An auxiliary marking method for the osteotomy range of the mandibular angle

Abstract

The present invention relates to the technical field of medical image analysis, and particularly relates to a method for assisting in marking the osteotomy range of the mandibular angle. The present invention selects the actual nerve edge according to the gray similarity and position distribution of two suspected nerve edges that are centered on the edge in a local area; according to the correlation between the horizontal component of the line segment between the safe osteotomy line of historical patients and the actual nerve edge and the width of the mandible, and the similarity of the change trend of the safe osteotomy line in the horizontal direction in the ipsilateral local area between the patient to be measured and the historical patients, a distance adjustment coefficient is obtained, and it is used to adjust the position of the safe osteotomy line in the local area of the patient to be measured to obtain an optimized osteotomy line. The present invention analyzes the correlation between the width of the mandible of the patient to be measured and the image distortion based on the position of the inferior alveolar neurovascular bundle, and uses the distance adjustment coefficient to eliminate the distortion during the panoramic image acquisition of the safe osteotomy line, so as to improve the rationality of the mandibular angle osteotomy range determined based on the optimized osteotomy line.

Description

Technical Field

[0001] The present invention relates to the technical field of medical image analysis, and particularly relates to a method for assisting in marking the osteotomy range of the mandibular angle. Background Art

[0002] Mandibular angle osteotomy plastic surgery is a common facial plastic surgery. By removing part of the bone in the mandibular angle area, the chin line is adjusted to make it smoother and more natural. The mandibular angle area is densely distributed with important nerve structures such as the facial nerve and the inferior alveolar nerve. When the surgical operation is improper, it may damage the nerves, causing problems such as facial numbness, facial paralysis or loss of sensation. Therefore, assisting in dividing the osteotomy range in mandibular angle osteotomy surgery is of great significance for protecting the key nerves of the mandible.

[0003] Generally, an oral panoramic image of the patient is collected using X-ray, and a safe osteotomy line is determined in the oral panoramic image, and the osteotomy line is projected onto the three-dimensional oral structure to determine the osteotomy range. The oral panoramic image unfolds the jawbone arch structure into a planar image. Projecting the three-dimensional oral structure onto the oral panoramic image will cause partial distortion of the oral situation, resulting in errors in the process of projecting the safe osteotomy line determined in the oral panoramic image onto the three-dimensional oral structure, and further leading to an inappropriate determined osteotomy range of the mandibular angle. Summary of the Invention

[0004] In order to solve the technical problem that the osteotomy range of the mandibular angle is inappropriate due to partial distortion of the oral situation in the oral panoramic image, the purpose of the present invention is to provide a method for assisting in marking the osteotomy range of the mandibular angle, and the specific technical solution adopted is as follows:

[0005] The present invention proposes a method for assisting in marking the osteotomy range of the mandibular angle, and the method includes:

[0006] Obtain the safe osteotomy line in the two local regions into which the mandibular bone region in the oral panoramic image of the patient is divided; the patient includes the patient to be measured and the historical patient;

[0007] Obtain the suspected nerve edges in the local region; form edge pairs from any two suspected nerve edges in the local region, and obtain the actual nerve edges in the local region according to the gray similarity and position distribution of the two suspected nerve edges in the edge pair;

[0008] According to the correlation between the horizontal component of the line segment between the safe osteotomy line and the actual nerve edge of the historical patient and the width of the mandible, and the similarity of the horizontal change trend of the safe osteotomy line in the ipsilateral local region between the patient to be measured and the historical patient, obtain the distance adjustment coefficient for each local region of the patient to be measured;

[0009] Based on the distance adjustment coefficient, adjust the position of the safe osteotomy line in the local region of the patient to be measured to obtain an optimized osteotomy line.

[0010] Further, the obtaining of the actual nerve edge in the local area includes:

[0011] Calculating the variance of the shortest distances from all pixel points on any suspected nerve edge in the edge pair to the other suspected nerve edge;

[0012] Arranging the gray values of the pixel points on the suspected nerve edge in order to obtain a gray sequence; obtaining the DTW value of the gray sequences of the two suspected nerve edges in the edge pair;

[0013] Obtaining the canine region and the third molar region in each local area, and the mandibular symmetry line dividing the two local areas; respectively passing through the pixel points corresponding to the maximum values of the ordinates of the pixel coordinates in the canine region and the third molar region in each local area, and making parallel lines to the mandibular symmetry line, which are sequentially recorded as the first reference line and the second reference line;

[0014] Calculating the average distances from the endpoints of the two suspected nerve edges in each edge pair in each local area to the first reference line and the second reference line, which are sequentially recorded as the first distance and the second distance;

[0015] Obtaining the nerve edge index of each edge pair according to the variance, the DTW value, the first distance and the second distance; recording the two suspected nerve edges in the edge pair corresponding to the largest nerve edge index in each local area as the actual nerve edge.

