WO2018035837A1 - Three-dimensional tooth axis estimation method and device - Google Patents
Three-dimensional tooth axis estimation method and device Download PDFInfo
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- WO2018035837A1 WO2018035837A1 PCT/CN2016/096851 CN2016096851W WO2018035837A1 WO 2018035837 A1 WO2018035837 A1 WO 2018035837A1 CN 2016096851 W CN2016096851 W CN 2016096851W WO 2018035837 A1 WO2018035837 A1 WO 2018035837A1
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
- A61C19/00—Dental auxiliary appliances
- A61C19/04—Measuring instruments specially adapted for dentistry
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- the present application relates to image processing, and more particularly to a method and apparatus for estimating a three-dimensional dental shaft.
- the present application provides a method and apparatus for estimating a three-dimensional dental shaft.
- the present application provides a method for estimating a three-dimensional dental shaft, comprising:
- a three-dimensional dental CT image is converted into a plurality of two-dimensional projection images, and three-dimensional dental axes are extracted from the two-dimensional projection images.
- the three-dimensional dental CT image is converted into a plurality of two-dimensional projection images, and the three-dimensional dental axes are extracted according to the two-dimensional projection image, which specifically includes:
- the above method, the dividing the two-dimensional projection image into a tooth contour specifically includes: [0014] preprocessing the two-dimensional projection image;
- the two-dimensional contour of the tooth is extracted by automatic or manual interaction.
- the above method, the extracting the two-dimensional axis according to the tooth contour specifically includes:
- a two-dimensional axis is extracted on the two-dimensional projected image, the extracted two-dimensional axis including a straight line along the long axis direction of the tooth contour and passing through the centroid point of the tooth contour.
- the three-dimensional dental CT image is projected to obtain a two-dimensional projection image, and specifically includes:
- the tooth alveolar bone region determined by the two-dimensional tooth axis of the first two-dimensional projection image on the left and right parallel axes of the tooth contour is a projection area to pass the two-dimensional tooth axis of the first two-dimensional projection image
- the normal of the plane is the projection direction, and the projection area is projected to obtain a plurality of two-dimensional projection images.
- the present application provides an apparatus for estimating a three-dimensional dental axis, the apparatus for converting a three-dimensional oral CT image into a plurality of two-dimensional projection images, and extracting according to the two-dimensional projection image Three-dimensional dental shaft.
- the device includes:
- a projection module configured to perform multiple projections on the three-dimensional dental CT image to obtain a plurality of two-dimensional projection images
- a segmentation module configured to respectively segment the tooth contours in the two-dimensional projection image
- an extraction module configured to extract a two-dimensional axis according to the tooth contour
- a synthesis module configured to synthesize a three-dimensional dental shaft according to the plurality of the two-dimensional axes.
- the segmentation module is further configured to preprocess the two-dimensional projection image, and extract the extracted two-dimensional contour of the tooth by using an automatic or manual interaction method on the pre-processed two-dimensional projection image.
- the extraction module is further configured to extract a two-dimensional axis on the two-dimensional projection image, the extracted two-dimensional axis includes a longitudinal axis along the contour of the tooth, and passes through a centroid of the contour of the tooth The line of points.
- the projection module is further configured to remove a tooth alveolar bone region from the three-dimensional oral CT image Extracting from the image, obtaining a dental arch curve from the tooth alveolar bone region, projecting the dental alveolar bone region in a projection direction of the dental arch curve to obtain a first two-dimensional projection image; a method in which a two-dimensional tooth axis of the first two-dimensional projection image defines a tooth alveolar bone region defined by left and right parallel axes of the tooth contour as a projection region, and a plane of the two-dimensional tooth axis of the first two-dimensional projection image The line is a projection direction, and the projection area is projected to obtain a plurality of two-dimensional projection images.
- the present application since the three-dimensional oral CT image is converted into multiple two-dimensional projection images, and the three-dimensional dental axis is extracted according to the two-dimensional projection image, the present application comprehensively considers the crown and root information, and only needs to The contouring of the teeth on multiple two-dimensional projection images eliminates the need for complete tooth segmentation in the patient's oral CT image, and the efficiency of the dental axis estimation is higher. At the same time, since the difference between the root and alveolar bone in the two-dimensional projection image is more obvious than the difference between the original oral CT images, the contour segmentation of the teeth is easier, and the estimated three-dimensional dental axes are more accurate.
- FIG. 1 is a flow chart of a method of the present application in an embodiment
- FIG. 2 is a flow chart of obtaining a two-dimensional tooth contour in one embodiment of the method of the present application
- FIG. 3 is a flow chart of obtaining a two-dimensional projected image in one embodiment of the method of the present application.
- FIG. 4 is a flow chart of obtaining a two-dimensional projected image in another embodiment of the method of the present application.
- FIG. 5 is a schematic diagram of functional modules of an apparatus of the present application in an embodiment.
- the method of estimating a three-dimensional dental shaft of the present application comprises three stages. The first stage is the extraction of the first two-dimensional axis.
- the first projection of the input original oral CT image is performed, and then the two-dimensional contour of the tooth is segmented in the projected image, and the two-dimensional axis of the tooth is extracted.
- the segmentation result is recorded as the tooth two-dimensional contour 1
- the extraction result is recorded as the tooth two-dimensional axis 1.
- the second stage is the extraction of the second two-dimensional axis.
- the input original oral CT image is subjected to the second projection (the second projection direction is different from the first projection direction), and then the two-dimensional contour of the tooth is segmented on the projection image, and the two-dimensional axis of the tooth is extracted.
- the segmentation result is recorded as the tooth 2D contour 2, and the extraction result is recorded as the tooth 2D axis 2.
- the third stage is the synthesis of three-dimensional dental axes.
- the three-dimensional axis that is, the estimated three-dimensional dental axis of the tooth, is synthesized based on the two two-dimensional axes extracted, that is, the two-dimensional axis 1 of the tooth and the two-dimensional axis 2 of the tooth.
- the technique does not require the complete segmentation of the teeth on hundreds of oral CT images, only the contour segmentation of each tooth in two projection images; and the difference between the root and the alveolar bone in the two projections is smaller than the original
- the difference between the two in the oral CT image is more pronounced, the contouring of the teeth is easier, and the estimated three-dimensional dental axes are more accurate.
- Embodiment 1 is a diagrammatic representation of Embodiment 1:
- the method for estimating a three-dimensional dental shaft of the present application includes:
- the three-dimensional dental CT image is converted into a plurality of two-dimensional projection images, and the three-dimensional dental axes are extracted from the two-dimensional projection images.
- another method for estimating a three-dimensional dental shaft of the present application includes the following steps:
- Step 102 Perform multiple projections on the three-dimensional oral CT image to obtain a plurality of two-dimensional projection images.
- Step 104 Segment the tooth contours in the two-dimensional projection image.
- Step 106 Extract a two-dimensional axis from the contour of the tooth.
- Step 108 synthesize a three-dimensional dental shaft according to a plurality of two-dimensional axes.
- Step 104 specifically, the method may include:
- Step 1042 Perform preprocessing on the two-dimensional projection image
- Step 1044 Extracting the two-dimensional contour of the tooth by using an automatic or manual interaction method on the pre-processed two-dimensional projection image.
- An automatic or manual interaction method on the pre-processed two-dimensional projection image.
- Image preprocessing is first performed on the two-dimensional projection image.
