Detector pose measurement and correction methods for FPD-based cone-beam XCT system

To eliminate the artifacts in computed tomography (CT) images caused by the flat plane detector (FPD) pose error in cone-beam X-ray CT (XCT) testing system, methods of error measurement and correction were proposed. The ellipse fitting method based on the least squares technique was used to get the detector pose error which is essential for projection coordinate establishing and matching with the reconstruction coordinate accurately. The correction method improves the original Feldkamp (FDK) reconstruction algorithm in the calculation of projection address based on the spatial coordinate transformation theory by which the projection address could be calculated correctly. The methods are of less computation consuming and without hardware calibration. The experimental result proves that the methods could eliminate the artifacts effectively and help reconstruct CT image with high accuracy.