[0016] Further, the obtaining of the distance adjustment coefficient for each local area of the patient to be measured includes:

[0017] Obtaining the mandibular width of the historical patients, performing curve fitting on the mandibular widths of all historical patients, and calculating the average slope of all points on the fitting curve, which is recorded as the first slope;

[0018] Selecting the actual nerve edge closest to the safety osteotomy line in the local area as the target edge, and recording the line segment of the shortest distance between the safety osteotomy line and its target edge as the distance line; performing curve fitting on the average value of the horizontal components of the distance lines of the two local areas of all historical patients, and calculating the average slope of all points on the fitting curve, which is recorded as the second slope;

[0019] Performing curve fitting on the horizontal components of the pixel points on the safety osteotomy line in the local area to obtain an osteotomy component line; calculating the average value of the root mean square errors of the osteotomy component lines in the same-side local areas of the patient to be measured and different historical patients, which is recorded as the osteotomy level difference degree of each local area of the patient to be measured;

[0020] Perform a negative correlation and normalization on the product of the absolute value of the difference between the first slope and the second slope and the osteotomy level difference degree to obtain the correlation degree of the patient to be measured and the historical patients in each local area;

[0021] Perform a normalization process on the mandibular width of the patient to be measured, and perform a negative correlation mapping on the product of the normalization result and the correlation degree to obtain the distance adjustment coefficient of each local area of the patient to be measured.

[0022] Further, adjusting the position of the safe osteotomy line in the local area of the patient to be measured based on the distance adjustment coefficient to obtain an optimized osteotomy line includes:

[0023] Use the distance adjustment coefficient to perform a weighted process on the horizontal component of the distance line in each local area of the patient to be measured, and use the square root result of the sum of the squares of the weighted result and the vertical component of the distance line as the optimized distance of the corresponding distance line;

[0024] Translate the safe osteotomy line of each local area of the patient to be measured along the direction where the distance line is located to obtain the optimized osteotomy line of the corresponding local area; the distance between the optimized osteotomy line and the target edge in the direction where the distance line is located is equal to the optimized distance.

[0025] Further, obtaining the nerve edge index of each edge pair according to the variance, the DTW value, the first distance and the second distance includes:

[0026] Calculate the sum value of the first distance and the second distance, and perform a negative correlation mapping on the product of the sum value, the variance and the DTW value to obtain the nerve edge index of each edge pair.

[0027] Further, obtaining the suspected nerve edge in the local area includes:

[0028] Optionally, a pixel point in the local area is recorded as an example point. Based on the symmetry line of the preset neighborhood of the example point, the preset neighborhood is divided into two parts. After calculating the sum of the gray values of the pixel points in each part, the absolute value of the difference between the corresponding sums of the two parts is recorded as the regional gray difference of the symmetry line; the symmetry line corresponding to the maximum value among the regional gray differences of all the symmetry lines of the preset neighborhood of the example point is recorded as the analysis line of the example point;

[0029] The pixel point with the smallest angle with the analysis line of the example point within the preset neighborhood range of the example point is recorded as the similar point; perform region growing on the pixel points in the local area and their similar points to obtain the suspected nerve edge.

[0030] Further, performing region growing on the pixel points in the local area and their similar points includes:

[0031] In the local area, a pixel point is selected as a growth point for regional growth, and similar points of the growth point that meet the preset growth conditions are used as new growth points for regional growth, until the similar points of the new growth points do not meet the preset growth conditions, the regional growth is stopped, and a suspected nerve edge is obtained;

[0032] The preset growth condition includes: the angle between the analysis line and the corresponding growth point is smaller than a preset angle threshold and the absolute value of the regional grayscale difference is smaller than a preset grayscale difference threshold.

[0033] Furthermore, the two local areas into which the mandibular area is divided are symmetrical about the mandibular symmetry line.

[0034] Furthermore, the mandibular width is equal to the longest distance of the mandibular region in the horizontal direction.

[0035] Furthermore, the preset neighborhood is eight neighborhoods.

[0036] The present invention has the following beneficial effects:

[0037] In the embodiment of the present invention, in order to avoid damaging the inferior alveolar nerve during mandibular angle osteotomy surgery, the position of the inferior alveolar nerve and blood vessels needs to be determined before adjusting the safe osteotomy line. The position of the nerve and blood vessels in the mandible is fixed, and the two blood vessel wall edges are parallel and the grayscale performance of the two blood vessel wall edges is similar. Combined with the position distribution and grayscale similarity of the two suspected nerve edges in the edge alignment, the actual nerve edge representing the blood vessel wall edge of the inferior alveolar nerve and blood vessels is selected; the oral panoramic image has a distorted structure in the horizontal direction, and the correlation between the horizontal component of the line segment between the safe osteotomy line and the actual nerve edge of the historical patient and the mandibular width is reversed. The correlation between the mandibular width of the historical patients and the horizontal distortion of the oral panoramic view is reflected. The similarity of the horizontal change trend of the safe osteotomy line in the local area on the same side of the patient to be tested and the historical patients reflects the correlation between the patient to be tested and the historical patients. The correlation between the mandibular width of the patient to be tested and the horizontal distortion of the oral panoramic view is analyzed by combining the two to determine the distance adjustment coefficient, which is used to present the required reduction degree of the horizontal component of the distance line. The safe osteotomy line is adjusted to eliminate the distortion of the oral framing view during the image acquisition process, and improve the rationality of the mandibular angle osteotomy range determined based on the optimized osteotomy line. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 The flowchart of steps of an auxiliary marking method for the mandibular angle osteotomy range provided by an embodiment of the present invention;

