Vertebral mechanical strength evaluation method, device, computer equipment and storage medium

Abstract

The embodiment of the present invention discloses a method, device, computer equipment and storage medium for evaluating the mechanical strength of a vertebra. The method comprises: acquiring CT image data of a vertebra; extracting a single segment of a vertebra from the CT image data of the vertebra as a vertebra to be evaluated for three-dimensional construction to obtain a three-dimensional structure of the vertebra to be evaluated; discretizing the three-dimensional structure of the vertebra to be evaluated to obtain a plurality of discrete unit bodies; adding discrete unit bodies for representing a splint on the upper and lower surfaces of the vertebra to be evaluated; describing the material properties of the discrete unit bodies to give them corresponding bone density, Young's modulus and Poisson's ratio; applying boundary conditions and constraints to the discrete unit bodies for representing the splints and establishing a set of stress and strain relationship equations for the vertebra to be evaluated according to the material properties of the discrete unit bodies; evaluating the vertebra to be evaluated under a preset load based on the set of stress and strain relationship equations for the vertebra to be evaluated to obtain the mechanical strength of the vertebra to be evaluated.

Description

Technical Field

[0001] The present invention relates to the field of medical data processing, and in particular to a vertebral mechanical strength evaluation method, device, computer equipment and storage medium. Background Art

[0002] The existing biomechanical finite element method uses computer simulation to perform mechanical analysis on the spinal vertebrae. During the analysis process, a variety of commercial software are needed to complete the import of medical imaging data, the preparation of finite element analysis, and the finite element solution. In this process, the existing technology has the following defects:

[0003] First, the technical path is complicated and cumbersome, and the overall analysis efficiency is low. During the whole process, users are required to manually complete the reconstruction of the three-dimensional model of the spinal vertebrae and the preparation for finite element analysis. Generally, it takes about 20 hours to analyze a single vertebra, which cannot meet the needs of fast and large-scale analysis.

[0004] Second, the operator needs to have a background in clinical medicine and biomechanics. In the process of reconstructing the three-dimensional model of the spinal vertebrae, the user needs to manually draw the structural contours with the help of two-dimensional imaging results to construct a three-dimensional model. Therefore, the user needs to have professional knowledge of the anatomical structure of the human spine. In addition, during the biomechanical finite element simulation process, the operator needs to have a deep understanding of finite element theory, be familiar with the theoretical basis of commercial software, and be able to operate the software proficiently for analysis.

[0005] Third, the differences in parameter settings during the operation will lead to deviations in the biomechanical calculation results. In the process of reconstructing the three-dimensional model of the spinal vertebrae, due to the irregular shape and complex structure of the spinal vertebrae and the limited imaging effect of CT image data, the CT data has defects in clarity, contrast and structural integrity; and due to the different understandings of the physiological and anatomical structure of the spine by users, the reconstruction results of the spinal vertebrae are greatly affected by the subjective judgment of the users, which in turn affects the final biomechanical calculation results.

[0006] Fourth, in the current finite element analysis process, the material parameters of bones in different areas of the spinal vertebrae are the same, and the actual bone density differences inside the actual bones are not taken into account, causing the finite element analysis results to deviate from the actual situation and have limited reference value.

[0007] In view of this, there is an urgent need to provide a vertebral mechanical strength assessment method with high analysis efficiency and high accuracy. Summary of the invention

[0008] The embodiments of the present invention provide a vertebral mechanical strength evaluation method, apparatus, computer equipment and storage medium, aiming to solve the problems of low accuracy and low efficiency in calculating the mechanical strength of spinal vertebrae in related technologies.

[0009] In a first aspect, an embodiment of the present invention provides a method for evaluating the mechanical strength of a vertebra, comprising: acquiring CT image data of a vertebra; extracting a single segment of a vertebra from the CT image data of the vertebra as the vertebra to be evaluated for three-dimensional construction to obtain the three-dimensional structure of the vertebra to be evaluated; discretizing the three-dimensional structure of the vertebra to be evaluated to obtain a plurality of discrete unit bodies; adding discrete unit bodies for representing splints on the upper and lower surfaces of the vertebra to be evaluated; describing the material properties of the discrete unit bodies to give them corresponding bone density, Young's modulus and Poisson's ratio; applying boundary conditions and constraints to the discrete unit bodies for representing the splints and establishing a set of stress and strain relationship equations for the vertebra to be evaluated based on the material properties of the discrete unit bodies; evaluating the vertebra to be evaluated under a preset load based on the set of stress and strain relationship equations for the vertebra to be evaluated to obtain the mechanical strength of the vertebra to be evaluated.

[0010] In a second aspect, an embodiment of the present invention further provides a vertebral mechanical strength assessment device, which includes a unit for executing the method of the first aspect.

[0011] In a third aspect, an embodiment of the present invention further provides a computer device, which includes a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the method of the first aspect is implemented.

[0012] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, wherein the storage medium stores a computer program, wherein the computer program includes program instructions, and the program instructions can implement the above method when executed by a processor.

[0013] The embodiment of the present invention provides a method, device, computer equipment and storage medium for evaluating the mechanical strength of a vertebra. The method includes: acquiring CT image data of a vertebra; extracting a single segment of a vertebra from the CT image data of the vertebra as a vertebra to be evaluated for three-dimensional construction to obtain the three-dimensional structure of the vertebra to be evaluated; discretizing the three-dimensional structure of the vertebra to be evaluated to obtain a plurality of discrete unit bodies; adding discrete unit bodies for representing splints on the upper and lower surfaces of the vertebra to be evaluated; describing the material properties of the discrete unit bodies to give them corresponding bone density, Young's modulus and Poisson's ratio; applying boundary conditions and constraints to the discrete unit bodies for representing the splints and establishing a set of stress-strain relationship equations for the vertebra to be evaluated according to the material properties of the discrete unit bodies; evaluating the vertebra to be evaluated under a preset load based on the set of stress-strain relationship equations for the vertebra to be evaluated to obtain the mechanical strength of the vertebra to be evaluated. The embodiment of the present invention first extracts the vertebra to be evaluated from the CT image to construct the three-dimensional structure of the vertebra to be evaluated; then the three-dimensional structure of the vertebra to be evaluated is discretized and smoothed and given material properties, and a stress-strain relationship equation group is established accordingly; finally, the mechanical strength of the vertebra to be evaluated is evaluated under a preset load based on the stress-strain relationship equation group. The whole process can be automatically analyzed without user participation, no professional background requirements for users, and the influence of user subjective factors is avoided, which greatly simplifies the user's operation steps, improves analysis efficiency, and has a high accuracy of evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0015] Figure 1 A schematic diagram of a flow chart of a method for evaluating vertebral mechanical strength provided by an embodiment of the present invention;

[0016] Figure 2 A schematic diagram of a sub-process of a vertebral mechanical strength assessment method provided by an embodiment of the present invention;

[0017] Figure 3 A schematic diagram of a sub-process of a vertebral mechanical strength assessment method provided by an embodiment of the present invention;

[0018] Figure 4 A schematic diagram of a sub-process of a vertebral mechanical strength assessment method provided by an embodiment of the present invention;

[0019] Figure 5A schematic diagram of a sub-process of a vertebral mechanical strength assessment method provided by an embodiment of the present invention;

[0020] Figure 6 A schematic diagram of a sub-process of a vertebral mechanical strength assessment method provided by an embodiment of the present invention;

[0021] Figure 7 A schematic diagram of a sub-process of a vertebral mechanical strength assessment method provided by an embodiment of the present invention;

[0022] Figure 8 A schematic block diagram of a vertebral mechanical strength assessment device provided by an embodiment of the present invention;

[0023] Fig. 9 A schematic block diagram of specific units of the vertebral mechanical strength assessment device provided by an embodiment of the present invention;

[0024] Fig.10 A schematic block diagram of a computer device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0027] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0028] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0029] Figure 1A schematic flow chart of a method for evaluating the mechanical strength of a vertebra provided by an embodiment of the present invention. The method for evaluating the mechanical strength of a vertebra is applied to a terminal. The terminal may be an electronic device with a communication function, such as a tablet computer, a laptop computer, or a desktop computer.

[0030] This example first briefly describes the evaluation object and the names of related technologies:

[0031] The spine is the pillar of the body, located in the middle of the back, with the upper end connected to the skull and the lower end reaching the tip of the coccyx. The spine is composed of vertebrae and intervertebral discs, of which 3 / 4 is composed of vertebral bodies and 1 / 4 is composed of intervertebral discs. The vertebral body is the main weight-bearing part of the vertebrae, and is short cylindrical, filled with cancellous tissue inside, with a thinner surface of dense tissue, and rough on both the upper and lower sides. It is connected to the adjacent vertebrae by intervertebral fibrocartilage. The spine has the functions of supporting the trunk, protecting the internal organs, protecting the spinal cord, and performing exercises.

