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High-Speed X-Ray Fluorescence Computed Tomography

D Vernekohl1*, L Xing1, (1) Stanford university School of Medicine, Stanford, CA


(Sunday, 7/29/2018) 4:00 PM - 4:30 PM

Room: Exhibit Hall | Forum 9

Purpose: X-ray fluorescence computed tomography (XFCT) has been proposed previously for molecular imaging in preclinical and clinical applications. The main advantage of XFCT over other modalities is the ability to detect molecular biomarkers at substantial depth in tissue, while maintaining high spatial resolution. In this study, X-ray focusing devices are utilized to simultaneously increase X-ray flux and imaging resolution. Additionally, a novel silicon drift detector (SDD) is exploited to ef�ciently acquire the XF signal for high sensitivity.

Methods: A polycapillary focusing optic was designed to generate a 2 mm diameter pencil beam with a 10x higher X-ray flux compared to standard collimation. A mouse sized phantom filled with silver contrast agents was translated and rotated with a motorized motion stage along the excitation beam. For the experimental evaluation, the data obtained with the SDD was reconstruction with a maximum likelihood expectation maximization algorithm. The obtained images were analyzed for contrast to noise ratio and the minimal detection threshold was determined.

Results: The XFCT data acquisition could be reduced by several hours. The X-ray source and detector are synergistically enhancing the imaging time and they operate stable over time. The quantitative analysis of the reconstructed images provided exceptional molecular sensitivity for the silver contrast agents and proved the liability and compatibility of the setup and the reconstruction framework.

Conclusion: The increased x-ray flux enabled a reduction in signal integration time and increase in imaging speed.It was presented that tiny amounts of contrast agents can be detected by XFCT within biologically relevant time frames. Our basic measurements emphasize the capability of the novel source and detector technologies to greatly enhance XFCT imaging in the energy regime below 40 keV.


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