Abstract: In cone-beam CT (Computed Tomography), because of the cross-talk between detector units caused by X-ray’s scatter (especially high energy X-ray’s scatter in industrial CT), the Signal-to-Noise of detector and the space resolution of reconstructed image are decreased, and the artifacts near the reconstructed image edges are also generated. In this paper, new scan loci and sampled method are used. The heavy metal partitions are fixed on the detector horizontally and vertically between the adjacent detector units. The object is scanned four times, and the projections are sampled four times. This sampled way could decrease the cross-talk of X-ray, and projections are complemented. In this paper, two helical loci are used. A kind of helical loci is named interlaced helix. Another kind of helical loci is parallel helix. After each scan, helical projections are reconstructed using helical FDK algorithm respectively. From the results of simulation experiments, we see the proposed scan loci and sampled method can efficiently reduce the artifacts caused by cross-talk of X-ray’s scatter and helical moving, and keep the space resolution of reconstructed images.

Key words: cross-talk of X-ray, interlaced helix scan, parallel helix scan, computer simulation, Cone-beam helical CT

摘要： 在锥束CT（Computed Tomography）中，由于X射线特别是高能X射线散射引起的探测器通道间的串扰，会降低探测器的信噪比和物体的空间分辨率，同时也会在图像的边缘产生伪影。本文采用了一种有利于机械实现的交错螺旋和平行螺旋的扫描方法，通过在探测器面板上加隔离网来减少射线串扰，并采集四次投影数据，以弥补加隔离网后投影数据的缺损。同时对改进的扫描方法和投影采集方法做了计算机仿真，从仿真实验的结果来看，采用探测器四次采样和交错螺旋或平行螺旋的扫描轨迹，能有效减少因射线串扰引起的伪影，并减少了由螺旋运动引起的伪影。

关键词: 射线串扰, 交错螺旋扫描, 平行螺旋扫描, 计算机仿真, 锥束螺旋CT