- adaptive pre-processing algorithm Otsu threshold algorithm, high and low hat filtering, butterfly filtering, bilateral filtering, adaptive scaling, etc. can be used to perform image preprocessing to improve tooth contour in 2D projection image. The clarity of the border.
- nth (n ⁇ 2) The projected image contains only one tooth, which is itself a separate tooth area, so there is no need to isolate the adjacent teeth described below.
- the gray value between the upper and lower jaws and the boundary between adjacent teeth is lower, so it is possible to use gray between the upper and lower jaws and between adjacent teeth.
- Straight lines or curves formed by lower pixels divide the upper and lower jaws and adjacent teeth to isolate the isolated teeth.
- the two-dimensional projection image will be divided into small pieces by these separation lines, and there is only one tooth in each small area, that is, the isolation of the independent teeth is realized on the two-dimensional projection image.
- step 106 may specifically include:
- the first two-dimensional projection image is obtained by projecting the three-dimensional dental CT image, which may specifically include:
- Step 1022 extracting a tooth alveolar bone region in a three-dimensional oral CT image
- Step 1024 extracting an arch curve according to the alveolar bone region of the tooth
- Step 1026 Projecting the tooth alveolar bone region with the normal direction of the arch curve as a projection direction
- the first projection image is obtained.
- the composition flow of the first projection image is as shown in FIG. 3.
- the projection area of the two-dimensional projection image 1 is defined in the dental alveolar bone region in the oral CT image.
- the process of extracting the alveolar bone region in the oral CT image is as follows: In the oral CT image, since the gray scale difference between the bone tissue (tooth, alveolar bone, other jaw tissue) and other tissues is large, a threshold can be used. Segmentation and other methods extract bone tissue from oral CT images. For the extracted bone tissue, the alveolar bone tissue in the bone tissue and other bone tissues such as the neck bone are broken by a ⁇ algorithm. In this case, the bone tissue is divided into several parts, and the largest three-dimensional connected area is the tooth alveolar bone area.
- the dental arch curve is obtained according to the extracted tooth alveolar bone region, and the normal line of the dental arch curve is used as the projection direction.
- the arch curve can be extracted
- the maximum grayscale projection of the tooth alveolar bone region is obtained by refinement, manual mapping combined with spline curve or other polynomial curve fitting.
- the first projected image is obtained by projecting the extracted alveolar bone region along the normal line of the arch curve.
- step 102 the obtaining of the nth (n ⁇ 2) projection images by the projection of the three-dimensional dental CT image may specifically include:
- Step 1028 The synthesis flow of the nth (n ⁇ 2) projection images is as shown in FIG. 4.
- the area of the alveolar bone defined by the two-dimensional axis of the first projected image on the left and right parallel axes of the contour of the tooth is the projection area.
- the projection area is projected by the normal line of the two-dimensional tooth axis passing through the first projected image, and the nth (n ⁇ 2) projection images are obtained.
- Embodiment 2 is a diagrammatic representation of Embodiment 1
- the apparatus for estimating a three-dimensional dental axis of the present application is for converting a three-dimensional dental CT image into a plurality of two-dimensional projection images, and extracting three-dimensional dental axes according to the two-dimensional projection images.
- another embodiment of the apparatus for estimating a three-dimensional dental shaft of the present application may include a projection module, a segmentation module, an extraction module, and a synthesis module.
- the projection module is configured to perform multiple projections on the three-dimensional oral CT image to obtain a plurality of two-dimensional projection images;
- the segmentation module is configured to respectively segment the two-dimensional projection image out of the tooth contour;
- the extraction module is configured to extract the two-dimensional axis according to the contour of the tooth a synthesis module for synthesizing a three-dimensional dental axis from a plurality of two-dimensional axes.
- the segmentation module is further configured to preprocess the two-dimensional projection image, and extract the two-dimensional contour of the tooth by using an automatic or manual interaction manner on the pre-processed two-dimensional projection image.
- FIG. 1 One embodiment of tooth contour segmentation in a synthetic two-dimensional projection image is shown in FIG. Image preprocessing is first performed on the 2D projection image.
- adaptive pre-processing algorithm Otsu threshold algorithm, high and low hat filtering, butterfly filtering, bilateral filtering, adaptive scaling, etc. can be used to perform image preprocessing to improve tooth contour in two-dimensional projection image. The clarity of the border.
- the nth (n ⁇ 2) projection images contain only one tooth, which is itself a separate tooth region, so there is no need to isolate the adjacent teeth described below.
- the gray value between the upper and lower jaws and the boundary between adjacent teeth is lower, so it is possible to use gray between the upper and lower jaws and between adjacent teeth.
- a straight line or curve composed of lower pixels divides the upper and lower jaws and adjacent teeth to achieve independent teeth The tooth is isolated.
- the two-dimensional projection image will be divided into small pieces by these separation lines, and there is only one tooth in each small area, that is, the isolation of the independent teeth is realized on the two-dimensional projection image.
- the extraction module of the present application is further configured to extract a two-dimensional axis on the two-dimensional projection image, the extracted two-dimensional axis including a straight line along the longitudinal direction of the tooth contour and passing through the centroid point of the tooth contour.
- the projection module is further configured to acquire the first and nth (n ⁇ 2) projection images.
- the first projection image is obtained by: extracting a tooth alveolar bone region in a three-dimensional oral CT image; extracting an arch curve according to the alveolar bone region; and performing the dental arch curve on the alveolar bone region of the tooth
- the normal direction is projected in the projection direction to obtain the first projected image.
- the composition flow of the first projected image is as shown in FIG. 3.
- the present application limits the projection area of the two-dimensional projection image 1 to the alveolar bone region in the oral CT image.
- the process of extracting the alveolar bone region in the oral CT image is as follows: In the oral CT image, since the gray scale difference between the bone tissue (tooth, alveolar bone, other jaw tissue) and other tissues is large, a threshold can be used. Segmentation and other methods extract bone tissue from oral CT images. For the extracted bone tissue, the alveolar bone tissue and other bone tissues such as the neck bone in the bone tissue are broken by a sputum algorithm. In this case, the bone tissue is divided into several parts, and the largest three-dimensional connected area is the tooth alveolar bone area.
- the dental arch curve is obtained according to the extracted tooth alveolar bone region, and the normal line of the dental arch curve is used as the projection direction.
- the arch curve can be obtained by refining, manual drawing combined with spline curve or other polynomial curve fitting on the maximum grayscale projection of the extracted alveolar bone region.
- the first projection image is obtained by projecting the extracted alveolar bone region along the normal line of the dental arch curve.
- Obtaining the three-dimensional oral CT image to obtain the nth (n ⁇ 2) projection images may specifically include: the dental teeth determined by the two-dimensional tooth axis of the first projection image on the left and right parallel axes of the tooth contours
- the trough area is the projection area. Projecting the projection area with a normal to the two-dimensional tooth axis of the first projected image as a projection direction, That is, the nth (n ⁇ 2) projection images are obtained.
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Abstract
A three-dimensional tooth axis estimation method, comprising: performing multiple projection operations on a three-dimensional CT image of an oral cavity to obtain multiple two-dimensional projection images (102); performing, on the two-dimensional projection images, segmentation to obtain tooth contours (104); extracting two-dimensional axis lines according to the tooth contours (106); and synthesizing, according to the multiple two-dimensional axis lines, a three-dimensional tooth axis (108). Also disclosed is a device corresponding to the three-dimensional tooth axis estimation method.
