In vivo x-ray imaging of the respiratory system using synchrotron sources and a compact light source

Abstract

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. 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.