not meet the completeness condition can also use this scheme.

[0058] After obtaining the projection data through scanning, CT analytical reconstruction algorithms, such as filtered backprojection algorithms, can be used to reconstruct the projection data to obtain the initial 3D reconstructed image. Specifically, the original image can be reconstructed based on the FDK (Feldkamp-Davis-Kress) algorithm or FDK derivative algorithms to obtain the initial 3D reconstructed image (i.e., a 3D reconstructed image containing cone-beam artifacts). More specifically, the FDK derivative algorithm can be any of G-FDK (General FDK), P-FDK (Parallel FDK), T-FDK (Tent FDK), HT-FDK (Hybridtent FDK), CC-FDK (Concentric Circle FDK), and HS-FDK (Half Scan FDK). For more detailed information on FDK-based algorithms and FDK derivative algorithms, please refer to existing technologies; further details will not be elaborated here.

[0059] It should be noted that the above is merely an exemplary description of a preferred embodiment. The method of reconstructing the initial three-dimensional reconstructed image based on the acquired projection data facilitates the application of the cone-beam CT image reconstruction method provided by this invention in the real-time imaging process of a cone-beam CT system. However, it is understood that this is not a limitation of this invention. In other embodiments, the initial three-dimensional reconstructed image can also be directly obtained from the cone-beam CT system itself, other storage devices associated with the cone-beam CT system, or the cloud.

[0060] Specifically, please see Figure 3 This diagram schematically illustrates the image reconstruction or transformation steps of the cone-beam CT image reconstruction method provided by this invention. For easier understanding, a cube represents the Cartesian coordinate system used in the current image, and a sphere represents the polar coordinate system used. Furthermore, multiple sampling points of the first bone tissue three-dimensional image schematically represent the first bone tissue three-dimensional image f. bone The three-dimensional image F of the third bone tissue is schematically represented using sampling points of the third bone tissue. bone (u, v, w), schematic representation of the fourth bone tissue three-dimensional image using sampling points. The radon data of the first bone tissue three-dimensional images is represented by sampling points of multiple first bone tissue three-dimensional images. The reference Radiant data F is represented by sampling points from multiple reference Radiant data. 3D_radon .

[0061] More specifically, in one exemplary embodiment, step S200 performs bone segmentation on the initial three-dimensional reconstructed image to obtain a first three-dimensional image of bone tissue f. bone Specifically, this includes: segmenting the initial three-dimensional reconstructed image using a threshold segmentation method based on the CT value range corresponding to the bone tissue, to obtain the first three-dimensional image f of the bone tissue. bone Therefore, the cone-beam CT image reconstruction method provided in this embodiment fully utilizes the characteristic that different tissues and organs, such as soft tissues and bones, have different absorption rates of X-rays, resulting in different CT value ranges for different types of tissues and organs. The initial three-dimensional reconstructed image is segmented using a threshold segmentation method to obtain the first three-dimensional image of the bone tissue. The segmentation method is simple and easier to implement.

[0062] Specifically, for example, in one exemplary embodiment, assuming the CT value of the pixel corresponding to bone tissue in the initial 3D reconstructed image is 250 (a preset threshold for bone tissue), then pixels with a CT value greater than 250 in the initial 3D reconstructed image can be identified as bone points, segmented, and a first 3D image of bone tissue can be obtained. Obviously, the specific value of the preset threshold of 250 for bone tissue is merely an exemplary description and not a limitation of the present invention. In practical applications, it should be reasonably set according to the object being examined, imaging parameters, etc.

[0063] It should be noted that although the threshold segmentation method was used as an example to describe the specific content of segmenting the initial 3D reconstructed image, this is not a limitation of the present invention. In other embodiments, other segmentation methods such as Otsu's method, machine learning, and deep learning can also be used to segment the initial 3D reconstructed image, which will not be described in detail here.