Description
发明名称：一种估算三维牙轴的方法和装置 技术领域 Title of Invention: A Method and Apparatus for Estimating Three-Dimensional Dental Shafts
[0001] 本申请涉及图像处理， 尤其涉及一种估算三维牙轴的方法和装置。 [0001] The present application relates to image processing, and more particularly to a method and apparatus for estimating a three-dimensional dental shaft.
[0002] 背景技术 BACKGROUND OF THE INVENTION
[0003] 在口腔正畸与牙齿种植中， 口腔医师需要借助牙轴进行治疗规划， 牙轴的不准 确和缺失可能导致方案规划的不合理和失败。 现有很多技术仅利用牙冠进行牙 轴估算， 这样估算的牙轴因不能反映牙根的方位， 结果不准确； 且仅考虑牙冠 信息不能确定仅有部分牙冠萌出或无牙冠萌出的阻生牙和埋伏牙的牙轴。 随着 计算机技术和口腔 CT扫描技术的发展， 口腔 CT图像在口腔正畸与口腔修复中受 到广泛应用。 有些技术虽然利用口腔 CT图像中完整的牙冠与牙根信息进行牙轴 估算， 但都需要首先从口腔 CT图像中分割出完整的牙齿。 由于口腔 CT图像中牙 根与牙槽骨灰度接近， 完整牙齿的分割非常困难， 这些技术容易造成牙轴估算 失败。 同吋， 同一患者的口腔 CT图像一般有几百张， 分割耗吋长， 效率低。 [0003] In orthodontics and dental implants, the dentist needs to use a dental shaft for treatment planning, and the inaccuracy and lack of the dental shaft may lead to unreasonable and unsuccessful planning. Many existing techniques only use the crown to estimate the axis of the tooth, so that the estimated axis can not reflect the orientation of the root, the result is not accurate; and only the crown information can not be determined that only part of the crown erupted or no crown eruption The teeth of the teeth and the impacted teeth. With the development of computer technology and oral CT scanning technology, oral CT images have been widely used in orthodontics and oral prosthetics. Some techniques use the complete crown and root information in the oral CT image for the estimation of the dental shaft, but all need to first segment the complete tooth from the oral CT image. Due to the close proximity of the root and alveolar bone in the oral CT image, the segmentation of the complete tooth is very difficult, and these techniques are prone to failure of the dental shaft estimation. At the same time, the same patient's oral CT image is usually several hundred, which is long and inefficient.
[0004] 发明内容 SUMMARY OF THE INVENTION
[0005] 本申请提供一种估算三维牙轴的方法和装置。 The present application provides a method and apparatus for estimating a three-dimensional dental shaft.
[0006] 根据本申请的第一方面， 本申请提供一种估算三维牙轴的方法， 其特征在于， 包括： According to a first aspect of the present application, the present application provides a method for estimating a three-dimensional dental shaft, comprising:
[0007] 将三维口腔 CT图像转换为多张二维投影图像， 根据所述二维投影图像提取三 维牙轴。 [0007] A three-dimensional dental CT image is converted into a plurality of two-dimensional projection images, and three-dimensional dental axes are extracted from the two-dimensional projection images.
[0008] 上述方法， 所述将三维口腔 CT图像转换为多张二维投影图像， 根据所述二维 投影图像提取三维牙轴， 具体包括： [0008] In the above method, the three-dimensional dental CT image is converted into a plurality of two-dimensional projection images, and the three-dimensional dental axes are extracted according to the two-dimensional projection image, which specifically includes:
[0009] 对三维口腔 CT图像进行多次投影获得多张二维投影图像； [0009] performing multiple projections on a three-dimensional oral CT image to obtain a plurality of two-dimensional projection images;
[0010] 在所述二维投影图像中分别分割出牙齿轮廓； [0010] dividing a tooth contour in the two-dimensional projection image;
[0011] 根据所述牙齿轮廓提取二维轴线； [0011] extracting a two-dimensional axis from the contour of the tooth;
[0012] 根据多个所述二维轴线合成三维牙轴。 [0012] synthesizing a three-dimensional dental shaft according to a plurality of the two-dimensional axes.
[0013] 上述方法， 所述将所述二维投影图像分割出牙齿轮廓， 具体包括：
[0014] 对所述二维投影图像进行预处理； [0013] The above method, the dividing the two-dimensional projection image into a tooth contour, specifically includes: [0014] preprocessing the two-dimensional projection image;
[0015] 采用自动或手动交互方式分割提取出牙齿二维轮廓。 [0015] The two-dimensional contour of the tooth is extracted by automatic or manual interaction.
[0016] 上述方法， 所述根据所述牙齿轮廓提取二维轴线， 具体包括： [0016] The above method, the extracting the two-dimensional axis according to the tooth contour, specifically includes:
[0017] 在二维投影图像上提取二维轴线， 提取的二维轴线包括沿所述牙齿轮廓的长轴 方向， 并通过所述牙齿轮廓的质心点的直线。 [0017] A two-dimensional axis is extracted on the two-dimensional projected image, the extracted two-dimensional axis including a straight line along the long axis direction of the tooth contour and passing through the centroid point of the tooth contour.
[0018] 上述方法， 对三维口腔 CT图像进行投影获得二维投影图像， 具体包括： [0018] The above method, the three-dimensional dental CT image is projected to obtain a two-dimensional projection image, and specifically includes:
[0019] 将牙齿牙槽骨区域从所述三维口腔 CT图像中提取出来； [0019] extracting a dental alveolar bone region from the three-dimensional oral CT image;
[0020] 从所述牙齿牙槽骨区域获取牙弓曲线； [0020] obtaining an arch curve from the alveolar bone region;
[0021] 将所述牙齿牙槽骨区域以所述牙弓曲线的法线方向为投影方向进行投影， 得到 第一张二维投影图像； [0021] projecting the tooth alveolar bone region in a projection direction of the arch curve to obtain a first two-dimensional projection image;
[0022] 以所述第一张二维投影图像的二维牙齿轴线在其牙齿轮廓的左右平行轴线所确 定的牙齿牙槽骨区域为投影区域， 以过所述第一张二维投影图像的二维牙齿轴 线的平面的法线为投影方向， 对所述投影区域进行投影， 得到多张二维投影图 像。 [0022] the tooth alveolar bone region determined by the two-dimensional tooth axis of the first two-dimensional projection image on the left and right parallel axes of the tooth contour is a projection area to pass the two-dimensional tooth axis of the first two-dimensional projection image The normal of the plane is the projection direction, and the projection area is projected to obtain a plurality of two-dimensional projection images.
[0023] 根据本申请的第二方面， 本申请提供一种估算三维牙轴的装置， 所述装置， 用 于将三维口腔 CT图像转换为多张二维投影图像， 并根据所述二维投影图像提取 三维牙轴。 [0023] According to a second aspect of the present application, the present application provides an apparatus for estimating a three-dimensional dental axis, the apparatus for converting a three-dimensional oral CT image into a plurality of two-dimensional projection images, and extracting according to the two-dimensional projection image Three-dimensional dental shaft.
[0024] 上述装置中， 所述装置包括： [0024] In the above device, the device includes:
[0025] 投影模块， 用于对三维口腔 CT图像进行多次投影获得多张二维投影图像； [0026] 分割模块， 用于在所述二维投影图像中分别分割出牙齿轮廓； [0025] a projection module, configured to perform multiple projections on the three-dimensional dental CT image to obtain a plurality of two-dimensional projection images; [0026] a segmentation module, configured to respectively segment the tooth contours in the two-dimensional projection image;
[0027] 提取模块， 用于根据所述牙齿轮廓提取二维轴线； [0027] an extraction module, configured to extract a two-dimensional axis according to the tooth contour;
[0028] 合成模块， 用于根据多个所述二维轴线合成三维牙轴。 [0028] a synthesis module, configured to synthesize a three-dimensional dental shaft according to the plurality of the two-dimensional axes.
