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

Abstract

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. Keywords: Micro-CT; Ring artifact correction; Flat-panel detector; Filtered back-projection; Small animal imaging. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i1.2645 J. Sci. Res. 2 (1), 37-45 (2010)

A comparative evaluation of ring artifacts reduction filters for X-ray computed microtomography images

“…In this study, an implementation in which median filtering of size N HP and N LP , respectively, was used for the intermediate steps. Variations of this approach have been proposed in [8] and [9] including an additional parameter for better isolating the stripes from the structure edges. A preliminary segmentation process is also suggested in [8].…”

Software architecture for multi-bed FDK-based reconstruction in X-ray CT scanners

“…We propose the following approach, following the same idea as in [43,45,47,51]: we divide each oblique sinogram in parts corresponding to a subset of projection angles and correct each part independently. For each part, a low-pass version is obtained by applying a 4-pixel median filter in the radial direction (kernel size was derived experimentally and depends on the expected thickness of the ring artifacts).…”

Complete Ring Artifacts Reduction Procedure for Lab-Based X-ray Nano CT Systems

“…In the field of high-resolution X-ray computed tomography (CT) with a micron and submicron spatial resolution, reconstructed CT data are often affected by severe ring artifacts. They appear as concentric ring-like features superimposed on the imaged scene and are centered on the object’s center of rotation creating either full rings (full scan over 360°) or half rings (half scan over 180°) [ 1 ]. Ring artifacts are mainly caused by imperfect detector pixels, where a perfect pixel’s response should be linearly proportional to the amount of photons incident on the detector.…”

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