Wang Jinghui, Chen Linchuan, Persson Mats, Rajbhandary Paurakh L, Kandlakunta Praneeth, Carini Gabriella, Fahrig Rebecca
J. Wang was with the Department of Radiology, Stanford University, Stanford, CA 94305 USA. He is now with the Department of Radiation Oncology, Stanford University, Stanford, CA 94305 USA.
L. Chen was with the Department of Computer Science and Engineering, The Ohio State University, Columbus OH 43210 USA. He is now with Google, 1600 Amphitheatre Parkway, Mountain View, CA 94043 USA.
IEEE Trans Nucl Sci. 2019 Jun;66(6):960-968. doi: 10.1109/TNS.2019.2917144. Epub 2019 May 15.
Due to pulse pileup, photon counting detectors (PCDs) suffer from count loss and energy distortion when operating in high count rate environments. In this paper, we studied the pulse pileup of a double-sided silicon strip detector (DSSSD) to evaluate its potential application in a mammography system. We analyzed the pulse pileup using pulses of varied shapes, where the shape of the pulse depends on the location of photon interaction within the detector. To obtain the shaped pulses, first, transient currents for photons interacting at different locations were simulated using a Technology Computer-Aided Design (TCAD) software. Next, the currents were shaped by a CR-RC shaping circuit, calculated using Simulink. After obtaining these pulses, both the different orders of pileup and the energy spectrum were calculated by taking into account the following two factors: 1) spatial distribution of photon interactions within the detector, and 2) time interval distribution between successive photons under a given photon flux. We found that for a DSSSD with thickness of 300 m, pitch of 25 m and strip length of 1 cm, under a bias voltage of 50 V, the variable pulse shape model predicts the fraction free of pileup can be > 90 % under a photon flux of 3.75 Mcps/mm. The double-sided silicon-strip detector is a promising candidate for digital mammography applications.
由于脉冲堆积，光子计数探测器（PCD）在高计数率环境下工作时会出现计数损失和能量畸变。在本文中，我们研究了双面硅条探测器（DSSSD）的脉冲堆积情况，以评估其在乳腺摄影系统中的潜在应用。我们使用不同形状的脉冲来分析脉冲堆积，其中脉冲形状取决于探测器内光子相互作用的位置。为了获得成形脉冲，首先，使用技术计算机辅助设计（TCAD）软件模拟了在不同位置相互作用的光子的瞬态电流。接下来，通过使用Simulink计算的CR-RC成形电路对电流进行成形。获得这些脉冲后，通过考虑以下两个因素来计算不同阶次的堆积和能谱：1）探测器内光子相互作用的空间分布，以及2）在给定光子通量下连续光子之间的时间间隔分布。我们发现，对于厚度为300μm、间距为25μm且条带长度为1cm的DSSSD，在50V偏置电压下，可变脉冲形状模型预测在3.75 Mcps/mm的光子通量下，无堆积的比例可以>90%。双面硅条探测器是数字乳腺摄影应用的一个有前途的候选者。