[0029] 上述装置中， 所述分割模块， 还用于对所述二维投影图像进行预处理， 对预处 理后的二维投影图像， 采用自动或手动交互方式分割提取出牙齿二维轮廓。 [0029] In the above device, the segmentation module is further configured to preprocess the two-dimensional projection image, and extract the extracted two-dimensional contour of the tooth by using an automatic or manual interaction method on the pre-processed two-dimensional projection image.
[0030] 上述装置中， 所述提取模块， 还用于在二维投影图像上提取二维轴线， 提取的 二维轴线包括沿所述牙齿轮廓的长轴方向， 并通过所述牙齿轮廓的质心点的直 线。 [0030] In the above apparatus, the extraction module is further configured to extract a two-dimensional axis on the two-dimensional projection image, the extracted two-dimensional axis includes a longitudinal axis along the contour of the tooth, and passes through a centroid of the contour of the tooth The line of points.
[0031] 上述装置中， 所述投影模块， 还用于将牙齿牙槽骨区域从所述三维口腔 CT图
像中提取出来， 从所述牙齿牙槽骨区域获取牙弓曲线， 将所述牙齿牙槽骨区域 以所述牙弓曲线的法线方向为投影方向进行投影， 得到第一张二维投影图像； 以所述第一张二维投影图像的二维牙齿轴线在其牙齿轮廓的左右平行轴线所确 定的牙齿牙槽骨区域为投影区域， 以过所述第一张二维投影图像的二维牙齿轴 线的平面的法线为投影方向， 对所述投影区域进行投影， 得到多张二维投影图 像。 [0031] In the above device, the projection module is further configured to remove a tooth alveolar bone region from the three-dimensional oral CT image Extracting from the image, obtaining a dental arch curve from the tooth alveolar bone region, projecting the dental alveolar bone region in a projection direction of the dental arch curve to obtain a first two-dimensional projection image; a method in which a two-dimensional tooth axis of the first two-dimensional projection image defines a tooth alveolar bone region defined by left and right parallel axes of the tooth contour as a projection region, and a plane of the two-dimensional tooth axis of the first two-dimensional projection image The line is a projection direction, and the projection area is projected to obtain a plurality of two-dimensional projection images.
[0032] 由于采用了以上技术方案， 使本申请具备的有益效果在于： [0032] Due to the adoption of the above technical solutions, the beneficial effects of the present application are:
[0033] 在本申请的具体实施方式中， 由于将三维口腔 CT图像转换为多张二维投影图 像， 根据二维投影图像提取三维牙轴， 本申请综合考虑了牙冠和牙根信息， 只 需要对每颗牙齿在多张二维投影图像上进行轮廓分割， 无需在患者口腔 CT图像 中进行完整牙齿的分割， 牙轴估算效率更高。 同吋， 由于二维投影图像上牙根 与牙槽骨的差异比原始的口腔 CT图像中两者的差异更明显一些， 牙齿轮廓分割 更加容易， 且估算的三维牙轴也更准确。 [0033] In the specific embodiment of the present application, since the three-dimensional oral CT image is converted into multiple two-dimensional projection images, and the three-dimensional dental axis is extracted according to the two-dimensional projection image, the present application comprehensively considers the crown and root information, and only needs to The contouring of the teeth on multiple two-dimensional projection images eliminates the need for complete tooth segmentation in the patient's oral CT image, and the efficiency of the dental axis estimation is higher. At the same time, since the difference between the root and alveolar bone in the two-dimensional projection image is more obvious than the difference between the original oral CT images, the contour segmentation of the teeth is easier, and the estimated three-dimensional dental axes are more accurate.
[0034] 附图说明 BRIEF DESCRIPTION OF THE DRAWINGS
[0035] 图 1为本申请的方法在一种实施方式中的流程图； 1 is a flow chart of a method of the present application in an embodiment;
[0036] 图 2为本申请的方法在一种实施方式中获得二维牙齿轮廓的流程图； [0036] FIG. 2 is a flow chart of obtaining a two-dimensional tooth contour in one embodiment of the method of the present application;
[0037] 图 3为本申请的方法在一种实施方式中获得二维投影图像的流程图； [0037] FIG. 3 is a flow chart of obtaining a two-dimensional projected image in one embodiment of the method of the present application;
[0038] 图 4为本申请的方法在另一种实施方式中获得二维投影图像的流程图； [0038] FIG. 4 is a flow chart of obtaining a two-dimensional projected image in another embodiment of the method of the present application;
[0039] 图 5为本申请的装置在一种实施方式中的功能模块示意图。 [0039] FIG. 5 is a schematic diagram of functional modules of an apparatus of the present application in an embodiment.
[0040] 具体实施方式 DETAILED DESCRIPTION
[0041] 下面通过具体实施方式结合附图对本申请作进一步详细说明。 [0041] The present application will be further described in detail below with reference to the accompanying drawings.
[0042] 本申请的估算三维牙轴的方法， 首先对口腔 CT图像进行 n(n≥2)次投影， 然后在 n张二维投影图像里分别分割出牙齿轮廓、 提取牙齿轮廓的二维轴线， 最后根据 n根二维轴线合成一根三维轴线， 即所求牙齿的三维牙轴。 随着 n的值增大， 即 投影次数增多， 估算的牙轴精确度增高。 以下以 n=2为例进行说明。 本申请的估 算三维牙轴的方法， 包括三个阶段。 第一阶段即第 1根二维轴线的提取。 对输入 的原始口腔 CT图像进行第 1次投影， 然后在投影图像中分割牙齿二维轮廓、 提取 牙齿二维轴线。 分割结果记为牙齿二维轮廓 1， 提取结果记为牙齿二维轴线 1。
第二阶段即第 2根二维轴线的提取。 对输入的原始口腔 CT图像进行第 2次投影 （ 第 2次投影方向与第 1次投影方向不同） ， 然后在投影图像上分割牙齿二维轮廓 、 提取牙齿二维轴线。 分割结果记为牙齿二维轮廓 2， 提取结果记为牙齿二维轴 线 2。 第三阶段即三维牙轴的合成。 根据提取得到的两根二维轴线即牙齿二维轴 线 1和牙齿二维轴线 2来合成三维轴线， 即所估计的牙齿的三维牙轴。 本技术不 需要在几百张的口腔 CT图像上进行完整牙齿的分割， 只需要对每颗牙齿在 2张投 影图像中进行轮廓分割； 且两张投影图上牙根与牙槽骨的差异比原始的口腔 CT 图像中两者的差异更明显， 牙齿轮廓分割更加容易， 所估算的三维牙轴更为准 确。 [0042] The method for estimating a three-dimensional dental axis of the present application first performs n(n≥2) projections on an oral CT image, and then separately divides a tooth contour, extracts a two-dimensional axis of the tooth contour in n two-dimensional projection images, and finally A three-dimensional axis is synthesized from the two two-dimensional axes, that is, the three-dimensional dental axes of the teeth sought. As the value of n increases, that is, the number of projections increases, the estimated accuracy of the dental axis increases. The following description will be made by taking n=2 as an example. The method of estimating a three-dimensional dental shaft of the present application comprises three stages. The first stage is the extraction of the first two-dimensional axis. The first projection of the input original oral CT image is performed, and then the two-dimensional contour of the tooth is segmented in the projected image, and the two-dimensional axis of the tooth is extracted. The segmentation result is recorded as the tooth two-dimensional contour 1, and the extraction result is recorded as the tooth two-dimensional axis 1. The second stage is the extraction of the second two-dimensional axis. The input original oral CT image is subjected to the second projection (the second projection direction is different from the first projection direction), and then the two-dimensional contour of the tooth is segmented on the projection image, and the two-dimensional axis of the tooth is extracted. The segmentation result is recorded as the tooth 2D contour 2, and the extraction result is recorded as the tooth 2D axis 2. The third stage is the synthesis of three-dimensional dental axes. The three-dimensional axis, that is, the estimated three-dimensional dental axis of the tooth, is synthesized based on the two two-dimensional axes extracted, that is, the two-dimensional axis 1 of the tooth and the two-dimensional axis 2 of the tooth. The technique does not require the complete segmentation of the teeth on hundreds of oral CT images, only the contour segmentation of each tooth in two projection images; and the difference between the root and the alveolar bone in the two projections is smaller than the original The difference between the two in the oral CT image is more pronounced, the contouring of the teeth is easier, and the estimated three-dimensional dental axes are more accurate.
