Craniomaxillofacial region registration method based on three-dimensional ultrasound of middle bone surface

Abstract

The embodiment of the invention provides a cranio-maxillofacial region registration method based on three-dimensional ultrasound of a middle bone surface, and the method comprises the steps: obtaining a preoperative CT image of a target cranio-maxillofacial region, and carrying out the three-dimensional reconstruction of the preoperative CT image, and obtaining a skull STL model; extracting preoperative image three-dimensional point cloud information of the bone surface in the skull STL model; setting a marker, acquiring pose information of the marker, and constructing a coordinate system according to the pose information; acquiring three-dimensional ultrasonic point cloud information of the bone surface in the target craniomaxillofacial region under the coordinate system; and performing coarse registration on the three-dimensional ultrasonic point cloud information and the preoperative image three-dimensional point cloud information for spatial alignment of the coordinate system. According to the method, precise registration of the cranio-maxillofacial region is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasound navigation, and in particular to a cranio-maxillofacial registration method based on three-dimensional ultrasound of the mid-face bone surface. Background Art

[0002] Currently, the commonly used registration technologies in oral and craniomaxillofacial surgery are mainly point-pair-based registration technology and soft tissue surface feature-based registration technology.

[0003] There are two point-pair-based registration methods: First, registration based on bone-anchored markers. Titanium screws are implanted in the patient's bone before surgery, and then a CT / MR scan is performed in parallel with surgical planning, with the titanium screws used as feature points for registration. This method has good accuracy and stability, but the bone-anchored markers are invasive, causing additional trauma to the patient, which is difficult for patients with facial deformities who aim to improve their facial appearance to accept; second, the registration method based on anatomical landmarks refers to the use of sutures and landmarks of the skeletal anatomical structure itself as registration points, but the geometric structure of the bones in the oral craniomaxillofacial region is complex, and it is often difficult to locate anatomical landmarks in the image space. For surgical spaces aimed at "minimally invasive", hidden incisions are difficult to expose enough anatomical landmarks, which fundamentally affects the registration accuracy.

[0004] Registration methods based on soft tissue surface features involve using infrared light or laser scanning within the surgical space to collect facial point clouds. These points are then registered with the facial data in image space using the Iterative Closest Point (ICP) algorithm. The more distinct the features of the collected areas and the greater the coverage, the higher the registration accuracy. This is currently the most commonly used registration technique in oral and craniofacial surgery. However, this registration method places high demands on the consistency of skin morphology between the image space and the surgical space. Oral and craniofacial surgical diseases often cause facial swelling and deformation, and patients struggle to maintain a consistent facial expression during CT / MRI scans and after surgical anesthesia, resulting in poor accuracy.

[0005] In summary, the navigation registration methods commonly used in oral craniomaxillofacial surgery at this stage have limitations such as additional trauma, feature dependence, and low accuracy. A low-invasive, high-precision navigation space registration technology is urgently needed in clinical practice. Summary of the Invention

[0006] The purpose of the embodiment of the present invention is to provide a method for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface, which achieves accurate craniomaxillofacial registration.

[0007] To achieve the above objectives, an embodiment of the present invention provides a method for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface, the method comprising: Obtaining a preoperative CT image of the target craniomaxillofacial region, and performing three-dimensional reconstruction on the preoperative CT image to obtain a skull STL model; Extracting preoperative three-dimensional point cloud information of the bone surface in the skull STL model; Setting a marker, obtaining position information of the marker, and constructing a coordinate system based on the position information; Acquiring three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface in the coordinate system; The three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image are roughly registered for spatial alignment of the coordinate system.

[0008] Optionally, obtaining three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface in the coordinate system includes: Scanning the target craniomaxillofacial bone surface with a three-dimensional ultrasound device to obtain initial three-dimensional ultrasound point cloud information; The initial three-dimensional ultrasonic point cloud information is spatially calibrated according to the time axis of the six-degree-of-freedom posture in the reference posture to obtain three-dimensional ultrasonic point cloud information.

[0009] Optionally, the marker is arranged on the head and / or ultrasound probe corresponding to the target craniomaxillofacial region; the ultrasound probe is a linear probe or a volume probe.

