A novel scatter correction method for energy-resolving photon-counting detector based CBCT imaging

BackgroundTo generate high-quality CT images for an energy-resolving photon-counting detector (PCD) based cone beam CT (CBCT) system, it is essential to mitigate the scatter shading artifacts.ObjectiveThe aim of this study is to explore the capability of an energy-modulated scatter correction method, named e-Grid, in removing the scatter shading artifacts in energy-resolving PCD CBCT imaging.MethodsIn the e-Grid method, a linear approximation is assumed between the high-energy primary/scatter signals and the low-energy primary/scatter signals acquired from the two energy windows of a PCD. Calibration experiments were conducted to determine the parameters used in the aforementioned signal model. Physical validation experiments with head and abdominal phantoms were performed on a PCD CBCT imaging benchtop system.ResultsIt was found that the e-Grid method could significantly eliminate scatter cupping artifacts in both low-energy and high-energy PCD CBCT imaging for objects with varying dimensions. Quantitatively, results demonstrated that the e-Grid method reduced scatter artifacts by more than 70% in both low-energy and high-energy PCD CBCT images.ConclusionsIn this study, it is demonstrated that the e-Grid scatter correction method has great potential for reducing scatter shading artifacts in energy-resolving PCD CBCT imaging.