[0043] 实施例一： [0043] Embodiment 1:
[0044] 本申请的估算三维牙轴的方法， 其一种实施方式， 包括： [0044] The method for estimating a three-dimensional dental shaft of the present application, an embodiment thereof, includes:
[0045] 将三维口腔 CT图像转换为多张二维投影图像， 根据二维投影图像提取三维牙 轴。 [0045] The three-dimensional dental CT image is converted into a plurality of two-dimensional projection images, and the three-dimensional dental axes are extracted from the two-dimensional projection images.
[0046] 如图 1所示， 本申请的估算三维牙轴的方法， 其另一种实施方式， 包括以下步 骤： [0046] As shown in FIG. 1, another method for estimating a three-dimensional dental shaft of the present application includes the following steps:
[0047] 步骤 102: 对三维口腔 CT图像进行多次投影获得多张二维投影图像。 [0047] Step 102: Perform multiple projections on the three-dimensional oral CT image to obtain a plurality of two-dimensional projection images.
[0048] 步骤 104: 在二维投影图像中分别分割出牙齿轮廓。 [0048] Step 104: Segment the tooth contours in the two-dimensional projection image.
[0049] 步骤 106: 根据牙齿轮廓提取二维轴线。 [0049] Step 106: Extract a two-dimensional axis from the contour of the tooth.
[0050] 步骤 108: 根据多个二维轴线合成三维牙轴。 [0050] Step 108: synthesize a three-dimensional dental shaft according to a plurality of two-dimensional axes.
[0051] 其中步骤 104， 具体可以包括： [0051] Step 104, specifically, the method may include:
[0052] 步骤 1042: 对二维投影图像进行预处理； [0052] Step 1042: Perform preprocessing on the two-dimensional projection image;
[0053] 步骤 1044: 对预处理后的二维投影图像， 采用自动或手动交互方式分割提取出 牙齿二维轮廓。 在合成的二维投影图像中牙齿轮廓分割的一种实施方式如图 2所 示。 首先对二维投影图像进行图像预处理。 这里可以采用自适应阈值算法、 Otsu 阈值算法、 高低帽滤波、 butterfly滤波、 双边滤波、 自适应比例变换等方法中的 一种或几种结合来进行图像预处理， 提高二维投影图像中牙齿轮廓边界的清晰 度。 [0053] Step 1044: Extracting the two-dimensional contour of the tooth by using an automatic or manual interaction method on the pre-processed two-dimensional projection image. One embodiment of tooth contour segmentation in a synthetic two-dimensional projection image is shown in FIG. Image preprocessing is first performed on the two-dimensional projection image. Here, adaptive pre-processing algorithm, Otsu threshold algorithm, high and low hat filtering, butterfly filtering, bilateral filtering, adaptive scaling, etc. can be used to perform image preprocessing to improve tooth contour in 2D projection image. The clarity of the border.
[0054] 由于第 1张投影图像中包含了所有的牙齿， 需要实现相邻牙齿的孤立。 而第 n(n
≥2)张投影图像上仅包含一颗牙齿， 其本身即为独立牙齿区域， 所以不需要进行 下述相邻牙齿的孤立。 在预处理之后的第 1张投影图像上， 上下牙颌之间的缝隙 处及相邻牙齿之间的边界处灰度值较低， 因此可以用上下牙颌之间及相邻牙齿 之间灰度较低像素构成的直线或曲线将上下牙颌及相邻牙齿分幵， 实现独立牙 齿的孤立。 此吋， 二维投影图像将被这些分离线分割成小块， 每一小块区域中 只有一颗牙齿， 即在二维投影图像上实现了独立牙齿的孤立。 [0054] Since all the teeth are included in the first projected image, it is necessary to achieve the isolation of the adjacent teeth. And nth (n ≥ 2) The projected image contains only one tooth, which is itself a separate tooth area, so there is no need to isolate the adjacent teeth described below. On the first projected image after pre-processing, the gray value between the upper and lower jaws and the boundary between adjacent teeth is lower, so it is possible to use gray between the upper and lower jaws and between adjacent teeth. Straight lines or curves formed by lower pixels divide the upper and lower jaws and adjacent teeth to isolate the isolated teeth. In this case, the two-dimensional projection image will be divided into small pieces by these separation lines, and there is only one tooth in each small area, that is, the isolation of the independent teeth is realized on the two-dimensional projection image.
[0055] 在独立牙齿区域中， 牙根周围常常会粘连一些牙槽骨组织， 因此可以采用阈值 分割、 形态学运算、 形状分析等算法去除牙根周围的部分牙槽骨组织， 并以此 吋独立牙齿区域中面积最大的联通区域的边界作为初始牙齿轮廓。 然后， 可采 用 Moore边界追踪算法、 gmph-cut算法、 活动轮廓、 水平集等算法优化初始牙齿 轮廓， 即得二维牙齿轮廓。 [0055] In the independent tooth region, some alveolar bone tissues are often adhered around the root of the tooth, so a part of the alveolar bone tissue around the root can be removed by an algorithm such as threshold segmentation, morphological operation, shape analysis, etc. The boundary of the largest area of the area in the area serves as the initial tooth contour. Then, Moore boundary tracking algorithm, gmph-cut algorithm, active contour, level set and other algorithms can be used to optimize the initial tooth contour, that is, the two-dimensional tooth contour.
[0056] 其中步骤 106， 具体可以包括： [0056] wherein the step 106 may specifically include:
[0057] 在二维投影图像上提取二维轴线， 提取的二维轴线包括沿牙齿轮廓的长轴方向 [0057] extracting a two-dimensional axis on the two-dimensional projection image, the extracted two-dimensional axis including the long axis direction along the contour of the tooth
， 并通过牙齿轮廓的质心点的直线。 And a straight line through the centroid point of the contour of the tooth.
