Coded apertures allow high-energy x-ray phase contrast imaging with laboratory sources

• Published in: Journal of applied physics 2011-07, Vol.110 (1), p.014906-014906-8
• Main Authors: Ignatyev, K., Munro, P. R. T., Chana, D., Speller, R. D., Olivo, A.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.3605514

This work analyzes the performance of the coded-aperture based x-ray phase contrast imaging approach, showing that it can be used at high x-ray energies with acceptable exposure times. Due to limitations in the used source, we show images acquired at tube voltages of up to 100 kVp, however, no intrinsic reason indicates that the method could not be extended to even higher energies. In particular, we show quantitative agreement between the contrast extracted from the experimental x-ray images and the theoretical one, determined by the behavior of the material's refractive index as a function of energy. This proves that all energies in the used spectrum contribute to the image formation, and also that there are no additional factors affecting image contrast as the x-ray energy is increased. We also discuss the method flexibility by displaying and analyzing the first set of images obtained while varying the relative displacement between coded-aperture sets, which leads to image variations to some extent similar to those observed when changing the crystal angle in analyzer-based imaging. Finally, we discuss the method's possible advantages in terms of simplification of the set-up, scalability, reduced exposure times, and complete achromaticity. We believe this would helpful in applications requiring the imaging of highly absorbing samples, e.g., material science and security inspection, and, in the way of example, we demonstrate a possible application in the latter.