[0010] Optionally, the coarse registration of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image for spatial alignment of the coordinate system includes: Obtaining the root mean square of the Euclidean distance between corresponding points after registration of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image; Determining the similarity between the three-dimensional ultrasound point cloud information and the three-dimensional point cloud of the preoperative image according to the root mean square; Obtaining a target registration error between the real coordinate system position of the anatomical landmark point and the virtual coordinate system in the preoperative CT as an average distance difference, and determining the navigation accuracy of the craniomaxillofacial landmark point in the target craniomaxillofacial region according to the average distance difference; The registration result of the target craniomaxillofacial region is determined according to the similarity and navigation accuracy.

[0011] Optionally, the craniomaxillofacial landmarks include soft tissue landmarks and hard tissue landmarks; The soft tissue landmarks include the inner canthus point, the outer canthus point, the nasal root point, and the nasal tip point; The hard tissue landmarks include the mesial incisal angle of the upper central incisor, the cusp of the upper canine and the mesial buccal cusp of the upper first molar.

[0012] Optionally, the method further includes: Preprocessing the three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface; The preprocessing includes denoising and smoothing.

[0013] On the other hand, the present invention also provides a device for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface, the device comprising: An acquisition module is used to acquire a preoperative CT image of the target craniomaxillofacial region and perform three-dimensional reconstruction on the preoperative CT image to obtain an STL model of the skull; A first processing module is used to extract preoperative image three-dimensional point cloud information of the bone surface in the skull STL model; A second processing module is configured to set a marker, obtain position information of the marker, and construct a coordinate system based on the position information; A third processing module is used to obtain three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface in the coordinate system; The fourth processing module is used to perform coarse registration on the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image for spatial alignment of the coordinate system.

[0014] Optionally, obtaining three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface in the coordinate system includes: Scanning the target craniomaxillofacial bone surface with a three-dimensional ultrasound device to obtain initial three-dimensional ultrasound point cloud information; Performing spatial calibration on the initial three-dimensional ultrasonic point cloud information according to the time axis of the six-degree-of-freedom posture in the reference posture to obtain three-dimensional ultrasonic point cloud information; The marker is arranged on the head and / or ultrasound probe corresponding to the target craniomaxillofacial region; The ultrasonic probe is a linear probe or a volume probe.

[0015] Optionally, the coarse registration of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image for spatial alignment of the coordinate system includes: Obtaining the root mean square of the Euclidean distance between corresponding points after registration of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image; Determining the similarity between the three-dimensional ultrasound point cloud information and the three-dimensional point cloud of the preoperative image according to the root mean square; Obtaining a target registration error between the real coordinate system position of the anatomical landmark point and the virtual coordinate system in the preoperative CT as an average distance difference, and determining the navigation accuracy of the craniomaxillofacial landmark point in the target craniomaxillofacial region according to the average distance difference; The registration result of the target craniomaxillofacial region is determined according to the similarity and navigation accuracy.

[0016] Optionally, the craniomaxillofacial landmarks include soft tissue landmarks and hard tissue landmarks; The soft tissue landmarks include the inner canthus point, the outer canthus point, the nasal root point, and the nasal tip point; The hard tissue landmarks include the mesial incisal angle of the upper central incisor, the cusp of the upper canine and the mesial buccal cusp of the upper first molar.

[0017] The present invention provides a method for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface, comprising: obtaining a preoperative CT image of the target craniomaxillofacial region, performing three-dimensional reconstruction of the preoperative CT image to obtain a skull STL model; extracting three-dimensional point cloud information of the preoperative image of the bone surface in the skull STL model; setting a marker, obtaining position information of the marker, constructing a coordinate system based on the position information, and constructing a coordinate system based on the position information; obtaining three-dimensional ultrasound point cloud information of the mid-face bone surface of the target craniomaxillofacial region in the coordinate system; and coarsely registering the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image for spatial alignment of the coordinate system. This method overcomes the shortcomings of the registration strategy based on soft tissue information by determining the three-dimensional ultrasound point cloud information of the mid-face bone surface of the target craniomaxillofacial region based on the marker, and combining the three-dimensional ultrasound point cloud information with the three-dimensional point cloud information of the preoperative image to obtain a coarse registration result.