[0064] Furthermore, in one exemplary embodiment, the Raydon data corresponding to the first three-dimensional image of bone tissue is calculated through the following steps:

[0065] S210: The three-dimensional image of the first bone tissue f bone Perform a three-dimensional Fourier transform to obtain a three-dimensional image F of the third bone tissue. bone (u, v, w).

[0066] Specifically, preferably, the three-dimensional image F of the third bone tissue is obtained by the following formula. bone (u, v, w):

[0067]

[0068] In the above formula, f(x, y, z) is the three-dimensional image of the first bone tissue corresponding to the Cartesian coordinate system, and x, y, z are the values ​​of the first bone tissue three-dimensional image f. bone The three-dimensional coordinates, N is the number of pixels in the image, u, v, w are the coordinates of the third bone tissue three-dimensional image F. bone The three-dimensional coordinates.

[0069] from Figure 3 It can be seen that at this time, the three-dimensional image f of the first bone tissue in the spatial domain is transformed by three-dimensional Fourier transform. bone Three-dimensional image of the third bone tissue converted to the frequency domain F bone (u, v, w), at this time, the three-dimensional image F of the third bone tissue bone (u, v, w) represents the equally spaced sampling of a three-dimensional cube.

[0070] S220: Three-dimensional image F of the third bone tissue bone Three-dimensional linear interpolation was performed on (u, v, w) to obtain a three-dimensional image of the fourth bone tissue. Specifically, ρ and θ are the three-dimensional spherical coordinates of the three-dimensional image of the fourth bone tissue. Let θ represent the meridian plane of the sphere, and let θ represent the polar angle direction of each meridian plane. This indicates the polar radius direction of each meridian.

[0071] S240: Three-dimensional image of the fourth bone tissue Perform a one-dimensional inverse Fourier transform along the polar radius to obtain the three-dimensional image F of the first bone tissue. bone The corresponding Leiden data.

[0072] Preferably, in one exemplary embodiment, step S200, which determines missing Radiant data based on the Radiant data to obtain reference Radiant data, specifically includes:

[0073] S250: Set the size of the shadow region in the Radiant space to |ρ|>SO|sinθ|, and fill the corresponding position of the shadow region with 0 to determine the missing Radiant data; and differentiate ρ to obtain the reference Radiant data; where ρ is the polar radius of the data point in the Radiant space, θ represents the polar angle, and SO is the distance from the X-ray tube focal point of the cone-beam CT system to the rotation center of the C-arm.

[0074] Therefore, the cone-beam CT image reconstruction method provided in this embodiment obtains Rayden reference data through direct Fourier transform and then realizes image reconstruction through two images. This not only saves the time-consuming step of complex orthographic projection, but also accurately obtains cone-beam artifact errors, thus laying the foundation for obtaining high-quality target three-dimensional reconstructed images.

[0075] Preferably, in one exemplary embodiment, step S300 reconstructs a second three-dimensional image of bone tissue based on the reference Raytheon data, specifically including:

[0076] S310: Perform a radial one-dimensional Fourier transform on the reference Radiant data in the vertical plane of Radiant space to obtain a first frequency domain result in a two-dimensional polar coordinate system; interpolate the first frequency domain result to a two-dimensional Cartesian coordinate system, and use a two-dimensional inverse Fourier transform to obtain a reconstruction result of the vertical plane;

[0077] S320: The reconstruction result of the vertical plane is subjected to a one-dimensional Fourier transform in the horizontal plane to obtain a second frequency domain result in a two-dimensional polar coordinate system; the second frequency domain result is interpolated to the two-dimensional Cartesian coordinate system, and the two-dimensional inverse Fourier transform is used to obtain the second three-dimensional image of the bone tissue.

