Driving Up the Cost of Clean Air

Background: Despite advances in imaging techniques, real-time visualization of the structure and dynamics of tissues and organs inside small living animals has remained elusive. Recently, we have been using synchrotron x-rays to visualize the internal anatomy of millimeter-sized opaque, living animals. This technique takes advantage of partially-coherent x-rays and diffraction to enable clear visualization of internal soft tissue not viewable via conventional absorption radiography. However, because higher quality images require greater x-ray fluxes, there exists an inherent tradeoff between image quality and tissue damage. Results: We evaluated the tradeoff between image quality and harm to the animal by determining the impact of targeted synchrotron x-rays on insect physiology, behavior and survival. Using 25 keV x-rays at a flux density of 80 μW/mm-2, high quality video-rate images can be obtained without major detrimental effects on the insects for multiple minutes, a duration sufficient for many physiological studies. At this setting, insects do not heat up. Additionally, we demonstrate the range of uses of synchrotron phase-contrast imaging by showing high-resolution images of internal anatomy and observations of labeled food movement during ingestion and digestion. Conclusion: Synchrotron x-ray phase contrast imaging has the potential to revolutionize the study of physiology and internal biomechanics in small animals. This is the only generally applicable technique that has the necessary spatial and temporal resolutions, penetrating power, and sensitivity to soft tissue that is required to visualize the internal physiology of living animals on the scale from millimeters to microns. Background The ability to visualize the internal anatomy of living animals is fundamental to our understanding of biology and medicine. Although imaging systems for respiratory, circulatory and musculoskeletal systems are available for large animals, real-time visualization of the internal processes of small animals has been limited by scaling factors and imaging technology. In order to visualize internal physiological mechanisms of millimeter-sized animals in real-time, a probe must have the following features: (1) Published: 1 March 2007 BMC Biology 2007, 5:6 doi:10.1186/1741-7007-5-6 Received: 28 January 2007 Accepted: 1 March 2007 This article is available from: http://www.biomedcentral.com/1741-7007/5/6 © 2007 Socha et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.