Abstract: Objective To study regular patterns of cone artifact resulted from interpolation algorithm of spiral CT.Methods Based on the principle of interpolation algorithm and back-projection reconstruction,a mathematical model of the reconstructed image was established to clarify the relation of the scanning parameters and the characteristics of the scanned object with the cone artifact.Experiments were carried out by a set of acrylic phantoms on siemens plus 4 CT scanners.Results The artifact in the image was directly proportional to the table increment per gantry rotation of the scanner,and was positively correlated to the tangent of half cone-angle and inversely to the radii in the reconstruction plane of the phantom.The theoretical analysis was validated by experimental results.Conclusion The cone artifact is related to the scanning parameters and the characteristics of the scanned object.