[0058] 步骤 102中， 对三维口腔 CT图像进行投影获得第 1张二维投影图像， 具体可以 包括： [0058] In step 102, the first two-dimensional projection image is obtained by projecting the three-dimensional dental CT image, which may specifically include:
[0059] 步骤 1022: 在三维口腔 CT图像中提取牙齿牙槽骨区域； [0059] Step 1022: extracting a tooth alveolar bone region in a three-dimensional oral CT image;
[0060] 步骤 1024: 根据牙齿牙槽骨区域提取牙弓曲线； [0060] Step 1024: extracting an arch curve according to the alveolar bone region of the tooth;
[0061] 步骤 1026: 对牙齿牙槽骨区域以所述牙弓曲线的法线方向为投影方向进行投影 [0061] Step 1026: Projecting the tooth alveolar bone region with the normal direction of the arch curve as a projection direction
， 得第 1张投影图像。 , the first projection image is obtained.
[0062] 第 1张投影图像的合成流程如图 3所示。 本申请中将二维投影图像 1的投影区域 限定在口腔 CT图像中牙齿牙槽骨区域。 在口腔 CT图像中提取牙齿牙槽骨区域的 过程如下： 在口腔 CT图像中， 由于骨骼组织 （牙齿、 牙槽骨、 其它颌骨组织） 与其他组织之间灰度差异较大， 可采用阈值分割等方法从口腔 CT图像中提取骨 骼组织。 对提取出的骨骼组织， 采用幵运算算法等方法将骨骼组织中的牙齿牙 槽骨组织与颈骨等其他骨骼组织断幵。 此吋， 骨骼组织被分为几部分， 其中体 积最大的三维连通区域即为牙齿牙槽骨区域。 然后， 根据提取得到的牙齿牙槽 骨区域获取牙弓曲线， 以牙弓曲线的法线为投影方向。 牙弓曲线可以在提取得
到的牙齿牙槽骨区域的最大灰度投影图上通过细化、 手动描点法结合样条曲线 或其他多项式曲线拟合等方法得到。 对提取得到的牙齿牙槽骨区域沿着牙弓曲 线的法线进行投影即得第 1张投影图像。 [0062] The composition flow of the first projection image is as shown in FIG. 3. In the present application, the projection area of the two-dimensional projection image 1 is defined in the dental alveolar bone region in the oral CT image. The process of extracting the alveolar bone region in the oral CT image is as follows: In the oral CT image, since the gray scale difference between the bone tissue (tooth, alveolar bone, other jaw tissue) and other tissues is large, a threshold can be used. Segmentation and other methods extract bone tissue from oral CT images. For the extracted bone tissue, the alveolar bone tissue in the bone tissue and other bone tissues such as the neck bone are broken by a 幵 algorithm. In this case, the bone tissue is divided into several parts, and the largest three-dimensional connected area is the tooth alveolar bone area. Then, the dental arch curve is obtained according to the extracted tooth alveolar bone region, and the normal line of the dental arch curve is used as the projection direction. The arch curve can be extracted The maximum grayscale projection of the tooth alveolar bone region is obtained by refinement, manual mapping combined with spline curve or other polynomial curve fitting. The first projected image is obtained by projecting the extracted alveolar bone region along the normal line of the arch curve.
[0063] 步骤 102中， 对三维口腔 CT图像进行投影获得第 n(n≥2)张投影图像的获取具体 可以包括： [0063] In step 102, the obtaining of the nth (n≥2) projection images by the projection of the three-dimensional dental CT image may specifically include:
[0064] 步骤 1028: 第 n(n≥2)张投影图像的合成流程如图 4所示。 以所述第 1张投影图像 的二维牙齿轴线在其牙齿轮廓的左右平行轴线所确定的牙齿牙槽骨区域为投影 区域。 以过所述第 1张投影图像的二维牙齿轴线的法线为投影方向， 对所述投影 区域进行投影， 即得第 n(n≥2)张投影图像。 [0064] Step 1028: The synthesis flow of the nth (n≥2) projection images is as shown in FIG. 4. The area of the alveolar bone defined by the two-dimensional axis of the first projected image on the left and right parallel axes of the contour of the tooth is the projection area. The projection area is projected by the normal line of the two-dimensional tooth axis passing through the first projected image, and the nth (n ≥ 2) projection images are obtained.
[0065] 实施例二： [0065] Embodiment 2:
[0066] 本申请的估算三维牙轴的装置， 用于将三维口腔 CT图像转换为多张二维投影 图像， 并根据二维投影图像提取三维牙轴。 [0066] The apparatus for estimating a three-dimensional dental axis of the present application is for converting a three-dimensional dental CT image into a plurality of two-dimensional projection images, and extracting three-dimensional dental axes according to the two-dimensional projection images.
[0067] 如图 5所示， 本申请的估算三维牙轴的装置， 其另一种实施方式， 可以包括投 影模块、 分割模块、 提取模块和合成模块。 其中， 投影模块， 用于对三维口腔 C T图像进行多次投影获得多张二维投影图像； 分割模块， 用于分别将二维投影图 像分割出牙齿轮廓； 提取模块， 用于根据牙齿轮廓提取二维轴线； 合成模块， 用于根据多个二维轴线合成三维牙轴。 [0067] As shown in FIG. 5, another embodiment of the apparatus for estimating a three-dimensional dental shaft of the present application may include a projection module, a segmentation module, an extraction module, and a synthesis module. The projection module is configured to perform multiple projections on the three-dimensional oral CT image to obtain a plurality of two-dimensional projection images; the segmentation module is configured to respectively segment the two-dimensional projection image out of the tooth contour; and the extraction module is configured to extract the two-dimensional axis according to the contour of the tooth a synthesis module for synthesizing a three-dimensional dental axis from a plurality of two-dimensional axes.
[0068] 在一种实施方式中， 分割模块还用于对二维投影图像进行预处理， 对预处理后 的二维投影图像， 采用自动或手动交互方式分割提取出牙齿二维轮廓。 [0068] In an embodiment, the segmentation module is further configured to preprocess the two-dimensional projection image, and extract the two-dimensional contour of the tooth by using an automatic or manual interaction manner on the pre-processed two-dimensional projection image.
[0069] 在合成的二维投影图像中牙齿轮廓分割的一种实施方式如图 2所示。 首先对二 维投影图像进行图像预处理。 这里可以采用自适应阈值算法、 Otsu阈值算法、 高 低帽滤波、 butterfly滤波、 双边滤波、 自适应比例变换等方法中的一种或几种结 合来进行图像预处理， 提高二维投影图像中牙齿轮廓边界的清晰度。 [0069] One embodiment of tooth contour segmentation in a synthetic two-dimensional projection image is shown in FIG. Image preprocessing is first performed on the 2D projection image. Here, adaptive pre-processing algorithm, Otsu threshold algorithm, high and low hat filtering, butterfly filtering, bilateral filtering, adaptive scaling, etc. can be used to perform image preprocessing to improve tooth contour in two-dimensional projection image. The clarity of the border.
[0070] 由于第 1张投影图像中包含了所有的牙齿， 需要实现相邻牙齿的孤立。 而第 n(n ≥2)张投影图像上仅包含一颗牙齿， 其本身即为独立牙齿区域， 所以不需要进行 下述相邻牙齿的孤立。 在预处理之后的第 1张投影图像上， 上下牙颌之间的缝隙 处及相邻牙齿之间的边界处灰度值较低， 因此可以用上下牙颌之间及相邻牙齿 之间灰度较低像素构成的直线或曲线将上下牙颌及相邻牙齿分幵， 实现独立牙
齿的孤立。 此吋， 二维投影图像将被这些分离线分割成小块， 每一小块区域中 只有一颗牙齿， 即在二维投影图像上实现了独立牙齿的孤立。 [0070] Since all the teeth are included in the first projected image, it is necessary to achieve the isolation of the adjacent teeth. On the other hand, the nth (n ≥ 2) projection images contain only one tooth, which is itself a separate tooth region, so there is no need to isolate the adjacent teeth described below. On the first projected image after pre-processing, the gray value between the upper and lower jaws and the boundary between adjacent teeth is lower, so it is possible to use gray between the upper and lower jaws and between adjacent teeth. A straight line or curve composed of lower pixels divides the upper and lower jaws and adjacent teeth to achieve independent teeth The tooth is isolated. In this case, the two-dimensional projection image will be divided into small pieces by these separation lines, and there is only one tooth in each small area, that is, the isolation of the independent teeth is realized on the two-dimensional projection image.
