Research On Cone-beam CT Image Correction

Cone-Beam Volume CT(CBVCT) refers to a technique for imaging all sections of an object using 3D reconstruction algorithms based on a series of X-ray projections collected by a flat panel detector. Owing to the advantages of faster scanning speed. higher spatial resolution and better utilization of X-ray photons compared with traditional 2D CT. cone-beam CT has a broad application perspective in industrial non-destructive testing and medical applications, and has become a hot research topic in the current international CT communities.This paper mainly focuses on research of CT image correction.Among all kinds of reconstruction algorithms for 3D cone-beam CT, FDK algorithm is widely used in practice, because it has simple mathematical expression, and can be easily implemented. The reconstruction effect is acceptable when the cone angle is small enough. However, for FDK algorithm, reconstructed image often suffers from artifacts caused by big cone angle and misaligned scanner geometry of CT system. In this paper, the improved FDK algorithm. TFDK algorithm, is introduced to solve the big cone angle problem. Reconstructed results of both algorithms are compared and analyzed. Besides, a method for calibration of misaligned scanner geometry in cone-beam CT with single-circle orbit is proposed. In this method, a simple phantom is used to estimate a set of parameters that describe the misaligned geometry of CT system. Based on the misaligned parameters, an improved FDK algorithm which can greatly correct the artifacts caused by scanner misalignments is proposed.