An MR intelligent guiding system and method for cervical lordotic adjustment

Abstract

The application discloses an MR intelligent guiding system and method for cervical vertebra inclined plate adjustment, and relates to the technical field of mixed reality.The method of the application acquires image data by scanning the cervical vertebra, reconstructs a three-dimensional virtual cervical vertebra model after processing, and accurately superimposes the virtual model and the actual cervical vertebra by using a space registration algorithm, thereby providing real-time visual guidance, angle and force calculation and safety threshold monitoring in an MR device, and realizing accurate and safe operation of the cervical vertebra inclined plate adjustment.The system of the application comprises an image data acquisition module, a three-dimensional modeling module, an MR scene fusion module, a dynamic adjustment guiding module and a data archiving module, solves the problems that traditional cervical vertebra inclined plate adjustment relies on experience and lacks accuracy, and improves the effect and safety of the adjustment operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mixed reality, in particular to an MR intelligent guiding system and method for cervical vertebra inclined plate adjustment. BACKGROUND

[0002] Cervical vertebra inclined plate adjustment is a common operation in the field of rehabilitation. The traditional method mainly relies on the experience and touch of the operator, lacks precise positioning and real-time feedback mechanism, and may lead to unstable adjustment effect. Mixed reality (MR) technology, as a technology that combines virtual information with real environment, has shown advantages in the field of auxiliary operation, and can provide intuitive visual guidance for operators.

[0003] In the prior art, some systems use MR technology for sports rehabilitation training, focusing on improving training enthusiasm through virtual scenes; some cervical vertebra adjustment devices achieve angle adjustment through mechanical structure, but do not combine MR technology to realize virtual-real fusion guidance. At present, the application of MR technology in the field of cervical vertebra inclined plate adjustment still has deficiencies, lacks a special guiding system for dynamic adjustment process, and cannot realize real-time monitoring of three-dimensional space position changes and personalized parameter calculation during the adjustment process, affecting the accuracy and efficiency of the adjustment. SUMMARY

[0004] The purpose of the present application is to provide an MR intelligent guiding system and method for cervical vertebra inclined plate adjustment to solve the problems raised in the background.

[0005] In order to solve the above technical problems, the present application provides the following technical solutions:

[0006] An MR intelligent guiding method for cervical vertebra inclined plate adjustment, comprising the following steps:

[0007] Step S100. Scanning the cervical vertebra using a scanning device to obtain image data of the target coverage area, and the image data is stored in DICOM format;

[0008] Step S200. Importing the image data of the target coverage area into a three-dimensional modeling software, performing segmentation and extraction processing on the image data, and generating a three-dimensional virtual cervical vertebra model;

[0009] Step S300. Spatially registering the three-dimensional virtual cervical vertebra model with the physical cervical vertebra through an MR device, so that the three-dimensional virtual cervical vertebra model and the physical cervical vertebra are accurately superimposed in the real scene;

[0010] Step S400. Calculating the adjustment angle, force parameter and safety threshold based on a preset mechanical model, displaying the adjustment path, angle indication and force feedback in real time through the MR device, and guiding the operator to complete the cervical vertebra inclined plate adjustment operation;

[0011] Step S500. After the adjustment is completed, the sensor data and virtual model information during the operation are archived.

[0012] Further, in step S100, a 64-slice spiral CT scanner is used to scan the target coverage area ranging from the occipital bone to the C7 vertebral segment.

[0013] Further, in step S200, the three-dimensional virtual cervical spine model is generated as follows:

[0014] The image data of the target coverage area is imported into a three-dimensional modeling software. A pixel point in the bony structure of the image data is selected as a seed point. The pixels with a gray value within a preset threshold range in the surrounding area are automatically included in the same region to achieve preliminary segmentation of the bony structure. The soft tissue area mistakenly included is manually erased or the missing bony structure details are supplemented by editing a mask tool. Based on the natural gap between the vertebral bodies, each segment of C1 to C7 is separated by using the cutting function of the three-dimensional modeling software. Based on the segmented and extracted C1 to C7 segments, a three-dimensional virtual cervical spine model is generated by using the three-dimensional modeling software.

[0015] Further, in step S300, the specific process of spatial registration of the three-dimensional virtual cervical spine model and the physical cervical spine is as follows:

[0016] S301. The operator wears an MR device and scans the real scene by a depth camera. Three real landmark points not on the same straight line in the real scene where the physical cervical spine is located are selected, and the coordinates are recorded as A(xA, yA, zA), B(xB, yB, zB), and C(xC, yC, zC), thereby constructing a spatial coordinate system. The x-axis vector is calculated with A as the origin, and is the unit vector from A to B, denoted as: The y-axis vector is calculated, denoted as: wherein represents the dot product of the vector and the vector C-A, which is the projection length between them; the z-axis vector is calculated, denoted as:

[0017] S302. In the three-dimensional virtual cervical spine model, three virtual points corresponding to the real landmark points are selected, denoted as A'(x'A, y'A, z'A), B'(x'B, y'B, z'B), and C'(x'C, y'C, z'C). The x', y', and z' axis vectors of the virtual coordinate system are calculated in the same way as the real scene. The rotation matrix R is constructed according to the dot product of the axis vectors of the spatial coordinate system and the virtual coordinate system, and the translation vector t of the origin of the virtual coordinate system and the origin of the real coordinate system is calculated, and the calculation formula is: t = (xA - R·x'A, y'A - R·y'A, zA - R·z'A). According to the rotation matrix R and the translation vector t, the corresponding homogeneous transformation matrix T is obtained, and For any point p in the virtual model, the coordinate in the space coordinate system is converted through the homogeneous transformation matrix T, and

[0018] S303. Calculate the average spatial distance D between the virtual point on the three-dimensional virtual cervical spine model and the real point on the corresponding entity cervical spine, compare the average spatial distance D with the preset threshold value D0, if the average spatial distance D is less than or equal to the preset threshold value D0, the registration is completed; otherwise, re-optimize R and t, repeat S301-S302 until the average spatial distance D is less than or equal to the preset threshold value D0.

