WO2021017819A1 - 一种基于虚拟现实的无射线牙齿x光根尖片虚拟成像方法 - Google Patents

一种基于虚拟现实的无射线牙齿x光根尖片虚拟成像方法 Download PDF

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WO2021017819A1
WO2021017819A1 PCT/CN2020/101916 CN2020101916W WO2021017819A1 WO 2021017819 A1 WO2021017819 A1 WO 2021017819A1 CN 2020101916 W CN2020101916 W CN 2020101916W WO 2021017819 A1 WO2021017819 A1 WO 2021017819A1
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virtual
ray
tooth
tracker
model
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PCT/CN2020/101916
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French (fr)
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曹汛
张艺迪
朱昊
廖倬逸
孙卫斌
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南京大学
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
    • A61B34/10—Computer-aided planning, simulation or modelling of surgical operations
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/50—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications
    • A61B6/51—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications for dentistry
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
    • A61B1/06—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor with illuminating arrangements
    • A61B1/0605—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor with illuminating arrangements for spatially modulated illumination
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/03—Computed tomography [CT]
    • A61B6/032—Transmission computed tomography [CT]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C9/00—Impression cups, i.e. impression trays; Impression methods
    • A61C9/004—Means or methods for taking digitized impressions
    • A61C9/0046—Data acquisition means or methods
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T19/00—Manipulating 3D models or images for computer graphics
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T19/00—Manipulating 3D models or images for computer graphics
    • G06T19/003—Navigation within 3D models or images
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T19/00—Manipulating 3D models or images for computer graphics
    • G06T19/20—Editing of 3D images, e.g. changing shapes or colours, aligning objects or positioning parts
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
    • G09B23/00—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes
    • G09B23/28—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for medicine
    • G09B23/283—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for medicine for dentistry or oral hygiene
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
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    • A61B2034/101—Computer-aided simulation of surgical operations
    • A61B2034/102—Modelling of surgical devices, implants or prosthesis
    • A61B2034/104—Modelling the effect of the tool, e.g. the effect of an implanted prosthesis or for predicting the effect of ablation or burring
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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    • A61B34/10—Computer-aided planning, simulation or modelling of surgical operations
    • A61B2034/101—Computer-aided simulation of surgical operations
    • A61B2034/105—Modelling of the patient, e.g. for ligaments or bones
    • A—HUMAN NECESSITIES
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    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
    • A61B34/10—Computer-aided planning, simulation or modelling of surgical operations
    • A61B2034/107—Visualisation of planned trajectories or target regions
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
    • A61B34/20—Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
    • A61B2034/2046—Tracking techniques
    • A61B2034/2055—Optical tracking systems
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
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Definitions

  • the invention belongs to the field of virtual reality, and in particular relates to a virtual imaging method of a non-ray tooth X-ray apical film based on virtual reality.
  • Virtual Reality is based on computer technology as the core, combining sensor systems with graphics, image recognition and generation systems, and network communication systems to generate a digital environment that is highly similar to a certain range of real environments in terms of sight, hearing, and touch. With the necessary equipment to produce the feeling and experience of being in the real environment.
  • virtual reality technology has begun to play a role in many fields, such as virtual simulation.
  • many skills training such as electronics and electrical engineering, fire safety, disaster management, construction, medical care, etc. face the following shortcomings: high cost; complicated steps; not easy to repeat; there may be life and health threats, and virtual reality technology can be built through construction Model to simulate the real environment, so that the above process can be safe, efficient, lossless and repeatable.
  • the medical applications of VR technology are mainly virtual surgery, telemedicine systems, virtual people, and medical education.
  • the first category is a system for diagnosis and treatment of periodontal diseases, such as the PerioSim simulator developed by the University of Illinois in the United States. This system also takes into account the simulation of soft and hard tissues. Periodontal operations are completed by tactile and force feedback. Teachers can Score students' actions under visualization.
  • the second type is the system used for oral implantation, such as the Nobel Guide system developed by Nobel Bioeare in Sweden, the Simplant system developed by Kusumoto N and others in Belgium, etc.
  • This type of system is used to train students to perceive the hand feeling of the implanter and master the implant The position and angle of the body in three dimensions. Perform detailed observations on the three-dimensional reconstruction model of the patient’s jaw bone generated based on CT scan data in omni-directional rotation and even arbitrary cross-sections to select the most suitable implant placement position, determine the type, number, specification, implant depth and direction of the implant .
