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

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TH-A-207-5 (Thursday, 7/14/2022) 7:30 AM - 8:30 AM [Eastern Time (GMT-4)]

Room 207

Purpose: To investigate 3D XRF imaging capabilities of an experimental benchtop XRF imaging system adopting a commercially available high energy-resolution pixelated CdTe detector system coupled with a custom-designed parallel-hole collimator.

Methods: An experimental benchtop XRF CT (XFCT) system was deployed with a commercially available pixelated detector system, known as High-Energy X-ray Imaging Technology (HEXITEC), adopting a 1-mm-thick CdTe sensor with 80×80 pixels on 250-μm pitch to provide 20mm × 20mm field-of-view. HEXITEC was coupled to a 5-cm thick collimator made of stainless steel containing 7×7 array of 2-mm-diameter parallel-hole apertures with 3-mm septa. A cone-beam of x-rays (125kVp at 24mA), filtered with 1.8-mm Tin, was used to irradiate a 3-cm diameter PMMA phantom containing 1.0, 0.5 and 0.3 wt.% gold nanoparticle (GNP) solutions in three 1.5-cm deep columns. The phantom was at 15-cm from the x-ray source and the detector-collimator system was at 10cm from the phantom orthogonal to the incident beam direction. The 360-degree rotation in 12-degree increment obtained 30 angular projections each at two detector positions. The Compton/XRF spectra were measured for 5s at each angular position. The pixel-level spectra from 10×10 pixels within each 2-mm aperture were added, which provided the net XRF signal. The net XRF signals from horizontal apertures were used to create sinogram. The filtered back projection algorithm was used to reconstruct the XFCT image. All seven slices were stacked, and 3D slicer was used to render the 3D image of the GNP-containing phantom.

Results: The non-uniform distributions of 1.0, 0.5 and 0.3 wt.% GNPs in their respective columns within the 3-cm PMMA phantom were observed from the 3D image.

Conclusion: The 3D distribution of GNPs within the PMMA phantom was obtained within practical timeframe of 5-minutes by using the current benchtop XFCT system adopting a pixelated CdTe detector system with a parallel-hole collimator.

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

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