Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Med Phys. 2021 Oct;48(10):6508-6523. doi: 10.1002/mp.15241. Epub 2021 Oct 11.
Advances in X-ray phase-contrast imaging can obtain excellent soft-tissue contrast of phase-shift, attenuation, and small-angle scatter. Here, we present fringe patterns for different design parameters of X-ray bi-prism interferometry imaging systems. Our aim is to develop bi-prism interferometry imaging systems with excellent polychromatic performance that produce high-contrast fringes with spatially incoherent X-ray illumination. We also introduce a novel X-ray tube design that uses temporal multiplexing to provide simultaneous virtual "electronic phase stepping" that replace "mechanical phase stepping" popular with grating-based interferometry setups.
In our investigation, we develop expressions for the irradiance distribution pattern of a bi-prism interferometer composed of multiple point sources and multiple bi-prisms. These expressions are used to plot fringe patterns for X-ray design parameters, including size of point source, number of point sources, and point source separation, and bi-prism design parameters including material, angle, number of bi-prisms, period, and bi-prism array to X-ray source and detector distances.
Results show that the fringe patterns for a bi-prism interferometry system are not longitudinally periodic as with grating interferometers that produce a Talbot-Lau carpet. It is also shown that at 59 keV X-rays the bi-prism material should be something comparable to nickel to obtain reasonable fringe visibility.
The irradiance distribution pattern demonstrates that bi-prism interferometry may provide comparable or improved fringe visibility to that of gratings. Special care is given to present our findings within the context of previous advancements. A single-shot image acquisition approach using a temporal multiplexed, high-power X-ray source provides virtual electronic phase stepping without focal spot sweeping. This provides multiple images, each at the same exposure and the same projection view, from different fringe locations that allow one to derive the attenuation, phase, and dark-field images of the sample without mechanical phase stepping of a grating.
X 射线相衬成像技术的进步可以获得出色的相移、衰减和小角度散射的软组织对比度。在这里，我们展示了不同 X 射线双棱镜干涉成像系统设计参数的条纹图案。我们的目标是开发具有出色多色性能的双棱镜干涉成像系统，该系统使用非相干 X 射线照明产生高对比度的条纹。我们还介绍了一种新颖的 X 射线管设计，该设计使用时间复用技术提供虚拟“电子相移”，以替代基于光栅的干涉仪设置中流行的“机械相移”。
在我们的研究中，我们开发了由多个点源和多个双棱镜组成的双棱镜干涉仪的辐照度分布模式表达式。这些表达式用于绘制 X 射线设计参数的条纹图案，包括点源大小、点源数量、点源分离以及双棱镜设计参数，包括材料、角度、双棱镜数量、周期和双棱镜阵列到 X 射线源和探测器的距离。
结果表明，双棱镜干涉仪系统的条纹图案不像产生泰伯-劳地毯的光栅干涉仪那样具有纵向周期性。还表明，在 59keV X 射线下，双棱镜材料应该类似于镍，以获得合理的条纹可见度。
辐照度分布模式表明，双棱镜干涉仪可以提供与光栅相当或更好的条纹可见度。特别注意在以前的进展背景下介绍我们的发现。使用时间复用、高功率 X 射线源的单次图像采集方法提供了虚拟电子相移，而无需扫描焦点。这提供了多个图像，每个图像的曝光和投影视图相同，来自不同的条纹位置，允许从不同的条纹位置获取样本的衰减、相位和暗场图像，而无需光栅的机械相移。