[0019] Further, the specific content of step S400 is as follows:

[0020] S401. Extract the cervical joint mechanical parameters including the vertebral body mass, centroid coordinates and rotational inertia from the three-dimensional virtual cervical spine model according to the bony structure obtained by the segmentation and extraction processing and C1 to C7 segments; calculate the cervical muscle force Fm by using Hill muscle model, the calculation formula is: Fm=k·Fmax(lm)·fv(vm), wherein k represents the muscle activation degree, the value range is between 0-1, which is set according to the muscle contraction state in the three-dimensional virtual cervical spine model; Fmax(lm) represents the maximum isometric contraction force under the current muscle length, which can be obtained by fitting the muscle length in the virtual model with the preset tension curve; fv(vm) represents the relationship function between muscle contraction speed and strength, fv(vm)=(1+vm / vmax) / [1+(vm / vmax)·(Fmax / F0)], wherein vm represents the actual contraction speed of the muscle, vmax represents the maximum contraction speed, Fmax represents the maximum isometric contraction force under the contraction speed vm, and F0 represents the reference force; for example, when the muscle length lm=0.1m, Fmax=200N is obtained by fitting, fv(vm)=(1+vm / vmax) / [1+(vm / vmax)·(Fmax / F0)], and Fm=a·Fmax(lm)·fv(vm) can be obtained by combining the cervical muscle force Fm;

[0021] S402. Based on the registration result of the three-dimensional virtual cervical vertebra model and the entity cervical vertebra, the offset state of the entity cervical vertebra target segment is identified by comparing with the preset reference cervical vertebra position, so as to extract the offset angle θ0 of the corresponding segment; wherein the preset reference cervical vertebra position is the reference position obtained by standardizing the image data of healthy people in advance; combined with the physiological activity range of the cervical vertebra and the adjustment safety requirement, a compensation angle Δθ is introduced, and the target adjustment angle θ calculation formula is: θ = θ0 + Δθ; wherein the value of Δθ needs to be dynamically determined based on the anatomical structure characteristics (such as joint space, vertebral stability) of the target segment in the virtual model, to ensure that the adjustment range is within the safety range; based on the geometric constraint relationship between the user body position and the inclined plate structure, the inclined angle α of the inclined plate is calculated, and the calculation formula is: α = arcsin [(h sin θ) / d)], wherein h is the displacement height of the user's head in the inclined plate direction, which is extracted from the spatial coordinate difference of the contact point of the head and the inclined plate in the three-dimensional virtual cervical vertebra model; d represents the distance from the target segment to the rotation axis of the inclined plate, which is obtained by measuring the spatial distance between the mass center of the target segment and the rotation axis in the three-dimensional virtual cervical vertebra model;

[0022] S403. According to Newton's second law, the required resultant force F of the cervical vertebra as a whole during adjustment is calculated, and F = M a, wherein M is the total mass of the cervical vertebra, and a is the target acceleration, which is set based on the smoothness requirement of the motion trajectory of the target segment in the three-dimensional virtual cervical vertebra model; the support force Fs of the inclined plate to the head is calculated, and Fs = m g cos α, wherein m is the mass of the head, which is obtained by converting the volume and density of the head structure in the three-dimensional virtual cervical vertebra model, and g is the acceleration of gravity; the additional force Fa of the manipulation is calculated, and the calculation formula is: Fa = F - Fs sin α + Ff, wherein Ff is the friction between the cervical vertebra and the surrounding soft tissue;

[0023] S404. Based on the compressive strength limit of the vertebral bone tissue, the maximum pressure Fmax-v that the vertebral body can withstand is calculated, and Fmax-v = σmax A, wherein σmax represents the compressive strength limit of the vertebral bone tissue, which is determined by material mechanics experiment; A represents the pressure area of the vertebral body, which is extracted from the cross-sectional size of the vertebral body of the target segment in the three-dimensional virtual cervical vertebra model; the target adjustment angle θ, the inclined angle α of the inclined plate, the additional force Fa of the manipulation and the maximum pressure Fmax-v are superimposed and displayed through the MR device, to dynamically indicate the adjustment path with arrows, and to display the difference between the current angle and the target angle, and the deviation between the current force and the recommended force in real time; when it is detected that the actual pressure Fmax-v suffered by the entity cervical vertebra is equal to the preset threshold value, the warning information is triggered.