  • the third category is a simulation system used in the field of oral and maxillofacial surgery, such as the Simplant system developed by Belgium Materials, which includes the three-dimensional structure of the cranio-maxillofacial bone and the soft tissue structure, and can perform partial surgical operations in a virtual environment.
  • Most of the existing surgical simulators use tactile simulation principles similar to those mentioned above, which can simulate bone cutting, osteotomy, bone displacement and postoperative prediction.
  • the fourth category is a simulation system for the diagnosis and treatment of dental and endodontic diseases, such as the Simodont digital virtual simulation dentist training system developed by Moog in the United States. Its operation also involves simulation force rendering and interaction. Both the virtual tool and the tooth are composed of a triangular network data structure. When the triangular piece at the cutting end of the tool intersects the triangular piece on the tooth surface, the amount of tissue removal is calculated according to the insertion depth of the tool to realize the deformation simulation of tooth tissue removal.
  • the above-mentioned methods have at least the following shortcomings: focus on the simulation of touch and force, the reconstructed three-dimensional structure is the surface information of the object, and does not involve the simulation of the tooth X-ray film, and cannot solve the problem of rendering in the traditional oral apical film assessment.
  • the present invention provides a virtual imaging method for a non-ray tooth X-ray apex film based on virtual reality.
  • a method for virtual imaging of non-ray tooth X-ray apical film based on virtual reality including the following steps:
  • the positioning system includes a base station and a tracker.
  • the dental film machine is placed within the visible range of the positioning system.
  • the tracker is fixed on the tube of the dental film machine.
  • the tracker can be used without a headset. Realize the tracking function; obtain the posture matrix and position data of the tracker;
  • S2 Scan multiple teeth to reconstruct the 3D digital model of the dentition; segment the 3D digital model to obtain the tooth shell model and the marrow cavity model respectively, and then make these two models into prefabricated bodies, and according to the actual tooth structure The feature sets corresponding translucent materials for the two models respectively;
  • S3 Set up a virtual imaging environment for tooth apical radiographs, add multiple planes and cylinders around the teeth to simulate the background of the tooth X-ray film, and measure the bounding box size of the 3D digital model of the dentition and the real-world dentition The size of the model bounding box, calculate the ratio of the two; adjust the size of the tooth shell model and the marrow cavity model in the virtual imaging environment, and set a reasonable position and orientation for the light and the virtual camera;
  • step S4 For the posture matrix and position data of the tracker acquired in step S1, first convert the posture matrix into Euler angles, and then distribute the position data to the virtual camera in real time through the network communication module, and replace the virtual camera with the tracker;
  • the positioning system adopts two base stations, the two base stations are placed facing each other and the front screens are parallel, and one of the base stations is used as the origin of the world coordinate system of the positioning system; the tooth film machine is placed between the two base stations, The head mold in the dental film machine faces the base station as the origin of the world coordinate system, and the Y axis of the tracker is parallel to the long axis of the tube and points to the head mold.
  • the tooth is scanned using Micro-CT or CBCT technology.
  • the tooth model includes two parts of dental pulp and enamel, and the material of the tooth shell model is set to white, and the material of the pulp cavity model is set to black.
  • step S3 a plurality of planes are added around the teeth to enclose the teeth, leaving only the front opening to simulate the environment of the oral cavity.
  • the acquired posture matrix and position data of the tracker complete the distribution process through a publish-subscribe model, where the port where the posture matrix and position data of the tracker are acquired is used as the publishing end, and the port where the virtual camera is located is used as the subscription end.
  • the present invention has significant advantages: by combining VR hardware with the dental film machine, a virtual imaging environment corresponding to the real world is established, and the position and posture of the dental film machine tube can be obtained in real time, and the virtual world can be calibrated.
  • the position of the three-dimensional model, and through efficient network communication to control the movement of the camera in the virtual world, the dental film machine can render the corresponding virtual tooth X-ray apical film without radiation, which solves the traditional oral apical film training and
  • the problem of no image generation and difficulty in determining the position during the assessment provides judgment evidence for the assessment of radioactive apical radiographs, improves the visibility and accuracy of the process, and makes it safe, efficient, lossless and repeatable.
  • FIG. 1 is a flowchart of a virtual imaging method provided by an embodiment of the present invention.
  • Fig. 2 is a flowchart of setting up a virtual environment in an embodiment of the present invention.