[0018] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present invention, but do not constitute a limitation of the embodiments of the present invention. In the accompanying drawings: Figure 1 1 is a flow chart of a method for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface according to the present invention; Figure 2 This is a schematic diagram of an STL model of a skull of the present invention; Figure 3 This is a schematic diagram of three-dimensional point cloud information of the bone surface in the middle of a preoperative imaging plane of the present invention; Figure 4 This is a schematic diagram of an ultrasound probe installation marker of the present invention; Figure 5 is a schematic diagram of the head marker of the present invention; Figure 6 This is a schematic diagram of point cloud information of the midface bone surface obtained by three-dimensional ultrasonic scanning of the present invention; Figure 7 It is a schematic diagram of a device for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface of the present invention.

[0020] Description of Reference Numerals 100- Device for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface; 200-Get module; 300-first processing module; 400-second processing module; 500-third processing module; 600-Fourth processing module. DETAILED DESCRIPTION

[0021] The following describes the specific implementation of the embodiment of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present invention and is not used to limit the embodiment of the present invention.

[0022] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application are in compliance with the relevant provisions of laws and regulations. In the embodiments of this application, certain software, components, models, and other existing solutions in the industry may be mentioned. These should be considered as exemplary. Their purpose is only to illustrate the feasibility of implementing the technical solution of this application, but it does not mean that the applicant has or will necessarily use such solutions.

[0023] Example 1 Figure 1 FIG. 1 is a flow chart of a method for craniomaxillofacial registration based on three-dimensional ultrasound of the midface bone surface according to the present invention. Figure 1 As shown, a craniomaxillofacial registration method of the present invention includes: step S101 is to obtain a preoperative CT image of the target craniomaxillofacial region, and perform three-dimensional reconstruction on the preoperative CT image to obtain a skull STL model.

[0024] Specifically, CT imaging uses precise X-ray beams and highly sensitive detectors to scan the human body layer by layer. Computers process the resulting data to generate high-resolution images of the body's interior in cross-sectional, coronal, or sagittal planes. CT images use varying shades of gray to reflect the degree of X-ray absorption by organs and tissues. They have high density resolution and can clearly display soft tissue and skeletal structures.

[0025] STL (stereolithography) models are the native file format of stereolithography CAD software created by 3D Systems. STL files describe only the surface geometry of a three-dimensional object, without any representation of color, texture, or other common CAD model attributes. The STL format specifies both ASCII and binary representations.

[0026] Step S102 is to extract the preoperative image three-dimensional point cloud information of the bone surface in the skull STL model.

[0027] According to a specific embodiment, the STL model is a 3D model that uses triangular facets to represent a spatial rigid body. The key to converting the STL model into a point cloud is how to extract or generate point data from these triangular facets for subsequent processing and analysis. Specifically, methods for extracting preoperative three-dimensional point cloud information from the bone surface in the skull STL model mainly include direct vertex extraction, uniform sampling on the facets, optimizing distribution based on random sampling, and simulating real scanning noise.

[0028] This method performs three-dimensional reconstruction on the preoperative CT and extracts point cloud information of the mid-face bone surface area for subsequent registration steps, reducing redundant point cloud information.

[0029] Step S103 sets a marker, obtains the position and posture information of the marker, and constructs a coordinate system according to the position and posture information.

[0030] According to a specific embodiment, the marker is arranged on the head and / or ultrasound probe corresponding to the target craniomaxillofacial region; the ultrasound probe is a linear probe or a volume probe.

[0031] Specifically, the posture information includes a six-degree-of-freedom posture, and the marker is a real-world posture information benchmark for patient registration and the surgical area.

[0032] Step S104 is to obtain three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface in the coordinate system.

[0033] According to a specific embodiment, the obtaining of the three-dimensional ultrasonic point cloud information of the target craniomaxillofacial middle bone surface in the coordinate system includes: scanning the target craniomaxillofacial middle bone surface by a three-dimensional ultrasonic device to obtain initial three-dimensional ultrasonic point cloud information; and spatially calibrating the initial three-dimensional ultrasonic point cloud information according to the time axis of the six-degree-of-freedom posture in the coordinate system to obtain three-dimensional ultrasonic point cloud information.

[0034] Specifically, the image sequence of the 3D ultrasound point cloud and the 6-DOF pose data sequence of the marker are time-aligned, and the 3D ultrasound point cloud is spatially calibrated based on the marker. The markers are fixed to the head and the ultrasound probe, and can be transformed into the same coordinate system through a matrix.

