高分辨率深硅光子计数传感器的首次实验评估
First Experimental Evaluation of a High-Resolution Deep Silicon Photon-Counting Sensor
AI总结：
本文首次实验评估了一种利用电荷共享实现约1 μm亚像素分辨率的深硅光子计数探测器原型，通过35 keV光束测量验证了Monte-Carlo模拟在电极附近的准确性，并指出未连接电极的影响需进一步研究。
摘要：
目的：当前的光子计数计算机断层扫描探测器由于像素尺寸变小时过度的电荷共享会降低剂量效率和能量分辨率，因此其像素尺寸被限制在约0.3 mm–0.5 mm。在这项工作中，我们展示了一个光子计数探测器原型的测量结果，该探测器利用电荷共享实现了理论上约$1 μ$m量级的亚像素分辨率。本研究的目标是利用测量结果验证我们的Monte-Carlo模拟，以支持进一步开发。方法：我们在MAX IV实验室的DanMAX光束线上，使用35 keV光子束测量了通道响应，并将测量结果与结合电荷输运模型的二维Monte Carlo模拟进行了比较。原型上只有少数通道被连接，以保持较低的引线键合数量。结果：当光束靠近电极时，测量结果与模拟结果总体上吻合良好，但随着光束远离电极，二者出现偏差。随着光束远离电极，感应电荷云信号似乎也呈线性增加。结论：测量结果与模拟结果之间的一致性表明，在光子相互作用靠近电极的情况下，Monte-Carlo模拟能够准确建模探测器的通道响应，同时也表明未连接的电极引入了需要进一步探索的不期望效应。由于相同的Monte-Carlo模拟此前已表明在相似几何结构下可实现约$1 μ$m的分辨率，这些结果令人鼓舞，表明超高分辨率探测器的实现已不遥远。
英文摘要：
Purpose: Current photon-counting computed tomography detectors are limited to a pixel size of around 0.3 mm-0.5 mm due to excessive charge sharing degrading the dose efficiency and energy resolution as the pixels become smaller. In this work, we present measurements of a prototype photon-counting detector that leverages the charge sharing to reach a theoretical sub-pixel resolution in the order of $1 μ$m. The goal of the study is to validate our Monte-Carlo simulation using measurements, enabling further development. Approach: We measure the channel response at the MAX IV Lab, in the DanMAX beamline, with a 35 keV photon beam, and compare the measurements with a 2D Monte Carlo simulation combined with a charge transport model. Only a few channels on the prototype are connected to keep the number of wire bonds low. Results: The measurements agree generally well with the simulations with the beam close to the electrodes but diverge as the beam is moved further away. The induced charge cloud signals also seem to increase linearly as the beam is moved away from the electrodes. Conclusions: The agreement between measurements and simulations indicates that the Monte-Carlo simulation can accurately model the channel response of the detector with the photon interactions close to the electrodes, which indicates that the unconnected electrodes introduce unwanted effects that need to be further explored. With the same Monte-Carlo simulation previously indicating a resolution of around $1 μ$m with similar geometry, the results are promising that an ultra-high resolution detector is not far in the future.
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