  • Fig. 3 is a flowchart of network communication in an embodiment of the present invention.
  • Figure 4 is a rendering result diagram in an embodiment of the present invention.
  • the method for virtual imaging of a radiographic tooth X-ray apex film based on virtual reality in this embodiment is as follows:
  • Micro-CT is specially used to scan and reconstruct objects with a small volume, with small scale and high resolution.
  • the imaging pixel size of the sample can be as small as 100 nanometers, and the object can be scanned up to 200 mm in diameter.
  • the reconstructed dentition model also contains the internal pulp cavity structure to facilitate subsequent perspective rendering.
  • the digital dentition 3D model obtained here can also be scanned with traditional CBCT.
  • the traditional CBCT voxel can reach 0.125mm, the resolution can reach the reconstruction speed of 2.0lp/mm, the reconstruction time is less than 15s, the imaging range is reasonable, and it can be scanned once.
  • the traditional CBCT scan resolution is slightly lower than that of Micro-CT, and it can be used instead of Micro-CT when the virtual imaging quality requirements are not high.
  • the positioning system includes two base stations and a tracker.
  • the two base stations are set up on a tripod and placed opposite each other.
  • the height is 2m and the distance is about 4m.
  • the channel of base station A is set to "b"
  • the channel of base station B is set to "c” "
  • base station B is used as the origin of the world coordinate system of the positioning system.
  • the dental film machine is placed between the two base stations, the head mold faces the base station B, the HTC Vive tracker is fixed on the upper surface of the tube, the Y axis of the tracker is parallel to the tube, and the positive direction of the Y axis points to the head mold. Change the requireHmd option in the default configuration file of the steamVR software from true to false, and use openVR to read the attitude and coordinates of the HTC Vive tracker.
  • the distance and height of the base station can also be flexibly adjusted according to the situation, as long as the tracker is within the field of view of the base station.
  • the tooth body is composed of enamel, dentin, dental pulp, and cementum.
  • the color of each tissue is different.
  • the tooth model is simplified into two parts: dental pulp and enamel, because the pulp in the tooth X-ray film
  • the cavity is black, and the other parts are white, so different materials are set for the medullary cavity and the outer shell.
  • the medullary cavity material is black, and the outer shell material is white.
  • the transparency of the black material is lower than that of the white material, which can simulate the root tip more reasonably.
  • the perspective effect of the film is
  • step (2) Convert the attitude matrix of the HTC Vive tracker read in step (2) into Euler angles, and use the publisher-subscriber model of ZeroMQ to complete the data distribution process, and step (2)
  • the acquired data serves as the publisher
  • Unity serves as the subscriber.
  • the publisher distributes the data one-way, and does not care whether all information is sent to the subscriber. If the subscriber is not connected when the publisher starts to publish information, the information will be directly discarded.
  • the subscriber is only responsible for receiving, not feedback, and when the consumption speed of the subscriber is slower than the publisher, data will be accumulated on the subscriber. Therefore, the publisher will continuously transmit data while the publisher is running. At this time, the subscriber does not receive data, only When the Unity program is running, the subscriber starts to receive data.
  • the X and Y coordinates of the tooth and the ball tube are the same, and only the Z axis coordinates are different. Measure the physical distance L between the middle tooth and the tracker, generally 25 ⁇ 35cm. According to the position of the tracker (a,b,c)(cm), the position of the tooth in Unity is (a,b,-cL), Align with the real world. At the same time, the surrounding environment (including various planes and cylinders) of the dentition model must also be transformed in the same way to ensure the correct background when rendering and saving the image.
  • the coordinate unit of the VR positioning system is m, which is also converted to cm, and converted to the Unity coordinate system according to the orientation of the dental film machine and the orientation of the locator.
  • the VR positioning system by establishing the virtual environment and imaging conditions of the digitized teeth, using the VR positioning system, it can simulate the tooth X-ray apical film shooting process without radiation, and render the corresponding image, which improves the tooth X The safety, visibility and accuracy of the optical apical film assessment.

