【作者】 杨建玺；

【导师】 钱晋武；

【作者基本信息】 上海大学 ， 机械制造及其自动化， 2007， 博士

【摘要】 计算机辅助外科是近年来新兴的一门集计算机技术、精密机械工程、数学、精密测量学、医学和图像工程学等于一体的交叉学科。其作用：(1)帮助医生对患者所患病情进行精确诊断；(2)手术过程中，可清楚观察到手术工具相对于患部的精确位置，从而指导医生快速、准确进行手术，节省手术时间，减少手术创伤。在骨伤科手术中，常采用封闭式髓内钉内固定技术来治疗胫骨、股骨骨折，手术现场调研结果表明目前国内采用的机械式定位和凭借医生经验进行髓内钉绞索孔定位的方法存在着难以准确定位和多次打孔以及多次拍摄X射线等缺陷。因此，利用计算机和机器人视觉技术，确定手术工具相对于人体组织结构或手术器械之间的空间位置关系具有重要的研究意义和应用前景。本文在充分分析国内外现状的基础上，结合我国国情，给出了基于C臂X射线影像手术导航的新思路。针对股骨、胫骨绞锁螺钉定位困难的手术问题，开发了手术导航的硬件系统和软件系统；详细地研究了摄像机标定过程中不考虑摄像机镜头失真的线性标定方法和考虑镜头失真的非线性标定方法，提出了线性模型+误差补偿的标定方法，不仅克服了线性标定误差大的不足，而且又避免了非线性模型难以求解且耗时的缺点，具有实用价值；为了提高系统最终的定位精度，用样条插值实现了图像边缘的亚象素提取，并结合最小二乘圆弧拟合算法，较为精确的计算出了标志点的重心坐标；在双目视觉的配准运算中，采用基于极线约束、顺序约束、几何相似性约束的对应点配准算法，使双目视觉点对之间较容易地实现了——对应；在手术导航的模拟试验中，利用三个标志点构建一个坐标系的原理，以C＋＋Builder和MATLAB为工具，求得了手术过程中电钻、髓内钉等的空间相对位置关系，实现了股骨、胫骨髓内钉绞锁螺钉定位的手术导航。总之，本文主要针对骨科手术导航中髓内钉远端定位螺钉孔位置难以确定的问题，仿照人类双目感知距离的方法，运用双目立体视觉技术，实现对三维空间目标点的定位。运用两个摄像机对同一目标从不同位置成像，进而从视差中恢复距离；通过对手术现场的仔细了解与手术医师的反复商榷，使用LED作为标志点，利用非接触式光学定位方法提取空间点位置信息：通过对摄像机的标定、图像处理及目标点重心的计算，求出空间点在虚拟世界坐标系下的三维坐标，从而确定了手术器械等的空间位姿，通过空间坐标转换及一系列定位计算，完成了手术导航实验系统。为手术导航系统的开发奠定了良好的基础。更多还原

【Abstract】 Computer aided surgery is a multi-discipline topic that including computer technology, precision machine, mathematics, precision measurement, medicine and image engineering. Its functions are as follows: (1) helping the surgeon to diagnose patient accurately. (2) Showing instruments’ exact position relative to focus, and the surgery can see the operation route and position clearly, thus reducing operation hurt and saving operation time. The common method is to use intra-medullary nail to fix the thighbone and shinbone fracture. Therefore, it is worthwhile to do research on ubiety btween operation tools and body tissue.By analyzing the present condition of domestic and foreign techniques, a new surgical navigation method that based on C-arm X-ray image is given, and the hardware and software of the surgical navigation system are developed. It helps to overcome the difficulty of interlocking intra-medullary nail’s orientation in thighbone and shinbone operation. There are two methods in CCD calibration, one is linear calibration, which doesn’t take lens’s distortion into account, and the other is nonlinear calibration which considers lens’s distortion. A new method by analyzing above two methods is given. First, calibrating the CCD in linear method, and then compensating the error. It not only reduces the error drastically in linear calibration, but also avoids the shortcoming of nonlinear calibration. In binocular matching, we advance corresponding point’s matching algorithm based on epipolar line bunch, order bunch and geometrical comparability bunch, and matching two CCD markers correctly.In the analog experiment of operation navigation, according to the theory that three points can form a coordinate, we get the relative position of the drill and the intra-medullary nail with the help of C++ Builder and MATLAB, and navigate thighbone and shinbone interlocking intra-medullary nail orientation correctly.In a word, the paper aims at the difficulty of how to locate intra-medullary nail’s outlying screw in fracture operation navigation, according to the method that binocular can apperceive depth, getting marker’s 3-D position with the help of binocular vision technology. The system gets two image of one object with two CCD, thus obtains depth from two CCD’s parallax. After investigating the operation spot and discussing with surgeons we use LED as markers, and get the marker’s 3-D position with a non-contact optics orientation method. After calibrating the CCD, processing the image, the system can figure out marker’s areal coordinates, get marker’s 3-D coordinate in dummy world coordinate system, thereby obtain instrument’s 3-D position and orientation. After the coordinate transformation and a series of orientation calculation, operation navigation comes true. It lays a foundation for the development of a surgical navigation system for practical use.更多还原