光CT的扇束投影重排方法及投影几何分析

在工业过程监控中,由于被测物理过程的发生时间短,因此光CT装置将不可能象医学CT那样有充足的时间进行"静态"成像,而是必须进行实时性较高的"动态"成像(或称为流动成像).其制约是光线扫描的投影视角和投影数量都不可能太多.根据这一情况,在医学CT中常用的一些图像重建算法如反投影法、滤波反投影法和投影重排方法都必须加以改进才能引用.为此,本文研究扇束投影重排方法在光学流动成像中的应用可行性,分析其计算方法和步骤,并确定光线扇束结构中的光源个数、扇形张角和探测器个数之间的约束关系,同时也分析了内插精度对图像质量的影响.在数值模拟实验中,将投影重排方法与反投影法的重建图象进行了比较,进一步评判本文方法的图象质量和成像实时性等方面的性能.

Analysis of Fan Beam Projections Recomposition Method and Projection Geometry on Optical Tomography

During the course of monitoring and controlling on industrial process, because physical process changes instantaneously, the optical CT can not take "static" imaging like the medical CT while it must carry out "dynamic" imaging (that is namely flow imaging) , which would lead to not enough projection angles and the number of projections ibr light beam scanning. According to this,the reconstruction algorithms such as Linear Back Projection (LPB),Filter Back Projection (FBP) and projection rearrangement method cannot be applied directly and must be improved. So, in this paper, the application feasibility of fan-beam projection rearrangement method in optical flow imaging is taken into account, the calculation approach is analyzed,and the restriction relations among the number of light sources, number of detectors and fan beam-divergence angle, what interpolation precision affects on image quality is analyzed too. In simulation experiment,by comparing the reconstruction images by LBP and projection rearrangement method, the image quality and real-time performance of the method in this paper are estimated.