[0040] Figure 2 The system structure diagram of an auxiliary marking system for the mandibular angle osteotomy range provided by an embodiment of the present invention;

[0041] Figure 3 The schematic diagram of a computer device of an auxiliary marking device for the mandibular angle osteotomy range provided by an embodiment of the present invention. Detailed implementation manners

[0042] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following combines the accompanying drawings and preferred embodiments to detail an auxiliary marking method for the mandibular angle osteotomy range proposed according to the present invention, its specific implementation manners, structures, features and effects. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

[0044] The following specifically describes the specific solution of an auxiliary marking method for the mandibular angle osteotomy range provided by the present invention with reference to the accompanying drawings.

[0045] Embodiment 1:

[0046] The present invention proposes an auxiliary marking method for the mandibular angle osteotomy range. Please refer to Figure 1 , which shows the flowchart of steps of an auxiliary marking method for the mandibular angle osteotomy range provided by an embodiment of the present invention. The method includes:

[0047] Step S1: Obtain the safe osteotomy line in two local regions where the mandibular region in the panoramic oral image of the patient is divided; the patient includes the patient to be measured and the historical patient.

[0048] Before collecting the oral image, the patient needs to correctly bite the locator and keep the head upright. The locator can keep the mouth at an appropriate opening angle. The doctor uses an X-ray machine to rotate around the patient's head to scan the oral cavity to obtain a panoramic oral image. In order to facilitate the analysis of the mandibular angle osteotomy range, it is necessary to extract the mandibular region in the panoramic oral image; based on the symmetry line of the mandibular region, that is, the mandibular symmetry line, it is divided into two symmetric local regions on the left and right sides. The doctor marks a safe osteotomy line, that is, the Kamiishi line, in each local region according to experience.

[0049] In the embodiments of the present invention, an image processing software such as Dubhewer software is used to perform image segmentation on an oral panoramic image to extract the mandibular region; in other embodiments, semantic segmentation can also be used to extract the mandibular region in the oral panoramic image; methods such as inputting the oral panoramic image into a trained neural network and outputting the mandibular region in the panoramic image are not limited herein.

[0050] It should be noted that in order to ensure the quality of the oral panoramic image, the patient needs to remove metal objects such as dentures, jewelry, and glasses in the oral cavity before the examination, and remain stationary during the scanning process.

[0051] Step S2: Obtain the suspected nerve edges within the local area; form an edge pair from any two suspected nerve edges within the local area, and obtain the actual nerve edges in the local area according to the gray-scale similarity and position distribution of the two suspected nerve edges in the edge pair.

[0052] The safe osteotomy line is mainly used to avoid inferior alveolar nerve injury in mandibular angle osteotomy plastic surgery. The position of the inferior alveolar neurovascular bundle needs to be determined before adjusting the safe osteotomy line. In an oral panoramic image, the inferior alveolar neurovascular bundle usually appears as a slender dark line, but local bone density abnormalities and certain jaw tumors in the mandible may also appear as slender lines in the image, affecting the determination of the position of the inferior alveolar nerve. Extract the dark line edges in the local area to obtain suspected nerve edges.

[0053] Preferably, in some possible implementation manners of the embodiments of the present invention, the method for obtaining suspected nerve edges includes: arbitrarily selecting a pixel point in the local area as an example point, dividing the preset neighborhood of the example point into two parts based on the symmetry line of the preset neighborhood, calculating the sum of the gray-scale values of the pixel points in each part, and then recording the absolute value of the difference between the corresponding sums of the two parts as the regional gray-scale difference of the symmetry line; selecting the symmetry line corresponding to the maximum value among the regional gray-scale differences of all symmetry lines in the preset neighborhood of the example point as the analysis line of the example point; recording the pixel point with the smallest angle with the analysis line of the example point within the preset neighborhood range of the example point as the similar point; performing region growing on the pixel points in the local area and their similar points to obtain suspected nerve edges.