[0078] Therefore, it can be seen that the present invention reconstructs a second three-dimensional image of bone tissue (bone tissue image containing cone tract artifacts) through two-stage (vertical plane and horizontal plane) inverse Fourier transform. This not only accurately estimates the cone tract artifact error, but also achieves faster reconstruction speed due to the direct Fourier transform-based reconstruction. In summary, this embodiment obtains a first three-dimensional image of bone tissue (bone tissue image containing cone tract artifacts) by bone segmentation of the initial three-dimensional reconstructed image; obtains the Radiant data corresponding to the first three-dimensional image of bone tissue through three-dimensional Fourier transform; fills the regions corresponding to the missing Radiant data with 0s to obtain the missing Radiant data, and obtains the second three-dimensional image of bone tissue (bone tissue image containing cone tract artifacts) through three-dimensional reconstruction. This lays a solid foundation for obtaining a cone tract artifact error image based on the first three-dimensional image of bone tissue (bone tissue image containing cone tract artifacts) and the second three-dimensional image of bone tissue (bone tissue image containing cone tract artifacts).

[0079] More specifically, step S300 obtains a cone-beam artifact error three-dimensional image based on the first three-dimensional image of bone tissue and the second three-dimensional image of bone tissue, specifically including:

[0080] S330: Subtract the first bone tissue three-dimensional image from the second bone tissue three-dimensional image to obtain the cone-beam artifact error three-dimensional image.

[0081] Since both the first and second three-dimensional bone tissue images are obtained from the initial three-dimensional reconstructed image, and cone-beam artifacts are mainly caused by bone tissue, the artifact error image corresponding to the bone tissue can be used as the cone-beam artifact error image contained in the initial three-dimensional reconstructed image. Therefore, the cone-beam CT image reconstruction method provided by the present invention can obtain a target three-dimensional reconstructed image with cone-beam artifacts removed by subtracting the first three-dimensional bone tissue image from the second three-dimensional bone tissue image.

[0082] Preferably, please continue to see Figure 2 The cone-beam CT image reconstruction method provided in one preferred embodiment further includes:

[0083] Gaussian filtering is applied to the cone-beam artifact error 3D image to obtain the target 3D reconstructed image based on the initial 3D reconstructed image and the Gaussian-filtered cone-beam artifact error 3D image.

[0084] Since cone-beam artifacts typically manifest as low-frequency signals, the cone-beam CT image reconstruction method provided in this embodiment employs Gaussian filtering to remove high-frequency effects, thereby further improving the image quality of the target 3D reconstructed image.

[0085] Correspondingly, step S400 obtains the target three-dimensional reconstruction image based on the initial three-dimensional reconstruction image and the cone-beam artifact error three-dimensional image, specifically including:

[0086] The target 3D reconstructed image is obtained by subtracting the Gaussian-filtered cone-beam artifact error 3D image from the initial 3D reconstructed image.

[0087] Example 2

[0088] This embodiment provides a cone-beam CT image reconstruction device. For details, please refer to [link to relevant documentation]. Figure 4 The diagram illustrates the structure of the cone-beam CT image reconstruction device provided in this embodiment. Figure 4 As can be seen, the cone-beam CT image reconstruction device provided in this embodiment includes: an initial image acquisition unit 101, a Raydon missing data acquisition unit 102, a cone-beam artifact error acquisition unit 103, and a target image acquisition unit 104.

[0089] Specifically, the initial image acquisition unit 101 is configured to reconstruct an initial three-dimensional reconstructed image based on the acquired projection data; wherein the projection data is acquired by a cone-beam CT system. The Raydon missing data acquisition unit 102 is configured to perform bone segmentation on the initial three-dimensional reconstructed image to obtain a first three-dimensional image of bone tissue; calculate the Raydon data corresponding to the first three-dimensional image of bone tissue, and determine the Raydon missing data based on the Raydon data to obtain reference Raydon data. The cone-beam artifact error acquisition unit 103 is configured to reconstruct a second three-dimensional image of bone tissue based on the reference Raydon data; and obtain a cone-beam artifact error three-dimensional image based on the first three-dimensional image of bone tissue and the second three-dimensional image of bone tissue. The target image acquisition unit 104 is configured to obtain a target three-dimensional reconstructed image based on the initial three-dimensional reconstructed image and the cone-beam artifact error three-dimensional image.

