Here we present a general alignment algorithm for an edge illumination x-ray phase contrast imaging system, which is used with the laboratory systems developed at UCL. It has the flexibility to be used with all current mask designs, and could also be applied to future synchrotron based systems. The algorithm has proved to be robust experimentally, and can be used for the automatization of future commercial systems through automatic alignment and alignment correction.

The aim of this paper is to apply the technique of quantitative x-ray diffraction analysis (QXDA) to trabecular bone tissue to demonstrate that quantitative data of the ratio of bone and marrow volumes within the trabecular region can be obtained. Apparatus has been constructed for measuring energy dispersive x-ray diffraction spectra of human femoral head samples in the diagnostic x-ray energy range. Individual diffraction peaks due to bone and marrow tissue were identified in the measured spectra. The relative intensities of the two peaks within the spectra quantify the relative proportions of the two components, and so the bone to marrow peak ratio is proposed as a parameter which is capable of providing information on the osteoporotic state of trabecular tissue. Preliminary results indicate a significant correlation between this method and the bone density measurement techniques of quantitative computed tomography and Compton scatter densitometry. Results have shown that the use of a synthetically prepared calibration curve can enable absolute measurement of bone or marrow volumes.

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.

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