[0054] The neurovascular structure presents as slender dark stripes, with one side of each edge being darker and the other side being lighter. If a pixel is located on the edge of the neurovascular structure, the edge divides the preset neighborhood of the pixel into two parts with a relatively large gray-scale difference. The analysis line of the pixel represents the local edge of the neurovascular structure. Since the neurovascular structure is relatively smooth, the directions of the analysis lines of adjacent pixels located on the edge of the neurovascular structure are relatively consistent, and the greater the likelihood that the example point and its similar points are located on the edge of the neurovascular structure. Therefore, it is necessary to perform region growing based on the pixels and their similar points within the local area. Since the edge of the neurovascular structure is relatively smooth and the gray-scale difference between the two sides of the pixels on the edge is relatively close, the smaller the included angle between the analysis lines of the growing point and its similar points and the closer the regional gray-scale difference, it is considered that the growing point and its similar points are located on the edge of the neurovascular structure. In the embodiment of the present invention, the region growing process is as follows: Arbitrarily select a pixel in the local area as the growing point to perform region growing, and use the similar points of the growing point that meet the preset growing conditions as the new growing points to perform region growing until the similar points of the new growing points do not meet the preset growing conditions, then stop the region growing to obtain suspected nerve edges. The preset growing conditions include: the included angle with the analysis line of the corresponding growing point is less than the preset angle threshold and the difference in regional gray-scale difference from the corresponding growing point is less than the preset gray-scale difference threshold.

[0055] It should be noted that in this embodiment, the preset neighborhood is an eight-neighborhood, and the symmetry lines of the eight-neighborhood of the example point include a horizontal symmetry line, a vertical symmetry line, a 45-degree diagonal line, and a 135-degree diagonal line.

[0056] In an implementation manner of the embodiment of the present invention, the preset neighborhood is an eight-neighborhood, the preset angle threshold is set to 45 degrees, and the preset gray-scale difference threshold is set to 10.

[0057] The neurovascular structure usually presents as a pipe pile or linear structure in the image, and the performance of the blood vessel wall in the image is relatively consistent. Then, the two edges representing the blood vessel wall are usually parallel and have similar gray-scales. At the same time, the inferior alveolar neurovascular structure is usually located between the third molar area and the premolar area of the mandible, starts to appear approximately 1 cm from the mesial or distal surface of the second molar of the mandible, and extends all the way to the area below the canine tooth. Therefore, the inferior alveolar neurovascular structure is located between the canine tooth and the third molar. Therefore, by analyzing the gray-scale similarity and position distribution of the two suspected nerve edges through the edge pair, the edge characteristics of the two edges presenting the inferior alveolar neurovascular structure are analyzed, and then the actual nerve edge is selected.

[0058] Preferably, in some possible implementation manners of the embodiments of the present invention, the method for obtaining the actual nerve margin includes: calculating the variance of the shortest distances from all pixel points on any one of the suspected nerve margins in the edge pair to the other suspected nerve margin; arranging the gray values of the pixel points on the suspected nerve margin in order to obtain a gray sequence; obtaining the DTW value of the gray sequences of the two suspected nerve margins in the edge pair; obtaining the canine region and the third molar region in each local region, and the mandibular symmetry line dividing the two local regions; respectively passing through the pixel points corresponding to the maximum values of the ordinates of the pixel coordinates in the canine region and the third molar region in each local region, and making parallel lines of the mandibular symmetry line, which are sequentially recorded as the first reference line and the second reference line; calculating the average distances from the endpoints of the two suspected nerve margins in each edge pair in each local region to the first reference line and the second reference line, which are sequentially recorded as the first distance and the second distance; obtaining the nerve margin index of each edge pair according to the variance, the DTW value, the first distance, and the second distance; and recording the two suspected nerve margins in the edge pair corresponding to the largest nerve margin index in each local region as the actual nerve margin. Among them, the dynamic time warping (DTW) algorithm and the pixel coordinates are well-known technologies to those skilled in the art and will not be elaborated here.

[0059] The parallel distribution of the two suspected nerve margins is measured by the variance of the shortest distances from the pixel points on any one of the suspected nerve margins in the edge pair to the other suspected nerve margin. The smaller the variance, the greater the possibility of parallel distribution of the two edges, and the greater the possibility of representing the blood vessel wall of the inferior alveolar nerve and blood vessels. The gray similarity of the two suspected nerve margins in the edge pair is measured by the DTW value of the gray sequences of the two suspected nerve margins. The smaller the DTW value, the more similar the gray distributions of the two edges, and the greater the possibility of representing the blood vessel wall of the inferior alveolar nerve and blood vessels. If the endpoints of the two suspected nerve margins in the edge pair close to the mandibular symmetry line are closer to the canine and the endpoints far from the mandibular symmetry line are closer to the third molar, that is, the smaller the first distance and the second distance, the more similar the gray distributions of the two edges, the greater the possibility of representing the blood vessel wall of the inferior alveolar nerve and blood vessels, and the greater the nerve margin index. The actual nerve margin refers to the blood vessel wall margin of the inferior alveolar nerve and blood vessels.