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Abstract

本发明公开了一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法。该方法包括：搭建VR定位系统，实时追踪与牙片机球管绑定的跟踪器的位置和空间姿态矩阵；扫描并重建牙列的数字化三维模型；为牙齿模型的外壳和内部髓腔分别设置不同的材质和透明度；搭建模拟口腔的虚拟环境；通过网络通信模块将跟踪器的姿态和位置赋值给虚拟摄像机，操纵虚拟摄像机运动；将跟踪器摆放于特定位置和朝向，标定得到虚拟环境中牙列模型位置坐标；将球管对准牙齿，渲染出虚拟根尖片。本发明的方法能够在无放射线发出的情况下，模拟牙齿X光根尖片拍摄过程并渲染出对应图像，提高了牙齿X光根尖片考核中的安全性、可视性和准确性。

Description

一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法 技术领域
本发明属于虚拟现实领域，具体涉及一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法。
背景技术
虚拟现实(Virtual Reality)是以计算机技术为核心，结合传感器系统与图形、图像识别和生成系统、网络通信系统，生成与一定范围真实环境在视、听、触感等方面高度近似的数字化环境，用户借助必要的装备产生亲临真实环境的感受和体验。随着计算机技术的发展，虚拟现实技术开始在多个领域发挥作用，如虚拟仿真领域。目前，许多技能的实训练习如电子电工、消防安全、灾害管理、建筑、医学护理等，面临以下缺点：成本高昂；步骤复杂；不易重复；可能有生命健康威胁，而虚拟现实技术能够通过建模来模拟真实环境，使上述过程能够安全、高效、无损耗、可重复。VR技术在医疗方面的应用主要是虚拟手术、远程医疗系统、虚拟人、医学教育等方面。
在传统口腔根尖片考核中，由于设备无射线发出，学生只能根据外部标记点将射线发射器摆放于估计的位置，并且无X光图像产生，教师只能根据设备的摆放位置和个人经验来确定学生是否能拍得正确的根尖片，学生的学习效率和考核可靠度不高。
目前，与虚拟现实结合的口腔诊疗仿真系统主要分为以下几类：
第一类是用于牙周病诊疗的系统，如美国伊利诺斯大学开发的模拟器PerioSim，该系统同时兼顾软硬组织的模拟，牙周操作以触觉和力觉反馈来完成，教师能在可视化下对学生的操作进行评分。
第二类是用于口腔种植的系统，如瑞典Nobel Bioeare公司开发的Nobel Guide系统，比利时Kusumoto N等人开发的Simplant系统等，该类系统用于训练学生感知种植机备洞的手感，掌握种植体在三维方向上的位置与角度。对基于CT扫描数据生成的患者颌骨三维重建模型进行全方位旋转甚至任意截面的细致观察，以选取最适宜种植体植入的位置，决定种植体的类型、数目、规格以及植入深度和方向。
第三类是用于口腔颌面外科领域的仿真系统，如比利时Materials公司开发的Simplant系统，包括颅颌面骨的三维结构和软组织结构，能在虚拟环境下进行部分手术操作。现有的大部分外科手术模拟器采用与前文所提到的相似的触觉模拟原理，可模拟切骨、截骨以及骨块位移和术后预测。
第四类是用于口腔牙体牙髓病诊疗的仿真系统，如美国穆格公司所开发的Simodont数字化虚拟仿真口腔医师培训系统，其操作同样涉及仿真力觉渲染和交互。虚拟工具和牙均由三角形网络数据结构组成，当工具切割端的三角片与牙面的三角片相交时，根据工具的嵌入深度计算出组织的去除量，实现牙体组织去除的形变模拟。
但是上述几类方法至少存在以下缺陷：集中于触觉和力觉的模拟，重建的三维结构都是物体的表面信息，不涉及牙齿X光片的模拟，不能解决传统口腔根尖片考核中无法渲染牙齿X光图像的问题。
发明内容
为了在无射线发出的情况下生成牙齿X光根尖片，本发明提供了一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法。
为了实现上述发明目的，本发明方法采用的技术方案如下：
一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法，包括如下步骤：
S1：使用VR硬件搭建空间定位系统，定位系统包括基站和跟踪器，牙片机置于定位系统可见范围内，跟踪器固定在牙片机的球管上，跟踪器在无头显情况下可实现追踪功能；获取跟踪器的姿态矩阵和位置数据；
S2：扫描多个牙齿，重建出牙列的3D数字化模型；将3D数字化模型进行分割处理，分别获取牙齿外壳模型和髓腔模型，之后将这两个模型制作为预制体，并根据实际牙齿结构特征分别为两个模型设置对应的半透明材质；
