摘要： 在实际的锥束工业CT中，射线源焦点与探测器中心的水平高度不一致及转心偏移等原因会使获得的实际投影数据发生偏移。如果直接利用实际扫描所得投影数据进行图像重建，得到的图像不清晰。针对以上问题，该文修正Katsevich精确重建算法，以适应偏心的CT成像系统。将投影数据的偏移转换为探测器中心的偏移。在重建过程中，根据探测器的中心偏移量，对滤波线方程、滤波前后的重排和校正以及反投影过程进行修正处理。计算机仿真实验结果证实，该方法可以有效减小投影数据的偏移对重建图像的影响。

关键词: 螺旋锥束CT, 偏移修正, Katsevich 算法, 图像重建, 计算机仿真

Abstract: In Industrial Computerized Tomography(ICT), the projections may deviate due to many factors, such as shifts center of rotation, the inconsistency of the vertical height between the radial focus with the detector center, etc. The reconstructed image will be out of clarity if the practical projections are used directly. The off-center rectification for spiral cone-beam CT based on Katsevich algorithm is investigated. The excursion of the projections is transformed to the excursion of the detector center. In the process of the reconstruction, the filtering line, re-sampling, correction and back-projection are revised respectively according to the detector center excursion. Computer simulation results validate that this method can reduce negative effects of the reconstructed image caused by excursion of the projections.

Key words: spiral cone-beam CT, excursion correction, Katsevich algorithm, image reconstruction, computer simulation

中图分类号: 

• TP391