转台单侧多次偏置的旋转扫描模式的重建算法

Reconstruction Algorithm for Unilateral Off-Centered Rotation Translation Multi-Scans

在用短的线阵探测器检测大尺寸物体时,人们提出了多种扫描模式,以扩大扫描视野,其中RT(rotation-translation),即旋转加平移扫描模式在工程上较为实用。针对CT转台单侧多次偏置的RT扫描模式,提出了反投影滤波型的重建算法。该算法可以直接重建CT图像,避免了已有算法所需要的数据重排,因而提高了计算效率和图像空间分辨力,使图像重建所需的投影数据减少约一半,从而在相同的旋转和平移次数下有效地扩大了扫描视野。实际CT扫描数据验证了重建算法的正确性。

In order to inspect large objects using short linear-detector array, several kinds of CT multi-scan modes have been developed, of which RT （rotation-translation） scan mode is practical in engineering. In this paper, we propose a backprojection-filtration（ BPF）-based reconstruction algorithm for unilateral off-centered RT multi-scans. The proposed algorithm can reconstruct CT image directly, without data rebinning process which was introduced in the existing algorithms. Hence it is of high computational efficiency and image spatial resolution. In addition, the projection data required in the image reconstruction are nearly half reduced. As a consequence, the field-of-view is enlarged under the same times of rotation and translation. The validity of the proposed algorithm is verified by the real CT data.