[0024] An MR intelligent guiding system for cervical vertebra inclined plate adjustment, comprising: an image data acquisition module, a three-dimensional modeling module, an MR scene fusion module, a dynamic adjustment guiding module and a data archiving module;

[0025] The image data acquisition module scans the cervical vertebrae using a scanning device to obtain image data of a target coverage area, and the image data is stored in DICOM format; the three-dimensional modeling module performs segmentation and extraction processing on the image data to generate a three-dimensional virtual cervical vertebra model containing C1 to C7 segments; the MR scene fusion module precisely superimposes the three-dimensional virtual cervical vertebra model and the physical cervical vertebra through a spatial registration algorithm; the dynamic adjustment guide module calculates adjustment parameters based on a mechanical model, displays guide information in real time through an MR device, and assists an operator to complete cervical vertebra plate adjustment; and the data archiving module processes and stores sensor data and virtual model information during the adjustment after the adjustment is completed.

[0026] Further, the image data acquisition module includes a scanning device control unit and a data format conversion unit;

[0027] The scanning device control unit controls the operation of the 64-slice spiral CT scanner, sets the scanning parameters, and the scanning range covers from the occipital bone to the C7 vertebral body segment; the data format conversion unit converts the original image data generated by the scanner into DICOM format storage.

[0028] Further, the three-dimensional modeling module includes a bony structure segmentation unit, a structure optimization unit, and a three-dimensional model generation unit;

[0029] The bony structure segmentation unit imports DICOM format image data and preliminarily extracts the bony structure of the cervical vertebrae; the structure optimization unit manually erases the mistakenly included soft tissue area or supplements the missing bony structure details by editing the mask tool, separates C1 to C7 segment vertebrae based on the natural intervertebral space using the cutting function; the three-dimensional model generation unit generates a three-dimensional virtual cervical vertebra model based on the segmented segment vertebra data through the reconstruction function of the three-dimensional modeling software.

[0030] Further, the MR scene fusion module includes a real coordinate system construction unit, a virtual coordinate system mapping unit, and a registration verification and optimization unit;

[0031] The real coordinate system construction unit controls the depth camera of the MR device to scan the real scene, identifies and records 3 non-collinear real landmark points around the physical cervical vertebrae, calculates the corresponding axial vectors, and thereby constructs a spatial coordinate system; the virtual coordinate system mapping unit selects virtual points corresponding to the real landmark points in the three-dimensional virtual cervical vertebra model, calculates the axial vectors of the virtual coordinate system, and constructs a rotation matrix and a translation vector through axial vector dot product; the registration verification and optimization unit calculates a homogeneous transformation matrix to convert the virtual model coordinates to the spatial coordinate system, measures the average spatial distance between the virtual points and the real points, compares with the preset threshold, and thereby performs registration verification and optimization.

[0032] Further, the dynamic adjustment guiding module comprises a mechanical parameter extraction unit, an adjustment parameter calculation unit and an MR real-time guiding unit.

[0033] The mechanical parameter extraction unit extracts cervical vertebra joint mechanical parameters from the three-dimensional virtual cervical vertebra model and calculates the cervical vertebra surrounding muscle force based on the Hill muscle model; the adjustment parameter calculation unit extracts the target segment offset angle by comparing the virtual model with the reference position, calculates the target adjustment angle in combination with the compensation angle, and deduces the inclined plate inclination angle based on the geometric relationship; the resultant force is calculated according to Newton's second law, the support force is calculated in combination with the head mass and the inclined plate angle, and the additional force of the manipulation is deduced; the maximum pressure bearing of the vertebral body is calculated based on the vertebral body compression strength limit and the stress area; the adjustment angle, the force parameter and the safety threshold are superimposed and displayed through the MR device by the MR real-time guiding unit, the adjustment path is indicated by the dynamic arrow, the angle and force deviation of the current and the target are fed back in real time, and the warning is triggered when the actual pressure is equal to the threshold.

[0034] Compared with the prior art, the present application has the beneficial effects that: the present application can provide accurate angle, force parameter and real-time feedback of adjustment path for the operator by accurately spatially registering the three-dimensional virtual cervical vertebra model with the entity cervical vertebra and combining real-time mechanical calculation, which greatly improves the accuracy of adjustment. The present application uses the MR device to display the adjustment path, angle indication and force feedback in real time during the adjustment process, so that the operator can monitor the position change and parameter deviation in the adjustment process at any time, effectively improving the efficiency and safety of the adjustment. The present application introduces dynamic adjustment angle, inclined plate inclination angle and manipulation additional force and other personalized parameters calculated based on the virtual model, and identifies the offset state in combination with the reference cervical vertebra position, which ensures that the adjustment range meets the requirements of individual anatomical structure characteristics and physiological activity range. At the same time, the real-time warning mechanism provided during the adjustment process can effectively avoid excessive force or improper angle during the adjustment process, thereby maximizing the safety of the operation. BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, which together with the embodiments of the application serve to explain the application, and do not constitute a limitation on the application. In the drawings:

[0036] Figure 1 is a module schematic diagram of an MR intelligent guiding system for cervical vertebra inclined plate adjustment. DETAILED DESCRIPTION

[0037] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0038] Please refer to Figure 1 The present application provides technical solutions:

[0039] An MR intelligent guiding system for cervical vertebra plate adjustment, comprising an image data acquisition module, a three-dimensional modeling module, an MR scene fusion module, a dynamic adjustment guiding module and a data archiving module;

[0040] The image data acquisition module scans the cervical vertebra using a scanning device to obtain image data of a target coverage area, and the image data is stored in DICOM format; the three-dimensional modeling module performs segmentation and extraction processing on the image data to generate a three-dimensional virtual cervical vertebra model containing C1 to C7 segments; the MR scene fusion module precisely superimposes the three-dimensional virtual cervical vertebra model and the physical cervical vertebra through a spatial registration algorithm; the dynamic adjustment guiding module calculates adjustment parameters based on a mechanical model and displays guiding information in real time through an MR device to assist an operator to complete cervical vertebra plate adjustment; and the data archiving module processes and stores sensor data and virtual model information in the operation process after the adjustment is completed.

