Virtual Endoscopy's Research And Application

VE(Virtual Endoscopy) is a new special technique which developed quickly these years. It is an integration of computer technique, computer graphics, computer image processing and virtual reality, and it is an application of medical virtual reality. Contrary to the optical endoscopy, VE does't put de endoscopy into the body , but use computer processing of 3D datasets to create simulated views of specific organs similar or equivalent to those produced by standard endoscopic procedures,so we can observe the pathological findings on the computer. The patients who need physical examination only need to make a CT or MRI scan to get the slices, then we can use the slice data to build the models of apparatus on the computer. VE works with the models. For the patients ,VE is painless. For the hospital ,VE also reduce the cost of the examines. Just because of these merits, VE is one of the most promising medical applications.This article research into the virtual endoscopy technique First, DICOM file is analyzed. DICOM file is widely applied in CT, MRI and PACS systems. After getting the information from DICOM files, the 3D reconstruction could be going on. Then, some 3D reconstructed algorithms based on surface rendering algorithm are introduced, and the realization process of Marching Cube algorithm is addressed briefly.Secondly, we introducing the related knowledge of Virtual Endoscopy, including the development of the VE, the theory of the VE, the process of carrying out and the approaches of each step. Path programming is a most important technique of VE. We discussed this part in detail. The path programming including three parts .First ,translating images into the binary digital images, second, skeletonization, and last, path-smoothing. The skeletonization algorithm is the core. Its significance is extracted the centerline of the tube and the camera will move along the centerline to get the observation. So the speed and accuracy of skeletonization algorithms affects the whole system's utility.This paper describes several kinds of skeletonization algorithm and optimize the topology thinning algorithm. Topology thinning algorithm is an effective method to getting the skeleton. This method is simple and the results are accuracy. But it is a time-consuming algorithm. Usually.the data base of medicine is very large, which seriously influence the practicality of the algorithm. This paper proposed several improvements to reduce the time-consuming. The improved algorithm works better and the experiments show that it can get the centerline rapidly and stably.Finally, practical path-smoothing algorithm based on NURBS is given since image jumping often occurs when flying along the result of skeletonization. Physical meaning of weight is uncovered and then theoretic evidence is provided to modify curve shape by using weight effectively.