[0032] CT (Computed Tomography), or electronic computer tomography, uses precisely collimated X-ray beams, gamma rays, ultrasound, etc., together with highly sensitive detectors to perform cross-sectional scans around a certain part of the human body one by one. It has the characteristics of fast scanning time and clear images, and can be used to examine a variety of diseases. The information obtained from the scan is calculated to obtain the X-ray attenuation coefficient or absorption coefficient of each voxel, and then arranged into a matrix, namely a digital matrix (digital matrix), which can be stored in a disk or CD. Through a digital / analog converter (digital / analog converter), each number in the digital matrix is ​​converted into a small square with varying grayscales from black to white, namely pixels (pixels), and arranged in a matrix to form a CT image. Therefore, a CT image is a reconstructed image. The X-ray absorption coefficient of each voxel can be calculated by different mathematical methods.

[0033] The full name of bone density is bone mineral density, which is an important indicator of bone strength. It is expressed in grams per cubic centimeter and is an absolute value.

[0034] Poisson's ratio refers to the ratio of the absolute value of the transverse normal strain to the axial normal strain when the material is subjected to unidirectional tension or compression. It is also called the transverse deformation coefficient. It is an elastic constant that reflects the transverse deformation of the material.

[0035] Young's modulus is a physical quantity that describes the ability of solid materials to resist deformation. When a metal wire with a length of L and a cross-sectional area of ​​S is stretched by ΔL under the action of force F, F / S is called stress, and its physical meaning is the force per unit cross-sectional area of ​​the metal wire; ΔL / L is called strain, and its physical meaning is the elongation corresponding to the unit length of the metal wire. The ratio of stress to strain is called elastic modulus. ΔL is a small change. Young's modulus, also known as tensile modulus, is the most common type of elastic modulus or modulus of elasticity. Young's modulus measures the stiffness of an isotropic elastic body and is defined as the ratio between uniaxial stress and uniaxial deformation within the range of application of Hooke's law. It is inclusive of the elastic modulus. In addition to Young's modulus, the elastic modulus also includes bulk modulus and shear modulus.

[0036] Figure 1 1 is a flow chart of a method for evaluating vertebral mechanical strength provided by an embodiment of the present invention. As shown in the figure, the method includes the following steps S110-S170.

[0037] S110 , acquiring CT image data of a vertebral body.

[0038] In one embodiment, CT image data refers to image data obtained by scanning the user's vertebral body. There are many ways to obtain CT image data. For example, the CT image data of the vertebral body can be obtained from a database that pre-stores vertebral body images. In actual use scenarios, users can download and import the CT image data of the vertebral body from the server through a terminal to obtain it. In addition, it can also be obtained directly from a CT scanner. After the patient is scanned by a CT scanner, the CT scanner sends the scanned CT image data to the terminal, and then the CT image data of the user can be obtained. This embodiment does not limit the method of obtaining CT image data. It should be noted that the CT image data in this embodiment is an original CT data sequence, which includes coordinate data and grayscale data, and has the characteristics of integrity, no compression, no information loss or deletion, etc.

[0039] S120: extracting a single segment of a vertebra from the CT image data of the vertebra as the vertebra to be evaluated, and performing three-dimensional construction to obtain a three-dimensional structure of the vertebra to be evaluated.

[0040] In one embodiment, since the human spine is composed of 26 vertebrae, namely 24 vertebrae (7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae), 1 sacrum, and 1 coccyx, and since the sacrum is composed of 5 bones and the coccyx is composed of 4 bones, a normal spine can also be composed of 33 bones. Therefore, one vertebra needs to be selected from the many vertebrae for corresponding mechanical strength analysis. After selecting a specific vertebra, a three-dimensional structure needs to be constructed first, and the obtained three-dimensional structure serves as the basis for subsequent mechanical strength analysis.

[0041] In one embodiment, if Figure 2 As shown, the step S120 may include steps S121-S123.

[0042] S121. Select a vertebral body of a single segment from the CT image data of the vertebral body through a selection box so that the vertebral body is within the selection box, wherein the CT image data includes coordinate data and grayscale data of all pixel points.

[0043] S122. Extracting the coordinate data and the grayscale data of the pixel points in the selection box, wherein the coordinate data and the grayscale data of the pixel points in the selection box are used to characterize the vertebral body to be evaluated.

[0044] S123, screening and arranging the coordinate data corresponding to the pixel points in the selection box according to the grayscale data thereof to construct the three-dimensional structure of the vertebral body to be evaluated.

[0045] In one embodiment, after the CT image data is acquired, the vertebral body of a single segment is selected through a selection box. Specifically, since the CT image data is the original CT sequence, it includes the coordinate data and grayscale data of all pixel points. The vertebral body of one segment is selected using the selection box so that all the vertebral bodies of the segment are located within the selection box. The entire digital information within the selection box is extracted through an inheritance algorithm, including the pixel coordinate data and grayscale data. Among them, the coordinate data is three-dimensional coordinate information, and the grayscale data is a grayscale value, which usually ranges from 0 to 255, with white being 255 and black being 0. The extracted pixel coordinate data and grayscale data are the vertebral body to be evaluated. Finally, since the extracted data includes both the vertebral body and the background area of ​​the non-vertebral body, it is necessary to remove the background area of ​​the non-vertebral body and retain the vertebral body part. Specifically, grayscale data is used for screening. Pixels with a grayscale value of 0 are the black background, and the black background part is the non-vertebral background area. Therefore, all pixels with a grayscale value of 0 are removed, and pixels with a grayscale value of not 0 are retained. In this way, the vertebrae can be screened out, and then the coordinate data corresponding to the screened pixels are arranged, and finally the three-dimensional structure of the vertebra to be evaluated is constructed.

[0046] It should be noted that after the three-dimensional structure of the vertebra to be evaluated is constructed, the three-dimensional structure can also be segmented. The vertebra to be evaluated is segmented into the upper surface of the spinal vertebra, the lower surface of the spinal vertebra, and the spinal vertebra area. This embodiment uses a deep neural network model to achieve segmentation. Specifically, a certain number of vertebral three-dimensional structures are first obtained as training data, wherein all vertebral three-dimensional structures in the training data have been annotated with structural features of the three-dimensional structure of the vertebra according to the anatomy of the spinal vertebra, and the annotated training data are annotated according to the structural features of the upper surface of the spinal vertebra, the lower surface of the spinal vertebra, and the spinal vertebra area in the anatomy. The training data is input into the deep neural network model for learning to obtain a neural network model for segmenting the three-dimensional structure of the vertebra. After the deep neural network model is trained, the three-dimensional structure of the vertebra to be evaluated is used as the input of the model and input into the deep neural network model for segmentation, so that the vertebra to be evaluated is divided into the upper surface of the spinal vertebra, the lower surface of the spinal vertebra, and the spinal vertebra area. Finally, the segmented upper surface of the spinal vertebra, the lower surface of the spinal vertebra, and the spinal vertebra area are given specific labels, and the segmented area is identified using the labels. After segmentation, it can be used to modify surface parameters and ultimately used to calculate the strength of the spinal vertebrae.

[0047] Exemplarily, the deep neural network model in this embodiment is trained using a convolutional neural network model. Convolutional neural networks (CNN) are a type of feedforward neural networks that include convolution calculations and have a deep structure, and are one of the representative algorithms for deep learning. Convolutional neural networks have representation learning capabilities and can perform shift-invariant classification on input information according to their hierarchical structure. The pattern recognition performed by the convolutional neural network model in this embodiment is mainly divided into four stages: data acquisition: three-dimensional structure image data; preprocessing: such as image denoising and image geometry correction; feature extraction: looking for some computer-recognized attributes that are used to describe the differences between the current image and other images; data classification: dividing the input image into a specific category. Of course, it can be understood that the present invention can also use other algorithm models to segment three-dimensional structures, which is not limited here.

[0048] S130, discretizing the three-dimensional structure of the vertebral body to be evaluated to obtain a plurality of discrete unit bodies.