S3：搭建牙齿根尖片拍摄的虚拟成像环境，在牙齿周围添加多个平面和柱体模拟牙齿X光片中的背景，并测量牙列的3D数字化模型的包围盒尺寸和真实世界的牙列模型包围盒尺寸，计算二者比例；调整虚拟成像环境中牙齿外壳模型和髓腔模型的大小，并为灯光和虚拟摄像机设置合理的位置与朝向；
S4：对于步骤S1中获取的跟踪器的姿态矩阵和位置数据，先将姿态矩阵转换为欧拉角后，与位置数据一起通过网络通信模块实时分发给虚拟摄像机，以跟踪器替代虚拟摄像机；
S5：将球管摆放至牙齿正前方，对准牙齿，测量牙列的中间牙齿与跟踪器的物理距离，根据此时跟踪器位置标定牙列的3D数字化模型在虚拟环境中的位置，与真实世界对齐；
S6：调整球管的位置和朝向，渲染对应的虚拟牙齿X光根尖片。
进一步地，所述步骤S1中，定位系统采用两台基站，两台基站相向摆放且前方屏幕平行，其中一个基站作为定位系统的世界坐标系原点；牙片机放置于两台基站之间，牙片机中的头模 面向作为世界坐标系原点的基站，跟踪器的Y轴与球管长轴平行且指向头模。
进一步地，所述步骤S2中，利用Micro-CT或者CBCT技术扫描牙齿。
进一步地，所述步骤S2中，牙齿模型中包括牙髓和牙釉质两部分，将牙齿外壳模型的材质设置为白色，将髓腔模型的材质设置为黑色。
进一步地，所述步骤S3中，在牙齿周围添加多个平面将牙齿包围起来，只留前方开口，以模拟出口腔的环境。
进一步地，所述步骤S4中，获取的跟踪器的姿态矩阵和位置数据通过发布订阅模型完成分发过程，其中，获取跟踪器的姿态矩阵和位置数据所在端口作为发布端，虚拟摄像机所在端口作为订阅端。
本发明与现有技术相比，具有显著优点：通过将VR硬件与牙片机结合，建立了与真实世界对应的虚拟成像环境，能够实时获取牙片机球管的位置和姿态，标定虚拟世界三维模型的位置，并通过高效的网络通信控制虚拟世界的摄像机运动，使牙片机能够在无放射线的情况下渲染出对应的虚拟牙齿X光根尖片，解决了传统口腔根尖片训练和考核中无图像产生和难以判断位置的问题，为无放射线的根尖片考核提供了判断证据，提高了该过程的可视性和准确性，使之能够安全、高效、无损耗、可重复。
附图说明
图1为本发明实施例提供的虚拟成像方法的流程图。
图2为本发明实施例中搭建虚拟环境的流程图。
图3为本发明实施例中的网络通信流程图。
图4为本发明实施例中渲染的结果图。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合附图对本发明实施方法进行清楚、完整地描述。
如图1所示，本实施例的一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法，具体过程如下：
(1)使用Micro-CT技术扫描由多个离体牙构成的牙列模型，重建出牙列的3D数字化模型。Micro-CT专门用于扫描重建体积较小的物体，规模小、分辨率高。样品的成像像素尺寸可小至100纳米，物体可扫描直径达200毫米。重建的牙列模型除外壳外，还包含内部髓腔结构，便于后续的透视渲染。
这里获取数字牙列3D模型也可用传统CBCT扫描，传统CBCT体素可达0.125mm，分辨率最高可达到2.0lp/mm的重建速度，重建时间低于15s，成像范围合理，可以一次扫描即可获得全口腔双牙列三维立体影像。传统CBCT扫描分辨率比Micro-CT略低，在虚拟成像质量要求不高的情况下，可以使用其替代Micro-CT。
(2)使用HTC Vive的基站和跟踪器搭建定位系统。定位系统包括两台基站和一台跟踪器，两台基站架设于三脚架上，相向摆放，高度在2m，相距4m左右，基站A的channel设为“b”，基站B的channel设为“c”，基站B作为定位系统的世界坐标系的原点。牙片机摆放在两台基站中间，头模面向基站B，HTC Vive跟踪器固定于球管上表面，跟踪器Y轴平行于球管，Y轴正方向指向头模。将steamVR软件默认配置文件中的requireHmd选项由true改为false，使用openVR读取HTC Vive跟踪器的姿态和坐标。
这里基站的距离和高度也可根据情况灵活调整，只要保证跟踪器处于基站的视场内即可。
(3)将步骤(1)中得到的3D数字化牙列模型导入三维动画建模软件Blender进行分割处理，分别得到牙齿外壳模型和髓腔模型，导出为.fbx模型，之后在Unity中将模型制作为预制体。牙体由釉质、牙本质、牙髓和牙骨质构成，每一种组织的颜色均不相同，本实施例将牙齿模型简化为牙髓和牙釉质两部分，因牙齿X光片中的髓腔为黑色，其他部分为白色，所以为髓腔和外壳分别设置不同的材质，其中髓腔材质为黑色，外壳材质为白色，黑色材质透明度低于白色材质透明度，能够较合理地模拟出根尖片的透视效果。
