窄角锥束CT的改进扫描方式

Improved scan method for narrow angle cone-beam computed tomography

基于圆形扫描轨道的FDK算法因其机械实现简单、算法效率高,已成为目前主要使用的三维锥束CT重建算法。但在工业CT(ICT)中,当探测器面阵的尺寸较小、射线束的水平张角较小,而待检测的工件较大时,单圆扫描的FDK重建算法受到限制。为解决小尺寸探测器检测大尺寸工件问题,本文研究了一种大步距平移加小分度旋转的扫描方式。与Ⅱ代锥束CT比,这种改进的扫描方式既可以节省扫描时间,数据的冗余量也比较少。仿真实验结果表明,这种改进的扫描方式具有良好的空间分辨率和密度分辨率。

Algorithm proposed by Feldkamp, Davis and Kress （FDK algorithm） is considered the major reconstruction algorithm in 3-D CT, which is based on circular orbit scan and is easy to implement in engineering, and has high efficiency. However, in Industrial Computed Tomography （ICT）, small detector that has small horizontal flare angle can not scan a large workpiece, the application of FDK algorithm based on circular orbit scan is limited. In order to solve the problem of large worlpiece 3 D industrial CT inspection using small detector, a scan method is proposed, which features large ste Ptranslation and small angle rotation. Compared with the 2^nd generation cone-beam CT, this method can save scanning time and reduce data redundancy. Simulation experiment results show that the improved scan method has good space resolution and density resolution.