H Moktan*, S Jayarathna, S H Cho, UT MD Anderson Cancer Center, Houston, TX

SU-J-207-4 (Sunday, 7/10/2022) 4:00 PM - 5:00 PM [Eastern Time (GMT-4)]

Room 207

Purpose: To compare the operational characteristics of single crystal and pixelated CdTe detectors coupled with parallel-hole collimators under identical benchtop XRF imaging conditions.

Methods: Commercially available energy-resolving x-ray detectors containing 1-mm thick CdTe as one single crystal (5mm×5mm - Amptek) and a pixelated sensor (80×80 pixels on a 250-μm pitch - HEXITEC) were coupled to 2-mm-aperture parallel-hole collimators and incorporated into an experimental benchtop XRF CT (XFCT) system. A cone-beam of x-rays (125kVp at 24mA), filtered with 1.8mm Tin, was used to irradiate each of 1-cm-diameter cylindrical plastic tubes for 10s. Each plastic tube containing 200-μL of gold nanoparticle (GNP) solution at different concentration was placed at 15-cm from the x-ray source for irradiation. The detector-collimator system was placed at 10-cm from the GNP-containing tubes, orthogonal to the incident beam direction. The Compton/XRF spectra from the GNP-containing tubes were measured using both CdTe detectors. For measurements with the pixelated detector, the per-pixel x-ray spectra from 10×10 pixels corresponding to the 2-mm collimator aperture were added to obtain the final spectra. The final spectra from both detectors were evaluated. The gold Kα1 XRF peak at 68.8keV was fitted with Gaussian distribution to evaluate the energy resolution in FWHM. The net XRF signals were derived from the spectra acquired with different concentrations of GNP solutions and analyzed for the estimation of GNP detection limits achievable from the use of both detectors.

Results: The photon counting efficiency and energy resolution of the pixelated detector system were lower than those of the single crystal detector system, resulting in the worse GNP detection limit of 0.0368wt.% (vs. 0.02wt.% with the single crystal detector).

Conclusion: The single crystal detector was found to perform better than the pixelated detector under the current experimental conditions, in terms of photon counting efficiency, energy resolution, and GNP detection limit.

Funding Support, Disclosures, and Conflict of Interest: Supported by the US National Institutes of Health under the award number R01EB020658

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