[0041] The image data acquisition module comprises a scanning device control unit and a data format conversion unit;

[0042] The scanning device control unit controls the operation of a 64-slice spiral CT scanner, sets scanning parameters, and the scanning range covers from the occipital bone to the C7 vertebral body segment; and the data format conversion unit converts the original image data generated by the scanner into DICOM format storage.

[0043] The three-dimensional modeling module comprises a bony structure segmentation unit, a structure optimization unit and a three-dimensional model generation unit;

[0044] The bony structure segmentation unit imports DICOM format image data and preliminarily extracts the bony structure of the cervical vertebra; the structure optimization unit manually erases the mistakenly included soft tissue area or supplements the missing bony structure details by editing a mask tool, and separates C1 to C7 segment vertebrae based on the natural intervertebral space by using a cutting function; and the three-dimensional model generation unit generates a three-dimensional virtual cervical vertebra model based on the segmented segment vertebra data through the reconstruction function of a three-dimensional modeling software.

[0045] The MR scene fusion module comprises a real coordinate system construction unit, a virtual coordinate system mapping unit and a registration verification and optimization unit;

[0046] The real coordinate system construction unit controls the depth camera of the MR device to scan the real scene, identifies and records three non-collinear real marker points around the entity cervical vertebra, calculates the corresponding axial vectors, and thus constructs the space coordinate system; the virtual coordinate system mapping unit selects virtual points corresponding to the real marker points in the three-dimensional virtual cervical vertebra model, calculates the axial vectors of the virtual coordinate system, and constructs a rotation matrix and a translation vector through axial vector dot product; the registration verification and optimization unit calculates a homogeneous transformation matrix, converts the virtual model coordinates to the space coordinate system, compares the average spatial distance between the virtual points and the real points with a preset threshold, and thus performs registration verification and optimization.

[0047] The dynamic adjustment guiding module includes a mechanical parameter extraction unit, an adjustment parameter calculation unit, and an MR real-time guiding unit.

[0048] The mechanical parameter extraction unit extracts cervical vertebra joint mechanical parameters from the three-dimensional virtual cervical vertebra model and calculates the muscle force around the cervical vertebra based on the Hill muscle model; the adjustment parameter calculation unit extracts the target segment offset angle by comparing the virtual model with the reference position, calculates the target adjustment angle in combination with the compensation angle, and deduces the inclined plate inclination angle based on geometric relationships; the total force is calculated according to Newton's second law, the support force is calculated in combination with the head mass and the inclined plate angle, and the additional force of the technique is deduced; the maximum pressure that the vertebral body can withstand is calculated based on the limit of the vertebral body compression strength and the stress area; the adjustment angle, the force parameter, and the safety threshold are displayed by the MR device through the MR device, the adjustment path is indicated by a dynamic arrow, the current and target angle and force deviation are fed back in real time, and a warning is triggered when the actual pressure is equal to the threshold.

[0049] An MR intelligent guiding method for cervical vertebra inclined plate adjustment, comprising the following steps:

[0050] Step S100. Scan the cervical vertebra using a scanning device, obtain image data of a target coverage area, and store the image data in DICOM format;

[0051] Step S200. Import the image data of the target coverage area into a three-dimensional modeling software, perform segmentation and extraction processing on the image data, and generate a three-dimensional virtual cervical vertebra model;

[0052] Step S300. Perform spatial registration of the three-dimensional virtual cervical vertebra model and the entity cervical vertebra through the MR device, so that the three-dimensional virtual cervical vertebra model and the entity cervical vertebra are accurately superimposed in the real scene;

[0053] Step S400. Calculate the adjustment angle, the force parameter, and the safety threshold based on a preset mechanical model, display the adjustment path, the angle indication, and the force feedback in real time through the MR device, and guide the operator to complete the cervical vertebra inclined plate adjustment operation;

[0054] Step S500. After the adjustment is completed, the sensor data and virtual model information during the operation are archived.

[0055] In step S100, a 64-slice spiral CT scanner is used to scan the target coverage area ranging from the occipital bone to the C7 vertebral body segment.

[0056] In step S200, the three-dimensional virtual cervical spine model is generated as follows:

[0057] The image data of the target coverage area is imported into the three-dimensional modeling software. By selecting a pixel point in the bony structure of the image data as a seed point, the pixels with a gray value within a preset threshold range in the surrounding area are automatically included in the same region, thereby achieving preliminary segmentation of the bony structure. The soft tissue area mistakenly included is manually erased or the missing bony structure details are supplemented by editing the mask tool. The C1 to C7 vertebral segments are separated based on the natural gap between the vertebral bodies by using the cutting function of the three-dimensional modeling software. Based on the segmented and extracted C1 to C7 vertebral segments, the three-dimensional virtual cervical spine model is generated by using the three-dimensional modeling software.

