Furenlid L R, Clarkson E, Marks D G, Barrett H H
Department of Radiology and Optical Sciences Center, University of Arizona, Tucson, Arizona 85724.
IEEE Nucl Sci Symp Conf Rec (1997). 2000 Aug;47(4):1399-1403. doi: 10.1109/23.872985. Epub 2002 Aug 6.
High-spatial-resolution solid-state detectors being developed for gamma-ray applications benefit from having pixel dimensions substantially smaller than detector slab thickness. This leads to an enhanced possibility of charge partially spreading to neighboring pixels as a result of diffusion (and secondary photon emission) transverse to the drift direction. An undesirable consequence is the effective magnification of the event "size" and the spatial overlap issues which result when two photons are absorbed in close proximity within the integration time of the detector/readout system. In this work, we develop the general statistics of spatial pileup in imaging systems and apply the results to detectors we are developing based on pixellated cadmium zinc telluride (CdZnTe) and a multiplexing application-specific integrated circuit (ASIC) readout. We consider the limitations imposed on total count rate capacity and explore in detail the consequences for the LISTMODE data-acquisition strategy. Algorithms are proposed for identifying and, where possible, resolving overlapping events by maximum-likelihood estimation. The efficacy and noise tolerance of these algorithms will be tested with a combination of simulated and experimental data in future work.
正在为伽马射线应用开发的高空间分辨率固态探测器，受益于其像素尺寸远小于探测器平板厚度。这导致电荷由于横向于漂移方向的扩散（以及二次光子发射）而部分扩散到相邻像素的可能性增加。一个不良后果是事件“大小”的有效放大以及当两个光子在探测器/读出系统的积分时间内被近距离吸收时产生的空间重叠问题。在这项工作中，我们开发了成像系统中空间堆积的一般统计数据，并将结果应用于我们正在基于像素化碲锌镉（CdZnTe）和复用专用集成电路（ASIC）读出开发的探测器。我们考虑了对总计数率容量的限制，并详细探讨了对列表模式数据采集策略的影响。提出了通过最大似然估计来识别并在可能的情况下解决重叠事件的算法。这些算法的有效性和噪声容限将在未来的工作中通过模拟和实验数据的组合进行测试。