[0049] In one embodiment, the purpose of the discrete processing is to split the three-dimensional structure into a limited number of tiny geometric unit bodies of equal volume size. Wherein, the geometric unit body is a hexahedral structure, which includes 8 vertices, each vertex is defined as a node of the unit body, and the nodes of the 8 unit bodies constitute the geometric unit body. After the geometric unit body obtained by discrete, its unit number and unit node number are assigned, the unit number is used to identify the unit body, and the unit node number is used to identify the node coordinates of the unit body. Thus, the geometric unit body obtained by discrete can be used to characterize the discrete unit body referred to in the present embodiment after assigning the corresponding number. The discrete unit body is used to provide an evaluation basis for subsequent mechanical strength evaluation.

[0050] In one embodiment, if Figure 3 As shown, the step S130 may include steps S131-S133.

[0051] S131, performing isotropic processing on the coordinate data of the pixel points in the selection box.

[0052] S132, adjusting the coordinate data after isotropic processing so that the vertebral body to be evaluated is positioned at a preset position.

[0053] S133, setting the pixel points whose grayscale data are not zero after the coordinate adjustment as nodes, and creating three-dimensional space coordinates according to the nodes to obtain discrete unit bodies.

[0054] In one embodiment, the process of discrete processing mainly includes isotropic processing and coordinate adjustment. Isotropic processing is a method based on data transformation, and its purpose is to ensure that the imported CT image data has consistency in data format after segmentation. In this embodiment, the isotropic processing input is the central geometric coordinates of each pixel of the CT image data, and after processing, it is output as the 8-node coordinates of each pixel. Based on the segmentation of the three-dimensional structure, the CT pixel points are transformed by the geometric layer thickness or layer distance, and the processed geometric information is isotropic. In this embodiment, the spatial geometry of the pixels of the three-dimensional structure after segmentation is read to construct a topological structure. Since the pixel space geometric position is the original center position of the pixel at this time, isotropic processing is performed through the topological structure optimization algorithm, and the geometric vertex coordinates of each pixel are calculated from the center position.

[0055] In addition, the discrete processing of this embodiment first adjusts the coordinates, and adjusts the geometric coordinates after segmentation so that the vertebra to be evaluated is at the center of the spatial coordinates. In this embodiment, the three-dimensional structure is extracted to adjust the geometric coordinate information. By overwriting the data of the original geometric coordinate information, the original geometric coordinate information is obtained to realize the rotation of the geometric coordinates. By locating the geometric center of the spinal vertebra in the coronal plane and the sagittal plane, the geometric coordinates of the center of the three-dimensional geometric body can be obtained. The vertebral inclination angle can be obtained using the image processing method, and it is used to correct the horizontal angle, thereby meeting the evaluation requirements of mechanical strength. Among them, the image processing includes reading the original CT geometric coordinate information, and the vertebral inclination angle can be obtained by establishing the sagittal center and the coronal center of the vertebra. It should be noted that the preset position in this embodiment is the coronal and sagittal planes of the spinal vertebra.

[0056] After the vertebra to be evaluated is spatially adjusted, the node setting of the three-dimensional reconstruction structure is performed. Since the processing object of the present application example is a three-dimensional reconstruction structure, when the node is set, the node coordinates finally generated must be three-dimensional coordinates. In this embodiment, it is first necessary to input the pixel points corresponding to the geometric construction after reconstruction, use the threshold method and the classification function normalization algorithm (such as the min-max algorithm), read the pixel points whose grayscale value is not 0 in the selection box, and save the information. After the node setting is completed, it is necessary to use the node creation algorithm to create the discrete unit node coordinates. In this embodiment, the node coordinates of the discrete unit need to meet the spatial cube structure of the unit, that is, it has the characteristics of equal length, width and height, and corresponds to the equal length of the three-dimensional space coordinate (x, y, z) direction. Since it is a spatial cube structure, each discrete unit has 8 nodes, and each node is located on the vertex of the cube. The unit node array set is constructed by the array construction method, and the array dimension is set to meet the three-dimensional structure requirements. Afterwards, the method of array dimension row and column fitting can be used to match the nodes of the three-dimensional reconstruction of the vertebra to be evaluated with the discrete unit node coordinates uniquely, and a discrete unit body based on the three-dimensional reconstruction of the vertebra is constructed.

[0057] S140, adding discrete unit bodies for representing splints on the upper surface and the lower surface of the vertebral body to be evaluated.

[0058] In one embodiment, in order to smooth the upper and lower surfaces of the segmented vertebral body to ensure that the upper and lower surfaces can evenly distribute and conduct the pressure, this embodiment adopts the method of adding a splint. In order to truly simulate the force of the vertebral body in the human body, this embodiment adopts the method of filling the upper and lower surfaces of the vertebral body with a polymer organic glass material polymethyl methacrylate (PMMA) on the upper and lower end surfaces of the vertebral body, so that the upper and lower end surfaces of the vertebral body remain horizontal.

[0059] In one embodiment, if Figure 4As shown, the step S140 may include steps S141-S143.

[0060] S141, reading the coordinate data along the axial direction of the vertebra to be evaluated.

[0061] S142: Determine the starting point of the upper surface and the end point of the lower surface of the vertebral body to be evaluated according to the read axial coordinate data.

[0062] S143, filling the vertebra to be evaluated with discrete units for representing splints according to the upper surface starting point and the lower surface end point of the vertebra to be evaluated, wherein the splints include an upper splint located on the upper surface of the vertebra to be evaluated and a lower splint located on the lower surface of the vertebra to be evaluated.

[0063] In one embodiment, in order to add a flat splint, the matrix information of the three-dimensional coordinates of the vertebra to be evaluated is subjected to coordinate transformation, vertebra positioning, and splint addition processing to obtain a new three-dimensional matrix of the vertebra, and the matrix information includes spatial coordinates, unit numbers, and unit attributes. The unit attributes are used to describe the tissue composition of the unit, including none, bone tissue, upper splint, and lower splint.

[0064] In this embodiment, the coordinate conversion process first reads the geometric three-dimensional coordinates and matrix information of the vertebra to be evaluated, locates the sagittal plane of the vertebra, finds its center point along the sagittal plane direction, and adjusts the sagittal plane where the center point is located to the horizontal. Then locates the coronal plane, finds its center point along the coronal plane direction, and adjusts the coronal plane where the center point is located to the horizontal. Through the above steps, the three-dimensional coordinate conversion of the vertebra to be evaluated is realized, and the effect is that the three-dimensional coordinates of the vertebra to be evaluated are consistent with the global coordinates of the space.

[0065] In this embodiment, the role of vertebral positioning is to identify the vertebral bone tissue area to be evaluated and find the upper and lower surfaces of the vertebral body. Since adding a splint requires automatically establishing a splint model on the upper and lower surfaces of the vertebral body, this vertebral positioning algorithm searches for the start and end points of the upper and lower surfaces of the vertebral body by reading CT coordinate data along the upper-lower axis of the vertebral body.

[0066] In this embodiment, the process of adding splints is to automatically generate splints in the non-bone tissue area along the upper and lower surface directions identified by the vertebral positioning algorithm, and define the splints added on the vertebral body as upper surface splints, and the splints added on the lower surface of the vertebral body as lower surface splints.

[0067] In this embodiment, the vertebral body part and the upper and lower surface splint areas of the vertebra to be evaluated are stored in a three-dimensional matrix with unit numbers and corresponding unit attributes. Unit attributes are used to describe the tissue composition of the unit, including none, bone tissue, upper splint, and lower splint. Each unit representing a splint is also identified and recorded by a unique unit number and attribute information, and saved in the background text information. When the unit of the splint is identified, the unit belonging to the splint is defined as a splint area by the unit number by identifying the attribute information.

[0068] S150, describing the material properties of the discrete unit body to give it corresponding bone density, Young's modulus and Poisson's ratio.

[0069] In one embodiment, after the unit discretization is completed, the material properties of all discrete units need to be set, and the material properties include bone density, Young's modulus and Poisson's ratio. The material properties of the discrete units are assigned to provide an evaluation basis for the subsequent mechanical strength evaluation.

[0070] In one embodiment, if Figure 5 As shown, the step S150 may include steps S151-S153.

[0071] S151. Input the grayscale data corresponding to the discrete unit body into a bone density model to output the bone density of the discrete unit body, and calibrate the bone density of the discrete unit body according to a preset calibration curve.

[0072] S152. Convert the bone density of the discrete unit body into Young's modulus based on the functional relationship between the bone density and the elastic modulus, wherein the Young's modulus of the discrete unit body includes the Young's modulus of the discrete unit body used to represent the splint.

[0073] S153. Assign a preset Poisson's ratio to the discrete unit body, wherein the preset Poisson's ratio is 0.3.

