Abstract
Near-field X-ray speckle tracking has been used in phase-contrast imaging and tomography as an emerging technique, providing higher contrast images than traditional absorption radiography. Most reported methods use sandpaper or membrane filters as speckle generators and digital image cross-correlation for phase reconstruction, which has either limited resolution or requires a large number of position scanning steps. Recently, we have proposed a novel coded-mask-based multi-contrast imaging (CMMI) technique for single-shot measurement with superior performance in efficiency and resolution compared with other single-shot methods. We present here a scanning CMMI method for the ultimate imaging resolution and phase sensitivity by using a coded mask as a high-contrast speckle generator, the flexible scanning mode, the adaption of advanced maximum-likelihood optimization to scanning data, and the multi-resolution analysis. Scanning CMMI can outperform other speckle-based imaging methods, such as X-ray speckle vector tracking, providing higher quality absorption, phase, and dark-field images with fewer scanning steps. Scanning CMMI is also successfully demonstrated in multi-contrast tomography, showing great potentials in high-resolution full-field imaging applications, such as in vivo biomedical imaging.
Highlights
Hard X-ray imaging has played an essential role in modern material, biomedical, and physical research
As one of the foremost imaging techniques, computed tomography (CT) has been widely used in visualizing biological tissue with three-dimensional information owing to the large penetration depth and non-destructive property of hard X-rays
Various phase-contrast imaging methods have been developed, such as propagationbased techniques [2], grating interferometry [3,4,5,6], and speckle tracking [7,8,9,10]. Among these methods, grating interferometry and speckle tracking have been used in various applications, such as phase-contrast and dark-field imaging, and tomography, wavefront sensing, and at-wavelength metrology [11,12,13,14,15,16,17,18,19,20] due to their quantitative measurements of absorption, phase, and dark-field signals
Summary
Hard X-ray imaging has played an essential role in modern material, biomedical, and physical research. As one of the foremost imaging techniques, computed tomography (CT) has been widely used in visualizing biological tissue with three-dimensional information owing to the large penetration depth and non-destructive property of hard X-rays. Since X-rays are much more sensitive to the sample phase than absorption, phase-contrast imaging and tomography have generated increased interest in studying biological samples, especially soft tissues [1]. Various phase-contrast imaging methods have been developed, such as propagationbased techniques [2], grating interferometry [3,4,5,6], and speckle tracking [7,8,9,10]. Speckle tracking has better spatial resolution and phase sensitivity, and has a more flexible implementation, allowing a wider range of applications
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