[0071] 在独立牙齿区域中， 牙根周围常常会粘连一些牙槽骨组织， 因此可以采用阈值 分割、 形态学运算、 形状分析等算法去除牙根周围的部分牙槽骨组织， 并以此 吋独立牙齿区域中面积最大的联通区域的边界作为初始牙齿轮廓。 然后， 可采 用 Moore边界追踪算法、 gmph-cut算法、 活动轮廓、 水平集等算法优化初始牙齿 轮廓， 即得二维牙齿轮廓。 [0071] In the independent tooth region, some alveolar bone tissues are often adhered around the root of the tooth. Therefore, threshold segmentation, morphological operations, shape analysis, and the like can be used to remove part of the alveolar bone tissue around the root of the tooth, and thereby separate the teeth. The boundary of the largest area of the area in the area serves as the initial tooth contour. Then, Moore boundary tracking algorithm, gmph-cut algorithm, active contour, level set and other algorithms can be used to optimize the initial tooth contour, that is, the two-dimensional tooth contour.
[0072] 本申请的提取模块， 还用于在二维投影图像上提取二维轴线， 提取的二维轴线 包括沿所述牙齿轮廓的长轴方向， 并通过牙齿轮廓的质心点的直线。 [0072] The extraction module of the present application is further configured to extract a two-dimensional axis on the two-dimensional projection image, the extracted two-dimensional axis including a straight line along the longitudinal direction of the tooth contour and passing through the centroid point of the tooth contour.
[0073] 在一种实施方式中， 投影模块还用于获取第 1张和第 n(n≥2)张投影图像。 [0073] In an embodiment, the projection module is further configured to acquire the first and nth (n≥2) projection images.
[0074] 第 1张投影图像的获取方式为： 在三维口腔 CT图像中提取牙齿牙槽骨区域； 根 据牙齿牙槽骨区域提取牙弓曲线； 对牙齿牙槽骨区域以所述牙弓曲线的法线方 向为投影方向进行投影， 得第 1张投影图像。 [0074] The first projection image is obtained by: extracting a tooth alveolar bone region in a three-dimensional oral CT image; extracting an arch curve according to the alveolar bone region; and performing the dental arch curve on the alveolar bone region of the tooth The normal direction is projected in the projection direction to obtain the first projected image.
[0075] 第 1张投影图像的合成流程如图 3所示。 本申请将二维投影图像 1的投影区域限 定在口腔 CT图像中牙齿牙槽骨区域。 在口腔 CT图像中提取牙齿牙槽骨区域的过 程如下： 在口腔 CT图像中， 由于骨骼组织 （牙齿、 牙槽骨、 其它颌骨组织） 与 其他组织之间灰度差异较大， 可采用阈值分割等方法从口腔 CT图像中提取骨骼 组织。 对提取出的骨骼组织， 采用幵运算算法等方法将骨骼组织中的牙齿牙槽 骨组织与颈骨等其他骨骼组织断幵。 此吋， 骨骼组织被分为几部分， 其中体积 最大的三维连通区域即为牙齿牙槽骨区域。 然后， 根据提取得到的牙齿牙槽骨 区域获取牙弓曲线， 以牙弓曲线的法线为投影方向。 牙弓曲线可以在提取得到 的牙齿牙槽骨区域的最大灰度投影图上通过细化、 手动描点法结合样条曲线或 其他多项式曲线拟合等方法得到。 对提取得到的牙齿牙槽骨区域沿着牙弓曲线 的法线进行投影即得第 1张投影图像。 [0075] The composition flow of the first projected image is as shown in FIG. 3. The present application limits the projection area of the two-dimensional projection image 1 to the alveolar bone region in the oral CT image. The process of extracting the alveolar bone region in the oral CT image is as follows: In the oral CT image, since the gray scale difference between the bone tissue (tooth, alveolar bone, other jaw tissue) and other tissues is large, a threshold can be used. Segmentation and other methods extract bone tissue from oral CT images. For the extracted bone tissue, the alveolar bone tissue and other bone tissues such as the neck bone in the bone tissue are broken by a sputum algorithm. In this case, the bone tissue is divided into several parts, and the largest three-dimensional connected area is the tooth alveolar bone area. Then, the dental arch curve is obtained according to the extracted tooth alveolar bone region, and the normal line of the dental arch curve is used as the projection direction. The arch curve can be obtained by refining, manual drawing combined with spline curve or other polynomial curve fitting on the maximum grayscale projection of the extracted alveolar bone region. The first projection image is obtained by projecting the extracted alveolar bone region along the normal line of the dental arch curve.
[0076] 第 n(n≥2)张投影图像的合成流程如图 4所示。 对三维口腔 CT图像进行投影获得 第 n(n≥2)张投影图像的获取具体可以包括： 以所述第 1张投影图像的二维牙齿轴 线在其牙齿轮廓的左右平行轴线所确定的牙齿牙槽骨区域为投影区域。 以过所 述第 1张投影图像的二维牙齿轴线的法线为投影方向对所述投影区域进行投影，
即得第 n(n≥2)张投影图像。 [0076] The synthesis flow of the nth (n≥2) projection images is as shown in FIG. 4. Obtaining the three-dimensional oral CT image to obtain the nth (n ≥ 2) projection images may specifically include: the dental teeth determined by the two-dimensional tooth axis of the first projection image on the left and right parallel axes of the tooth contours The trough area is the projection area. Projecting the projection area with a normal to the two-dimensional tooth axis of the first projected image as a projection direction, That is, the nth (n ≥ 2) projection images are obtained.
以上内容是结合具体的实施方式对本申请所作的进一步详细说明， 不能认定本 申请的具体实施只局限于这些说明。 对于本申请所属技术领域的普通技术人员 来说， 在不脱离本申请构思的前提下， 还可以做出若干简单推演或替换。 The above is a further detailed description of the present application in conjunction with the specific embodiments, and the specific implementation of the application is not limited to the description. For the ordinary person skilled in the art to which the present invention pertains, several simple deductions or substitutions may be made without departing from the spirit of the present application.
技术问题 technical problem
问题的解决方案 Problem solution
发明的有益效果
Advantageous effects of the invention
Claims
[权利要求 1] 一种估算三维牙轴的方法， 其特征在于， 包括： [Claim 1] A method for estimating a three-dimensional dental shaft, comprising:
将三维口腔 CT图像转换为多张二维投影图像， 根据所述二维投影图 像提取三维牙轴。 The three-dimensional dental CT image is converted into a plurality of two-dimensional projection images, and the three-dimensional dental axes are extracted based on the two-dimensional projection images.
