Spatio‐energetic cross‐talk in photon counting detectors: N × N binning and sub‐pixel masking
Spatio‐energetic cross‐talk in photon counting detectors: N × N binning and sub‐pixel masking
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DOI：
10.1002/mp.13146
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发表时间：
2018-03
期刊：
影响因子：
3.8
通讯作者：
K. Taguchi;K. Stierstorfer;C. Polster;Okkyun Lee;S. Kappler
中科院分区：
文献类型：
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作者：
K. Taguchi;K. Stierstorfer;C. Polster;Okkyun Lee;S. Kappler
较小像素尺寸的x射线光子计数探测器（PCDs）具有以下两种相互冲突的影响。一方面，较小的像素尺寸提高了处理高计数率x射线（即脉冲堆积）的能力，因为每个PCD像素的入射率随着尺寸的减小而降低。另一方面，较小的像素尺寸增加了相邻像素之间串扰和重复计数（或一般的n-元计数）的机会，因为虽然光子产生的相同大小的电子电荷云与PCD尺寸无关，但相对于PCD尺寸的电荷云尺寸随着PCD尺寸的减小而增加。此外，以下两个方面是实际PCD计算机断层扫描系统中的实用配置：N×N-pixel分束和抗散射网格。当n元计数发生时，这些数据在采集后的过程中被分类/添加，数据的方差将大于其平均值。反散射网格可以通过在像素边界附近或在一个像素的宽度内完全阻挡主x射线来消除或减少串扰和n元计数。在这项研究中，我们使用新开发的Photon Counting Toolkit （PcTK version 3.2; https://pctk.jhu.edu）研究了PCD像素大小、N×N-pixel分组和像素掩蔽对软组织对比度可见性的影响。
Smaller pixels sizes of x-ray photon counting detectors (PCDs) have the two conflicting effects as follows. On one hand, smaller pixel sizes improve the ability to handle high count rates of x-rays (i.e., pulse pileups) because incident rates onto each PCD pixel decreases with decreasing the size. On the other hand, smaller pixel sizes increase chances of crosstalk and double-counting (or n-tuple-counting in general) between neighboring pixels, because, while the same size of electron charge cloud generated by a photon is independent of PCD sizes, the charge cloud size relative to the PCD size increases with decreasing the PCD size. In addition, the following two aspects are practical configurations in actual PCD computed tomography systems: N×N-pixel binning and anti-scatter grids. When n-tuple-counting occurs and those data are binned/added during post-acquisition process, the variance of the data will be larger than its mean. The anti-scatter grids may eliminate or decrease the cross-talk and n-tuple-counting by blocking primary x-rays near pixel boundaries or for the width of one pixel entirely. In this study, we studied the effects of PCD pixel sizes, N×N-pixel binning, and pixel masking on soft tissue contrast visibility using newly developed Photon Counting Toolkit (PcTK version 3.2; https://pctk.jhu.edu).