[0090] Since the cone-beam CT image reconstruction device provided in this embodiment is based on the same principle as the cone-beam CT image reconstruction method provided in the various embodiments of Embodiment 1 above, more detailed descriptions of the initial image acquisition unit 101, the Raydon missing data acquisition unit 102, the cone-beam artifact error acquisition unit 103, and the target image acquisition unit 104 of the cone-beam CT image reconstruction device provided in this embodiment will not be elaborated here. For detailed descriptions, please refer to the relevant descriptions of the cone-beam CT image reconstruction method provided in the various embodiments of Embodiment 1 above for an adaptive understanding. Furthermore, since the cone-beam CT image reconstruction device provided in this embodiment belongs to the same inventive concept as the cone-beam CT image reconstruction method provided in the various embodiments of Embodiment 1 of this invention, the cone-beam CT image reconstruction device provided in this embodiment has at least all the advantages of the cone-beam CT image reconstruction method provided in the various embodiments of Embodiment 1 above. For detailed descriptions, please refer to the advantages of the cone-beam CT image reconstruction method above, which will not be listed here one by one.

[0091] Example 3

[0092] This embodiment provides an electronic device; please refer to [reference needed]. Figure 5 The diagram illustrates the block structure of the electronic device provided in this embodiment. Figure 5 As shown, the electronic device includes a processor 201 and a memory 203. The memory 203 stores a computer program. When the computer program is executed by the processor 201, it implements the cone-beam CT image reconstruction method described above. Since the electronic device provided in this embodiment belongs to the same inventive concept as the cone-beam CT image reconstruction methods provided in the various embodiments of Embodiment 1 above, the electronic device provided in this embodiment has at least all the advantages of the cone-beam CT image reconstruction methods provided in the various embodiments of Embodiment 1 above. For details, please refer to the relevant description of the cone-beam CT image reconstruction method above, which will not be repeated here.

[0093] like Figure 5 As shown, the electronic device also includes a communication interface 202 and a communication bus 204, wherein the processor 201, the communication interface 202, and the memory 203 communicate with each other via the communication bus 204. The communication bus 204 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus 204 can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is used in the figure, but this does not indicate that there is only one bus or one type of bus. The communication interface 202 is used for communication between the aforementioned electronic device and other devices.

[0094] The processor 201 referred to in this invention can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor. The processor 201 is the control center of the electronic device, connecting various parts of the entire electronic device through various interfaces and lines.

[0095] The memory 203 can be used to store the computer program. The processor 201 implements various functions of the electronic device by running or executing the computer program stored in the memory 203 and calling the data stored in the memory 203.

[0096] The memory 203 may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0097] Example 4

[0098] This embodiment provides a readable storage medium storing a computer program. When executed by a processor, the computer program can implement the cone-beam CT image reconstruction method described above. Since the readable storage medium provided in this embodiment belongs to the same inventive concept as the cone-beam CT image reconstruction methods provided in the various embodiments of Embodiment 1 above, the storage medium provided in this embodiment possesses at least all the advantages of the cone-beam CT image reconstruction methods provided in the various embodiments of Embodiment 1 above, which will not be repeated here.

[0099] The readable storage medium of embodiments of the present invention can be any combination of one or more computer-readable media. The readable medium can be a computer-readable signal medium or a computer-readable storage medium. Computer-readable storage media can be, for example, but not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: electrical connections having one or more wires, portable computer hard disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, apparatus, or device.