[0058] In this embodiment, the specific analysis process of generating the three-dimensional virtual cervical spine model is as follows:

[0059] DICOM format is an international standard for medical images, containing metadata such as pixel value, layer thickness, and pixel spacing. The three-dimensional modeling software can restore the spatial position relationship of the image (such as the z-axis coordinate of each layer of image) by analyzing these metadata. When importing, the data integrity needs to be verified to ensure that there is no missing layer or format error, providing a continuous three-dimensional data basis for subsequent segmentation.

[0060] In the cervical spine image, the gray value of the bony structure (such as the vertebral body) and the soft tissue (such as the muscle and the intervertebral disc) is significantly different (the gray value of the bony structure is higher), which is the core basis for segmentation. By selecting a seed point (such as a pixel in the vertebral body area), the pixels with a gray value within a preset threshold range in the surrounding area are automatically included in the same region, thereby achieving preliminary segmentation of the bony structure. The preset threshold needs to be dynamically adjusted according to the image contrast, for example, the gray value range is set to [200, 1000] (the typical gray value range of bone tissue in CT image). Due to the complexity of the cervical spine structure (such as the gray value of the adjacent area of the vertebral body and the intervertebral disc is close), automatic segmentation may occur misjudgment, which needs to be manually erased or supplemented by editing the mask tool. The C1 to C7 vertebral bodies are separated based on the natural gap (such as the intervertebral space) between the vertebral bodies by using the cutting function of the three-dimensional modeling software, thereby facilitating the subsequent analysis of the morphological parameters of each vertebral body.

[0061] In the scanning process, the model surface may have burrs (such as isolated pixel points or irregular protrusions) due to device noise or motion artifacts. A median filter algorithm is used to smooth the model surface. The principle is to replace the gray value of each pixel point with the median value of the neighborhood pixels, effectively removing salt and pepper noise. For example, a 3x3 pixel neighborhood window is set, and median filtering calculation is performed on each vertex of the model surface.

[0062] In step S300, the specific process of spatial registration of the three-dimensional virtual cervical vertebra model and the entity cervical vertebra is as follows:

[0063] S301. The operator wears the MR device, scans the real scene through the depth camera, selects three real landmark points in the real scene where the entity cervical vertebra is located, and records the coordinates as A(xA, yA, zA), B(xB, yB, zB), and C(xC, yC, zC), thereby constructing a spatial coordinate system; wherein A point is taken as the origin, the x-axis vector is calculated, and is the unit vector from A to B, denoted as: The y-axis vector is calculated, denoted as: wherein denotes the dot product of the vector and the vector C-A, and the projection length between them; the z-axis vector is calculated, denoted as:

[0064] S302. Select 3 virtual points corresponding to the real landmark points in the three-dimensional virtual cervical vertebra model, denoted as A'(x'A, y'A, z'A), B'(x'B, y'B, z'B), and C'(x'C, y'C, z'C); calculate the x', y', and z' axis vectors of the virtual coordinate system in the same way as the real scene; construct a rotation matrix R according to the dot product of the axis vectors of the spatial coordinate system and the virtual coordinate system, and calculate the translation vector t of the origin of the virtual coordinate system and the origin of the real coordinate system, and the calculation formula is: t = (xA - R x'A, y'A - R y'A, zA - R z'A); according to the rotation matrix R and the translation vector t, the corresponding homogeneous transformation matrix T is obtained, and For any point p in the virtual model, convert it to the coordinates in the spatial coordinate system through the homogeneous transformation matrix T, and

[0065] S303. Calculate the average spatial distance D between the virtual points on the three-dimensional virtual cervical vertebra model and the real points on the corresponding entity cervical vertebra, compare the average spatial distance D with the preset threshold value D0, if the average spatial distance D is less than or equal to the preset threshold value D0, the registration is completed; otherwise, optimize R and t again, repeat S301-S302 until the average spatial distance D is less than or equal to the preset threshold value D0.

[0066] The specific content of step S400 is as follows:

[0067] S401. The mechanical parameters of the cervical spine joint are extracted from the three-dimensional virtual cervical spine model based on the segmented and extracted bony structures and C1 to C7 segments, including the mass of the vertebral body, the mass center coordinates, and the moment of inertia; the Hill muscle model is used to calculate the muscle force Fm around the cervical spine, and the calculation formula is: Fm=k·Fmax(lm)·fv(vm), wherein k represents the muscle activation degree, the value range is between 0-1, and is set according to the muscle contraction state in the three-dimensional virtual cervical spine model; Fmax(lm) represents the maximum isometric contraction force under the current muscle length, which can be obtained by fitting the muscle length and the preset tension curve in the virtual model; fv(vm) represents the relationship function between muscle contraction speed and strength, fv(vm)=(1+vm / vmax) / [1+(vm / vmax)·(Fmax / F0)], wherein vm represents the actual contraction speed of the muscle, vmax represents the maximum contraction speed, Fmax represents the maximum isometric contraction force under the contraction speed vm, and F0 represents the reference force; for example, when the muscle length lm=0.1 m, Fmax=200 N is obtained by fitting, fv(vm)=(1+vm / vmax) / [1+(vm / vmax)·(Fmax / F0)], and Fm=a·Fmax(lm)·fv(vm) can be obtained by combining the muscle force Fm around the cervical spine;

[0068] These parameters extracted by the virtual model can accurately map the mechanical properties of the entity cervical spine. The Hill model can effectively simulate the dynamic force condition of the muscle in the adjustment process, and provide a solid biomechanical basis for the subsequent calculation of the adjustment angle and force parameter. The past methods of building a cervical spine mechanical analysis model, such as establishing a finite element model based on CT scan data, can also obtain some mechanical parameters, but there are deficiencies in simulating the dynamic force of the muscle. Compared with the past methods, the present method uses the virtual model for its intuitiveness and accuracy, and uses the Hill model in the muscle model construction, which is more in line with the mechanical performance of the muscle in the actual physiological state, and improves the accuracy and practicability of the model.