[0060] Therefore, the variance, the DTW value, the first distance, and the second distance are all negatively correlated with the nerve margin index. In the embodiments of the present invention, the sum value of the first distance and the second distance is calculated, and the product of the sum value, the variance, and the DTW value is subjected to a negative correlation mapping to obtain the nerve margin index of each edge pair. In the embodiments of the present invention, the correlation relationship between the variance, the DTW value, the first distance, the second distance, and the nerve margin index can also be constructed through other basic mathematical operations, which will not be limited and elaborated here.

[0061] It should be noted that in the embodiments of the present invention, the opposite number of the above product is used as the exponent of the exponential function with the natural constant as the base to achieve the negative correlation mapping processing of the product. Other negative correlation mapping methods such as taking the reciprocal and taking the negative number can also be selected, which are not limited herein.

[0062] In the embodiments of the present invention, the panoramic oral image is input into the trained neural network, and the panoramic oral image with the canine region and the third molar region marked is output. In other embodiments, the doctor directly marks the canine region and the third molar region in the local area of the panoramic oral image according to experience.

[0063] Step S3: According to the correlation between the horizontal component of the line segment between the safe osteotomy line of the historical patient and the actual nerve margin and the width of the mandible, and the similarity of the change trend of the safe osteotomy line in the horizontal direction in the ipsilateral local area between the patient to be measured and the historical patient, obtain the distance adjustment coefficient for each local area of the patient to be measured.

[0064] The safe osteotomy line needs to be located at a certain distance above the inferior alveolar neurovascular bundle. If the distance is too close, the inferior alveolar neurovascular bundle may be damaged during the operation. If the distance is too far, the surgical effect may not be achieved. Therefore, it is necessary to adjust the safe osteotomy line based on the position of the safe osteotomy line and the inferior alveolar neurovascular bundle. The panoramic oral image unfolds the jaw arch structure into a planar image, resulting in distortion of the horizontal structure, i.e., stretching or compression, so that there is a difference in the horizontal distance between the panoramic oral image and the oral cavity of the patient to be measured. The increase in the width of the mandible will exacerbate the distortion of the panoramic oral image. The correlation between the horizontal component of the line segment between the safe osteotomy line of the historical patient and the actual nerve margin and the width of the mandible reflects the correlation between the width of the mandible of the historical patient and the distortion of the panoramic oral image in the horizontal direction. The similarity of the change trend of the safe osteotomy line in the horizontal direction in the ipsilateral local area between the patient to be measured and the historical patient reflects the correlation between the patient to be measured and the historical patient. By combining the two, the correlation between the width of the mandible of the patient to be measured and the distortion of the panoramic oral image in the horizontal direction is analyzed, and then the distance adjustment coefficient for eliminating the distortion of the panoramic oral image in the horizontal direction is determined.

[0065] Preferably, in some possible implementation manners of the embodiments of the present invention, the method for obtaining the distance adjustment coefficient includes: obtaining the mandibular width of historical patients, performing curve fitting on the mandibular widths of all historical patients, calculating the average value of the slopes of all points on the fitting curve, and denoting it as the first slope; selecting the actual nerve edge closest to the safe osteotomy line in the local area as the target edge, and denoting the line segment of the shortest distance between the safe osteotomy line and its target edge as the distance line; performing curve fitting on the average value of the horizontal components of the distance lines of the two local areas of all historical patients, and calculating the average value of the slopes of all points on the fitting curve and denoting it as the second slope; performing curve fitting on the horizontal components of the pixel points on the safe osteotomy line in the local area to obtain the osteotomy component line; calculating the average value of the root mean square errors of the osteotomy component lines in the same-side local areas of the patient to be measured and different historical patients respectively, and denoting it as the osteotomy level difference degree of each local area of the patient to be measured; performing negative correlation and normalization processing on the product of the absolute value of the difference between the first slope and the second slope and the osteotomy level difference degree to obtain the correlation degree between the patient to be measured and the historical patients in each local area; performing normalization processing on the mandibular width of the patient to be measured, and performing negative correlation mapping on the product of the normalization result and the correlation degree to obtain the distance adjustment coefficient of each local area of the patient to be measured.