[0074] In one embodiment, the bone density material property is calculated using discrete units as input using the principle of interaction between radiation and bone and the attenuation coefficient during CT sampling. Specifically, each tiny unit after discretization has its unique identification number. The grayscale value of each unit can be obtained through the grayscale data in the CT image data, and then the bone density value of each unit can be obtained through the bone density model and stored. Among them, the bone density algorithm model is a muscle\fat calibration algorithm, and (1) the CT value (measured) and relative bone density of muscle tissue are known; (2) the CT value (measured) and relative bone density of fat tissue are known. A fitting curve is established by knowing (1) (2), and then the CT value of bone tissue is measured, and the bone density can be obtained by the established curve. In this embodiment, the CT values ​​of selected muscle tissue and subcutaneous fat tissue are used as references, and a preset calibration curve is established in combination with the CT value of muscle / fat tissue / relative bone density to obtain the three-dimensional bone density value of each discrete unit.

[0075] In addition, the vertebral body to be evaluated in this embodiment is regarded as a linear elastic body composed of cortical bone and cancellous bone, and both the cortical bone and the cancellous bone have macroscopically isotropic material properties. In this model, the cortical bone and the cancellous bone only have different Young's modulus values. It should be noted that the Young's modulus of each unit is calculated based on the bone density value of each unit. Compared with the use of the same Young's modulus for all units of the entire vertebral body, this conversion method makes the model more realistic, accurate and reliable. The calculation of Young's modulus adopts the research conclusions of Beaupre et al. of Stanford University in the United States and Fischer et al. of the Jülich Research Center in Germany. The piecewise functional relationship between the bone density used in this embodiment and the macroscopic elastic modulus is:

[0076] E = 0.001 (unit bone density = 0.00)

[0077]

[0078] E=5407*unit bone density+469(0.27mg / cm 3 <Unit bone density <0.60mg / cm 3 )

[0079]

[0080] It should also be noted that the surface splints are constructed to simulate the polymer organic glass material polymethyl methacrylate (PMMA), and its essential material properties are different from those of bones, so the Young's modulus of the surface splint needs to be defined separately. According to existing references, the Young's modulus is 2500MPa.

[0081] Poisson's ratio is an inherent property of the material and needs to be calculated according to the data obtained from basic mechanical tests. In this embodiment, the Poisson's ratio is set to 0.3 for both the cancellous bone and the cortical bone in the vertebral body according to existing references.

[0082] S160, applying boundary conditions and constraint conditions to the discrete unit body used to represent the splint and establishing a set of stress-strain relationship equations for the vertebral body to be evaluated according to the material properties of the discrete unit body.

[0083] In one embodiment, since the force direction of the vertebra to be evaluated is mainly on its upper surface and lower surface, this embodiment adopts the method of applying external force to the upper surface and lower surface of the vertebra to be evaluated to evaluate it. The vertebra to be evaluated will produce a certain deformation when subjected to external force. Therefore, the deformation of the vertebra to be evaluated can be determined by applying external force, and the relationship between the stress and strain of the vertebra to be evaluated can be obtained. Among them, the boundary condition refers to applying a displacement toward the lower surface on the upper surface of the vertebra to be evaluated, and the constraint condition refers to fixing the lower surface of the vertebra to be evaluated so that it cannot move or rotate. Therefore, under the given boundary conditions and constraint conditions, the stress and strain relationship of the vertebra to be evaluated can be obtained. In addition, it should be noted that because the deformation of the vertebra to be evaluated caused by force is related to the material itself, it is necessary to introduce material properties to ensure the accuracy of the obtained stress and strain relationship.

[0084] In one embodiment, if Figure 6 As shown, the step S160 may include steps S161-S162.

[0085] S161. Apply a preset displacement amount toward the lower surface of the discrete unit body used to represent the upper clamping plate, and apply a clamp constraint to the discrete unit body used to represent the lower clamping plate to determine the strain component of the discrete unit body.

[0086] S162: Establish a set of stress-strain relationship equations of the vertebral body to be evaluated based on elastic mechanics according to the strain components of the discrete unit body and the material properties of the discrete unit body.

[0087] In one embodiment, to calculate the mechanical strength value of the vertebra to be evaluated under a uniaxial compression environment, an overload boundary condition needs to be applied, such as applying a downward force or displacement on the upper surface of the vertebra to be evaluated to put it in a damaged state, and evaluating the mechanical strength value at this time. The preset displacement is the displacement applied downward from the upper surface. The fixed support constraint is to fix the lower surface of the vertebra to be evaluated and constrain it to be immobile.

[0088] In the calculation model of this embodiment, fixed constraints are applied to the discrete unit body on the lower surface of the vertebral body after filling with PMMA, that is, the six degrees of freedom of the unit body:

[0089] U1=U2=U3=UR1=UR2=UR3=0

[0090] Where U i (i=1, 2, 3) represents the translational freedom of the unit body, UR i (i=1, 2, 3) represents the rotational freedom of the unit body.

[0091] Apply a consistent vertical displacement to the lower surface of the vertebral body on the discrete unit cell on the upper surface of the vertebral body, and fix the other five degrees of freedom on the upper surface of the vertebral body:

[0092]

[0093] Where U i (i=1, 2, 3) represents the translational freedom of the unit body, UR i (i=1, 2, 3) represents the rotational freedom of the unit body.

[0094] The translational and rotational degrees of freedom of the unit body are the displacement and rotation (u, v, w) of the unit body nodes. The displacement (translational and rotational degrees of freedom) of the discrete unit body can be transformed into the strain components of the discrete unit body by the geometric equation:

[0095]

[0096] Therefore, for the discrete unit obtained by discrete processing, a set of relational equations is established, namely the stress-strain relational equations, which are expressed in tensor form as follows:

[0097] σ ij =E ijkl ε kl ,Right now

[0098] In the above formula, i, j, k, l = 1, 2, 3, respectively representing the three axes of the spatial coordinate system. The matrix form of the above formula is:

[0099]

[0100] In the above formula, σ i (i=1, 2, 3) and τ ij (i, j = 1, 2, 3, i ≠ j) represent the normal stress and shear stress of the discrete unit, ε i (i=1, 2, 3) and γ ij (i, j = 1, 2, 3, i ≠ j) represent the normal strain and shear strain of the discrete unit body respectively, E is the Young's modulus calculated based on the three-dimensional bone density, μ is the Poisson's ratio, i.e. 0.3, and G is the shear modulus, where G = E / (2*(1+v)).

[0101] S170, evaluating the vertebral body to be evaluated under a preset load based on the stress-strain relationship equation group of the vertebral body to be evaluated to obtain the mechanical strength of the vertebral body to be evaluated.

[0102] In one embodiment, after obtaining the stress-strain relationship equations of the vertebra to be evaluated, a preset load is given to determine the shape variable of the vertebra to be evaluated. Thus, the mechanical strength of the vertebra to be evaluated can be evaluated using a mechanical empirical formula based on the shape variable of the vertebra to be evaluated. Figure 7 As shown, step S170 may include steps S171-S174.

[0103] S171. Based on mechanical equilibrium, the stress-strain relationship equation group of the vertebra to be evaluated is processed by the conjugate gradient method under a preset load to obtain the displacement value of the discrete unit body.

[0104] In one embodiment, in a mechanical system, balance means that in an inertial reference system, an object is subjected to several forces and remains stationary, in a state of uniform linear motion, or in a state of uniform rotation around an axis. This is called the object being in a state of balance, or simply the object's "balance". The mechanical balance of the vertebra to be evaluated in this embodiment is manifested as the balance between the stress tensor and the external force. Among them, the preset load refers to the external force on the discrete unit.

[0105] In this embodiment, the integral form of the mechanical balance condition of the vertebral body to be evaluated is:

[0106]

[0107] Where D ijkl is the stiffness matrix containing all discrete body elements, that is, it is composed of the stiffness matrices of each discrete body element in step S162, is the input parameter, e ij (v)e kl ( u ) is the unit node displacement in tensor form, P is the external force on the unit node, that is, the preset load, and e is the Derichlet function.

[0108] Specifically, the conjugate gradient method is used to solve the mechanical equilibrium equation of the vertebra to be evaluated to obtain the displacement value of the unit node, that is, e ij (v)e kl ( u). The conjugate gradient method is a method between the steepest descent method and the Newton method. It only uses the first-order derivative information, but overcomes the disadvantage of the slow convergence of the steepest descent method, and avoids the disadvantage of the Newton method that it needs to store and calculate the Hesse matrix and invert it. The conjugate gradient method is not only one of the most useful methods for solving large linear equations, but also one of the most effective algorithms for solving large nonlinear optimization. Among various optimization algorithms, the conjugate gradient method is a very important one. Its advantages are small storage requirements, step convergence, high stability, and no need for any external parameters. The conjugate gradient method can save storage space to the maximum extent and improve computational efficiency. In the present invention, 5000 recursions are used. The number of iterations is determined by the solution accuracy. Under the condition of 5000 iterations, it can be guaranteed that the error between the result calculation accuracy and the direct solution is less than 10 -5 .

