虚拟血管内导丝的运动仿真

发布时间：2018-04-29 12:09

本文选题：血管介入治疗 + 三维可视化　；参考：《北京工业大学》2013年硕士论文

【摘要】：近几年来，心血管疾病日益成为人们健康的重要杀手。每年有成百上千万的人死于心血管疾病。放射介入疗法目前已经被广泛的用于治疗血管疾病，并成为最及时、最有效的方法之一。通过现有虚拟现实技术，对血管内导丝的运动进行了仿真模拟，有助于解决传统介入手术医生培训无法在临床环境下进行的问题。本文详细的介绍了虚拟血管介入手术培训系统中的软件部分，通过三维建模方法构建虚拟的血管三维模型，以及手术器械(导管/导丝)，导丝在血管中实时的进行碰撞检测，并在完成碰撞之后发生运动改变，而且通过质点-弹簧模型算法对碰撞区域的导丝进行物理建模，，最终实现了基于MFC的软件设计。三维血管模型与导丝模型的导入设计，是在3DSlicer开发软件中扩展了VMTK开发包，其中集成了水平集分割算法，导入真实的人体心脏MRI图像，选取分割区域，同时选取种子点，完成对心脏血管的分割，最终分割出一支右冠状动脉血管。导丝与血管壁的碰撞检测与碰撞消除的实现，首先提取局部三角面片信息，通过选择以导丝首个分段的中心点为球心点坐标，以导丝首段分段的一半长度为半径构建一个三维虚拟球体，选取所有包含在球体内部的三角面片信息，然后与首段导丝进行空间中的相交检测完成碰撞检测的过程。判断碰撞检测结果，如果发生碰撞，导丝运动方向即发生改变，并以发生碰撞的面片（血管模型的最小单元）作为反射面，经反射后沿血管壁内侧反射角方向运动，确保导丝不会穿出血管。碰撞区域的导丝进行质点-弹簧模型的物理建模方法，是将碰撞区域的导丝部分离散为一些由弹簧连接的质点，每个质点相互受到弹簧的作用力，并假设发生反射的质点不仅受到前后两个节点的弹簧拉力，而且收到了一个虚拟弹簧体的力，目的是为了改变导丝的平滑性。通过三个质点对反射点的作用力改变它的空间坐标，完成导丝的物理建模。同时此部分还将质点-弹簧模型应用到血管跳动的模拟中，并提出了一种简单的实现血管造影效果的方法。系统软件设计实现了交互式操作界面，操作界面包括血管模型的显示窗口，以及模拟导丝的前进与后退按钮，其中实现了串口通信的功能，通过采集单片机传送的位移信号，导丝实时改变运动状态，并加入了力反馈信息。虚拟血管内导丝的运动仿真是血管内介入手术培训系统中重要的组成部分，能够提供给医生一个可重复操作的教学系统。本系统的成功研制对于建立拥有我国自主知识产权的医学模拟教学系统具有积极的推动作用。
[Abstract]:In recent years, cardiovascular disease has become an important killer of human health. Millions of people die of cardiovascular disease every year. Interventional radiotherapy has been widely used in the treatment of vascular diseases and has become one of the most timely and effective methods. By using the existing virtual reality technology, the motion of the intravascular guide wire is simulated, which is helpful to solve the problem that the traditional training of interventional surgeon can not be carried out in the clinical environment. In this paper, the software of virtual vascular interventional surgery training system is introduced in detail, and the virtual vascular 3D model is constructed by 3D modeling method, and the instrument (catheter / guide wire) is used to detect the collision in the blood vessel in real time. The motion changes after the collision is completed, and the physical modeling of the guide wire in the collision area is carried out by the mass-spring model algorithm. Finally, the software design based on MFC is realized. The import design of 3D vascular model and wire guide model is to extend the VMTK development kit in the 3DSlicer development software, which integrates the level set segmentation algorithm, imports the real human heart MRI image, selects the segmentation area, and selects the seed point. Complete the segmentation of the heart vessel, and finally segment a right coronary artery. In order to detect and eliminate the collision between the guide wire and the vascular wall, the information of the local triangular surface is extracted first, and the center point of the first segment of the guide wire is selected as the coordinate of the spherical center point. A three-dimensional virtual sphere is constructed with half the length of the first segment of the guide wire as the radius, and all the information of the triangle surface contained in the sphere is selected, and then the collision detection process is completed by intersecting with the leading wire in the space. Judging the result of collision detection, if the collision occurs, the direction of the guide wire will change, and the surface of the collision (the smallest unit of the vascular model) will be used as the reflective surface, and then it will move along the direction of the inner reflection angle of the vascular wall after reflection. Make sure the guide wire does not penetrate the blood vessel. The physical modeling method of the mass-spring model of the guide wire in the impact area is to discretize the guide wire part of the impact area into some mass connected by the spring, and each mass is subjected to the spring force each other. It is assumed that the reflected mass is not only subjected to the spring tension of the front and rear nodes, but also to the force of a virtual spring body, in order to change the smoothness of the guide wire. The physical modeling of the guide wire is completed by changing the spatial coordinates of the three particles acting on the reflection point. At the same time, the mass-spring model is applied to the simulation of blood vessel beating, and a simple method to realize the effect of angiography is proposed. The system software designs and implements the interactive operation interface, which includes the display window of blood vessel model, and the forward and backward buttons of analog guide wire. The function of serial port communication is realized, and the displacement signal transmitted by single chip microcomputer is collected. The guide wire changes the motion state in real time and adds force feedback information. The motion simulation of virtual intravascular guide wire is an important part of the training system of intravascular interventional surgery. It can provide a repeatable teaching system for doctors. The successful development of this system can promote the establishment of a medical simulation teaching system with independent intellectual property rights in China.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TP391.9

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