Feature-Sensitive Ring Artifact Correction for Computed Tomography

In computed tomography (CT) reconstruction, ring artifacts emerge from miscalibrated or defective detector elements. Correction algorithms often introduce diffusion or do not correctly accommodate the behaviour of those artifacts. Miscalibration stems from noise in the detector images during the calibration process and is always present to some degree. We propose a method for correcting ring artifacts from miscalibrated detector elements in the sinogram. Our approach compensates for errors both in the individual gain as well as offset of pixel values. We reduce diffusion by inferring gain and offset information for each pixel from its neighbors only in a subset of all projections. We show that our method is effective at mitigating the shortcomings of purely offset based approaches and approaches using all projections. Furthermore, our method can be efficiently implemented compensating for most overhead times. Under usual circumstances, our method can be implemented to function with no additional time overhead at all.