MARS-CT: Multi-energy (Spectroscopic) Computed Tomography
Using Photon Counting Detectors

6.23.2009

SPEAKER: Anthony Butler, University of Otago Christchurch, the University of Canterbury, and CERN (European Centre for Nuclear Research)

MODERATOR: Kirby Vosburgh, PHD, CIMIT

Video not available.

Forum Summary

When x-ray photons pass through tissue, they are attenuated in a way that is dependent on their energy and on the composition of the tissue sample.  Thus, the attenuation of an x-ray beam varies with photon energy.  Traditional methods of computed tomography integrate across all photon energies when measuring photon density, but spectroscopic techniques measure multiple points on the attenuation-versus-energy curve for each point in the sample being imaged.  The goal of researchers developing MARS-CT (Medipix All Resolution System – Computed Tomography) is to bring spectroscopic x-ray imaging into clinical practice.

MARS imaging makes use of Medipix detectors developed by physicists at the European Organization for Nuclear Research (CERN).  These detectors count individual photons and measure the energy of each photon, providing resolution based on photon energy in addition to spatial and temporal resolution.  This imaging modality promises to provide improved image quality and improved tissue contrast.

Researchers working with Dr. Anthony Butler have created a micro-CT scanner for imaging small animals and pathology samples.  The scientists experimented with contrast agents such as barium and iodine, and they found that MARS-CT enabled them to distinguish these compounds from bone fairly easily.  MARS-CT also makes it possible to remove many artifacts from CT images because artifacts tend to be consistent across all photon energies and can be subtracted out of images.

In the future, the researchers developing MARS-CT hope to incorporate improved Medipix detectors into their system and to create a larger system capable of full-body imaging.  They would also like to explore applications of their imaging modality to the visualization of atheromatous plaques, tissue scaffolds, and high-Z labels. 

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