Bright synchrotron x-ray sources enable imaging with short exposure times, and hence in a high-speed image sequence. These x-ray movies can capture not only sample structure, but also how the sample changes with time, how it functions. The use of a synchrotron x-ray source also provides high spatial coherence, which facilitates the capture of not only a conventional attenuation-based x-ray image, but also phase-contrast and dark-field signals. These signals are strongest from air/tissue interfaces, which means that they are particularly useful for examining the respiratory system.
We have performed a range of x-ray imaging studies that look at lung function, airway surface function, inhaled and instilled treatment delivery, and treatment effect in live small animal models [Morgan, 2019]. These have utilized a range of optical set-ups and phase-contrast imaging methods in order to be sensitive to the relevant sample features, and be compatible with high-speed imaging. For example, we have used a grating interferometer to measure how the airsacs in the lung inflate during inhalation, via changes in the dark-field signal [Gradl, 2018], a single-exposure, single-grid set-up to capture changes in the liquid lining of the airways [Morgan, 2015] and propagation-based phase contrast to image clearance of inhaled debris [Donnelley, 2019]. Studies have also utilized a range of analysis methods to extract how the sample features change within a time-sequence of two-dimensional projections or three-dimensional volumes.
While these imaging studies began in large-scale synchrotron facilities, we have recently performed these kinds of studies at an inverse-Compton-based compact synchrotron, the Munich Compact Light Source (MuCLS) [Gradl, 2018b].
1. Morgan, Kaye, et al., “Methods for dynamic synchrotron X-ray imaging of live animals.”, under review 01/2019.
2. Gradl, R., et al. "Dynamic in vivo chest x-ray dark-field imaging in mice." IEEE Transactions on Medical Imaging (2018).
3. Morgan, Kaye S., et al. "In vivo X-ray imaging reveals improved airway surface hydration after a therapy designed for cystic fibrosis." American Journal of Respiratory and Critical Care Medicine 190.4 (2014): 469-472.
4. Donnelley, Martin, et al. "Live-pig-airway surface imaging and whole-pig CT at the Australian Synchrotron Imaging and Medical Beamline." Journal of Synchrotron Radiation 26.1 (2019).
5. Gradl, Regine, et al. "In vivo Dynamic Phase-Contrast X-ray Imaging using a Compact Light Source." Scientific Reports 8.1 (2018b): 6788.
X-rays enable non-invasive and high-resolution imaging that has become central to medical diagnostics and security. While conventional x-ray imaging captures only strongly-attenuating materials like bone or metal, in recent years new x-ray modalities have been developed that can capture weakly-attenuating materials. In particular, variations in x-ray phase can reveal soft tissue structures like the lungs and incoherent scattering of x-rays can describe sub-pixel structures like fine powders.
Most techniques that can capture these image modalities require precision optics to convert the phase and incoherent scattering effects to measurable variations in the image intensity, and use multiple exposures to separate the effects. Recent work has been able to extract the three modalities using a single exposure (enabling dynamic and low-dose imaging) and without the need for precision optics (reducing the cost of a set-up). This is possible using structured x-ray illumination and post-measurement computational analysis. The x-ray illumination can be either a grid-like periodic pattern [1,2], or a completely random pattern, such as the pattern produced when a piece of sandpaper is placed in the x-ray beam . Local shifts in the illumination pattern result from x-ray phase variations, and a ‘blurring-out’ of the illumination pattern indicates the presence of sub-pixel structures that scatter the x-ray light.
This talk will describe these new methods of x-ray imaging, touching on mathematical models that predict the wavefield behavior, methods of computational analysis and applications to biomedical research .
 K. Morgan, T. Petersen, M. Donnelley, et al., Optics Express 24 (2016).
 K. Morgan, P. Modregger, S. Irvine, et al., Optics Letters, 38 (2013).
 K. Morgan, D. Paganin and K. Siu, Applied Physics Letters 100 (2012).
 K. Morgan, M. Donnelley, N. Farrow et al., AJRCCM 190 (2014).
Conference Committee Involvement (1)
X-ray and Neutron Phase Imaging with Gratings
8 September 2015 | Bethesda, Maryland, United States