探测器倾斜的锥束FDK修正重建算法

在锥束工业CT系统中,通常要求射线源焦点、物体旋转中心、平板探测器中心三点在一条直线上,与平板探测器垂直。由于机械的定位误差,探测器定位后会出现一定角度的倾斜现象,如果直接利用平板探测器倾斜后采集的投影数据进行重建,重建结果将会出现偏离,产生伪影。针对该问题,利用系统标定的方法测得探测器倾斜角度,利用机械校正对其进行粗调,利用提出的基于探测器倾斜的FDK修正算法进行微调,经过两次校正可以有效抑制由于平板探测器倾斜造成的伪影,通过实验验证了该方法的可行性。

Correction FDK reconstruction algorithm for cone beam CT with tilted detector

In the system of cone beam CT, it is required to have source focus, the center of objects and the center of flat detector collin- ear. The line should be vertical to the fiat detector. However, due to a positioning error of the machines, the detector might be tilted with a few angles. If directly using the data collected from a tilted flat detector to reconstruction, the result will be wrong, and an artifact might be brought out. In solving this problem, the method measures tilt angle of detector by system calibration and roughly adjusts the angle by mechanical correction, and uses the proposed FDK-based detector tilt correction algorithm to fine-tune, and after two correc- tion can effectively suppress the flat probe due to artifacts. Through the experimental results this method is verified the feasibility.