【作者】 刘济全；

【导师】 吕维雪； 段会龙；

【作者基本信息】 浙江大学 ， 生物医学工程， 2002， 博士

【摘要】 在人类与疾病的斗争过程中，必然要求从人体获取各种各样尽可能丰富的、反映人体各种生理、病理状态的解剖及功能信息。由于人类在依靠视觉获取信息方面具有超常的能力，以视觉信息的形式来体现各类医学对象中所包含的丰富隐含信息，在临床对疾病的诊断、治疗以及科研教学活动中具有重大的意义。现代医学影像技术的发展，使得从人体上获取的信息越来越详实，极大地丰富了医学对象的内容。对于这些信息的利用，传统的方法往往是观察者根据胶片或者数字形式的二维图像，依靠“在头脑中进行三维对象重现”来进行分析和诊断。然而，要准确地把握分析对象的生理病理性质、空间几何特征及其与周围生物组织之间的空间关系，仅凭这种传统方法是极为困难的。计算机技术以及科学计算可视化的迅猛发展，使得人们可以通过可视化的方法，以一种直观、逼真、有效的形式对各种医学对象中丰富的隐含信息加以利用。医学对象可视化就是通过对具有空间特性的医学对象在静态或动态三维空间中进行处理，以视觉信息的形式充分反映出医学对象中丰富的隐含信息，在临床诊断、治疗以及科研教学中有着广泛的应用前景。近年来，医学对象可视化的研究一直是国际上的研究热点之一。 虚拟心脏模型提供了心电正问题和逆问题的研究和应用基础，虚拟内窥镜由于其非侵入性的特点具有传统内窥镜无可比拟的优势。采用可视化的方法对这两个医学对象进行研究是医学对象可视化中的重要内容。 本文的主要内容是针对医学对象可视化的要求，设计和实现一个医学对象实时可视化系统及技术平台，并在这个平台上对虚拟心脏模型医学对象和虚拟内窥镜医学对象的可视化进行研究。具体来说，研究工作主要包括： 从医学对象所涵盖的内容及其分类对医学对象进行了深入的分析和讨论。 综述了医学对象可视化的发展历史、研究内容、研究现状、发展趋势以及医学对象可视化系统的研究内容及其应用，并着重介绍了医学对象可视化的主要基础算法。 针对目前医学对象可视化系统中绘制和交互实时性较差的问题，从系统结构和技术实现上，对先进的可视化软件工具集VTK以及实时体绘制硬件系统VolumePro进行了深入的分析，由此给出了基于VTK和VolumePro软硬件综合的医学对象实时可视化系统及技术平台解决方案。 基于该解决方案，设计并实现了一个通用的医学对象实时可视化系统及技术平台4DView。4DView提供了Marching Cubes、Dividing Cubes等 l 加j以夯＠￥M③wOWMW％＠ig＆＆Z． 面绘制算法和各种体绘制算法，如光线投射、纹理映射以及VohimePro 所采用的算法等，能够实现高效的实时绘制和交互特性。此外，4DView 还具备了很好的可扩展性和开放性，能够作为研究理论方法和验证结果 的科研平台。 ＋ 针对医学对象可视化过程操作复杂、对专业知识要求高的问题，4DView 初步设计和实现了显示协议，为目前可视化系统存在的这些问题寻求到 了一种可能的解决方案。 ．在4DView平台上，对LFX虚拟心脏模型这一特殊的医学对象的可视 化进行了开拓性的研究，初步完成了虚拟心脏可视化的工作。通过体元 映射法和顶点投影映射法实现了该医学对象模型本身以及两个关键仿 真结果——心电兴奋时序图和体表电位图的可视化，从而将该医学对象 从一个数学模型拓展成了物理可视化模型，使得该模型更为接近真实的 人体心脏。 ．对虚拟内窥镜技术进行了深入的研究，在4DVew平台上创建了基于体 绘制的虚拟内窥镜原型系统，并提供了基于标准数据和实际临床数据的 可视化结果。 总而言之，虽然目前国际上存在很多可视化系统，但普遍存在绘制和交互实 时性较差、操作复杂和对专业知识的要求高等弊端。本文通过给出基于VTK和 VolumePro软硬件综合的解决方案，在普通计算机上实现了医学对象实时可视化 系统及技术平台4DVew，并在4DView上对显示协议进行了初步设计和实现， 为以上这些问题的解诀寻求到了可能的方案。通过在LFX虚拟心脏模型中引入 可视化技术，将该模型从一个数学模型拓展成了物理可视化模型，使得其仿真效 果更为接近真实的人体心脏。最后，在4DVew平?更多还原

【Abstract】 To fight with diseases, it is necessary to acquire varieties of anatomical and functional information, which represent the human physiological or abnormal status. Because of the super ability of human to obtain information by vision, in the area of clinical diagnosis, treatment, scientific research and education, etc., it is of great significance to describe the wealthy hidden information of medical objects in visual form. With the evolution of modern medical imaging technologies, the information obtained from human body rum to be more full and accurate, which greatly enriches the content of medical object. Conventionally, these information are viewed as films or digital 2D images, and the observers make analysis and diagnosis by imaging the 3D scene in their brain. So it is very difficult to accurately grasp the physiological or abnormal situation, geometrical characteristics of the object and spatial relationship with surrounding anatomical tissues. With the rapid development of computer technology and scientific computing visualization, it is possible to utilize the wealthy hidden information of medical objects in an illustrative, vivid and effective manner by visualization. Through processing medical objects with spatial property in static or dynamic 3D space, medical object visualization sufficiently illustrates the wealthy hidden information of medical objects in visual form. So it has bright future of application in the above-mentioned area. Study of medical object visualization is one of the hotspot of scientific research in the world currently.Virtual cardiac model provides the basis for study of the forward problem and inverse problem in electrocardiograph, and virtual endoscopy has great advantages over traditional endoscopy because of its non-invasive property, so it is meaningful to study these two medical objects by visualization.In this thesis the main research work is composed of designing and implementing a medical object visualization system and technique platform, and making in-depth visualization study on the two medical objects of virtual cardiac model and virtual endoscopy based on the platform. Specifically: The content and classification of medical object is deeply analyzed and discussed. A survey on medical object visualization is made, which comprises the history, research focus, current status and developing trend of medical object visualization and the research work and application of medical object visualization system. Especially, some fundamental algorithms of medical object visualization are introduced. Aim at the poor real-time problem of current medical object visualization systems, a thorough analysis of system architecture and technique implementation is made on the advanced VTK visualization toolkit softwareand the VolumePro real-time volume rendering hardware. Accordingly, a scheme for medical object visualization system and technique platform to solve the problem is provided, which is based on the integration of VTK and VolumePro. 4DView, which is a general real-time medical object visualization system and technique platform, is designed and implemented. 4DView provides varieties of visualization algorithms, including surface rendering algorithm, such as Marching Cubes, Dividing Cubes, etc., and volume rendering algorithm, such as Ray Casting, Texture Mapping, algorithm used in VolumePro, and so on. Thus, 4DView is able to act as scientific research platform because of its extensible design and implementation. Against the problems of complex interaction and requirement of professional knowledge in medical object visualization system, display protocol is designed and implemented primarily in 4DView, which is a possible scheme to solve those problems. Based on 4DView platform, research on visualization of LFX virtual cardiac model is carried out and primarily completed. The model itself and two key simulation results, Excitation Propagation Map and Body Surface Potential Map, are visualized after preproc更多还原