Abstract：
Objective.An ultra-fine-pitch deep silicon detector has been developed for clinical photon-counting computed tomography (CT). With a small pixel size of 14 × 650μm2, it has shown potential to reach micrometre spatial resolution in previous simulation studies. A detector prototype with such geometry has been manufactured, and we report on the first experimental evaluation of its count-rate performance.Approach.The measurement was carried out at MAX IV synchrotron laboratory with 35 keV monochromatic x-rays. By inserting tungsten attenuators of 50, 75, 100, 150, 200, 225, 325μm-thicknesses into the beam, the response of the detector to fluence rates from 3.3 × 107to 1.3 × 1011mm-2s-1was characterized.Main results.The measurement result showed that the detector exhibited count rate linearity up to 6.66 × 108mm-2s-1with 13% count loss and was still functional at count rate up to 2.9 × 1010mm-2s-1. A semi-nonparalyzable dead-time model was fitted to the count-rate behaviour of the detector, showing great agreement with the measured data, with an estimated nonparalyzable dead time of 2.9 ns.Significance.This is the first experimental evaluation of the count-rate performance for a deep silicon detector with such small pixel geometry. The results suggest that this type of detector shows the potential to be used at fluence rates encountered in clinical CT with little count loss due to pile-up.
摘要：
Objective.已开发出一种超细间距深硅探测器，用于临床光子计数计算机断层扫描（CT）。具有14×650μm2的小像素尺寸，在先前的模拟研究中已显示出达到微米空间分辨率的潜力。已经制造了具有这种几何形状的探测器原型，我们报告了其计数率性能的首次实验评估。方法。在MAXIV同步加速器实验室用35keV单色X射线进行测量。通过将50、75、100、150、200、225、325μm厚度的钨衰减器插入梁中，表征了检测器对通量率的响应，范围从3.3＊107到1.3＊1011mm-2s-1。主要结果。测量结果表明，该检测器显示出高达6.66*108mm-2s-1的计数率线性，计数损失为13％，并且在高达2.9*1010mm-2s-1的计数率下仍起作用。将半不可瘫痪的死区时间模型拟合到检测器的计数率行为，与实测数据非常吻合，估计不可瘫痪的死时间为2.9ns。意义。这是对具有如此小像素几何形状的深硅检测器的计数率性能的首次实验评估。结果表明，这种类型的探测器显示出在临床CT中遇到的注量率下使用的潜力，而由于堆积而导致的计数损失很小。
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