基于CT图像的人体组织边界提取及三维描述

利用活体信息数据,建立有限元模型,进行生物力学响应分析,是人体损伤分析和人体组织分析的一种重要手段.本文利用IDL语言直接读取符合DICOM格式的医学CT图像数据并进行处理,提取出感兴趣区域的边界信息,自动生成DXF格式文件.通过对多幅CT切片实验,取得较好的效果,为医学CT图像的三维重建和有限元模型的建立提供了一种有效的解决方法.     

逆向工程与快速制造技术在人工假体上的应用

利用逆向工程技术,对人体股骨进行了反求设计,完成了股骨的CAD模型;基于Pro/E设计环境,采用自顶向下的设计方法进行了人工假体的详细设计;采用FDM2000原型机制造出假体实验验证模型,实现了股骨假体的逆向到原型的设计与快速制造;综合评定制造模型精度合理,可以为后续工程分析提供参考。结果表明,逆向工程与快速原型制造技术综合应用,对人体运动功能的修复、提高诊断和手术水平、缩短时间、节省费用都有显著意义。     

基于STL的股骨快速原型制造

讨论了由CT数据生成人体骨骼快速原型模型STL文件的技术路线 ,构造了人体股骨的实体模型 ,通过与快速成型制造系统之间的数据交换 ,制造了具有完整解剖特征的人体股骨模型。     

基于CAD/CAM软件的股骨模型三维重建及数控加工

运用通用CAD/CAM软件Mimics,Imageware,CATIA,对股骨模型进行三维模型重建及数控加工程序编制,配备四轴数控雕刻机床进行数控加工,提出了一套完整的股骨模型三维重建及数控加工的方法.     

基于STL的股骨快速原型制造

讨论了由CT数据生成人体骨骼快速原型模型STL文件的技术路线，构造了人体股骨的实体模型，通过与快速成型制造系统之间的数据交换，制造了具有完整解剖持征的人体股骨模型。     

股骨下端松质骨横向拉伸应力松弛方程

研究了股骨下端松质骨的粘弹性力学性质.对股骨下端松质骨横向进行了横向拉伸应力松驰实验,得出了股骨下端松质骨横向拉伸应力松弛数据和曲线.用三参数模型处理实验数据,得出了股骨下端松质骨横向拉伸应力松驰方程及曲线,并对实验结果进行了分析讨论.     

非封闭三角网格模型边界特征的自动识别

孔洞修补是反求工程中的重点研究内容之一,孔洞修补必须要准确定位和识别孔洞边界。非封闭三角网格模型边界和孔洞边界的识别多采用人机交互方法。提出一种新的孔洞边界自动识别方法:将边界顶点和边界网格向该边界对应的投影特征平面投影以获得边界投影多边形,利用平面几何多边形内角和知识进行自动识别,若边界投影多边形所对应的无网格部分夹角总和等于多边形的内角和则为孔洞边界,反之则为模型边界。通过实例验证,该方法能够自动识别出模型边界和孔洞边界并分离,提高了在非封闭三角网格模型中孔洞边界识别的效率。     

边界表达模型的局部几何更新方法

与历史无关造型技术已成为三维CAD系统令人关注的研究方向之一,对于带有拓扑和几何信息的轻量化模型进行直接编辑是该技术的典型应用。鉴于B-rep模型的变化实际上表现为其内部拓扑和几何的变化,本文基于拓扑结构保持不变的前提,对三维模型一个或多个几何面改变时其相邻边界的几何一致性更新方法进行了研究。提出并分析了适合于多面体模型的边界几何求交方法,并进一步给出了融入模型重构的综合算法。通过实例验证了上述方法的可行性。     

基于网格模型的空腔建模算法

提出了一个基于网格模型的空腔建模算法,目的是实现骨髓腔的精确建模.算法基于先离散后重建的思想,从三维网格模型的离散点云数据中搜索空腔边界环,根据空腔边界环进行三角划分得到最终的三维空腔模型.改进了判断内、外边界环的关系的射线法,并提出基于分层的三维点集空间直接三角划分算法,最后以股骨骨髓腔和牙髓腔的建模为例,验证了该算法的有效性和稳定性.     

