Research On The Precision Of Reconstruction Of CT Filter Back Projection Algorithm

The cone beam CT has been widely used in practice because of its advantages such as high radiation efficiency,short scanning time and high resolution.The filtered back projection algorithm of cone beam CT is widely used because of its simple mathematical form and easy implementation.However,due to the limitation of practical application coditions,with the decrease of scanning radius,the cone angle increases,and the quality of reconstruction decreases.Based on this problem,the main contents of this paper are as follows:Firstly,we study the effect to reconstruction accuracy of fan-beam FBP algorithm from the scanning radius of the ima ging system,the experimental results show that the reconstruction quality is better with the larger scan radius;and study the effect to reconstruction accuracy from the weighting function,and the experimental results show that the constant weighting causes lager errors than the general weighting.At the same time,the above conclusions are extended to the cone-beam FDK algorithm.The PFDK is the one algorithm of the extending FDK algorithm.Artefacts in images reconstructed by the FDK algorithm deteriorate with increasing cone angle,to solve this problem,a three-dimensional weighted PFDK algorithm for image reconstruction is presented in this paper,Simultaneously studying the effect to quality of reconstruction image from different interpolation interval in the radial direction,we compare the reconstructed results of using the total number of three different interpolation(interpolation interval are 1 unit,0.5 units,0.25 units respectively).The experimental results s howed that the impact of the cone angle can be effectively reduced by the given algorithm,and we can get satisfactory reconstruction when using two times the total number of interpolation.