Research On Cone Beam XCT Reconstruction Algorithm Based On Flat Panel Detector

Computed tomography technology refers to measure and obtain the cross-section of objectfrom different ray projection angles. And the features of cone-beam CT include scanningspeed、high image resolution、high radiation use efficiency, and cone beam CT has becameresearch focus and developing direction. According to the features of the collected projectiondata of flat panel detector, firstly，the thesis discusses the principle of X-Ray imaging;secondly, this article discusses elaborates the reconstruction principles and algorithms oftwo-dimensional equidistant fan-beam CT and three-dimensional cone-beam CT; lastly ,thepaper research the reconstruction filter of CT and remove the ring artifacts of industry CT.The research of this paper divides into three parts：1. The article discuss the Radon transform and explain in detail the concrete form oftwo dimensional and three Radon transform in image reconstruction ; at the same time forcentral slice theorem make the preliminary interpretation. Based on Radon transform andcentral slice theorem, this paper derive and analyze the filter back-projection frame workalgorithm and equidistant fan-beam CT reconstruction algorithm .2. This article research the design of CT reconstruction filter .By analyzing thedefinition of CT reconstruction filter ,it derive a new filter ;By comparison with R-L filter S-Lfilter cosine filter and RL-SL mix filter ,it finds the reconstruction results closed to theoriginal image.3. It derive the FDK reconstruction algorithm of circular trajectory cone beam CT andanalyze the error of this algorithm .By modifying the weighting factor ,it reduce the effect ofreconstruction results because of the limit of cone angle .In order to remove the CT ring artifacts ,which is caused by the defect of flat panel detector pixel , the article firstly analyzethe feature of ring artifacts ,then propose method of polar coordinate and the method of sinecorrection ,which remove the ring artifacts of reconstructed image ideally .