(4)在Unity中搭建牙齿根尖片拍摄的虚拟成像环境，在牙齿周围添加多个黑色不透明平面作为牙齿X光片背景，在牙列中间添加黑色不透明柱体，避免拍摄后牙时由于牙弓走向而同时拍摄到另一侧后牙，测量数字牙列模型的包围盒尺寸和真实世界的牙列模型包围盒尺寸，调节比例为1:1，灯光采用directional light模拟日光，设置流程如图2所示。
此处在不添加背景黑色平面时，仅仅将虚拟摄像机的Clear Flags设置为Solid Color模式也可达到同样的渲染效果，但是在保存图像时背景会呈现透明状态，因此添加黑色平面作为背景。
(5)将步骤(2)中读取的HTC Vive跟踪器的姿态矩阵转换为欧拉角，采用ZeroMQ的发布者(publisher)-订阅者(subscriber)模式完成数据分发过程，将步骤(2)获取的数据作为发布端，Unity作为订阅端，发布端单向分发数据，且不关心是否把全部信息发送给订阅端。如果发布端开始发布信息时，订阅端尚未连接上来，则这些信息会被直接丢弃。订阅端只负责接收，而不能反馈，且在订阅端消费速度慢于发布端的情况下，会在订阅端堆积数据，因此发布端运行时会不断地传输数据，此时订阅端不接收数据，只有Unity程序运行时，订阅端才开 始接收数据。使用Python的zmq模块完成通信的发布端，在发布端绑定一个本地端口，将跟踪器的欧拉角和位置数据不断通过端口发送，使用C#的NetMQ模块完成通信的订阅端，在订阅端连接并监听端口，接收消息后赋值给摄像机，具体通信流程如图3所示。
(6)将球管摆放至头模的牙齿正前方，指向牙列的中间，且水平对准牙齿，牙齿与球管的X,Y坐标相同，仅Z轴坐标值不同。测量中间牙齿与跟踪器的物理距离L，一般为25～35cm，根据此时跟踪器位置(a,b,c)(cm)标定牙齿在Unity中的位置为(a,b,-c-L)，与真实世界对齐。与此同时，牙列模型的周围环境(包括各种平面和柱体)也要做相同的变换，以保证渲染和保存图像时有正确的背景。VR定位系统的坐标单位为m，将其同样转换为cm，并根据牙片机摆放朝向和定位器摆放朝向转换到Unity坐标系。
(7)调整摄像机视角大小，使视图中显示的牙齿数量小于6颗，与真实的牙齿X光片保持一致，将牙片机球管摆放到合适的位置，对准牙齿，按键刷新画面，渲染出对应的虚拟牙齿X光根尖片，渲染结果如图4所示。
因此，本实施例通过建立数字化牙齿的虚拟环境和成像条件，使用VR定位系统，能够在无放射线发出的情况下，模拟牙齿X光根尖片拍摄过程，并渲染出对应图像，提高了牙齿X光根尖片考核中的安全性、可视性和准确性。

Claims (6)

  1. 一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法，其特征在于，包括如下步骤：
    S1：使用VR硬件搭建空间定位系统，定位系统包括基站和跟踪器，牙片机置于定位系统可见范围内，跟踪器固定在牙片机的球管上，跟踪器在无头显情况下可实现追踪功能；获取跟踪器的姿态矩阵和位置数据；
    S2：扫描多个牙齿，重建出牙列的3D数字化模型；将3D数字化模型进行分割处理，分别获取牙齿外壳模型和髓腔模型，之后将这两个模型制作为预制体，并根据实际牙齿结构特征分别为两个模型设置对应的半透明材质；
    S3：搭建牙齿根尖片拍摄的虚拟成像环境，在牙齿周围添加多个平面和柱体模拟牙齿X光片中的背景，并测量牙列的3D数字化模型的包围盒尺寸和真实世界的牙列模型包围盒尺寸，计算二者比例；调整虚拟成像环境中牙齿外壳模型和髓腔模型的大小，并为灯光和虚拟摄像机设置合理的位置与朝向；
    S4：对于步骤S1中获取的跟踪器的姿态矩阵和位置数据，先将姿态矩阵转换为欧拉角后，与位置数据一起通过网络通信模块实时分发给虚拟摄像机，以跟踪器替代虚拟摄像机；
    S5：将球管摆放至牙齿正前方，对准牙齿，测量牙列的中间牙齿与跟踪器的物理距离，根据此时跟踪器位置标定牙列的3D数字化模型在虚拟环境中的位置，与真实世界对齐；
    S6：调整球管的位置和朝向，渲染对应的虚拟牙齿X光根尖片。
  2. 根据权利要求1所述的一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法，其特征在于，所述步骤S1中，定位系统采用两台基站，两台基站相向摆放且前方屏幕平行，其中一个基站作为定位系统的世界坐标系原点；牙片机放置于两台基站之间，牙片机中的头模面向作为世界坐标系原点的基站，跟踪器的Y轴与球管长轴平行且指向头模。