[0035] Three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface is collected using a three-dimensional ultrasonic device, including: acquiring a two-dimensional ultrasonic image using a linear probe or acquiring a three-dimensional ultrasonic image using a volumetric probe, and extracting three-dimensional ultrasonic point cloud information from the three-dimensional ultrasonic image. The two-dimensional ultrasonic image is reconstructed into a three-dimensional ultrasonic image using an algorithm in combination with the ultrasonic image posture information acquired from the landmark, or the three-dimensional ultrasonic image is directly reconstructed using a volumetric probe. The three-dimensional ultrasonic device can render and display the three-dimensional ultrasonic point cloud in real time, and can perform denoising, smoothing, and optimization on the acquired three-dimensional ultrasonic image using post-processing techniques.

[0036] Step S105 is to perform a rough registration of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image for spatial alignment of the coordinate system.

[0037] According to a specific embodiment, the rough alignment of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image includes: obtaining the root mean square of the Euclidean distance between corresponding points after the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image are aligned; determining the similarity between the three-dimensional ultrasound point cloud information and the three-dimensional point cloud of the preoperative image based on the root mean square; obtaining the target alignment error between the real coordinate system position of the anatomical landmark point and the virtual coordinate system in the preoperative CT as the average distance difference, and determining the navigation accuracy of the craniomaxillofacial landmark point in the target craniomaxillofacial region based on the average distance difference; and determining the alignment result of the target craniomaxillofacial region based on the similarity and navigation accuracy.

[0038] The formula for calculating the root mean square is RMS= , where N is the number of measurements. The root mean square of the Euclidean distance (Xi) between several corresponding points (closest points) of the two point cloud data is calculated in mm. The smaller the root mean square value, the more similar the two point cloud data are.

[0039] Target registration error, i.e., average distance difference d= , the unit is mm, n is the number of anatomical landmarks obtained, i To obtain the i anatomical landmarks, Represents the real coordinate system position coordinates, Represents the position coordinates of the image coordinate system in the preoperative CT scan. The smaller the average distance difference, the higher the navigation accuracy.

[0040] The craniomaxillofacial landmarks include soft tissue landmarks and hard tissue landmarks; the soft tissue landmarks include the inner canthus point, the outer canthus point, the nasal root point, and the nasal tip point; the hard tissue landmarks include the mesial incisal angle of the upper central incisor, the cusp of the upper canine, and the mesial buccal cusp of the upper first molar.

[0041] In addition, depending on the navigation accuracy, you can choose to supplement the three-dimensional ultrasonic point cloud information of other areas of the target craniomaxillofacial region for scanning and perform precise registration based on surface registration technology, or you can choose to use a navigation probe to perform precise registration based on point-to-point technology of craniomaxillofacial anatomical landmarks.

[0042] The method further comprises: pre-processing the three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface; the pre-processing comprises denoising and smoothing.

[0043] The present invention installs markers on the head and the ultrasound probe to accurately obtain the position information of the craniomaxillofacial region and the three-dimensional ultrasound point cloud, and then performs coarse alignment and fine alignment correction with the extracted CT point cloud information of the mid-face bone surface. Compared with the commonly used clinical surface alignment technology based on the laser point cloud information of the mid-face soft tissue, it has higher accuracy and is suitable for various surgeries such as craniomaxillofacial surgical trauma, tumors, orthognathic surgery, and foreign body removal.

[0044] Example 2 The present invention also proposes another specific embodiment, which specifically includes: Figure 2 As shown in the figure, the preoperative craniomaxillofacial CT images were obtained and reconstructed into a skull STL model. Figure 3 As shown, the three-dimensional point cloud information of the bone surface in the middle of the STL model is extracted for subsequent registration.

[0045] like Figure 4 and Figure 5 As shown in the figure, markers are installed on the head and ultrasound probe. Figure 6 As shown, a three-dimensional ultrasound device is used to scan and obtain point cloud information of the mid-face bone surface.

[0046] The mid-face bone surface point cloud information obtained by the three-dimensional ultrasound device is aligned with the mid-face bone surface point cloud information of the preoperative image to obtain a rough alignment result, and the root mean square is calculated to evaluate the similarity between the two.