运用快速成型技术的人工骨骼实体模型重建

将快速成型技术运用于骨骼实体模型的三维重建研究中,以人体下肢股骨近端为例,通过对原始CT图像数据进行阈值分割,提取股骨近端轮廓曲线,拟合成数字模型.利用快速成型机可以将股骨近端的数字模型实体化,得到与实际骨骼拟合程度较高的实体模型.     

膝关节三维模型的构建

通过对逆向工程技术的研究,提出了一种构建膝关节三维模型的新方法。首先,分别对已有膝关节假体原型和志愿者的股骨远端及胫骨近段进行数据的采集;其次,利用逆向工程软件Geomagic和Mimics分别对膝关节假体原型的点云数据和股骨远端和胫骨近端的CT图像进行处理,然后利用三维软件PRO/E进行再设计;最后按顺序在PRO/E软件中装配成膝关节三维模型。模型的建立为进一步进行膝关节生物力学分析提供了方法与平台,同时也为人工膝关节模型数据库的建立提供了方法。     

基于多视角照片重构物体三维模型研究

提出了一种基于照片重构三维模型方法。利用相机对物体轮廓图像多角度采集,通过每个轮廓曲线生成投影锥体,再用投影锥体相交的方法获得近似物体的多面体可见壳。     

基于照片的实体建模方法的现状及展望

基于照片的实体建模方法指通过摄像、图像处理获得物体三维模型的方法。该方法源于计算机视觉,是一种方便快捷的三维建模方法。对基于照片的实体建模基础理论与方法进行了论述,并对目前国内外的研究动态进行了分析,提出了进一步研究的方向。     

定做式人工髋关节设计与加工中股骨轮廓提取方法

本文提出在设计定做式人工髋关节时使用的一种股骨ＣＴ片轮廓提取方法。采用本文论述的轮廓提取方法，作者得到了股骨的截面数据，并从而利用ＣＡＤ软件进行了股骨的三维重建，并在快速原型设备上得到了股骨的实体。     

Development and numerical validation of a finite element model of the muscle standardized femur

The human femur is one of the parts of the musculo-skeletal system most frequently analysed by means of the finite element (FE) method. Most FE studies of the human femur are based on computed tomography data sets of a particular femur. Since the geometry of the chosen sample anatomy influences the computed results, direct comparison across various models is often difficult or impossible. The aim of the present work was to develop and validate a novel three-dimensional FE model of the human femur based on the muscle standardized femur (MuscleSF) geometry. In the new MuscleSF FE model, the femoral attachment of each muscle was meshed separately on the external bone surface. The model was tested under simple load configurations and the results showed good agreement with the converged solution of a former study. In the future, using the validated MuscleSF FE model for numerical studies of the human femur will provide the following benefits: (a) the numerical accuracy of the model is known; (b) muscle attachment areas are incorporated in the model, therefore physiological loading conditions can be easily defined; (c) analyses of the femur under physiological load cases will be replicable; (d) results based on different load configurations could be compared across various studies.     

基于浮力的二维轮廓测量及其重构算法研究

提出一种基于液体浮力的适于二维轮廓测量的计算模型和测量方法,阐述了该方法的测量原理与重构算法,由阿基米德定律,利用电子天平逐层测算被测实体浸入液面不同深度时所受浮力,通过计算相应片层的质量、重心等信息,得到能表征被测实体二维轮廓的二进制图像,仿真计算结果证明该方法是有效和可行的。     

