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Virtual Body Structures

Abstract
     Since the Visible Human (VH) Project data became available, great deal of research and development activity has resulted in innovative information technologies. This foundation makes it now possible to develop a network based, multi-institutional, collaborative virtual environments for real-time teaching of human anatomy and surgery. To meet the challenge of creating the next generation anatomical training tools, we will have to fully leverage the existing VH information technologies.  Our own research in this area is directed towards the development of a library of 3D stereoscopic, haptic, anatomical models (virtual body structures) that can be shared among many research institutions. Models are palpable by using a haptic device and can be visualized stereoscopically in several modes on any PC.

 

In this paper we describe a PC-based tool, which we call VBS, which creates 3D virtual body structures using segmented and classified Visible Human Male data. The segmented data set contains over 1400 body structures. The tool allows the user to select body structures from a slice, region of the body, or any anatomical system, create their 3D models, and then visualize and manipulate them as needed. The standard manipulation capabilities include translucent visualization, interactive rotation, translation, and scaling. The high resolution of the data allows for distinctions between fine anatomical structures such as skin, fat, muscle, cartilage, blood vessels, and bone.

 

The algorithm underlying VBS is described in detail. VBS allows for simultaneous generation of several structures automatically, making it easy to build large 3D models. This is a real advantage over manual systems that create one structure at a time and then merge them into a more complex set of structures. While VBS creates realistic structures (in minutes) with rigid objects and soft tissues such as the liver or kidneys, however, twisted structures such as the intestines or the brain are difficult to produce.  These extended soft-tissue structures are too complex on each slice to connect reliably in the fashion required by our algorithm.

 

One of our goal is to develop methods of evaluating the accuracy of the slices and segmented data. For example, alignment for some slices is off and this produces twists in 3D structures.  Once the evaluating process is in place, we expect to provide feedback for the data, and thus iteratively improve the accuracy of the data for the re-segmentation process. A library of 3D models can be used as canonical structures to automate a part of the segmentation process. It can also enable the development of real-time 3D models for patient specific data, especially when shape analysis and dynamic deformation is incorporated.

 

To make these structures readily accessible, we have designed a Web-based system (Web-VBS) that allows a user at a distant location to download 3D models. For visualization, the user may use a 3D VRML viewer or download a haptic anatomical modeler (HAM) developed in our lab.  The special feature of HAM is that it enables 3D graphical models haptic at a click of a mouse, thus making the models palpable.

 

 
Keywords: 3D Anatomical Structures, algorithm, haptics stereoscopic, Virtual Body Structures (VBS), Web-based VBS

 

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