Experimental Demonstration of Novel Imaging

► Experimental demonstration of novel imaging geometries for x-ray fluorescence computed tomography

X-ray fluorescence computed tomography (XFCT) is an emerging imaging modality that maps the three-dimensional (3D) distribution of elements, generally metals, in ex vivo specimens and potentially in living animals and humans. Many endogenous metals and metal ions, such as Fe, Cu, and Zn, play critical roles in signal transduction and reaction catalysis, while others (Hg, Cd, Pb) are quite toxic even in trace quantities.In the postgenomic era, the new disciplines of metallogenomics, metalloproteomics, and metallomics are emerging for the systematic study of endogenous metals. These disciplines would benefit greatly from the spatially resolved maps of trace-element distribution provided by XFCT. In addition, exogenous metals are often critical components of new in vivo molecular imaging agents: Gd and Mn are used in magnetic resonance imaging agents, and Cd and Au are used in nanoparticle-based optical imaging agents. When applied to tissue samples excised from animal models, for instance, XFCT techniques could provide calibration and subcellular localization information critical for the continued advancement of these technologies.

 

The experimental setup for the preliminary pinhole XFCT study: (a) experimental setup at Argonne APS beam line, (b) schematic of the experimental setup. The detection system consists of an X-ray CCD detector and a multiple pinhole aperture. The translation stage was used to perform a 1D translation of the object through the sheet beam. The rotation stage was used only during the separate process of acquiring a standard transmission CT for attenuation correction.

 

Three views of a 3D rendering of the reconstructed elemental distribution with data acquired in the pinhole geometry. (Red = iron, green = zinc, blue = bromine).

 

G. Fu, L.-J. Meng, P. Eng, M. Newville, P. Vargas, P. LaRiviere, "Experimental demonstration of novel imaging geometries for x-ray fluorescence computed tomography", Medical Physics,  40, issue 6, (2013), http://dx.doi.org/10.1118/1.4801907