Photon-counting detectors provide several potential advantages in biomedical x-ray imaging including fast and readout noise free data acquisition, sharp pixel response, and high dynamic range. Grating-based phase-contrast imaging is a biomedical imaging method, which delivers high soft-tissue contrast and strongly benefits from photon-counting properties. However, silicon sensors commonly used in photon-counting detectors have low quantum efficiency for mid- to high-energies, which limits high throughput capabilities when combined with grating-based phase contrast imaging. In this work, we characterize a newly developed photon-counting prototype detector with a gallium arsenide sensor, which enables imaging with higher quantum efficiency, and compare it with a silicon-based photon-counting and a scintillation-based charge integrating detector. In detail, we calculated the detective quantum efficiency (DQE) of all three detectors based on the experimentally measured modulation transfer function, noise power spectrum, and photon fluence. In addition, the DQEs were determined for two different spectra, namely, for a 28 kVp and a 50 kVp molybdenum spectrum. Among all tested detectors, the gallium arsenide prototype showed the highest DQE values for both x-ray spectra. Moreover, other than the comparison based on the DQE, we measured an ex vivo murine sample to assess the benefit using this detector for grating-based phase contrast computed tomography. Compared to the scintillation-based detector, the prototype revealed higher resolving power with an equal signal-to-noise ratio in the grating-based phase contrast computed tomography experiment.

中文翻译：

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GaAs光子计数探测器的生物医学X射线成像：比较研究

光子计数检测器在生物医学X射线成像中提供了多个潜在优势，包括快速和无噪声读出的数据采集，清晰的像素响应和高动态范围。基于光栅的相衬成像是一种生物医学成像方法，可提供高的软组织对比度，并从光子计数特性中受益匪浅。但是，光子计数探测器中常用的硅传感器对中至高能量的量子效率较低，这在与基于光栅的相衬成像结合使用时会限制高吞吐能力。在这项工作中，我们表征了一个新开发的带有砷化镓传感器的光子计数原型探测器，该探测器能够实现更高的量子效率，并将其与基于硅的光子计数和基于闪烁的电荷积分探测器进行比较。详细地，我们根据实验测量的调制传递函数，噪声功率谱和光子注量计算了所有三个探测器的探测量子效率（DQE）。此外，针对两个不同的光谱（即28 kVp和50 kVp钼光谱）确定了DQE。在所有测试过的探测器中，砷化镓原型在两个X射线光谱中均显示出最高的DQE值。此外，除了基于DQE的比较之外，我们还测量了 砷化镓原型在两个X射线光谱中均显示出最高的DQE值。此外，除了基于DQE的比较之外，我们还测量了 砷化镓原型在两个X射线光谱中均显示出最高的DQE值。此外，除了基于DQE的比较之外，我们还测量了离体鼠样品以评估使用该检测器进行基于光栅的相衬计算机断层扫描的益处。与基于闪烁的探测器相比，该原型在基于光栅的相衬计算机断层扫描实验中显示出更高的分辨能力，且具有相同的信噪比。