An Optimal Design of Collimating Gap Height for Two Dimensional Industrial Computed Tomography Scanning

摘要

A designing method is proposed for the optimal design of collimating gap height in 2D-ICT(Two Dimensional Industrial Computed Tomography). This method is based on the variation of the projection contrast, through computer simulation, the curve of projection contrast versus collimating gap height at different type of modulation transfer function are obtained. At the beginning of the curve, the contrast increases linearly along with the increasing of the collimating gap height. And with the more increasing of the gap height, the projection contrast is close to saturation and the non-linear relation between them is obvious. And then to continue increasing the collimating gap height can't improve the projection contrast. The curve also displays that the higher the cut-off frequency of the imaging system is, the higher the slope of the linear segment of the curve will be, which means that the optimal collimating gap height is narrower at the same contrast value. On the base of the discovery, the author assumes that when the contrast arrives to 0.95 the corresponding collimating gap height is the optimal value, which can be regarded as the guidance of 2D-ICT system design.