Interpolation And Filter Research In Filter Back-projection Image Reconstruction Algorithm

Computerized Tomography is refered to as CT, that is computed tomography imaging technology, and it is the imaging technology of reconstruction imaging objects in cross-section of information from different angles of the scanning projection J. Radon proposed the well-known Radon transform in 1917, and the theory of CT has become an important basis for CT reconstruction. At present, the main method of image reconstruction is divided into two categories: analytical method and iterative method. In this paper, filter back-projection method is the first method, and it is a more mature CT reconstruction algorithm, and it is also the first successful commercial applications of the algorithm. This algorithm is so business that major companies and research institutions in the core of this algorithm - interpolation function and reconstruction filter. Therefore the units and individuals who want to enter the ways, it is necessary to systematically study that algorithm, in particular the choice of interpolation function and the design of the reconstruction filter.The main contents of this paper are as follows:1. We use the interpolation of many characteristic points to improve the fan-beam filter back-projection reconstruction algorithm. This method adopt interpolation through many characteristic points, so that the reconstruction can get more information from the projection, and then take the average value of the information ,and final we get the pixel gray value of reconstruction . This method of image reconstruction get a more precise internal information of the object's.2. In the actual CT scanning process, the ray is not straight line in the sense of geometry, but has a certain width.In the back-projection process, we study the each pixel within the beam coverage ratio to be weighted back-projection data , then has a precise calculation of the amount of information contained in pixels. And accordingly to improve the parallel-beam back-projection filtering reconstruction algorithms.3. The P-FDK(Rearrange the projection data then get reconstruction) is one algorithm of the extending FDK algorithms. To satisfy the voxel of the artifical division and due to the ralation between the defined voxel in real objects and others close to it .So we give an improved technique for P-FDK algorithm, which is a 3D₆neighborhood P-FDK algorithm. We collect the data through experiment to validate algorithm, the result shows that the improved algorithm is better than traditional algorithms in image quality.4. Reconstruction filter is an important part of back-projection filtering algorithm. This paper based on the R-L and S-L mixed filter, find a new type of mixed filters. It is formed by the R-L filter and a new filter, the new filter is found from the definition and property of the ideal filter. Simulation verification, the new mixed filter way can improve the quality of image reconstruction.This article also briefly introduce the standard FDK algorithm and properties, and methods of introduction of the computer implementation process, the final data collected through the experiment then reconstruct that, we have been got more ideal image reconstruction.