[0047] The three-dimensional ultrasound point cloud information is denoised and smoothed, and based on the coarse registration result, a secondary registration is performed with the three-dimensional point cloud information of the bone surface in the middle of the preoperative image surface. Based on the secondary registration, point-to-point registration is performed using soft tissue and hard tissue landmarks to complete the fine registration.

[0048] This method determines the three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface based on landmarks, and combines the three-dimensional ultrasonic point cloud information with the three-dimensional point cloud information of preoperative images to obtain a coarse registration result, overcoming the shortcomings of the registration strategy based on soft tissue information and achieving precise registration of the craniomaxillofacial region.

[0049] Example 3 On the other hand, the present invention also proposes a device for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface, such as Figure 7As shown, the device 100 for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface includes: an acquisition module 200, used to acquire a preoperative CT image of the target craniomaxillofacial region, and perform three-dimensional reconstruction of the preoperative CT image to obtain a skull STL model; a first processing module 300, used to extract three-dimensional point cloud information of the preoperative image of the bone surface in the skull STL model; a second processing module 400, used to set a marker, obtain the position information of the marker, and construct a coordinate system based on the position information; a third processing module 500, used to obtain three-dimensional ultrasonic point cloud information of the mid-face bone surface of the target craniomaxillofacial region in the coordinate system; a fourth processing module 600, used to perform coarse registration of the three-dimensional ultrasonic point cloud information and the three-dimensional point cloud information of the preoperative image, for spatial alignment of the coordinate system.

[0050] The obtaining of the three-dimensional ultrasonic point cloud information of the target craniomaxillofacial middle bone surface in the coordinate system includes: scanning the target craniomaxillofacial middle bone surface by a three-dimensional ultrasonic device to obtain initial three-dimensional ultrasonic point cloud information; spatially calibrating the initial three-dimensional ultrasonic point cloud information according to the time axis of the six-degree-of-freedom posture in the reference posture to obtain three-dimensional ultrasonic point cloud information; the marker is arranged on the head and / or ultrasonic probe corresponding to the target craniomaxillofacial region; the ultrasonic probe is a linear probe or a volume probe.

[0051] The coarse registration of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image includes: obtaining the root mean square of the Euclidean distance between corresponding points after the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image are registered; determining the similarity of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud of the preoperative image based on the root mean square; obtaining the target registration error between the real coordinate system position of the anatomical landmark point and the virtual coordinate system in the preoperative CT as the average distance difference, and determining the navigation accuracy of the target craniomaxillofacial landmark point based on the average distance difference; determining the registration result of the target craniomaxillofacial region based on the similarity and navigation accuracy. The craniomaxillofacial landmark points include soft tissue landmark points and hard tissue landmark points; the soft tissue landmark points include the inner canthus point, the outer canthus point, the nasion point, and the nasal tip point; the hard tissue landmark points include the mesial incisal angle of the upper central incisor, the cusp of the upper canine, and the mesial buccal cusp of the upper first molar.

[0052] The present invention provides a method for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface, comprising: obtaining a preoperative CT image of the target craniomaxillofacial region, performing three-dimensional reconstruction of the preoperative CT image to obtain a skull STL model; extracting three-dimensional point cloud information of the preoperative image of the bone surface in the skull STL model; setting a marker, obtaining position information of the marker, constructing a coordinate system based on the position information; obtaining three-dimensional ultrasound point cloud information of the mid-face bone surface of the target craniomaxillofacial region in the coordinate system; and coarsely registering the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image for spatial alignment of the coordinate system. This method overcomes the shortcomings of the registration strategy based on soft tissue information by determining the three-dimensional ultrasound point cloud information of the mid-face bone surface of the target craniomaxillofacial region based on the marker, and combining the three-dimensional ultrasound point cloud information with the three-dimensional point cloud information of the preoperative image to obtain a coarse registration result.

[0053] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0054] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0055] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0056] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0057] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0058] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0059] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can be implemented using any method or technology for information storage. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change RAM (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media, such as modulated data signals and carrier waves.

[0060] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0061] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface, characterized in that: The method includes: Obtaining a preoperative CT image of the target craniomaxillofacial region, and performing three-dimensional reconstruction on the preoperative CT image to obtain a skull STL model; Extracting preoperative three-dimensional point cloud information of the bone surface in the skull STL model; Setting a marker, obtaining position information of the marker, and constructing a coordinate system based on the position information; Acquiring three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface in the coordinate system; The three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image are roughly registered for spatial alignment of the coordinate system.