[0109] S172. Determine the support reaction force received by the lower clamping plate according to the displacement of the discrete unit body used to represent the lower clamping plate and its corresponding unit stiffness, wherein the unit stiffness is represented by Young's modulus and Poisson's ratio of the discrete unit body.

[0110] In one embodiment, the displacement of the discrete unit body used to represent the lower clamping plate is obtained according to step S171, and the unit stiffness is the stiffness matrix represented in the above step S162, that is:

[0111]

[0112] Each discrete unit body has a corresponding Young's modulus and Poisson's ratio. Therefore, the stiffness matrix of the discrete unit body can be expressed as the above form. The support reaction force received by the discrete unit body is expressed as the product of the displacement of the discrete unit body and the unit stiffness. That is:

[0113] F 支 =e ij (V)e kl (u) · Unit stiffness

[0114] S173, determining the stiffness of the vertebral body to be evaluated according to the total support reaction force of all the discrete unit bodies used to represent the lower splint and the preset displacement.

[0115] In one embodiment, the mechanical strength value of the vertebra to be evaluated needs to be determined based on the sum of the support reaction forces of all discrete unit nodes on the bottom surface of the vertebral body lower splint. Therefore, in this embodiment, the support reaction forces received by all discrete unit bodies corresponding to the lower splint are summed to obtain the total support reaction force. The ratio of the total support reaction force of the vertebra to be evaluated to the displacement value of the upper end surface of the vertebra to be evaluated is the stiffness value of the vertebra to be evaluated. Among them, the preset displacement is the displacement value of the upper end surface of the vertebra to be evaluated. Specifically, the stiffness of the vertebra to be evaluated is calculated as follows:

[0116] F 椎体总支反力 =∑ bottom unit node support reaction

[0117] K=F 推体总支反力 / μ

[0118] Wherein, K represents stiffness, μ represents deformation, which is the change in height of the whole body composed of the vertebral body and PMMA in a single axial direction, and its unit is mm, which is the preset displacement mentioned above.

[0119] S174. Evaluate the vertebral body to be evaluated according to the stiffness of the vertebral body to be evaluated and the height of the vertebral body to be evaluated to obtain the mechanical strength of the vertebral body to be evaluated, wherein the height of the vertebral body to be evaluated is obtained according to the coordinate data.

[0120] In one embodiment, the height of the vertebra to be evaluated is obtained from the coordinate data. Specifically, the height can be determined according to the coordinates of the highest point and the lowest point of the vertebra to be evaluated. Therefore, after obtaining the height and stiffness of the vertebra to be evaluated, the mechanical empirical formula is used to evaluate the vertebra to be evaluated, and then the mechanical strength of the vertebra to be evaluated is obtained. That is, the final output result is the mechanical strength F of the vertebra to be evaluated. max , which can also be called bone strength. Among them, the formula for the maximum external force that the vertebra to be evaluated can withstand under compression in the preset load direction is, that is, the mechanical empirical formula is:

[0121] F max =0.0068*K*H

[0122] Among them, F max : is the maximum external force that the vertebra to be evaluated can withstand under compression in the preset load direction, and its unit is N, Newton; K: stiffness, used to describe the ability of the vertebra to be evaluated to resist elastic deformation when subjected to force, and its unit is N / mm, Newton / millimeter; H: the height of the vertebra to be evaluated, and its unit is mm, millimeter. F = compression load, the external force that causes the vertebra to be compressed in a single axial direction, that is, the preset load, and its unit is N, Newton.

[0123] This embodiment adopts F max The reasons for using it as the final output are as follows: Under a single axial compression condition, the maximum external force that the vertebra to be evaluated can withstand can be verified by classical mechanical tests, and the results are usually used to describe the bone quality evaluation of the vertebral body.

[0124] Figure 8 FIG. 2 is a schematic block diagram of a vertebral mechanical strength assessment device 200 provided in an embodiment of the present invention. Figure 8As shown, corresponding to the above vertebral mechanical strength evaluation method, the present invention also provides a vertebral mechanical strength evaluation device 200. The vertebral mechanical strength evaluation device 200 includes a unit for executing the above vertebral mechanical strength evaluation method, and the device can be configured in a desktop computer, a tablet computer, a laptop computer, etc. Specifically, please refer to Figure 8 The vertebral mechanical strength evaluation device 200 includes an acquisition unit 210 , a three-dimensional construction unit 220 , a discrete unit 230 , a splint unit 240 , a material unit 250 , a building unit 260 and an evaluation unit 270 .

[0125] The acquisition unit 210 is used to acquire CT image data of the vertebral body.

[0126] The three-dimensional construction unit 220 is used to extract a single segment of a vertebra from the CT image data of the vertebra as the vertebra to be evaluated and perform three-dimensional construction to obtain the three-dimensional structure of the vertebra to be evaluated.

[0127] In one embodiment, if Fig. 9 As shown, the three-dimensional construction unit 220 includes a selection unit 221 , an extraction unit 222 and a construction subunit 223 .

[0128] The selection unit 221 is used to select a single segment of a vertebra in the CT image data of the vertebra through a selection box so that the vertebra is within the selection box, wherein the CT image data includes coordinate data and grayscale data of all pixel points.

[0129] The extraction unit 222 is used to extract the coordinate data and the grayscale data of the pixel points in the selection box, wherein the coordinate data and the grayscale data of the pixel points in the selection box are used to characterize the vertebra to be evaluated.

[0130] The construction subunit 223 is used to filter and arrange the coordinate data corresponding to the pixel points in the selection box according to the grayscale data thereof to construct the three-dimensional structure of the vertebral body to be evaluated.

[0131] The discrete unit 230 is used to discretize the three-dimensional structure of the vertebral body to be evaluated to obtain a plurality of discrete unit bodies.

[0132] In one embodiment, if Fig. 9 As shown, the discrete unit 230 includes an isotropic unit 231 , a coordinate adjustment unit 232 and a creation unit 233 .

[0133] The isotropic unit 231 is used to perform isotropic processing on the coordinate data of the pixel points in the selection box.

[0134] The coordinate adjustment unit 232 is used to coordinate adjust the coordinate data after isotropic processing so that the vertebral body to be evaluated is positioned at a preset position.

[0135] The creation unit 233 is used to set the pixel points whose grayscale data are not zero after the coordinates are adjusted as nodes, and create three-dimensional space coordinates according to the nodes to obtain discrete unit bodies.

[0136] The splint unit 240 is used to add discrete unit bodies representing the splint on the upper surface and the lower surface of the vertebral body to be evaluated.

[0137] In one embodiment, if Fig. 9 As shown, the clamping unit 240 includes a reading unit 241 , a determining unit 242 and a filling unit 243 .

[0138] The reading unit 241 is used to read the coordinate data along the axial direction of the vertebra to be evaluated.

[0139] The determination unit 242 is used to determine the starting point of the upper surface and the end point of the lower surface of the vertebral body to be evaluated according to the read axial coordinate data.

[0140] The filling unit 243 is used to fill the vertebra to be evaluated with discrete units for representing splints according to the upper surface starting point and the lower surface end point of the vertebra to be evaluated, wherein the splints include an upper splint located on the upper surface of the vertebra to be evaluated and a lower splint located on the lower surface of the vertebra to be evaluated.

[0141] The material unit 250 is used to describe the material properties of the discrete unit body to give it the corresponding bone density, Young's modulus and Poisson's ratio.

[0142] In one embodiment, if Fig. 9 As shown, the material unit 250 includes a bone density unit 251 , a Young's modulus unit 252 and a Poisson's ratio unit 253 .

[0143] The bone density unit 251 is used to input the grayscale data corresponding to the discrete unit body into the bone density model to output the bone density of the discrete unit body, and calibrate the bone density of the discrete unit body according to a preset calibration curve.

[0144] The Young's modulus unit 252 is used to convert the bone density of the discrete unit body into Young's modulus based on the functional relationship between the bone density and the elastic modulus, wherein the Young's modulus of the discrete unit body includes the Young's modulus of the discrete unit body used to represent the splint.

[0145] The Poisson's ratio unit 253 is used to assign a preset Poisson's ratio to the discrete unit body, wherein the preset Poisson's ratio is 0.3.