[权利要求 2] 如权利要求 1所述的估算三维牙轴的方法， 其特征在于， 所述将三维 口腔 CT图像转换为多张二维投影图像， 根据所述二维投影图像提取 三维牙轴， 具体包括： [Claim 2] The method for estimating a three-dimensional dental axis according to claim 1, wherein the three-dimensional dental CT image is converted into a plurality of two-dimensional projection images, and three-dimensional dental axes are extracted according to the two-dimensional projection image, specifically Includes:
对三维口腔 CT图像进行多次投影获得多张二维投影图像； 在所述二维投影图像中分别分割出牙齿轮廓； Performing multiple projections on the three-dimensional dental CT image to obtain a plurality of two-dimensional projection images; respectively, segmenting the tooth contours in the two-dimensional projection images;
根据所述牙齿轮廓提取二维轴线； Extracting a two-dimensional axis from the contour of the tooth;
根据多个所述二维轴线合成三维牙轴。 A three-dimensional dental shaft is synthesized from a plurality of said two-dimensional axes.
[权利要求 3] 如权利要求 2所述的估算三维牙轴的方法， 其特征在于， 所述根据所 述二维投影图像分割出牙齿轮廓， 具体包括： [Claim 3] The method for estimating a three-dimensional dental axis according to claim 2, wherein the segmenting the tooth contour according to the two-dimensional projection image comprises:
对所述二维投影图像进行预处理； Preprocessing the two-dimensional projection image;
对预处理后的二维投影图像， 采用自动或手动交互方式分割提取出牙 齿二维轮廓。 For the pre-processed two-dimensional projection image, the two-dimensional contour of the tooth is extracted by automatic or manual interaction.
[权利要求 4] 如权利要求 2所述的估算三维牙轴的方法， 其特征在于， 所述根据所 述牙齿轮廓提取二维轴线， 具体包括： [Claim 4] The method for estimating a three-dimensional dental shaft according to claim 2, wherein the extracting the two-dimensional axis according to the contour of the tooth comprises:
在二维投影图像上提取二维轴线， 提取的二维轴线包括沿所述牙齿轮 廓的长轴方向， 并通过所述牙齿轮廓的质心点的直线。 A two-dimensional axis is extracted on the two-dimensional projected image, the extracted two-dimensional axis including a straight line along the long axis direction of the tooth profile and passing through the centroid point of the tooth profile.
[权利要求 5] 如权利要求 2所述的估算三维牙轴的方法， 其特征在于， 对三维口腔 [Claim 5] The method of estimating a three-dimensional dental shaft according to claim 2, wherein the three-dimensional oral cavity
CT图像进行投影获得二维投影图像， 具体包括： 将牙齿牙槽骨区域从所述三维口腔 CT图像中提取出来； Obtaining a CT image to obtain a two-dimensional projection image specifically includes: extracting a tooth alveolar bone region from the three-dimensional oral CT image;
从所述牙齿牙槽骨区域获取牙弓曲线； Obtaining an arch curve from the alveolar bone region of the tooth;
将所述牙齿牙槽骨区域以所述牙弓曲线的法线方向为投影方向进行投 影， 得到第一张二维投影图像； Projecting the tooth alveolar bone region in a projection direction of the arch curve to obtain a first two-dimensional projection image;
以所述第一张二维投影图像的二维牙齿轴线在其牙齿轮廓的左右平行 轴线所确定的牙齿牙槽骨区域为投影区域， 以过所述第一张二维投影
图像的二维牙齿轴线的平面的法线为投影方向， 对所述投影区域进行 投影， 得到多张二维投影图像。 a tooth alveolar bone region defined by a two-dimensional tooth axis of the first two-dimensional projection image on a left and right parallel axis of the tooth contour as a projection area to pass the first two-dimensional projection The normal of the plane of the two-dimensional tooth axis of the image is the projection direction, and the projection area is projected to obtain a plurality of two-dimensional projection images.
一种估算三维牙轴的装置， 其特征在于， A device for estimating a three-dimensional dental shaft, characterized in that
所述装置， 用于将三维口腔 CT图像转换为多张二维投影图像， 并根 据所述二维投影图像提取三维牙轴。 The device is configured to convert a three-dimensional dental CT image into a plurality of two-dimensional projection images, and extract three-dimensional dental axes according to the two-dimensional projection images.
如权利要求 6所述的估算三维牙轴的装置， 其特征在于， 包括： 投影模块， 用于对三维口腔 CT图像进行多次投影获得多张二维投影 图像； The device for estimating a three-dimensional dental shaft according to claim 6, comprising: a projection module, configured to perform multiple projections on the three-dimensional dental CT image to obtain a plurality of two-dimensional projection images;
分割模块， 用于在所述二维投影图像中分别分割出牙齿轮廓； 提取模块， 用于根据所述牙齿轮廓提取二维轴线； a segmentation module, configured to respectively segment a tooth contour in the two-dimensional projection image; and an extraction module, configured to extract a two-dimensional axis according to the tooth contour;
合成模块， 用于根据多个所述二维轴线合成三维牙轴。 a synthesis module for synthesizing a three-dimensional dental shaft according to a plurality of said two-dimensional axes.
如权利要求 6所述的估算三维牙轴的装置， 其特征在于， The apparatus for estimating a three-dimensional dental shaft according to claim 6, wherein
所述分割模块， 还用于对所述二维投影图像进行预处理， 对预处理后 的二维投影图像， 采用自动或手动交互方式分割提取出牙齿二维轮廓 如权利要求 6所述的估算三维牙轴的装置， 其特征在于， The segmentation module is further configured to perform pre-processing on the two-dimensional projection image, and extract the extracted two-dimensional contour of the tooth by using an automatic or manual interaction manner on the pre-processed two-dimensional projection image. The estimation according to claim 6. a device for three-dimensional dental shaft, characterized in that
所述提取模块， 还用于在二维投影图像上提取二维轴线， 提取的二维 轴线包括沿所述牙齿轮廓的长轴方向， 并通过所述牙齿轮廓的质心点 的直线。 The extraction module is further configured to extract a two-dimensional axis on the two-dimensional projected image, the extracted two-dimensional axis including a straight line along a longitudinal direction of the tooth contour and passing through a centroid point of the tooth contour.
如权利要求 6所述的估算三维牙轴的装置， 其特征在于， The apparatus for estimating a three-dimensional dental shaft according to claim 6, wherein
所述投影模块， 还用于将牙齿牙槽骨区域从所述三维口腔 CT图像中 提取出来， 从所述牙齿牙槽骨区域获取牙弓曲线， 将所述牙齿牙槽骨 区域以所述牙弓曲线的法线方向为投影方向进行投影， 得到第一张二 维投影图像； 以所述第一张二维投影图像的二维牙齿轴线在其牙齿轮 廓的左右平行轴线所确定的牙齿牙槽骨区域为投影区域， 以过所述第 一张二维投影图像的二维牙齿轴线的平面的法线为投影方向， 对所述 投影区域进行投影， 得到多张二维投影图像。
The projection module is further configured to extract a tooth alveolar bone region from the three-dimensional oral CT image, obtain an arch curve from the tooth alveolar bone region, and use the tooth alveolar bone region to the tooth The normal direction of the bow curve is projected in the projection direction to obtain a first two-dimensional projection image; the tooth alveolar bone region determined by the two-dimensional tooth axis of the first two-dimensional projection image determined by the left and right parallel axes of the tooth contour is a projection The area is a projection direction of a plane passing through a plane of the two-dimensional tooth axis of the first two-dimensional projection image, and the projection area is projected to obtain a plurality of two-dimensional projection images.
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