(Sunday, 7/14/2019) 4:00 PM - 5:00 PM
Room: 303
Purpose: To validate direct gold L-shell x-ray fluorescence (XRF) imaging results using a tissue-mimicking phantom containing capillary tubes filled with known concentrations of gold nanoparticles (GNPs).
Methods: For GNP-loaded tube construction, capillary tubes made of plastic (diameter ~3 mm, height =1.5 cm) were sealed at one end. The tubes were then filled with GNP solutions of different concentrations and sealed at the other end. For the system calibration, each GNP tube was positioned vertically on a mounting holder and irradiated. The scattered + XRF photon spectrum was recorded by a collimated silicon drift detector (SDD). For a tissue-mimicking phantom construction, the GNP-filled tubes with known concentrations were placed in a “Eâ€? shaped pattern, and sandwiched between three layers of cheese (Ï? ~ 1.12 g/cm³; two for better suspension of the tube and one for additional support). The phantom was positioned vertically so that the SDD faced directly the “Eâ€? shape in one layer of cheese. A full scan of the phantom was performed by translating the SDD horizontally and vertically from the starting position in 1 mm intervals to obtain the photon spectra. Gold L-shell XRF signal was extracted from the detected photon spectrum for each scanning position. XRF signals over the 20 mm x 20 mm area of the phantom were then mapped and converted to GNP concentrations using the calibration curve.
Results: The “E� shape of the phantom was well visible in the XRF image/map and all three arms of “E� were spatially resolved within ~2 mm. The measured GNP concentrations were in good agreement with the known GNP concentrations.
Conclusion: This investigation demonstrated that direct gold L-shell XRF imaging could be used for accurate quantification of both the spatial distribution and the local concentration of GNPs within thin (~ a few millimeter-thick) tissue-like samples.
Funding Support, Disclosures, and Conflict of Interest: Supported by NIH/NIBIB R01EB020658
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