提高三维ICT成像空间分辨率的扫描方式及其重建算法

对三维工业计算机层析成像(Three Dimensional Industrial Computed Tomography, 3D-ICT)空间分辨率提高技术进行了研究, 提出了一种通过1/4面阵探测器偏置扫描提高成像空间分辨率的锥束3D-ICT扫描方式, 推导了它的基于平行束重排的滤波反投影重建算法.这种方法首先通过面阵探测器中心相对于旋转中心偏移四分之一个探测单元宽度的扫描结构获取二维投影序列, 再对其进行平行束投影重排, 最后利用平行射束特点实现投影水平方向采样频率加倍, 从而提高3D-ICT水平方向的重建空间分辨率.计算机仿真结果证明了该扫描方式和重建算法的正确性.利用该种方法, 可使3D-ICT水平方向重建空间分辨率提高近1倍. 

Scan mode and its reconstruction algorithm for improving spatial resolution of 3D-ICT

Spatial resolution improvement techniques for three dimensional industrial computed tomography(3D-ICT) have been researched in this paper.A cone-beam 3D-ICT scan mode was proposed to improve the spatial resolution by the quarter-detector offset.Its filter back-projection reconstruction algorithm based on the parallel beam rebin principle was deduced.Firstly this method acquires the two dimensional projection sequence by offsetting the detector center a quarter of the detector channel width with respect to the iso-center.Secondly it rebins these projects into parallel data.Finally it doubles the sampling frequency of parallel data with the symmetry between two projection view angles with an angle interval 180°.Computer simulation results prove the correction and the validity of this algorithm.Using this algorithm,the spatial resolution can be improved approximate 100% along the horizontal reconstruction direction.