Sampling and aliasing consequences of quarter-detector offset use in helical CT.
Sampling and aliasing consequences of quarter-detector offset use in helical CT.
复制标题
螺旋 CT 中四分之一探测器偏移使用的采样和混叠后果。
DOI：
10.1109/tmi.2004.826950
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发表时间：
2004
影响因子：
10.6
通讯作者：
Pan,Xiaochuan
中科院分区：
文献类型：
--
作者：
LaRivière,PatrickJ;Pan,Xiaochuan
本文分析了在螺旋CT中采用四分之一探测器偏移（QDO）的采样和混叠后果。QDO通常用于常规CT中，以通过消除数据冗余来减少平面内混叠，从而改善径向采样。在螺旋CT中，利用这些相同的冗余来改进纵向采样，因此使用QDO似乎是不明智的。螺旋CT的两个几何形状的相对优点进行了研究，通过进行多维采样分析的投影空间采样以及傅立叶串扰分析的对象的傅立叶基组件之间的串扰。一个标准的扇束螺旋CT的几何形状和一个假设的平行束CT的几何形状，这有助于照亮更复杂的扇束结果，进行了分析。使用采样分析，发现使用QDO导致与不使用QDO时产生的非常不同的频谱平铺。然而，由于在实践中出现的投影数据谱的基本支撑的形状，两种配置导致非常相似或相同量的谱重叠。这种观点也预测了空间变化的纵向混叠，已观察到在螺旋CT。串扰结果与多维抽样分析结果一致。因此，从混叠和串扰的观点来看，在两种几何形状之间没有发现令人信服的差异。
In this paper, the sampling and aliasing consequences of employing a quarter-detector-offset (QDO) in helical computed tomography (CT) are analyzed. QDO is often used in conventional CT to reduce in-plane aliasing by eliminating data redundancies to improve radial sampling. In helical CT, these same redundancies are exploited to improve longitudinal sampling and so it might seem ill-advised to employ QDO. The relative merit of the two geometries for helical CT is studied by conducting a multidimensional sampling analysis of projection-space sampling as well as a Fourier crosstalk analysis of crosstalk among the object's Fourier basis components. Both a standard fanbeam helical CT geometry and a hypothetical parallel-beam CT geometry, which helps illuminate the more complicated fanbeam results, are analyzed. Using the sampling analysis, it was found that the use of QDO leads to very different spectral tiling than arise when not using QDO. However, due to the shape of the essential support of the projection data spectra that arises in practice, both configurations lead to very similar or identical amounts of spectral overlap. This perspective also predicts the spatially variant longitudinal aliasing that has been observed in helical CT. The crosstalk results were consistent with those of the multidimensional sampling analysis. Thus, from the standpoint of aliasing and crosstalk, no compelling difference is found between the two geometries.