【作者】 姚富光；

【导师】 肖沙里；

【作者基本信息】 重庆大学 ， 仪器科学与技术， 2004， 硕士

【摘要】 20世纪医学的重要的成果之一,计算机断层摄像技术(Computerized Tomography,CT)的出现,使放射治疗学发生了革命性的变化。现代医学图像与计算机技术的发展以及它们之间的相互融合,使得基于CT的三维可视化医学辅助系统的设计与开发成为现实。医学CT图像三维重建是目前的一个研究热点问题,是一个多学科交叉的研究领域,是计算机图形学和图像处理在生物医学工程中的重要应用。它涉及数字图像处理、计算机图形学以及医学等领域的相关知识。医学CT图像三维重建及可视化在诊断医学、手术规划及模拟仿真、整形及假肢外科、放射治疗规划、解剖教学等方面都有重要应用。论文简单介绍了国内外医学图像可视化的研究现状,针对医学CT图像三维重建的关键技术进行了研究,分析了包括图像的预处理,组织和器官的分割与提取、单轮廓线间的三维表面重建、等值面提取进行三维模型构造、重建模型的表面网格简化等涉及三维重建的方法及其原理,分析了标准MC算法计算量大且不易实现的不足,提出了基于医用螺旋CT的图像重建算法SMC(special MC),并应用SMC算法,在微机上实现了医用CT的三维重建系统,论文对该系统的设计和使用的算法进行了介绍。本文有如下两个特点:(1) 针对标准MC法的不足,对该算法进行了改进,在此基础上提出了一种面拟合算法SMC,该算法定义了一种三态(+1,0,-1)状态函数,利用同层CT图像像素与其四邻域的同号性,只需要对体元的各顶点进行判断就可得到重建表面,无需计算双曲线的渐近线来判断二义性,减少了重建复杂性。(2) 采用边删除算法进行三角模型简化,用多因素加权平均进行优先级判断,以网格平坦程度作为首要判断依据,减少了运算时间,提高简化速度。更多还原

【Abstract】 The appearance of one of the greatest achievement in medical research in 20th Century —— Computerized Tomography, have brought a revolutionary change to radiotherapy research. With the development of the modern medical imaging technology and the computer technology, and their interaction as well, to design or product a 3D visualized medical accessory system has become reality. At present, 3D reconstruction from medical images is an extensive-research subject with multi-disciplinary interaction, and it is an important application of computer graphics and image processing in biomedicine engineering. It relates to the subjects of digital image processing, computer graphics and some related knowledge of medical. 3D reconstruction and visualization from medical images are widely used in diagnostic, surgery planning and simulation, plastic and artificial limb surgery, radiotherapy planning, and teaching in anatomy.This dissertation summarizes the present status, both domestic and abroad, of medical image visualization. In this dissertation, the key technologies of 3D reconstruction from medical CT are studied, and some concerned principles and algorithms are analyzed, including image preprocessing, segmentation and extraction of human tissues or organs, 3D surfaces reconstruction from contours, 3D models construction by isosurface extracting, meshes simplifying of the reconstructed models, and so on. This paper analyzes the shortage of the normal MC algorithm that causes huge consumption of operation and is hard to work out, then presents SMC method which aims at the 3D reconstruction from medical spiral CT images. With SMC, a 3D reconstruction PC system from medical CT has been set up, this dissertation explicates the design and methods of the system.This dissertation has two features below:(1) According to the shortage of normal MC algorithm, a surface-fitting method modified from normal MC is presented. This method defines a status function with 3 status(+1,0,-1), with which it need only judging the status of each vertex in the chamber to reconstruct the surfaces by using the character that a pixel has the same sign as its 4 neighborhood in one CT image. This method avoids calculating the asymptote of hyperbola to judge the ambiguity, and reduces the complexity of reconstruction. <WP=6>(2) Using edge deleting algorithm to simplify the meshes of the reconstructed models, calculating the priority by the weighted mean of multi-element, and taking the flatness level of meshes as the chief factor. This will shorten the operating time of meshes simplifying.更多还原