Seminars Archive

X-Ray Optics R&D for Biomedical Imaging Application and Machine Diagnostics at the Canadian Light Source

Abstract
The synchrotron provides an ideal environment to develop new approaches to x-ray imaging. At the Canadian Light Source (CLS) there are a number of activities on the Biomedical Imaging and Therapy (BMIT) beamlines directed to advancing the x-ray optics used for wide-field imaging and machine diagnostics. These optics have been used to improve existing methods as well as provide new capabilities not possible before. Optics have been developed to improve and extend K-Edge Subtraction which is a form of functional imaging using either induced or endogenous contrast agents such as iodine, xenon or barium. The optic provides higher imaging intensity due to dramatically improved energy dispersive properties and improved artifact reduction. An extension of this system optimized for energy dispersion has been used to CT image selenium compounds of different oxidation state (speciation) and successfully independently determined the concentration of those compounds (selenite, selenate, and seleno-methionine). The small vertical beam size of a synchrotron limits its usability in some applications. Micro-CT imaging requires multiple scans to produce a full projection, and certain dynamic imaging experiments such as dynamic lung imaging simply are not possible; a larger vertical beam is desirable to enable such experiments which can be accomplished with a long beamline. A beam expander was developed that makes the source appear to originate at distance much farther away. This was accomplished using a double crystal bent Laue monochromator in a non-dispersive divergent geometry. The flux (photons/area/time) has been measured and found to be comparable to the existing flat Bragg DCM in use at BMIT-BM. An improved version preserves the phase and coherence properties of the output beam. Finally, a project that derived from some of the K-Edge Subtraction work has shown that the synchrotron beam position and angle can be determined at a single location in a synchrotron beamline. New work proves that the source size and angular distribution (emittance) can also be found and the system has the sensitivity to measure these four properties (position, angle, size and divergence) of the source for the new high brightness (MBA lattices) synchrotrons.