[0146] The establishing unit 260 is used to apply boundary conditions and constraint conditions to the discrete unit body used to represent the splint and establish a set of stress and strain relationship equations of the vertebral body to be evaluated according to the material properties of the discrete unit body.

[0147] In one embodiment, if Fig. 9 As shown, the establishing unit 260 includes an applying unit 261 and an establishing subunit 262 .

[0148] an applying unit 261, used for applying a preset displacement amount toward a lower surface of the discrete unit body used to represent the upper clamping plate, and applying a clamp constraint to the discrete unit body used to represent the lower clamping plate to determine a strain component of the discrete unit body;

[0149] The establishing subunit 262 is used to establish a set of stress-strain relationship equations of the vertebral body to be evaluated based on elastic mechanics according to the strain components of the discrete unit body and the material properties of the discrete unit body.

[0150] The evaluation unit 270 is used to evaluate the vertebral body to be evaluated under a preset load based on the stress-strain relationship equation group of the vertebral body to be evaluated to obtain the mechanical strength of the vertebral body to be evaluated.

[0151] In one embodiment, if Fig. 9 As shown, the evaluation unit 270 includes a processing unit 271, a support reaction unit 272, a stiffness unit 273 and an evaluation sub-unit 274.

[0152] The processing unit 271 is used to process the stress-strain relationship equation group of the vertebral body to be evaluated by the conjugate gradient method under a preset load based on mechanical balance to obtain the displacement value of the discrete unit body.

[0153] The support reaction force unit 272 is used to determine the support reaction force it receives based on the displacement of the discrete unit body used to represent the lower clamping plate and its corresponding unit stiffness, wherein the unit stiffness is represented by the Young's modulus and Poisson's ratio of the discrete unit body.

[0154] The stiffness unit 273 is used to determine the stiffness of the vertebra to be evaluated according to the total support reaction force of all the discrete unit bodies used to represent the lower splint and the preset displacement.

[0155] The evaluation subunit 274 is used to evaluate the vertebral body to be evaluated according to the stiffness of the vertebral body to be evaluated and the height of the vertebral body to be evaluated to obtain the mechanical strength of the vertebral body to be evaluated, wherein the height of the vertebral body to be evaluated is obtained according to the coordinate data.

[0156] It should be noted that those skilled in the art can clearly understand that the specific implementation process of the above-mentioned vertebral mechanical strength assessment device 200 and each unit can refer to the corresponding description in the aforementioned method embodiment, and for the convenience and brevity of description, it will not be repeated here.

[0157] The above-mentioned vertebral mechanical strength evaluation device can be implemented in the form of a computer program. The computer program can be used in Fig.10 Runs on the computer device shown.

[0158] See also Fig.10 , Fig.10 500 is a schematic block diagram of a computer device provided in an embodiment of the present application. The computer device 500 may be a terminal, wherein the terminal may be an electronic device with communication function such as a smart phone, a tablet computer, a laptop computer, a desktop computer, a personal digital assistant, and a wearable device.

[0159] See also Fig.10 The computer device 500 includes a processor 502 , a memory and a network interface 505 connected via a system bus 501 , wherein the memory may include a non-volatile storage medium 503 and an internal memory 504 .

[0160] The non-volatile storage medium 503 can store an operating system 5031 and a computer program 5032. The computer program 5032 includes program instructions, and when the program instructions are executed, the processor 502 can execute a vertebral mechanical strength assessment method.

[0161] The processor 502 is used to provide computing and control capabilities to support the operation of the entire computer device 500 .

[0162] The internal memory 504 provides an environment for the operation of the computer program 5032 in the non-volatile storage medium 503. When the computer program 5032 is executed by the processor 502, the processor 502 can execute a method for evaluating the mechanical strength of a vertebral body.

[0163] The network interface 505 is used to communicate with other devices over the network. Fig.10 The structure shown in the figure is merely a block diagram of a portion of the structure related to the solution of the present application, and does not constitute a limitation on the computer device 500 to which the solution of the present application is applied. The specific computer device 500 may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0164] The processor 502 is used to run a computer program 5032 stored in a memory to implement the following steps: acquiring CT image data of a vertebra; extracting a single segment of a vertebra from the CT image data of the vertebra as a vertebra to be evaluated for three-dimensional construction to obtain a three-dimensional structure of the vertebra to be evaluated; discretizing the three-dimensional structure of the vertebra to be evaluated to obtain a plurality of discrete unit bodies; adding discrete unit bodies for representing a splint on the upper and lower surfaces of the vertebra to be evaluated; describing the material properties of the discrete unit bodies to give them corresponding bone density, Young's modulus and Poisson's ratio; applying boundary conditions and constraints to the discrete unit bodies for representing the splints and establishing a set of stress-strain relationship equations for the vertebra to be evaluated based on the material properties of the discrete unit bodies; evaluating the vertebra to be evaluated under a preset load based on the set of stress-strain relationship equations for the vertebra to be evaluated to obtain the mechanical strength of the vertebra to be evaluated.

[0165] In one embodiment, when the processor 502 implements the step of extracting a single segment of a vertebra from the CT image data of the vertebra as the vertebra to be evaluated for three-dimensional construction to obtain the three-dimensional structure of the vertebra to be evaluated, the processor 502 specifically implements the following steps: selecting a single segment of a vertebra from the CT image data of the vertebra through a selection box so that it is within the selection box, wherein the CT image data includes coordinate data and grayscale data of all pixel points; extracting the coordinate data and the grayscale data of the pixel points within the selection box, wherein the coordinate data and the grayscale data of the pixel points within the selection box are used to characterize the vertebra to be evaluated; and screening and arranging the coordinate data corresponding to the grayscale data of the pixel points within the selection box to construct the three-dimensional structure of the vertebra to be evaluated.

[0166] In one embodiment, when the processor 502 implements the step of discretizing the three-dimensional structure of the vertebra to be evaluated to obtain multiple discrete unit bodies, it specifically implements the following steps: isotropically processing the coordinate data of the pixel points in the selection box; adjusting the coordinate data after the isotropic processing so that the vertebra to be evaluated is positioned at a preset position; setting the pixel points whose grayscale data are not zero after the coordinate adjustment as nodes, and creating three-dimensional space coordinates according to the nodes to obtain discrete unit bodies.

[0167] In one embodiment, when the processor 502 implements the step of adding discrete units for representing splints on the upper surface and the lower surface of the vertebra to be evaluated, it specifically implements the following steps: reading the coordinate data along the axial direction of the vertebra to be evaluated; determining the starting point of the upper surface and the end point of the lower surface of the vertebra to be evaluated based on the read axial coordinate data; filling the vertebra to be evaluated with discrete units for representing splints based on the starting point of the upper surface and the end point of the lower surface of the vertebra to be evaluated, wherein the splint includes an upper splint located on the upper surface of the vertebra to be evaluated and a lower splint located on the lower surface of the vertebra to be evaluated.

[0168] In one embodiment, when the processor 502 implements the material property description of the discrete unit body to assign it the corresponding bone density, Young's modulus and Poisson's ratio, including the steps, it specifically implements the following steps: inputting the grayscale data corresponding to the discrete unit body into the bone density model to output the bone density of the discrete unit body, and calibrating the bone density of the discrete unit body according to a preset calibration curve; converting the bone density of the discrete unit body into Young's modulus based on the functional relationship between bone density and elastic modulus, wherein the Young's modulus of the discrete unit body includes the Young's modulus of the discrete unit body used to represent the splint; assigning a preset Poisson's ratio to the discrete unit body, wherein the preset Poisson's ratio is 0.3.

[0169] In one embodiment, when the processor 502 implements the step of applying boundary conditions and constraints to the discrete unit body used to represent the splint and establishing a group of equations for the stress and strain relationship of the vertebra to be evaluated based on the material properties of the discrete unit body, it specifically implements the following steps: applying a preset displacement toward the lower surface of the discrete unit body used to represent the upper splint, and applying a fixed support constraint to the discrete unit body used to represent the lower splint to determine the strain component of the discrete unit body; establishing a group of equations for the stress and strain relationship of the vertebra to be evaluated based on elastic mechanics according to the strain component of the discrete unit body and the material properties of the discrete unit body.