[0066] The increase in the mandibular width will exacerbate the distortion of the panoramic oral image. Different patients may have different distortions of the panoramic oral image due to the difference in the mandibular width. It is necessary to analyze whether the patient to be measured and the historical patients have the same distortion situation. The horizontal component of the distance line is affected by the distortion of the panoramic oral image. When analyzing the correlation between the mandibular width and the distance line, the horizontal component is considered. The first slope and the second slope respectively reflect the change trend of the mandibular width of the historical patients and the change trend of the horizontal component of the distance line. If the difference between the first slope and the second slope is smaller, the greater the possibility that there is a positive correlation between the mandibular width of the historical patients and the horizontal component of the distance line, indicating that the greater the mandibular width of the historical patients, the more obvious the stretching distortion of the panoramic oral image in the horizontal direction. At the same time, the smaller the osteotomy level difference degree, the more consistent the change trends of the osteotomy component lines of the patient to be measured and the historical patients, indicating that the stronger the correlation between the patient to be measured and the historical patients. Furthermore, when the mandibular width of the patient to be measured is larger, the panoramic oral image is more severely affected by the horizontal stretching distortion. Therefore, if the mandibular width of the patient to be measured is larger and the correlation degree between the patient to be measured and the historical patients is larger, the panoramic oral image of the patient to be measured is more severely affected by the horizontal stretching distortion. In order to reduce the influence of distortion during the image acquisition process, it is necessary to reduce the horizontal component of the distance line. Therefore, it is necessary to perform negative correlation mapping on the product of the mandibular width of the patient to be measured and the correlation degree to obtain the distance adjustment coefficient.

[0067] In an embodiment of the present invention, the opposite number of the data to be processed is used as the exponent of the exponential function with the natural constant as the base, so as to achieve negative correlation and normalization or negative correlation mapping processing of the data to be processed. The historical patients include patients with various mandibular widths. If the mandibular width of the patient to be measured is within the range of the mandibular widths of the historical patients, then in this embodiment, the maximum-minimum normalization processing is performed on the mandibular width of the patient to be measured by using the mandibular widths of the historical patients.

[0068] It should be noted that the line segment connecting any two pixel points located on the safety osteotomy line and its target edge and corresponding to the shortest distance between the pixel points is denoted as the distance line. When performing curve fitting on the horizontal components of the pixel points on the safety osteotomy line in the local area, the abscissa in the fitting process is the position of the pixel point on the safety osteotomy line, and the ordinate is the horizontal component of the pixel point. When analyzing the root mean square error of the osteotomy component lines of the patient to be measured and the historical patients, it is necessary to align the pixel points at the same position on the two osteotomy component lines.

[0069] In an implementation manner of an embodiment of the present invention, the curve fitting method is the least squares method.

[0070] In an implementation manner of an embodiment of the present invention, the mandibular width is equal to the longest distance of the mandibular region in the horizontal direction.

[0071] Step S4: Based on the distance adjustment coefficient, adjust the position of the safety osteotomy line in the local area of the patient to be measured to obtain an optimized osteotomy line.

[0072] The distance adjustment coefficient represents the degree of reduction required for the horizontal component of the distance line. The smaller the distance adjustment coefficient, the greater the degree of reduction required for the horizontal component of the distance line due to horizontal stretching distortion of the panoramic image of the patient to be measured. Furthermore, the position of the safety osteotomy line is adjusted to determine an optimized osteotomy line that eliminates the influence of horizontal distortion generated during the panoramic image acquisition process.

[0073] Preferably, in some possible implementation manners of an embodiment of the present invention, the method for obtaining the optimized osteotomy line includes: weighting the horizontal component of the distance line in each local area of the patient to be measured by using the distance adjustment coefficient, and taking the square root of the sum of the squares of the weighted result and the vertical component of the distance line as the optimized distance corresponding to the distance line; translating the safety osteotomy line in each local area of the patient to be measured along the direction where the distance line is located to obtain the optimized osteotomy line corresponding to the local area; the distance between the optimized osteotomy line and the target edge in the direction where the distance line is located is equal to the optimized distance.

[0074] The optimized osteotomy line is in the oral two-dimensional image, but the mandibular angle osteotomy plastic surgery is performed on the three-dimensional mandible of the patient to be measured. It is necessary to project the optimized osteotomy line into the three-dimensional mandible model of the patient to be measured. The specific method is as follows: First, generate the three-dimensional mandible model of the patient to be measured through cone beam CT; Second, extract feature points on the panoramic oral image and the three-dimensional mandible model of the patient to be measured, such as the tips and roots of teeth, etc.; Then, use the feature registration algorithm to perform feature matching on the feature points of the panoramic oral image and the three-dimensional mandible model, and calculate the geometric transformation matrix from the panoramic oral image to the three-dimensional mandible model; Finally, project the two optimized osteotomy lines of the panoramic oral image onto the three-dimensional mandible model through the transformation matrix, and use 3D modeling software such as Mimics software to load the three-dimensional model and the projection lines for visualization to obtain the optimized osteotomy line in the three-dimensional mandible model of the patient to be measured.

[0075] Intercepting the mandibular part below the optimized osteotomy line in the three-dimensional mandible model of the patient to be measured will not damage the inferior alveolar neurovascular bundle; the doctor determines the appropriate cutting direction and position in the mandibular part below the optimized osteotomy line in the three-dimensional mandible model according to the facial needs of the patient to be measured.

[0076] So far, the present invention is completed.

