University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom.
University College London, GOS Institute of Child Health, London, United Kingdom.
Phys Med Biol. 2024 May 7;69(10):105017. doi: 10.1088/1361-6560/ad4000.
To report on a micro computed tomography (micro-CT) system capable of x-ray phase contrast imaging and of increasing spatial resolution at constant magnification.The micro-CT system implements the edge illumination (EI) method, which relies on two absorbing masks with periodically spaced transmitting apertures in the beam path; these split the beam into an array of beamlets and provide sensitivity to the beamlets' directionality, i.e. refraction. In EI, spatial resolution depends on the width of the beamlets rather than on the source/detector point spread function (PSF), meaning that resolution can be increased by decreasing the mask apertures, without changing the source/detector PSF or the magnification.We have designed a dedicated mask featuring multiple bands with differently sized apertures and used this to demonstrate that resolution is a tuneable parameter in our system, by showing that increasingly small apertures deliver increasingly detailed images. Phase contrast images of a bar pattern-based resolution phantom and a biological sample (a mouse embryo) were obtained at multiple resolutions.The new micro-CT system could find application in areas where phase contrast is already known to provide superior image quality, while the added tuneable resolution functionality could enable more sophisticated analyses in these applications, e.g. by scanning samples at multiple scales.
报告一种能够进行 X 射线相位对比成像并在保持放大率不变的情况下提高空间分辨率的微型计算机断层扫描（micro-CT）系统。该 micro-CT 系统实现了边缘照明（EI）方法，该方法依赖于光束路径中具有周期性间隔的透射孔的两个吸收掩模；这些掩模将光束分裂成一束束，并对光束的方向性（即折射）敏感。在 EI 中，空间分辨率取决于光束的宽度而不是源/探测器点扩展函数（PSF），这意味着可以通过减小掩模孔径来提高分辨率，而不会改变源/探测器 PSF 或放大率。我们设计了一种具有多个不同尺寸孔径带的专用掩模，并使用该掩模证明了分辨率是我们系统中的一个可调参数，因为越来越小的孔径可以提供越来越详细的图像。使用多个分辨率获得了基于条形图案的分辨率体模和生物样本（小鼠胚胎）的相位对比图像。新型 micro-CT 系统可能会在已经知道相位对比可提供更高质量图像的领域中得到应用，而增加的可调分辨率功能可以在这些应用中实现更复杂的分析，例如在多个尺度上扫描样本。
