Advacam 光子计数、像素化X射线探测器

Journal of Instrumentation-使用基于Timepix3芯片的光子计数探测器提高X射线相衬成像能力信噪比

2022-06-17 11:25:06 Karida
  • 相关产品:Advacam

X 射线相位对比成像提供了一种区分具有相似密度和有效原子序数的材料的方法,使用传统的 X 射线吸收对比很难做到这一点。近年来,已经开发了多种方法来使用非相干实验室源获取 X 射线相位对比图像。单掩模边缘照明设置已被证明能应用于很多应用,它对纵向相干性和掩模对准的限制较宽松,并且能够在单个样本曝光中进行双向相位对比图像。不幸的是,单掩模边缘照明装置的折射灵敏度以及因此的信噪比受到探测器伪影的限制。此外,它需要多次曝光才能进行暗场成像 - 一种能够对小于图像分辨率的微结构进行成像的方法。文章建议在单个掩模成像设置中使用带有 Timepix3 像素读出芯片的 Advapix 探测器,以提高相位对比图像中的信噪比。这是利用 Timepix3 芯片同时获取单光子事件的快速到达时间和超阈值测量的能力来实现的,这使得单个光子的子像素识别成为可能。在本文中,我们证明与传统采集方法相比,使用单光子的亚像素识别可以将信噪比提高至少 67±5%。从而可以显着减少所需的样品剂量。这表明使用 Timepix3 芯片改进 X 射线相衬成像具有很大的潜力。此外结果证明了,在单个掩模边缘照明设置中,使用Timepix3在单个样本曝光中进行暗场成像的可能性。

Virtual subpixel approach for single-mask phase-contrast imaging using Timepix3

X-ray phase contrast imaging provides a method to distinguish materials with similar density and effective atomic number, which otherwise would be difficult using conventional X-ray absorption contrast. In recent years, multiple methods have been developed to acquire X-ray phase contrast images using incoherent laboratory sources. The single mask edge illumination setup has been demonstrated as a possible candidate for large scale applications due to its relaxed restrictions on longitudinal coherence and mask alignment, and for its ability to do bi-directional phase contrast images in a single sample exposure. Unfortunately, the single mask edge illumination setup’s refraction sensitivity, and thereby signal to noise, is limited by detector artifacts. Furthermore, it requires multiple exposures to perform dark-field imaging, a method that enables imaging of micro-structures smaller than the image resolution. We propose using an Advapix detector with Timepix3 pixel-readout chip in a single mask imaging setup to improve signal to noise ratio in phase contrast images. This is achieved using the Timepix3 chip’s ability to simultaneously acquire fast time of arrival and time over threshold measurement of single photon events, which enables sub-pixel identification of individual photons. In this paper, we demonstrate that signal to noise ratio can be improved by at least 67± 5 % using subpixel identification of single photons compared to conventional acquisitions methods. Thereby the required sample dose can be reduced considerably. This shows that there is a great potential in using Timepix3 chip to improve x-ray phase contrast imaging. Further, the results indicate the possibility for dark field imaging in a single sample exposure using Timepix3 in a single mask edge illumination setup.


Dreier, Erik Schou, et al. "Virtual subpixel approach for single-mask phase-contrast imaging using Timepix3." Journal of Instrumentation 14.01 (2019): C01011.