[0077] Embodiment 2:

[0078] The present invention provides an auxiliary marking system for the osteotomy range of the mandibular angle. Please refer to Figure 2 , which shows the system structure diagram of an auxiliary marking system for the osteotomy range of the mandibular angle provided by an embodiment of the present invention. The system includes:

[0079] A data acquisition module 510, configured to obtain the safe osteotomy line in the mandibular region of the panoramic oral image of the patient; the patient includes the patient to be measured and the historical patient;

[0080] A nerve edge extraction module 520, configured to obtain the suspected nerve edges in the local region; form an edge pair from any two suspected nerve edges in the local region, and obtain the actual nerve edge in the local region according to the gray similarity and position distribution of the two suspected nerve edges in the edge pair;

[0081] An adjustment coefficient analysis module 530, configured to obtain the distance adjustment coefficient of each local region of the patient to be measured according to the correlation between the horizontal component of the line segment between the safe osteotomy line and the actual nerve edge of the historical patient and the width of the mandible, and the similarity of the horizontal change trend of the safe osteotomy lines in the ipsilateral local regions of the patient to be measured and the historical patient;

[0082] An osteotomy range adjustment module 540, configured to adjust the position of the safe osteotomy line in the local region of the patient to be measured based on the distance adjustment coefficient to obtain the optimized osteotomy line.

[0083] It should be noted that: For the device provided in the above embodiments, only the division of the above functional modules is used for illustration. In actual applications, the above functions can be allocated to different functional modules as needed, that is, the internal structure of the computer device is divided into different functional modules to complete all or part of the functions described above. In addition, an auxiliary marking system for the mandibular angle osteotomy range and an embodiment of the auxiliary marking method for the mandibular angle osteotomy range provided in the above embodiments belong to the same concept. The specific implementation process can be found in the method embodiments and will not be elaborated here.

[0084] Embodiment 3:

[0085] Figure 3 The schematic diagram of a computer device of an auxiliary marking device for the mandibular angle osteotomy range provided by an embodiment of the present invention. Exemplarily, as Figure 3 shown, the computer device includes: a memory 601, a processor 602, and a computer program 603 stored in the memory 601 and running on the processor 602. Among them, when the processor 602 executes the computer program 603, the computer device can execute any one of the auxiliary marking methods for the mandibular angle osteotomy range introduced above.

[0086] In addition, the embodiments of the present application also protect a device, which may include a memory and a processor. Among them, an executable program code is stored in the memory, and the processor is used to call and execute the executable program code to execute an auxiliary marking method for the mandibular angle osteotomy range provided by the embodiments of the present application.

[0087] In this embodiment, the device can be divided into functional modules according to the above method examples. For example, it can correspond to each functional module, or two or more functions can be integrated into one processing module. The above integrated module can be implemented in the form of hardware. It should be noted that the division of modules in this embodiment is illustrative, only a logical function division, and there may be other division methods in actual implementation.

[0088] It should be understood that the device provided in this embodiment is used to execute the above-mentioned auxiliary marking method for the mandibular angle osteotomy range, so the same effect as the above implementation method can be achieved.

[0089] In the case of adopting an integrated unit, the device may include a processing module and a storage module. Among them, when the device is applied to a device, the processing module can be used to control and manage the actions of the device. The storage module can be used to support the device to execute mutual program codes, etc.

[0090] Among them, the processing module can be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits included in the disclosure of this application. The processor can also be a combination that implements computing functions, such as including a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc. The storage module can be a memory.

[0091] It should be noted that the above sequence of embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0092] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments.

[0093] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for auxiliary marking of mandibular angle osteotomy range, characterized in that: The method includes: Obtaining a safe osteotomy line in which the mandibular region is divided into two local regions in an oral panoramic view of the patient; the patient includes a patient to be tested and a historical patient; Obtaining suspected nerve edges in the local area; forming an edge pair from any two suspected nerve edges in the local area, and obtaining the actual nerve edge in the local area according to the grayscale similarity and position distribution of the two suspected nerve edges in the edge pair; According to the correlation between the horizontal component of the line segment between the safety osteotomy line and the actual nerve edge of the historical patients and the mandibular width, and the similarity of the horizontal change trend of the safety osteotomy line in the ipsilateral local area between the patient to be tested and the historical patients, the distance adjustment coefficient of each local area of ​​the patient to be tested is obtained; adjusting the position of the safe osteotomy line in the local area of ​​the patient to be tested based on the distance adjustment coefficient to obtain an optimized osteotomy line; The method for obtaining the optimized osteotomy line comprises: The actual nerve edge closest to the safety osteotomy line in the local area is selected as the target edge, and the line segment with the shortest distance between the safety osteotomy line and its target edge is recorded as the distance line; Using the distance adjustment coefficient, weighted processing is performed on the horizontal component of the distance line in each local area of ​​the patient to be tested, and the square root of the sum of the squares of the components of the distance line in the vertical direction is taken as the optimized distance of the corresponding distance line; The safe osteotomy line of each local area of ​​the patient to be tested is translated along the direction of the distance line to obtain the optimized osteotomy line of the corresponding local area; the distance between the optimized osteotomy line and the target edge in the direction of the distance line is equal to the optimized distance.