  3. 根据权利要求1所述的一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法，其特征在于，所述步骤S2中，利用Micro-CT或者CBCT技术扫描牙齿。
  4. 根据权利要求1所述的一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法，其特征在于，所述步骤S2中，牙齿模型中包括牙髓和牙釉质两部分，将牙齿外壳模型的材质设置为白色，将髓腔模型的材质设置为黑色。
  5. 根据权利要求1所述的一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法，其特征在于，所述步骤S3中，在牙齿周围添加多个平面将牙齿包围起来，只留前方开口，以模拟出口腔的环境。
  6. 根据权利要求1所述的一种基于虚拟现实的无射线牙齿X光根尖片虚拟成像方法，其特征在于，所述步骤S4中，获取的跟踪器的姿态矩阵和位置数据通过发布订阅模型完成分发过程，其中，获取跟踪器的姿态矩阵和位置数据所在端口作为发布端，虚拟摄像机所在端口作为订阅端。
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180168780A1 (en) * 2016-12-16 2018-06-21 Align Technology, Inc. Augmented reality enhancements for dental practitioners
CN108389488A (zh) * 2018-03-05 2018-08-10 泉州医学高等专科学校 一种互动式口腔模拟系统
CN108665533A (zh) * 2018-05-09 2018-10-16 西安增材制造国家研究院有限公司 一种通过牙齿ct图像和三维扫描数据重建牙列的方法
CN109035386A (zh) * 2018-06-22 2018-12-18 泰康保险集团股份有限公司 一种齿科vr成像方法及装置
CN110458941A (zh) * 2019-07-29 2019-11-15 南京大学 一种基于虚拟现实的无射线牙齿x光根尖片虚拟成像方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101944156B (zh) * 2010-08-03 2013-05-08 西安科技大学 一种单颗牙齿包容体的确定方法
WO2018036853A1 (de) * 2016-08-26 2018-03-01 Vita Zahnfabrik H. Rauter Gmbh & Co. Kg Zahneinheit sowie verfahren zur herstellung einer prothesenbasis

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180168780A1 (en) * 2016-12-16 2018-06-21 Align Technology, Inc. Augmented reality enhancements for dental practitioners
CN108389488A (zh) * 2018-03-05 2018-08-10 泉州医学高等专科学校 一种互动式口腔模拟系统
CN108665533A (zh) * 2018-05-09 2018-10-16 西安增材制造国家研究院有限公司 一种通过牙齿ct图像和三维扫描数据重建牙列的方法
CN109035386A (zh) * 2018-06-22 2018-12-18 泰康保险集团股份有限公司 一种齿科vr成像方法及装置
CN110458941A (zh) * 2019-07-29 2019-11-15 南京大学 一种基于虚拟现实的无射线牙齿x光根尖片虚拟成像方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
XIAO YONG: "Development of a Virtual Reality-based simulation Training System for Root Canal Preliminary Treatment)", CHINESE MASTER'S THESES FULL-TEXT DATABASE, no. 4, 1 May 2017 (2017-05-01), pages 1 - 59, XP009525927, ISSN: 1674-0246 *

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