An Efficient Ring Artifact Reduction Method Based on Projection Data for Micro-CT Images

Ring artifacts are very troublesome in a flat-panel based micro computed tomography (micro-CT) since they might severely degrade visibility of the micro-CT images. Unlike ring artifacts in other types of micro-CTs such as image-intensifier based micro-CT, ring artifacts in a flat-panel detector based micro-CT are hardly removable since the sensitivity of the pixel elements in a flat-panel detector is less uniform than in other types of x-ray detectors. The dependence of the ring artifacts on many imaging conditions, such as tube voltage, detector integration time and phantom size, was first investigated. Based on the observation that the ring artifacts are not imaging-condition-invariant in a flat-panel detector based micro-CT, an efficient ring artifact correction method has been developed based on post-processing. In the filtered sinogram, the ring artifact positions are identified and then the defective lines are corrected in the original projection data before the filtered back-projection. Experimental results on capacitor phantom, contrast phantom and bone images verify the efficacy of the proposed method.