Geometric artifacts correction of equiangular fan-beam industrial CT system

To address the issue of geometric artifacts in equiangular fan-beam industrial computed tomography (CT) systems, this paper proposes a projection sinogram-based method for correcting these artifacts. Firstly, we discuss the formation mechanism of geometric artifacts in equiangular fan-beam industrial CT system when there is geometric deviation. Secondly, we establish a geometric model that incorporates these deviations and mathematically describe the projected position curve of a point within the plane. Subsequently, we use a needle gauge as a surrogate for the point, and fit the curve in the projection sinusoidal graph obtained from scanning the needle gauge to calibrate the geometric deviations. Finally, we introduce the calibrated geometric deviations into the filtered back projection (FBP) algorithm to achieve more accurate reconstructed images. The proposed method precisely calibrates geometrical deviations in the equiangular fan-beam industrial computed tomography (CT) system and effectively eliminates geometric artifacts in the reconstructed CT images, this is demonstrated by simulation and practical experiment. This method has also been successfully applied in engineering practice.