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Improving Paralysis Compensation in Photon Counting Detectors.
IEEE Transactions on Medical Imaging ( IF 10.6 ) Pub Date : 2020-09-02 , DOI: 10.1109/tmi.2020.3019461
Scott S. Hsieh , Kris Iniewski

Photon counting detectors (PCDs) are classically described as being either paralyzable or nonparalyzable. When the PCD is paralyzed, it is no longer sensitive to the detection of additional flux. A recent strategy in PCD design has been to compensate for detector paralysis by embedding specialized paralysis compensation electronics into the application-specific integrated circuit (ASIC). One such compensation mechanism is the pileup trigger, which places an additional energy bin at very high energy that is triggered only during pileup. Another compensation mechanism is the retrigger architecture, which converts a paralyzable PCD into a nonparalyzable PCD. We propose a third mechanism that modifies the retrigger architecture using dedicated secondary counters. We studied the incremental benefit of these three paralysis compensation mechanisms in simulation. We modeled the spectral response using Monte Carlo simulations and then estimated the variance in basis material decomposition of a single pixel using the Cramér-Rao lower bound (CRLB). In the absence of paralysis compensation, noise in basis material images shows sharp increases at moderate flux (near the characteristic count rate) due to contrast inversion and again at high flux. The pileup trigger reduces noise at high flux but does not eliminate contrast inversion. The retrigger architecture eliminates contrast inversion but does not reduce noise at high flux. Our proposed retrigger architecture with dedicated secondary counters reduce noise at both moderate and high flux.

中文翻译:

改善光子计数检测器的瘫痪补偿。

光子计数检测器(PCD)通常被描述为可麻痹的或不可麻痹的。当PCD瘫痪时,它对检测额外的通量不再敏感。PCD设计中的最新策略是通过将专用的瘫痪补偿电子器件嵌入到专用集成电路(ASIC)中来补偿检测器的瘫痪。一种这样的补偿机制是堆积触发器,其将额外的能量箱置于仅在堆积期间被触发的非常高的能量。另一个补偿机制是重新触发架构,该架构将可瘫痪的PCD转换为不可瘫痪的PCD。我们提出了第三种机制,该机制使用专用的辅助计数器来修改重新触发架构。我们在仿真中研究了这三种麻痹补偿机制的增量收益。我们使用蒙特卡洛模拟对光谱响应进行建模,然后使用Cramér-Rao下界(CRLB)估算单个像素的基础材料分解的方差。在没有麻痹补偿的情况下,基础材料图像中的噪声会由于对比度反转而在中等通量下(在特征计数率附近)急剧增加,而在高通量下会再次急剧增加。堆积触发器可降低高通量时的噪声,但不能消除对比度反转。重触发架构消除了对比度反转,但并未降低高通量下的噪声。我们提出的带有专用辅助计数器的重新触发架构可降低中高通量的噪声。我们使用蒙特卡洛模拟对光谱响应进行建模,然后使用Cramér-Rao下界(CRLB)估算单个像素的基础材料分解的方差。在没有麻痹补偿的情况下,基础材料图像中的噪声会由于对比度反转而在中等通量下(在特征计数率附近)急剧增加,而在高通量下会再次急剧增加。堆积触发器可降低高通量时的噪声,但不能消除对比度反转。重触发架构消除了对比度反转,但并未降低高通量下的噪声。我们提出的带有专用辅助计数器的重新触发架构可降低中高通量的噪声。我们使用蒙特卡洛模拟对光谱响应进行建模,然后使用Cramér-Rao下界(CRLB)估算单个像素的基础材料分解的方差。在没有麻痹补偿的情况下,基础材料图像中的噪声会由于对比度反转而在中等通量下(在特征计数率附近)急剧增加,而在高通量下会再次急剧增加。堆积触发器可降低高通量时的噪声,但不能消除对比度反转。重触发架构消除了对比度反转,但并未降低高通量下的噪声。我们提出的带有专用辅助计数器的重新触发架构可降低中高通量的噪声。基础材料图像中的噪声显示由于对比度反转而在中等通量下(在特征计数率附近)急剧增加,而在高通量下又显着增加。堆积触发器可降低高通量时的噪声,但不能消除对比度反转。重触发架构消除了对比度反转,但并未降低高通量下的噪声。我们提出的带有专用辅助计数器的重新触发架构可降低中高通量的噪声。基础材料图像中的噪声显示由于对比度反转而在中等通量下(在特征计数率附近)急剧增加,而在高通量下又显着增加。堆积触发器可降低高通量时的噪声,但不能消除对比度反转。重触发架构消除了对比度反转,但并未降低高通量下的噪声。我们提出的带有专用辅助计数器的重新触发架构可降低中高通量的噪声。
更新日期:2020-09-02
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