汽车前部结构对骑自行车人颅脑损伤防护特性的影响

以深入的事故调查为基础建立汽车—骑自行车人碰撞分析模型,提出可降低颅脑损伤风险的汽车前部结构改进措施。针对真实的汽车与自行车碰撞事故,采用多体动力学软件MADYMO进行事故重建,评估仿真模型及方法的有效性。通过定义轿车、SUV、MPV三种常用车型前部结构参数(包含保险杠高度、保险杠伸出长度、发动机罩前缘高度、发动机罩长度、发动机罩角度和挡风玻璃角度),分析汽车行驶速度以及前部结构对于骑自行车人颅脑损伤的影响,并讨论骑自行车人颅脑损伤防护的可行措施。仿真结果表明:汽车碰撞速度、发动机罩前缘高度和保险杠高度对骑自行车人颅脑损伤有显著影响;尤其对于轿车,适当地降低其发动机罩前缘及保险杠高度可以有效地降低骑自行车人颅脑损伤的风险。     

The muscle standardized femur: a step forward in the replication of numerical studies in biomechanics

The standardized femur is the computer aided design (CAD) solid model of a synthetic human femur, commonly used in experiments in vitro, available in the public domain through the International Society of Biomechanics Finite Element Mesh Repository. Currently used by hundreds of researchers, it was made available to simplify the experimental cross-validation of numerical studies as well as their replication by other researchers. One aspect that the standardized femur left uncovered is the definition of muscles and ligaments. In particular, for a variety of simulations it would be extremely useful to map on to the femoral surface the insertion of the principal muscles. The aim of the present study was to create a new solid model, called the muscle standardized femur, where the femoral insertion of each muscle is mapped on to the surface of the femur. Published data on muscle insertion morphometry were registered to the model by applying an affine scaling defined on bone landmarks. Good agreement was found with another similar study in which only the insertion centres were defined. The new model will be made available in the public domain for no-profit uses. When combined with published data on the direction and intensity of muscular forces this model is expected to make a useful contribution to the steadily growing library of models and data sets made available to the biomechanical community.     

A three-dimensional morphometrical study of the distal human femur.

The objective of this paper is to present a method to describe the three-dimensional variations of the geometry of the three portions forming the distal part of the human femur: the medial and lateral femoral condyles and the intercondylar fossa. The contours of equally spaced sagittal slices were digitized on the distal femur to determine its surface topography. Data collection was performed using a digitizer system which utilizes low-frequency, magnetic field technology to determine the position and orientation of a magnetic field sensor in relation to a specified reference frame. The generalized reduced gradient optimization method was used to reconstruct the profile of each slice utilizing two primitives: straight-line segments and circular arcs. The profile of each slice within the medial femoral condyle was reconstructed using two circular arcs: posterior and distal. The profile of each slice within the lateral femoral condyle was reconstructed using three circular arcs: posterior, distal and anterior. Finally, the profile of each slice within the intercondylar fossa was reconstructed using two circular arcs: proximal-posterior and anterior, and a distal-posterior straight-line segment tangent to the proximal-posterior circular arc. Combining the data describing the profiles of the different slices forming the distal femur, the posterior portions of each of the medial and lateral femoral condyles were modelled using parts of spheres having an average radius of 20 mm. The anterior portion of the lateral condyle was approximated to a right cylinder having its circular base parallel to the sagittal plane with an average radius of 26 mm. The anterior portion of the intercondylar fossa was modelled using an oblique cylinder having its circular base parallel to the sagittal plane with an average radius of 22 mm. Furthermore, it is suggested that the distal portion of the lateral femoral condyle could be modelled using parts of two oblique cones while the distal portion of the medial femoral condyle could be modelled using a part of a single oblique cone, all cones having their circular bases parallel to the sagittal plane. It is also suggested that the posterior portion of the intercondylar fossa could be modelled using two oblique cones: a proximal cone having its base parallel to the sagittal plane and a distal cone having its base parallel to the frontal plane.     

基于CATIA的逆向工程中的曲面重建

曲面模型的建立是逆向工程技术中极为关键的一步。本文通过一个具体实例,介绍了如何利用CATIA V5逆向工程模块调入点云,经过滤、网格化,到创建扫描线、生成曲线、填充曲面最后建立起曲面模型的数据处理过程,为读者提供了一种逆向工程中曲面重建的基本方法。