2. The method according to claim 1, characterized in that The step of obtaining three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface in the coordinate system includes: Scanning the target craniomaxillofacial bone surface with a three-dimensional ultrasound device to obtain initial three-dimensional ultrasound point cloud information; The initial three-dimensional ultrasonic point cloud information is spatially calibrated according to the time axis of the six-degree-of-freedom posture in the coordinate system to obtain three-dimensional ultrasonic point cloud information.

3. The method according to claim 1 or 2, characterized in that The marker is arranged on the head and / or ultrasound probe corresponding to the target craniomaxillofacial region; The ultrasonic probe is a linear probe or a volume probe.

4. The method according to claim 1, wherein The coarse registration of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image includes: Obtaining the root mean square of the Euclidean distance between corresponding points after registration of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image; Determining the similarity between the three-dimensional ultrasound point cloud information and the three-dimensional point cloud of the preoperative image according to the root mean square; Obtaining a target registration error between the real coordinate system position of the anatomical landmark point and the virtual coordinate system in the preoperative CT as an average distance difference, and determining the navigation accuracy of the craniomaxillofacial landmark point in the target craniomaxillofacial region according to the average distance difference; The registration result of the target craniomaxillofacial region is determined according to the similarity and navigation accuracy.

5. The method according to claim 4, characterized in that The craniomaxillofacial landmarks include soft tissue landmarks and hard tissue landmarks; The soft tissue landmarks include the inner canthus point, the outer canthus point, the nasal root point, and the nasal tip point; The hard tissue landmarks include the mesial incisal angle of the upper central incisor, the cusp of the upper canine and the mesial buccal cusp of the upper first molar.

6. The method according to claim 1, characterized in that The method further includes: Preprocessing the three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface; The preprocessing includes denoising and smoothing.

7. A device for craniomaxillofacial registration based on three-dimensional ultrasound of the mid-face bone surface, characterized in that: The device includes: An acquisition module is used to acquire a preoperative CT image of the target craniomaxillofacial region and perform three-dimensional reconstruction on the preoperative CT image to obtain an STL model of the skull; A first processing module is used to extract preoperative image three-dimensional point cloud information of the bone surface in the skull STL model; A second processing module is configured to set a marker, obtain position information of the marker, and construct a coordinate system based on the position information; A third processing module is used to obtain three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface in the coordinate system; The fourth processing module is used to perform coarse registration on the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image for spatial alignment of the coordinate system.

8. The device according to claim 7, characterized in that The step of obtaining three-dimensional ultrasonic point cloud information of the target craniomaxillofacial bone surface in the coordinate system includes: Scanning the target craniomaxillofacial bone surface with a three-dimensional ultrasound device to obtain initial three-dimensional ultrasound point cloud information; Performing spatial calibration on the initial three-dimensional ultrasonic point cloud information according to the time axis of the six-degree-of-freedom posture in the coordinate system to obtain three-dimensional ultrasonic point cloud information; The marker is arranged on the head and / or ultrasound probe corresponding to the target craniomaxillofacial region; The ultrasonic probe is a linear probe or a volume probe.

9. The device according to claim 7, characterized in that The coarse registration of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image includes: Obtaining the root mean square of the Euclidean distance between corresponding points after registration of the three-dimensional ultrasound point cloud information and the three-dimensional point cloud information of the preoperative image; Determining the similarity between the three-dimensional ultrasound point cloud information and the three-dimensional point cloud of the preoperative image according to the root mean square; Obtaining a target registration error between the real coordinate system position of the anatomical landmark point and the virtual coordinate system in the preoperative CT as an average distance difference, and determining the navigation accuracy of the craniomaxillofacial landmark point in the target craniomaxillofacial region according to the average distance difference; The registration result of the target craniomaxillofacial region is determined according to the similarity and navigation accuracy.

10. The device according to claim 9, characterized in that The craniomaxillofacial landmarks include soft tissue landmarks and hard tissue landmarks; The soft tissue landmarks include the inner canthus point, the outer canthus point, the nasal root point, and the nasal tip point; The hard tissue landmarks include the mesial incisal angle of the upper central incisor, the cusp of the upper canine and the mesial buccal cusp of the upper first molar.

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