Multi-material Finite Element Modeling Based On The Medical Images

With the rapid development of biomechanical simulation system, the result of medical simulation is demanded similar to the real human body not only in topology but also in physical characteristics. However, CT, MRI and other medical images can hardly be applied in quantitative analysis of the simulation system including the computation of physical parameters. Therefore, a simulation and modeling method based on medical images is needed for the analysis of biomechanical simulation.Our group has done some basic research on the finite element modeling based on the medical images. The finite element model (FEM) of single material organization can be built. But in practical application, analysis of the interaction between the different organizations is often needed. Therefore,our emphases is on the building of multi-material FEM.The main content of this research is to build a multi-material FEM from the medical images. Firstly, the original slice data would be converted to volume data for the three-dimensional visualization and processing. The shape and structure of complex medical objects can be shown by the method of volume rendering. Using the proper 3D segmentation algorithms and point selection in the scene, we can achieve several interested objects which are marked in different values. Through the multi-material filter, the marked results will be processed and combined together into a 3D multi-material solid model. We extracted the iso-surfaces of every material solid and the common surface between them according to the marked values. Then the surface model of multi-material can be gotten. Finally, the FEM with coupled surface was built from the surface model.A large number of image processing algorithms are involved in the modeling process. For the aim of avoiding the re-development of basic algorithms, VTK (Visualization Toolkit) and ITK (Insight Segmentation and Registration Toolkit) which are the popular developing kits nowadays are used in the image processing and visualization.In this paper, after researching the visualization, segmentation, reconstruction and the finite element modeling methods of three-dimensional data, we have developed a multi-material finite modeling software. The software has a friendly user interface and operating environment, and has the function of reading, cutting, segmentation, reconstruction, visualization, surface mesh modeling and outputting.