[0100] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0101] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0102] In summary, compared with the prior art, the cone-beam CT image reconstruction method, apparatus, electronic device, and storage medium provided by the present invention have the following advantages:

[0103] The cone-beam CT image reconstruction method provided by this invention first obtains an initial 3D reconstructed image (i.e., a 3D reconstructed image containing cone-beam artifacts) through a single 3D reconstruction; then, it obtains a first 3D bone tissue image (a bone tissue image containing cone-beam artifacts) by bone segmentation of the initial 3D reconstructed image; and calculates (e.g., through 3D Fourier transform) the Raydon data, and further determines the missing Raydon data (e.g., filling the region corresponding to the missing Raydon data with 0s, the larger the cone angle, the larger the region corresponding to the missing Raydon data) to obtain reference Raydon data, thereby providing a basis for obtaining the reference Raydon data through a second 3D reconstruction. The first three-dimensional image of bone tissue (bone tissue image including cone-beam artifacts) lays the foundation; then, based on the first three-dimensional image of bone tissue (bone tissue image without cone-beam artifacts) and the second three-dimensional image of bone tissue (bone tissue image including cone-beam artifacts), the cone-beam artifact error image can be obtained; finally, based on the initial three-dimensional reconstructed image and the cone-beam artifact error three-dimensional image (since cone-beam artifacts are mainly caused by bone tissue, the artifact error image corresponding to bone tissue can be used as the cone-beam artifact error image contained in the initial three-dimensional reconstructed image), the target three-dimensional reconstructed image with cone-beam artifacts removed is obtained. Therefore, the cone-beam CT image reconstruction method provided by this invention, since the acquisition of cone-beam artifact error is essentially based on the region corresponding to the missing Raydon data, does not limit the size of the cone angle, and is applicable to both large and small cone-angle projections. Therefore, it can effectively remove cone-beam artifacts and improve the quality of the reconstructed image in large cone-angle projections. Furthermore, the entire reconstruction process not only eliminates the time-consuming orthographic projection step, but also requires only two image reconstructions, and the target 3D reconstructed image can be obtained in a single execution (without iteration), which can significantly improve the reconstruction speed.

[0104] Since the cone-beam CT image reconstruction device, electronic device and storage medium provided by the present invention belong to the same inventive concept as the cone-beam CT image reconstruction method provided by the present invention, the cone-beam CT image reconstruction device, electronic device and storage medium provided by the present invention have at least all the advantages of the cone-beam CT image reconstruction method provided by the present invention. For details, please refer to the relevant description of the cone-beam CT image reconstruction method above, which will not be repeated here.

[0105] It should be noted that the apparatus and methods disclosed in the embodiments herein can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings show the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments herein. In this regard, each block in a flowchart or block diagram may represent a module, program, or part of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system to perform the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0106] In addition, the functional modules in the various embodiments of this article can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0107] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure are within the protection scope of the present invention. Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the present invention and its equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A cone-beam CT image reconstruction method, characterized in that, include: An initial three-dimensional reconstructed image is obtained based on the acquired projection data; wherein, the projection data is acquired by a cone-beam CT system; Bone segmentation is performed on the initial three-dimensional reconstructed image to obtain a first three-dimensional image of bone tissue; the Radiant data corresponding to the first three-dimensional image of bone tissue is calculated, and the missing Radiant data is determined based on the Radiant data to obtain reference Radiant data; Based on the reference Leiden data, a second three-dimensional image of bone tissue is reconstructed; and based on the first three-dimensional image of bone tissue and the second three-dimensional image of bone tissue, a cone-beam artifact error three-dimensional image is obtained. Based on the initial 3D reconstructed image and the cone-beam artifact error 3D image, the target 3D reconstructed image is obtained; The missing Radiant data and the reference Radiant data are determined as follows: the size of the shadow area in the Radiant space is set to... And fill the values ​​at the corresponding positions in the shaded areas with 0 to determine the missing data of the Leiden; and for By performing differentiation, the reference Raydon data is obtained; wherein, Let be the polar radius of the data point in the radon space. Indicates the polar angle. The distance from the focal point of the X-ray tube to the rotation center of the C-arm in the cone-beam CT system is denoted as ...

2. The cone-beam CT image reconstruction method according to claim 1, characterized in that, include: The projection data is acquired by using a single circular scanning trajectory or a spiral scanning trajectory.

