CT ring artefact suppression via detector calibration: from monochromatic to polychromatic x-ray sources

This study validates the effectiveness of a quantitative detector calibration-originally developed for monochromatic synchrotron radiation-when applied with a polychromatic x-ray source, using both a Hamamatsu CMOS flat panel detector and a WidePIX photon-counting detector with Timepix chips. We show that, despite the energy dependence of the detector response, this calibration is a simple yet robust tool for suppressing computed tomography (CT) ring artefacts in both attenuation contrast and phase contrast CT. Furthermore, we demonstrate that this algorithm is effective even when the ring artefacts are present at a level below the shot noise. This makes it especially useful for data that is filtered in a way that suppresses noise, such as low-dose imaging via phase retrieval.