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

Background To 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. Objective The 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. Methods In 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. Results It 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. Conclusions In 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.