[0069] In the present embodiment, the mass of each vertebral body mi is calculated by the model volume and the known bone density, for example, the model volume of the second cervical vertebra is measured as 27.78 cm 3 , and its mass m2=1.8 g / cm 3 ×27.78 cm 3 ÷1000=0.05 kg. The mass center coordinates ri=(xi, yi, zi) are approximately replaced by the geometric center of the vertebral body; for the moment of inertia, the vertebral body is approximated as an ellipsoid, the semi-axes a=0.02 m, b=0.015 m, and c=0.01 m are known, and the formula is:

[0070] Ixx=(1 / 5)mi(b2 +c 2 ), Iyy = (1 / 5)mi(a 2 +c 2 ), Izz = (1 / 5)mi(a 2 +b 2 ) are calculated.

[0071] S402. Based on the registration result of the three-dimensional virtual cervical spine model and the entity cervical spine, the offset state of the target segment of the entity cervical spine is identified by comparing with the preset reference cervical spine position, so as to extract the offset angle θ0 of the corresponding segment; wherein the preset reference cervical spine position is the reference position obtained by standardizing the image data of the healthy population in advance; combined with the physiological activity range of the cervical spine and the adjustment safety requirement, a compensation angle Δθ is introduced, and the calculation formula of the target adjustment angle θ is: θ = θ0 + Δθ; wherein the value of Δθ needs to be dynamically determined based on the anatomical structure characteristics (such as joint space and vertebral stability) of the target segment in the virtual model, to ensure that the adjustment range is within the safety range; based on the geometric constraint relationship between the user body position and the inclined plate structure, the inclined angle α of the inclined plate is calculated, and the calculation formula is: α = arcsin[(h·sinθ) / d)], wherein h is the displacement height of the user's head in the direction of the inclined plate, which is extracted from the spatial coordinate difference of the contact point of the head and the inclined plate in the three-dimensional virtual cervical spine model; d represents the distance from the target segment to the rotation axis of the inclined plate, which is obtained by measuring the spatial distance between the mass center of the target segment and the rotation axis in the three-dimensional virtual cervical spine model;

[0072] S403. According to Newton's second law, the required resultant force F of the cervical spine as a whole during the adjustment process is calculated, and F = M·a, wherein M is the total mass of the cervical spine, and a is the target acceleration, which is set based on the smoothness requirement of the motion trajectory of the target segment in the three-dimensional virtual cervical spine model; the support force Fs of the inclined plate to the head is calculated, and Fs = m·g·cosα, wherein m is the mass of the head, which is obtained by converting the volume and density of the head structure in the three-dimensional virtual cervical spine model, g is the acceleration of gravity; the additional force Fa of the hand method is calculated, and the calculation formula is: Fa = F - Fs·sinα + Ff, wherein Ff is the friction between the cervical spine and the surrounding soft tissue;

[0073] S404. Based on the compression strength limit of the vertebral bone tissue, the maximum pressure Fmax-v that the vertebral body can withstand is calculated, and Fmax-v=σmax·A, wherein σmax represents the compression strength limit of the vertebral bone tissue, which is determined by a material mechanics experiment; A represents the pressure area of the vertebral body, which is extracted from the cross-sectional size of the target segment vertebral body in the three-dimensional virtual cervical vertebra model; the target adjustment angle θ, the inclined plate inclination angle α, the additional force Fa of the manipulation, and the maximum pressure Fmax-v are superimposed and displayed through the MR device, to dynamically indicate the adjustment path with an arrow, and to display the difference between the current angle and the target angle, and the deviation between the current force and the recommended force in real time; when it is detected that the actual pressure Fmax-v that the solid cervical vertebra bears is equal to the preset threshold value, the warning information is triggered.

