Virtual Endoscopy System. Computer-aided Identification

Virtual Endoscopy is an application of virtual reality in modern medicine. It simulates fibre endoscopy by representing the inner surface of hollow organ employing 3D reconstructed CT or MRI data which incorporates the research about Computer Graphics. It has advantage like safety, non-invasion, adapt to vulnerable, infant and extremely narrowed organs which fibre endoscopy not compare to. The complementarity of fibre endoscopy and Virtual Endoscopy is obviously. So, the research of Virtual Endoscopy has high value in clinical diagnosis.The first part in this thesis is the development of the key technology in the VE system, and so is the clinic trial of the VE System. The second and third parts is the research of new direct of the VE: The unfold of the inner surface and the Computer-Aided Detection (CAD) for Virtual Endoscopy.The two key technology of the VE System are: The Auto-extracted centerline and the interaction volume rendering of the VE. For the first technology, we put forward a new method which making use of the distance trasform and maximum-cost spanning tree Algorithm to extract the centerline .This method not only can pick-up the best fly-through path of the 3-D organ, but also,it can deal with the multi-branch object. After impoving some aspect of this method, it can finish the layout of the path quickly and automatically. For the second technology, we put forward a new method of coordinate transformation, which is making use of the parallel processing for the DT field on the first technology to accelerate the image creation. So the interaction of the new VE system is real-time and easy to control, And our clinic trial has prove that.In the research on the inner surface of organ unfolding, we have tried many methods. Because the essence of this problem is a transformation from 3D to 2D, so how to deal with the distortion is the most important. The topological technology is the most correct way to finish this transformation, but the it is not better as the method of visual revise because the doctors want to see the images more like the natural shape in the organs of the patients, not as the flatten shape on a plane with some distortion. On other hand, The result of flatten surface can not suit those case of the narrow organ by pathologic factor. For these reason, the unfold technology can not replace the 3D effect to observe the pathological changes on the inner surface, the only reason to use the unfold technology is to fast look through the inner surface. So the unfold technology is not as important as the CAD technology of the VE, but it still has some meaning to be developed as an assistant way to find the pathological changes.In the research of the CAD, We have tried some classical methods, especially for the auto-detected of the colon polyp. But we want to develop a new way, which can be used into the auto-detected for more pathological changes. We have applied serval pathological templates to fit this condition. The template is picked up from some of clinic VE examine, and the key technology is ICP registration. The ICP Algorithm is used to picking up the new templates and recognizes the pathological changes. The scheme for Detection of Polyps is search all over the entire inner surface of the cavity organ (i.e. colon).For every voxel of the surface ,collect the neighbor voxels of it as a center and compare to the templates by ICP. The candidate region is chosen by the threshold. The clinic trial has proved that the new method can detect the colon polypus and other some pathological changes automatically. We trust that this method have much potential.The final part of this paper, we have indicated some expectation of the VE technology...