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Preliminary Results On Benchtop X-Ray Fluorescence Computed Tomography (XFCT) Imaging of Gold Nanoparticle-Loaded Objects Using a Fully Spectroscopic Pixelated X-Ray Detector

M F Ahmed1*, S Jayarathna1 , L O'Ryan2 , S H Cho1 , (1) The University of Texas MD Anderson Cancer Center, Houston, TX, (2) Quantum Detectors, Ltd., Oxford, UK


(Tuesday, 7/16/2019) 7:30 AM - 9:30 AM

Room: 221AB

Purpose: To experimentally test the feasibility of using a spectroscopic pixelated cadmium telluride (CdTe) detector for benchtop XFCT imaging of a gold nanoparticle (GNP)-loaded small animal-sized phantom.

Methods: We tested the performance of a Hexitec detector (80 × 80 pixels, pixel dimensions of 250 μm × 250 μm × 1 mm, Quantum Detectors, UK) by scanning a GNP-loaded phantom using the 1.8-mm Sn-filtered 125 kVp beam in our experimental benchtop XFCT system. The detector was coupled with a custom-made parallel-hole or pinhole collimator. An in-house algorithm was developed to extract gold K-shell XRF signal from 6400 x-ray spectra scored by the detector per frame. The energy resolution and counting efficiency of the detector were compared with those of a single crystal CdTe detector (5 mm × 5 mm × 1 mm, XR-100T-CdTe; Amptek, USA) exposed to the same incident x-ray beam.

Results: Under the current experimental conditions, the energy resolution of the Hexitec detector was estimated to be ~1 keV-FWHM at 68.8 keV, compared to ~0.7 keV-FWHM for the Amptek detector. The counting efficiency of the Hexitec detector was found ~36% of that of the Amptek detector. Nevertheless, since no detector translation was needed, the Hexitec detector, in comparison with the Amptek detector, allowed >60 times faster imaging of a 2 cm × 2 cm × 2 cm area, while not degrading the detection limit and spatial resolution. Regarding the collimation, better image quality was observed for parallel-hole collimation due to i) better shielding by parallel-hole collimator from scattered photons and leakage of the primary beam and ii) imperfect alignment of pinhole collimator.

Conclusion: While it provided somewhat worse energy resolution and counting efficiency than the Amptek detector, the Hexitec detector allowed an order of magnitude faster XFCT imaging of a GNP-loaded phantom with comparable detection limit and spatial resolution.

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


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