[0170] In one embodiment, when the processor 502 implements the step of evaluating the vertebra to be evaluated under a preset load based on the stress-strain relationship equation group of the vertebra to be evaluated to obtain the mechanical strength of the vertebra to be evaluated, the processor 502 specifically implements the following steps: based on mechanical equilibrium, the stress-strain relationship equation group of the vertebra to be evaluated is processed by the conjugate gradient method under a preset load to obtain the displacement value of the discrete unit body; the support reaction force received by the discrete unit body according to the displacement of the discrete unit body used to represent the lower splint and its corresponding unit stiffness, wherein the unit stiffness is represented by Young's modulus and Poisson's ratio of the discrete unit body; the stiffness of the vertebra to be evaluated is determined according to the total support reaction force of all the discrete unit bodies used to represent the lower splint and the preset displacement; the vertebra to be evaluated is evaluated according to the stiffness of the vertebra to be evaluated and the height of the vertebra to be evaluated to obtain the mechanical strength of the vertebra to be evaluated, wherein the height of the vertebra to be evaluated is acquired according to the coordinate data.

[0171] It should be understood that in the embodiment of the present application, the processor 502 may be a central processing unit (CPU), and the processor 502 may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Among them, the general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0172] It can be understood by those skilled in the art that all or part of the processes in the method for implementing the above embodiment can be completed by instructing the relevant hardware through a computer program. The computer program includes program instructions, and the computer program can be stored in a storage medium, which is a computer-readable storage medium. The program instructions are executed by at least one processor in the computer system to implement the process steps of the embodiment of the above method.

[0173] Therefore, the present invention also provides a storage medium. The storage medium can be a computer-readable storage medium. The storage medium stores a computer program, wherein the computer program includes program instructions. When the program instructions are executed by a processor, the processor executes the following steps: obtaining CT image data of a vertebra; extracting a single segment of a vertebra from the CT image data of the vertebra as a vertebra to be evaluated for three-dimensional construction to obtain the three-dimensional structure of the vertebra to be evaluated; discretizing the three-dimensional structure of the vertebra to be evaluated to obtain a plurality of discrete unit bodies; adding discrete unit bodies for representing a splint on the upper and lower surfaces of the vertebra to be evaluated; describing the material properties of the discrete unit bodies to give them corresponding bone density, Young's modulus and Poisson's ratio; applying boundary conditions and constraints to the discrete unit bodies for representing the splints and establishing a set of stress and strain relationship equations for the vertebra to be evaluated according to the material properties of the discrete unit bodies; evaluating the vertebra to be evaluated under a preset load based on the set of stress and strain relationship equations for the vertebra to be evaluated to obtain the mechanical strength of the vertebra to be evaluated.

[0174] In one embodiment, when the processor executes the program instructions to implement the step of extracting a single segment of a vertebra from the CT image data of the vertebra as the vertebra to be evaluated for three-dimensional construction to obtain the three-dimensional structure of the vertebra to be evaluated, the processor specifically implements the following steps: selecting a single segment of a vertebra from the CT image data of the vertebra through a selection box so that it is within the selection box, wherein the CT image data includes coordinate data and grayscale data of all pixel points; extracting the coordinate data and the grayscale data of the pixel points within the selection box, wherein the coordinate data and the grayscale data of the pixel points within the selection box are used to characterize the vertebra to be evaluated; and screening and arranging the coordinate data corresponding to the grayscale data of the pixel points within the selection box to construct the three-dimensional structure of the vertebra to be evaluated.

[0175] In one embodiment, when the processor executes the program instructions to implement the step of discretizing the three-dimensional structure of the vertebra to be evaluated to obtain multiple discrete unit bodies, the processor specifically implements the following steps: isotropically processing the coordinate data of the pixel points in the selection box; adjusting the coordinates of the isotropically processed coordinate data so that the vertebra to be evaluated is positioned at a preset position; setting the pixel points whose grayscale data are not zero after the coordinate adjustment as nodes, and creating three-dimensional space coordinates according to the nodes to obtain discrete unit bodies.

[0176] In one embodiment, when the processor executes the program instructions to implement the step of adding discrete units for representing splints on the upper and lower surfaces of the vertebra to be evaluated, the processor specifically implements the following steps: reading the coordinate data along the axial direction of the vertebra to be evaluated; determining the starting point of the upper surface and the end point of the lower surface of the vertebra to be evaluated based on the read axial coordinate data; filling the vertebra to be evaluated with discrete units for representing splints based on the starting point of the upper surface and the end point of the lower surface of the vertebra to be evaluated, wherein the splint includes an upper splint located on the upper surface of the vertebra to be evaluated and a lower splint located on the lower surface of the vertebra to be evaluated.

[0177] In one embodiment, when the processor executes the program instructions to implement the step of describing the material properties of the discrete unit body to assign it the corresponding bone density, Young's modulus and Poisson's ratio, the following steps are specifically implemented: the grayscale data corresponding to the discrete unit body is input into the bone density model to output the bone density of the discrete unit body, and the bone density of the discrete unit body is calibrated according to a preset calibration curve; the bone density of the discrete unit body is converted into Young's modulus based on the functional relationship between bone density and elastic modulus, wherein the Young's modulus of the discrete unit body includes the Young's modulus of the discrete unit body used to represent the splint; and a preset Poisson's ratio is assigned to the discrete unit body, wherein the preset Poisson's ratio is 0.3.

[0178] In one embodiment, when the processor executes the program instructions to implement the steps of applying boundary conditions and constraints to the discrete unit bodies used to represent the splint and establishing a group of equations for the stress and strain relationship of the vertebra to be evaluated based on the material properties of the discrete unit bodies, the processor specifically implements the following steps: applying a preset displacement toward the lower surface of the discrete unit body used to represent the upper splint, and applying a fixed support constraint to the discrete unit body used to represent the lower splint to determine the strain component of the discrete unit body; establishing a group of equations for the stress and strain relationship of the vertebra to be evaluated based on elastic mechanics according to the strain component of the discrete unit body and the material properties of the discrete unit body.

[0179] In one embodiment, when the processor executes the program instructions to implement the step of evaluating the vertebra to be evaluated under a preset load based on the stress-strain relationship equation group of the vertebra to be evaluated to obtain the mechanical strength of the vertebra to be evaluated, the following steps are specifically implemented: based on mechanical equilibrium, the stress-strain relationship equation group of the vertebra to be evaluated is processed by the conjugate gradient method under a preset load to obtain the displacement value of the discrete unit body; the support reaction force received by the discrete unit body according to the displacement of the discrete unit body used to represent the lower splint and its corresponding unit stiffness, wherein the unit stiffness is represented by Young's modulus and Poisson's ratio of the discrete unit body; the stiffness of the vertebra to be evaluated is determined according to the total support reaction force of all the discrete unit bodies used to represent the lower splint and the preset displacement; the vertebra to be evaluated is evaluated according to the stiffness of the vertebra to be evaluated and the height of the vertebra to be evaluated to obtain the mechanical strength of the vertebra to be evaluated, wherein the height of the vertebra to be evaluated is acquired according to the coordinate data.

[0180] The storage medium may be a USB flash drive, a mobile hard disk, a read-only memory (ROM), a magnetic disk, or an optical disk, etc., which are computer-readable storage media that can store program codes.

[0181] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0182] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of each unit is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0183] The steps in the method of the embodiment of the present invention can be adjusted in order, combined and deleted according to actual needs. The units in the device of the embodiment of the present invention can be combined, divided and deleted according to actual needs. In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0184] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, terminal, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention.

[0185] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for evaluating vertebral mechanical strength, characterized in that: include: Acquire CT image data of vertebral bodies; Selecting a single segment of a vertebra from the CT image data of the vertebra through a selection box so that the vertebra is within the selection box, wherein the CT image data includes coordinate data and grayscale data of all pixel points; Extracting the coordinate data and the grayscale data of the pixel points in the selection box, wherein the coordinate data and the grayscale data of the pixel points in the selection box are used to characterize the vertebral body to be evaluated; According to the grayscale data of the pixel points in the selection box, the corresponding coordinate data are screened and arranged to construct the three-dimensional structure of the vertebra to be evaluated; Performing isotropic processing on the coordinate data of the pixel points in the selection box; Adjusting the coordinate data after isotropic processing so that the vertebral body to be evaluated is positioned at a preset position; The pixel points whose grayscale data are not zero after the coordinates are adjusted are set as nodes, and three-dimensional space coordinates are created according to the nodes to obtain discrete unit bodies; Reading the coordinate data along the axial direction of the vertebra to be evaluated; Determine the starting point of the upper surface and the end point of the lower surface of the vertebral body to be evaluated according to the read axial coordinate data; Filling the vertebral body to be evaluated with discrete units for representing a splint according to the starting point of the upper surface and the end point of the lower surface of the vertebral body to be evaluated, wherein the splint includes an upper splint located on the upper surface of the vertebral body to be evaluated and a lower splint located on the lower surface of the vertebral body to be evaluated; Describing the material properties of the discrete unit body to assign corresponding bone density, Young's modulus and Poisson's ratio to the discrete unit body; Applying boundary conditions and constraint conditions to the discrete unit body used to represent the splint and establishing a set of stress-strain relationship equations of the vertebral body to be evaluated according to the material properties of the discrete unit body; The vertebral body to be evaluated is evaluated under a preset load based on the stress-strain relationship equation group of the vertebral body to be evaluated to obtain the mechanical strength of the vertebral body to be evaluated.

