The polychromatic retrigger: a new tool to mitigate pileup in spectral photon-counting computed-tomography

IF 1.9 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY
Carlo Amato, Christian Disch, Pietro Zambon
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Abstract

High photon rates, like the ones required in clinical computed tomography, can generate pulse pileup in photon-counting detectors, and in extreme cases induce system paralysis. The instant retrigger technology has been developed by DECTRIS Ltd. to counteract such phenomena, effectively making detectors non-paralyzable. The instant retrigger behavior is regulated by a quantity named retrigger time, which originally was the same for all the energy thresholds of the detector. We developed a new ASIC that features an improved version of the instant retrigger (polychromatic retrigger) that allows different retrigger times for each of the four energy thresholds. In this work, we investigate how this feature can be exploited in computed tomography to mitigate pileup artifacts. Using a Monte Carlo method, we modeled a full computed tomography system with four energy thresholds (20, 50, 70 and 90 keV), and we simulated head scans from low (1×107 cps/mm2) to high (1×109 cps/mm2) photon count rates for different values of the retrigger time. The quality of the resulting images generally degrades when increasing the photon rates (pileup artifacts) and, at the same time, it becomes strongly dependent on the retrigger time. We show how, even at high incoming rates, it is possible to identify for each energy threshold a retrigger time value that restores almost completely the image quality obtained in the low count-rate scenario. The analysis indicates that the higher the energy threshold, the longer the retrigger time has to be set.
多色再触发:减轻光谱光子计数计算机断层成像中堆积现象的新工具
临床计算机断层扫描所需的高光子率会在光子计数探测器中产生脉冲堆积,在极端情况下会导致系统瘫痪。DECTRIS 有限公司开发的瞬时再触发技术可以抵消这种现象,有效地使探测器不再瘫痪。瞬时再触发行为由一个名为再触发时间的量来调节,该量最初对探测器的所有能量阈值都是相同的。我们开发了一种新的 ASIC,它具有改进版的瞬时重触发(多色重触发),允许四个能量阈值中的每个阈值具有不同的重触发时间。在这项工作中,我们研究了如何在计算机断层扫描中利用这一特性来减少堆积伪影。我们使用蒙特卡洛方法,模拟了一个具有四个能量阈值(20、50、70 和 90 keV)的全计算机断层扫描系统,并模拟了从低(1×107 cps/mm2)到高(1×109 cps/mm2)光子计数率的不同再触发时间值的头部扫描。当光子率增加时,得到的图像质量普遍下降(堆积伪影),同时,图像质量与再触发时间密切相关。我们的研究表明,即使在高传入率的情况下,也能为每个能量阈值确定一个重新触发时间值,从而几乎完全恢复在低计数率情况下获得的图像质量。分析表明,能量阈值越高,重触发时间必须设置得越长。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Frontiers in Physics
Frontiers in Physics Mathematics-Mathematical Physics
CiteScore
4.50
自引率
6.50%
发文量
1215
审稿时长
12 weeks
期刊介绍: Frontiers in Physics publishes rigorously peer-reviewed research across the entire field, from experimental, to computational and theoretical physics. This multidisciplinary open-access journal is at the forefront of disseminating and communicating scientific knowledge and impactful discoveries to researchers, academics, engineers and the public worldwide.
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