[0074] It should be noted that the relational terms herein such as first and second and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0075] Finally, it should be noted that: the above only describes the preferred embodiments of the present application, and does not limit the present application, although the foregoing embodiments of the present application are described in detail, for those skilled in the art, the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An MR intelligent guiding method for cervical vertebrae wedge plate adjustment, comprising the following steps: S100. Scanning the cervical vertebrae using a scanning device to obtain image data of a target coverage area, and the image data is stored in DICOM format; S200. Importing the image data of the target coverage area into a three-dimensional modeling software, segmenting and extracting the image data, and generating a three-dimensional virtual cervical vertebrae model; S300. Spatially registering the three-dimensional virtual cervical vertebrae model with the entity cervical vertebrae through an MR device, so that the three-dimensional virtual cervical vertebrae model is accurately superimposed with the entity cervical vertebrae in a real scene; S400. Calculating adjustment angle, force parameter and safety threshold based on a preset mechanical model, and displaying adjustment path, angle indication and force feedback in real time through the MR device to guide an operator to complete the cervical vertebrae wedge plate adjustment operation; S500. After the adjustment is completed, archiving sensor data and virtual model information during the operation; S400 comprises: S401. Extracting cervical vertebrae joint mechanical parameters including vertebral body mass, center of mass coordinates and moment of inertia from the three-dimensional virtual cervical vertebrae model according to the C1 to C7 segmental vertebrae obtained by segmentation and extraction processing; using Hill muscle model to calculate the cervical vertebrae surrounding muscle force Fm=k·Fmax(lm)·fv(vm), wherein k represents the muscle activation degree, the value range is between 0-1; Fmax(lm) represents the maximum isometric contraction force under the current muscle length; fv(vm) represents the relationship function between muscle contraction speed and strength, fv(vm)=(1+vm / vmax) / [1+(vm / vmax)·(Fmax / F0)], wherein vm represents the actual contraction speed of the muscle, vmax represents the maximum contraction speed, Fmax represents the maximum isometric contraction force under the contraction speed vm, and F0 represents the reference force; S402. Comparing with the preset reference cervical vertebrae position based on the registration result of the three-dimensional virtual cervical vertebrae model and the entity cervical vertebrae, identifying the offset state of the target segment of the entity cervical vertebrae, and extracting the offset angle θ0 of the corresponding segment; wherein the preset reference cervical vertebrae position is a reference position obtained by standardizing the image data of a healthy population in advance; a compensation angle Δθ is introduced to calculate the target adjustment angle θ=θ0+Δθ in combination with the physiological activity range of the cervical vertebrae and the adjustment safety requirement; based on the geometric constraint relationship between the user body position and the wedge plate structure, the wedge plate inclination angle α=arcsin[(h·sinθ) / d)] is calculated, wherein h is the displacement height of the user's head in the wedge plate direction; d represents the distance from the target segment to the wedge plate rotation axis; S403. According to Newton's second law, the required resultant force F of the cervical vertebrae as a whole during the adjustment process is calculated, and F=M·a, wherein M is the total mass of the cervical vertebrae, and a is the target acceleration based on the smoothness requirement of the motion trajectory of the target segment in the three-dimensional virtual cervical vertebrae model; the support force Fs of the wedge plate on the head is calculated as m·g·cosα, wherein m is the mass of the head, and g is the acceleration of gravity; the additional force Fa of the hand method is calculated as Fa=F-Fs·sinα+Ff, wherein Ff is the friction force between the cervical vertebrae and the surrounding soft tissue; S404. Based on the compression strength limit of the vertebral bone tissue, the maximum pressure Fmax-v that the vertebral body can withstand is calculated, Fmax-v = σmax·A, where σmax represents the compression strength limit of the vertebral bone tissue; A represents the pressure area of the vertebral body; the target adjustment angle θ, the inclined plate inclination angle α, the manual additional force Fa, and the maximum pressure Fmax-v are superimposed and displayed through the MR device, and the adjustment path is indicated by dynamic arrows, and the difference between the current angle and the target angle and the deviation between the current force and the recommended force are displayed in real time; when it is detected that the actual pressure Fmax-v borne by the entity cervical vertebra is equal to the preset threshold value, an alarm information is triggered.

2. A method for MR-guided cervical subluxation reduction according to claim 1, wherein: In the step S100, a 64-slice spiral CT scanner is used to scan the target coverage area ranging from the occipital bone to the C7 vertebral segment.

3. A method for MR-guided cervical subluxation reduction as claimed in claim 1, wherein: In the step S200, the three-dimensional virtual cervical vertebra model is generated as follows: The image data of the target coverage area is imported into a three-dimensional modeling software, a pixel point in the bony structure of the image data is selected as a seed point, the pixel points with a gray value within a preset threshold range in the surrounding area are automatically included in the same region to achieve preliminary segmentation of the bony structure, the soft tissue region mistakenly included is manually erased or the details of the bony structure missed are supplemented by editing a mask tool, the C1 to C7 vertebral segments are separated based on the natural gap between the vertebral bodies by using the cutting function of the three-dimensional modeling software, and the three-dimensional virtual cervical vertebra model is generated by using the three-dimensional modeling software based on the segmented and extracted C1 to C7 vertebral segments.