3. The cone-beam CT image reconstruction method according to claim 1, characterized in that, The Raydon data corresponding to the first three-dimensional image of bone tissue is calculated using the following steps: A three-dimensional Fourier transform is performed on the first three-dimensional image of bone tissue to obtain a third three-dimensional image of bone tissue; Three-dimensional linear interpolation is performed on the three-dimensional image of the third bone tissue to obtain a three-dimensional image of the fourth bone tissue; A one-dimensional inverse Fourier transform along the polar radius direction is performed on the three-dimensional image of the fourth bone tissue to obtain the Raydon data corresponding to the three-dimensional image of the first bone tissue.

4. The cone-beam CT image reconstruction method according to claim 1, characterized in that, The process of reconstructing a second three-dimensional image of bone tissue based on the reference Raydon data includes: A radial one-dimensional Fourier transform is performed on the reference Radiant data in the vertical plane of Radiant space to obtain the first frequency domain result in a two-dimensional polar coordinate system; the first frequency domain result is then interpolated to a two-dimensional Cartesian coordinate system, and a two-dimensional inverse Fourier transform is used to obtain the reconstruction result of the vertical plane; The reconstruction result of the vertical plane is subjected to a one-dimensional Fourier transform in the horizontal plane to obtain a second frequency domain result in a two-dimensional polar coordinate system; the second frequency domain result is then interpolated to the two-dimensional Cartesian coordinate system, and the two-dimensional inverse Fourier transform is used to obtain the three-dimensional image of the second bone tissue.

5. The cone-beam CT image reconstruction method according to claim 1, characterized in that, Also includes: The cone-beam artifact error 3D image is subjected to Gaussian filtering to obtain the target 3D reconstructed image based on the initial 3D reconstructed image and the Gaussian-filtered cone-beam artifact error 3D image.

6. The cone-beam CT image reconstruction method according to any one of claims 1-5, characterized in that, include: Based on the CT value range corresponding to the bone tissue, the initial three-dimensional reconstructed image is segmented using a threshold segmentation method to obtain the first three-dimensional image of the bone tissue.

7. A cone-beam CT image reconstruction device, characterized in that, include: The initial image acquisition unit is configured to reconstruct an initial three-dimensional reconstructed image based on the acquired projection data; wherein the projection data is acquired by a cone-beam CT system. The Radiant missing data acquisition unit is configured to perform bone segmentation on the initial three-dimensional reconstructed image to obtain a first three-dimensional image of bone tissue; calculate the Radiant data corresponding to the first three-dimensional image of bone tissue; and determine the Radiant missing data based on the Radiant data to obtain reference Radiant data. The cone-beam artifact error acquisition unit is configured to reconstruct a second three-dimensional image of bone tissue based on the reference Raydon data; and to obtain a three-dimensional image of cone-beam artifact error based on the first three-dimensional image of bone tissue and the second three-dimensional image of bone tissue. The target image acquisition unit is configured to obtain a target three-dimensional reconstructed image based on the initial three-dimensional reconstructed image and the cone-beam artifact error three-dimensional image; The missing Radiant data and the reference Radiant data are determined as follows: the size of the shadow area in the Radiant space is set to... And fill the values ​​at the corresponding positions in the shaded areas with 0 to determine the missing data of the Leiden; and for By performing differentiation, the reference Raydon data is obtained; wherein, Let be the polar radius of the data point in the radon space. Indicates the polar angle. The distance from the focal point of the X-ray tube to the rotation center of the C-arm in the cone-beam CT system is denoted as ...

8. An electronic device, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program, which, when executed by the processor, implements the cone-beam CT image reconstruction method according to any one of claims 1 to 6.

9. A readable storage medium, characterized in that, The readable storage medium stores a computer program, which, when executed by a processor, implements the cone-beam CT image reconstruction method according to any one of claims 1 to 6.

Images