2. The method for evaluating vertebral mechanical strength according to claim 1, characterized in that: The material property description of the discrete unit body to give it corresponding bone density, Young's modulus and Poisson's ratio includes: Inputting the grayscale data corresponding to the discrete unit body into a bone density model to output the bone density of the discrete unit body, and calibrating the bone density of the discrete unit body according to a preset calibration curve; The bone density of the discrete unit body is converted into Young's modulus based on the functional relationship between the bone density and the elastic modulus, wherein the Young's modulus of the discrete unit body includes the Young's modulus of the discrete unit body used to represent the splint; A preset Poisson's ratio is assigned to the discrete unit body, wherein the preset Poisson's ratio is 0.

3.

3. The method for evaluating vertebral mechanical strength according to claim 2, characterized in that: The step of applying boundary conditions and constraint conditions to the discrete unit body used to represent the splint and establishing a set of stress-strain relationship equations of the vertebral body to be evaluated according to the material properties of the discrete unit body comprises: Applying a preset displacement amount toward the lower surface of the discrete unit body used to represent the upper clamping plate, and applying a clamp constraint to the discrete unit body used to represent the lower clamping plate to determine the strain component of the discrete unit body; Based on elastic mechanics, a group of stress-strain relationship equations of the vertebral body to be evaluated is established according to the strain components of the discrete unit body and the material properties of the discrete unit body.

4. The method for evaluating vertebral mechanical strength according to claim 3, characterized in that: The step of evaluating the vertebral body to be evaluated under a preset load based on the stress-strain relationship equation group of the vertebral body to be evaluated to obtain the mechanical strength of the vertebral body to be evaluated includes: Based on mechanical equilibrium, the stress-strain relationship equation group of the vertebral body to be evaluated is processed by the conjugate gradient method under a preset load to obtain the displacement value of the discrete unit body; Determine the support reaction force received by the lower clamping plate according to the displacement of the discrete unit body used to represent the lower clamping plate and its corresponding unit stiffness, wherein the unit stiffness is represented by Young's modulus and Poisson's ratio of the discrete unit body; Determine the stiffness of the vertebral body to be evaluated according to the total support reaction force of all the discrete unit bodies used to represent the lower splint and the preset displacement; The vertebral body to be evaluated is evaluated according to the stiffness of the vertebral body to be evaluated and the height of the vertebral body to be evaluated to obtain the mechanical strength of the vertebral body to be evaluated, wherein the height of the vertebral body to be evaluated is obtained according to the coordinate data.

5. A vertebral mechanical strength assessment device, characterized in that: include: Acquisition unit, three-dimensional construction unit, discrete unit, splint unit, material unit, establishment unit, and evaluation unit; The acquisition unit is used to acquire CT image data of the vertebral body; The three-dimensional construction unit is used to extract a single segment of a vertebra from the CT image data of the vertebra as the vertebra to be evaluated and perform three-dimensional construction to obtain the three-dimensional structure of the vertebra to be evaluated; The discrete unit is used to discretize the three-dimensional structure of the vertebral body to be evaluated to obtain a plurality of discrete unit bodies; The splint unit is used to add discrete unit bodies representing splints on the upper surface and the lower surface of the vertebral body to be evaluated, and includes a reading unit, a determining unit and a filling unit; The reading unit is used to read coordinate data along the axial direction of the vertebra to be evaluated; The determination unit is used to determine the starting point of the upper surface and the end point of the lower surface of the vertebral body to be evaluated according to the read axial coordinate data; The filling unit is used to fill the vertebra to be evaluated with a discrete unit body used to represent a splint according to the upper surface starting point and the lower surface end point of the vertebra to be evaluated, wherein the splint includes an upper splint located on the upper surface of the vertebra to be evaluated and a lower splint located on the lower surface of the vertebra to be evaluated; The material unit is used to describe the material properties of the discrete unit body to give it corresponding bone density, Young's modulus and Poisson's ratio; Establishing a unit for applying boundary conditions and constraint conditions to the discrete unit body used to represent the splint and establishing a set of stress and strain relationship equations of the vertebral body to be evaluated according to the material properties of the discrete unit body; The evaluation unit is used to evaluate the vertebral body to be evaluated under a preset load based on the stress-strain relationship equation group of the vertebral body to be evaluated to obtain the mechanical strength of the vertebral body to be evaluated; The three-dimensional construction unit includes a selection unit, an extraction unit and a construction subunit; The selection unit is used to select a vertebral body of a single segment from the CT image data of the vertebral body through a selection box so that the vertebral body is within the selection box, wherein the CT image data includes coordinate data and grayscale data of all pixel points; The extraction unit is used to extract the coordinate data and the grayscale data of the pixel points in the selection box, wherein the coordinate data and the grayscale data of the pixel points in the selection box are used to characterize the vertebral body to be evaluated; The construction subunit is used for screening and arranging the coordinate data corresponding to the pixel points in the selection box according to the grayscale data thereof to construct the three-dimensional structure of the vertebral body to be evaluated; Discrete elements include isotropic elements, coordinate adjustment elements, and creation elements; The isotropic unit is used to perform isotropic processing on the coordinate data of the pixel points in the selection box; The coordinate adjustment unit is used to coordinate adjust the coordinate data after isotropic processing so that the vertebral body to be evaluated is positioned at a preset position; The creation unit is used to set the pixel points whose grayscale data are not zero after the coordinates are adjusted as nodes, and to create three-dimensional space coordinates according to the nodes to obtain discrete unit bodies.

6. The vertebral mechanical strength evaluation device according to claim 5, characterized in that: Material units include bone density unit, Young's modulus unit and Poisson's ratio unit; The bone density unit is used to input the grayscale data corresponding to the discrete unit body into the bone density model to output the bone density of the discrete unit body, and calibrate the bone density of the discrete unit body according to a preset calibration curve; The Young's modulus unit is used to convert the bone density of the discrete unit body into the Young's modulus based on the functional relationship between the bone density and the elastic modulus, wherein the Young's modulus of the discrete unit body includes the Young's modulus of the discrete unit body used to represent the splint; The Poisson's ratio unit is used to assign a preset Poisson's ratio to the discrete unit body, wherein the preset Poisson's ratio is 0.

3.

7. The vertebral mechanical strength evaluation device according to claim 6, characterized in that: The establishment unit includes an application unit and an establishment subunit; The applying unit is used to apply a preset displacement amount toward the lower surface of the discrete unit body used to represent the upper clamping plate, and to apply a clamp constraint to the discrete unit body used to represent the lower clamping plate to determine the strain component of the discrete unit body; The subunit is established to establish a set of stress-strain relationship equations of the vertebral body to be evaluated based on elastic mechanics according to the strain components of the discrete unit body and the material properties of the discrete unit body.

8. The vertebral mechanical strength evaluation device according to claim 7, characterized in that: The evaluation unit includes a processing unit, a support reaction unit, a stiffness unit and an evaluation subunit; The processing unit is used to process the stress-strain relationship equation group of the vertebral body to be evaluated by the conjugate gradient method under a preset load based on mechanical balance to obtain the displacement value of the discrete unit body; The support reaction force unit is used to determine the support reaction force received by the lower clamping plate according to the displacement of the discrete unit body used to represent the lower clamping plate and its corresponding unit stiffness, wherein the unit stiffness is represented by the Young's modulus and Poisson's ratio of the discrete unit body; The stiffness unit is used to determine the stiffness of the vertebral body to be evaluated according to the total support reaction force of all the discrete unit bodies used to represent the lower splint and the preset displacement; The evaluation subunit is used for evaluating the vertebral body to be evaluated according to the stiffness of the vertebral body to be evaluated and the height of the vertebral body to be evaluated to obtain the mechanical strength of the vertebral body to be evaluated, wherein the height of the vertebral body to be evaluated is obtained according to the coordinate data.

9. A computer device, characterized in that: The computer device includes a memory and a processor, the memory stores a computer program, and the processor implements the method according to any one of claims 1 to 4 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, wherein the computer program includes program instructions, and when the program instructions are executed by a processor, the method according to any one of claims 1 to 4 can be implemented.

Images