4. The MR intelligent guidance method for cervical lordosis adjustment of claim 3, wherein: In the step S300, the specific process of the spatial registration of the three-dimensional virtual cervical vertebra model and the entity cervical vertebra is as follows: S301. The operator wears the MR device, scans the real scene through the depth camera, selects three real landmark points not on the same straight line in the real scene where the entity cervical vertebra is located, and records the coordinates as: A(xA, yA, zA), B(xB, yB, zB), C(xC, yC, zC), thereby constructing a spatial coordinate system; wherein taking the A point as the origin, calculating the x-axis vector, and being the unit vector from A to B, denoted as: ; The y-axis vector is calculated and denoted as: where denotes the dot product of the vectors and is the length of the projection between the two; the z-axis vector is calculated and denoted as: ; S302. Select three virtual points corresponding to the real landmark points in the three-dimensional virtual cervical vertebra model, denoted as: A'(x'A, y'A, z'A), B'(x'B, y'B, z'B), C'(x'C, y'C, z'C); the same method as the real scene is adopted to calculate the x', y', z' axis vectors of the virtual coordinate system; a rotation matrix R is constructed according to the dot product of the axis vectors of the space coordinate system and the virtual coordinate system, and a translation vector t of the origin of the virtual coordinate system and the origin of the real coordinate system is calculated, and the calculation formula is: t = (xA-R·x'A, y'A-R·y'A, zA-R·z'A); according to the rotation matrix R and the translation vector t, the corresponding homogeneous transformation matrix T is obtained, and ; for any point p in the virtual model, the coordinates in the space coordinate system are converted through the homogeneous transformation matrix T, and ; S303. The average spatial distance D between the virtual point on the three-dimensional virtual cervical vertebra model and the real point on the corresponding entity cervical vertebra is calculated, and the average spatial distance D is compared with the preset threshold value D0. If the average spatial distance D is less than or equal to the preset threshold value D0, the registration is completed; otherwise, R and t are re-optimized, and S301-S302 are repeated until the average spatial distance D is less than or equal to the preset threshold value D0.

5. An MR intelligent guidance system for cervical lordotic adjustment, applying the MR intelligent guidance method for cervical lordotic adjustment of any one of claims 1-4, characterized in that: The system comprises an image data acquisition module, a three-dimensional modeling module, an MR scene fusion module, a dynamic adjustment guiding module, and a data archiving module. The image data acquisition module uses a scanning device to scan the cervical vertebra to obtain image data of a target coverage area, and the image data is stored in a DICOM format; the three-dimensional modeling module performs segmentation and extraction processing on the image data to generate a three-dimensional virtual cervical vertebra model containing C1 to C7 vertebral segments; the MR scene fusion module accurately superimposes the three-dimensional virtual cervical vertebra model and the entity cervical vertebra by using a spatial registration algorithm; the dynamic adjustment guiding module calculates adjustment parameters based on a mechanical model, displays guiding information in real time through an MR device, and assists an operator to complete the cervical vertebra inclined plate adjustment; and the data archiving module processes and stores sensor data and virtual model information in the operation process after the adjustment is completed.

6. The MR intelligent guidance system for cervical lordosis adjustment as claimed in claim 5, wherein: The image data acquisition module comprises a scanning device control unit and a data format conversion unit. The scanning device control unit controls the operation of the 64-slice spiral CT scanner, sets the scanning parameters, and the scanning range covers the segment from the occipital bone to the C7 vertebral body; the data format conversion unit converts the original image data generated by the scanner into DICOM format for storage.

7. The MR intelligent guidance system for cervical lordosis adjustment as claimed in claim 5, wherein: The three-dimensional modeling module includes a bony structure segmentation unit, a structure optimization unit, and a three-dimensional model generation unit; The bony structure segmentation unit imports DICOM format image data and preliminarily extracts the cervical vertebral bony structure; the structure optimization unit manually erases the soft tissue area mistakenly included or supplements the missing bony structure details by editing the mask tool, and separates C1 to C7 segments of the vertebrae based on the natural intervertebral space by cutting function; the three-dimensional model generation unit generates a three-dimensional virtual cervical vertebra model based on the segmented segmental vertebra data through the reconstruction function of the three-dimensional modeling software.

8. The MR intelligent guidance system for cervical lordosis adjustment as claimed in claim 5, wherein: The MR scene fusion module includes a real coordinate system construction unit, a virtual coordinate system mapping unit, and a registration verification and optimization unit; The real coordinate system construction unit controls the depth camera of the MR device to scan the real scene, identifies and records three non-collinear real landmark points around the entity cervical vertebra, calculates the corresponding axial vectors, and thus constructs the space coordinate system; the virtual coordinate system mapping unit selects the virtual points corresponding to the real landmark points in the three-dimensional virtual cervical vertebra model, calculates the axial vectors of the virtual coordinate system, and constructs the rotation matrix and translation vector through the axial vector dot product; the registration verification and optimization unit calculates the homogeneous transformation matrix, converts the virtual model coordinates to the space coordinate system, measures the average spatial distance between the virtual points and the real points, compares with the preset threshold, and thus performs registration verification and optimization.

9. The MR intelligent guidance system for cervical lordosis adjustment as claimed in claim 5, wherein: The dynamic adjustment guiding module includes a mechanical parameter extraction unit, an adjustment parameter calculation unit, and an MR real-time guiding unit; The mechanical parameter extraction unit extracts the cervical vertebra joint mechanical parameters from the three-dimensional virtual cervical vertebra model, and calculates the cervical vertebra surrounding muscle force based on the Hill muscle model; The adjustment parameter calculation unit extracts the target segment offset angle by comparing the virtual model with the reference position, calculates the target adjustment angle combined with the compensation angle, and deduces the inclined plate inclination angle based on the geometric relationship; The resultant force is calculated according to Newton's second law, the support force is calculated combined with the head mass and the inclined plate angle, and the additional force of the technique is deduced; The maximum bearing pressure of the vertebral body is calculated based on the limit of the vertebral body compression strength and the stress area; the adjustment angle, force parameter and safety threshold are displayed through the MR device by the MR real-time guiding unit, the adjustment path is indicated by the dynamic arrow, the angle and force deviation of the current and target are fed back in real time, and the warning is triggered when the actual pressure is equal to the threshold.

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