Three-dimensional Ct Reconstruction Algorithm Optimization

Along with the application of 3D-CT (three Dimensional Computed Tomography) become more and more broad, the investigation of 3D-CT reconstruction-alogrithms have become a hotspot.Among all kinds of reconstruction-algorithms, approximate algorithms are widely used in practice. Among various based in filtered back-projection algorithms, FDK(Feldkamp -Davis-Kress) algorithm is the mainstream methods all the times. FDK algorithm have simple mathematics expressions, and can be easily implemented. The acquired reconstruction effect is good when cone angle is small. The researches of this dissertation are base on FDK algorithm.In the practical application of 3D-CT technology, slow speed and small scan dynamic area are two key problem that baffle the development of 3D-CT technology. The study of this dissertation aim at the two problems, put forward some improved means, acquire nicer effect.The first part of this dissertation analyze the relativity of reconstructed pixel coordinate and relativity of projection address, use these relativities and drive by projection to reconstruct image. This way can greatly improve the speed of reconstruction. When the image is 256 × 256 × 256, speed can be improved about 20 times. At the same time, put forward the way how dispart image for reconstruction and storage.The second part of this dissertation design a new circular trajectory scan mode. This scan mode expand the scan diameter to two times and easy to implement. At the same time, educe the FDK algorithm formula for this scan mode.