2. The method for auxiliary marking of mandibular angle osteotomy range according to claim 1, characterized in that: The obtaining of the actual nerve edge in the local area comprises: Calculate the variance of the shortest distances from all pixels on any suspected nerve edge in the edge pair to the other suspected nerve edge; The grayscale values ​​of the pixels on the suspected nerve edge are arranged in order to obtain a grayscale sequence; the DTW values ​​of the grayscale sequences of the two suspected nerve edges in the edge pair are obtained; Obtain the canine area and the third molar area in each local area, and the mandibular symmetry line dividing the two local areas; draw parallel lines to the mandibular symmetry line through the pixel points corresponding to the maximum values ​​in the ordinates of the pixel coordinates in the canine area and the third molar area in each local area, and record them as the first reference line and the second reference line respectively; Calculate the average distances from the endpoints of the two suspected nerve edges in each edge pair of each local area to the first reference line and the second reference line, respectively, and record them as the first distance and the second distance respectively; According to the variance, the DTW value, the first distance and the second distance, a neural edge index of each edge pair is obtained; and two suspected neural edges in the edge pair corresponding to the largest neural edge index in each local area are recorded as actual neural edges.

3. The method for auxiliary marking of mandibular angle osteotomy range according to claim 1, characterized in that: The step of obtaining the distance adjustment coefficient of each local area of ​​the patient to be tested includes: Obtain the mandibular width of historical patients, perform curve fitting on the mandibular width of all historical patients, and calculate the mean slope of all points on the fitting curve, which is recorded as the first slope; Performing curve fitting on the mean values ​​of the components of the distance lines in the two local areas of all historical patients in the horizontal direction, and calculating the mean value of the slopes of all points on the fitting curve as the second slope; Perform curve fitting on the horizontal components of the pixel points on the safe osteotomy line in the local area to obtain the osteotomy component line; calculate the mean of the root mean square errors of the osteotomy component lines in the local areas on the same side of the patient to be tested and different historical patients, and record them as the osteotomy level difference of each local area of ​​the patient to be tested; Performing negative correlation and normalization processing on the product of the absolute value of the difference between the first slope and the second slope and the osteotomy level difference, so as to obtain the correlation between the patient to be tested and the historical patient in each local area; The mandibular width of the patient to be tested is normalized, and a negative correlation mapping is performed on the product of the normalization result and the correlation degree to obtain a distance adjustment coefficient for each local area of ​​the patient to be tested.

4. The method for auxiliary marking of mandibular angle osteotomy range according to claim 2, characterized in that: The obtaining of a neural edge index of each edge pair according to the variance, the DTW value, the first distance and the second distance includes: The sum of the first distance and the second distance is calculated, and the product of the sum, the variance and the DTW value is negatively correlated to obtain a neural edge index of each edge pair.

5. The method for auxiliary marking of mandibular angle osteotomy range according to claim 1, characterized in that: The obtaining of the suspected nerve edge in the local area includes: A pixel point in any local area is recorded as an example point, and the preset neighborhood is divided into two parts based on the symmetry line of the preset neighborhood of the example point. After the cumulative sum of the grayscale values ​​of the pixel points in each part is calculated, the absolute value of the difference between the corresponding cumulative sums of the two parts is recorded as the regional grayscale difference of the symmetry line; the symmetry line corresponding to the maximum value of the regional grayscale difference of all symmetry lines of the preset neighborhood of the example point is selected and recorded as the analysis line of the example point; The pixel point with the smallest angle with the analysis line of the example point within the preset neighborhood of the example point is recorded as a similar point; and the pixel point in the local area and its similar point are subjected to region growth to obtain a suspected nerve edge.

6. The method for auxiliary marking of mandibular angle osteotomy range according to claim 5, characterized in that: The performing region growing on the pixel points and similar points in the local region comprises: In the local area, a pixel point is selected as a growth point for regional growth, and similar points of the growth point that meet the preset growth conditions are used as new growth points for regional growth, until the similar points of the new growth points do not meet the preset growth conditions, the regional growth is stopped, and a suspected nerve edge is obtained; The preset growth condition includes: the angle between the analysis line and the corresponding growth point is smaller than a preset angle threshold and the absolute value of the regional grayscale difference is smaller than a preset grayscale difference threshold.

7. The method for auxiliary marking of mandibular angle osteotomy range according to claim 2, characterized in that: The two local areas into which the mandibular region is divided are symmetrical with respect to the mandibular symmetry line.

8. The method for auxiliary marking of mandibular angle osteotomy range according to claim 1, characterized in that: The mandibular width is equal to the longest distance of the mandibular region in the horizontal direction.

9. The method for auxiliary marking of mandibular angle osteotomy range according to claim 5, characterized in that: The preset neighborhood is eight neighborhoods.

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