PhD position: Rapid x-ray phase and dark field imaging

The honours project will involve measuring and quantifying these ‘phase-contrast’ and ‘dark-field’ signals captured with these methods, specifically when resolved over time. There are opportunities for computational modelling to elucidate the imaging process, experimental implementation on various x-ray sources and numerical analysis of the resulting images.  Depending on the preferences of the student, the project could also look at incorporating new algorithms [5] into the image analysis code.

X-ray imaging has become an essential tool in the medical field, but conventional absorption methods are still limited in their ability to differentiate between different types of soft tissue. Various methods of phase-contrast x-ray imaging enable visualisation of soft tissue by taking advantage of the changes in the direction of x-ray propagation [1].    In addition, a ‘dark field’ signal can be collected that maps scattering by structures that are too small to resolve directly, like the air sacs in the lungs or cracks in manufactured parts [1].  These image modalities are already being applied in biomedical research [2].    However, many of these methods require multiple images to reconstruct the phase or dark-field images, which is an obstacle when imaging breathing, moving subjects or where the total imaging time should not be too long (e.g. airport security).    Therefore, we are developing methods that either work with only a single exposure [3] or that carefully time image capture to match sample/patient movement [4].

References

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[1] Marco Endrizzi, “Phase contrast x-ray imaging”, Nuclear Inst. And Methods in Physics Research A (2017).

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[2] PhysicsWorld – “Making the invisible visible”

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[3] Kaye Morgan, Timothy Petersen, Martin Donnelley, Nigel Farrow, David Parsons and David Paganin, “Capturing and visualizing transient x-ray wavefront topological features by single-grid phase imaging”, Opt. Express 24 (2016).

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[4] R. Gradl et al. – Dynamic in vivo chest x-ray dark-field imaging in mice. IEEE transactions on medical imaging, 38(2), pp.649-656 –

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[5] K. S. Morgan and D. M. Paganin, 2019. – Applying the Fokker–Planck equation to grating-based x-ray phase and dark-field imaging. Scientific reports, 9(1), pp.1-14. –

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