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Investigation of X-Ray Detection Configurations for X-Ray Fluorescence Computed Tomography (XFCT) Imaging of Gold Nanoparticle-Loaded Small Animal-Sized Phantoms: A Monte Carlo Study

M F Ahmed*, L Deng , S Jayarathna , S H Cho , The University of Texas MD Anderson Cancer Center, Houston, TX


(Sunday, 7/14/2019) 4:00 PM - 5:00 PM

Room: Exhibit Hall | Forum 1

Purpose: To investigate different x-ray detection configurations for XFCT imaging of gold nanoparticle (GNP) distribution in small animals/phantoms and analyze their performance in terms of system sensitivity and spatial resolution.

Methods: We designed two different benchtop XFCT systems consisting of cadmium telluride (CdTe) pixelated detectors and collimators: i) a configuration ideally desired for high sensitivity including a detector with large pixels (1 mm × 1 mm) coupled with parallel-hole collimator and ii) a configuration readily implementable using commercially available technologies including a detector with small pixels (0.25 mm × 0.25 mm) coupled with pinhole collimator. The system sensitivity (or GNP detection limit) and spatial resolution were tested using custom-made 5-cm diameter PMMA phantoms containing GNP-loaded regions with different concentrations, size, and spatial distributions. Feasibility of imaging an area larger than the detector size was also tested using different magnifications in the pinhole system.

Results: The narrower the width of GNP regions the lower the system sensitivity (higher detection limit) was observed, regardless of the detection configuration. Owing to photon counting statistics, the system sensitivity for a given size of GNP-loaded region can be improved by using a detector with larger pixels at the expense of spatial resolution. In terms of detector collimation, unlike parallel-hole collimator, pinhole collimator can be used to image an area larger than the detector size at the expense of spatial resolution.

Conclusion: We investigated the effects of detector pixel size and collimation on the sensitivity and spatial resolution of a benchtop XFCT system. While a detector consisting of large pixels and with dimensions larger than the imaging object, if available, would be desirable to achieve good system sensitivity, a small detector with small pixels can in principle be used while achieving comparable sensitivity and spatial resolution via pinhole collimation.

Funding Support, Disclosures, and Conflict of Interest: Supported by NIH/NIBIB R01EB020658


Not Applicable / None Entered.


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