螺旋CT图像锥形伪影的模拟与实验

目的研究螺旋CT插值算法引起的锥形伪影的特征。方法根据插值算法和反投影重建基本原理建立重建图像的数学模型,阐明锥形伪影与扫描参数和被扫描物属性的函数关系;采用自制体模在SiemensPlus4扫描仪上进行实验验证。结果理论分析发现,伪影占图像的比重与扫描仪机架旋转1周的进床距离和锥形体模半锥角的正切值成正比,与重建位置的体模半径成反比。体模实验结果与理论分析相符。结论插值算法引起的锥形伪影与扫描参数和被扫描物属性存在确定关系。

Simulation and experimental study of cone artifact in spiral CT

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.