Program Information
Improving Lead Detection in Plaster-Of-Paris Bone Phantoms Using a Grazing-Angle X-Ray Fluorescence (GAXRF) Method
S Al-Hamdani , M Gherase , A Huda*, California State University, Fresno, CA
Presentations
WE-RAM1-GePD-I-2 (Wednesday, August 2, 2017) 9:30 AM - 10:00 AM Room: Imaging ePoster Lounge
Purpose: The adverse health effects of human lead (Pb) exposure were studied for the past several decades. Despite decreasing the human Pb exposure by its removal from common chemicals such as paint and gasoline, concerns still remain in developing countries and in children where developmental problems were linked to low Pb blood concentration (<10 μg/dL). About 95% of the human Pb burden is in bone. Therefore, the bone Pb concentration is a better indicator of exposure than blood Pb. In vivo measurements of Pb concentration in tibia bone are performed using a K-shell x-ray fluorescence method that uses the gamma-rays emitted by the Cd-109 radioisotope for Pb excitation. The L-shell x-ray fluorescence (LXRF) is an alternative method researched in the 1980s which can excite bone Pb with a more practical x-ray tube. Lower intensity LXRF emissions, however, pose challenges for the method’s translation to in vivo studies. Grazing-angle XRF (GAXRF) is a technique in which sensitivity is enhanced by designing a small incident angle (≲ few degrees) to reduce the x-ray scatter.
Methods: GAXRF was employed using a cylindrical 75 μg/g Pb-doped plaster-of-Paris bone phantom, a 25-μm x-ray beam, and a counting x-ray detector. The bone phantom was placed tangent to the x-ray beam and then moved in 100-μm steps using a positioning stage. One 30 s x-ray spectrum was acquired for each position. Within a 2 mm range an optimal position was found for which the Pb Lα and Pb Lβ peak heights were measured. The procedure was repeated for 7 bone phantoms doped with varying Pb concentrations: 0, 8, 15, 30, 45, 60, and 75 μg/g.
Results: Calibration lines were obtained for each LXRF peak and a Pb minimum detection limit of 3.3±0.2 μg/g was calculated.
Conclusion: The results show improvement when compared to recently published LXRF studies.
Funding Support, Disclosures, and Conflict of Interest: The research was supported by a start-up fund from the College of Science and Mathematics (CSM) from the California State University, Fresno. The presenting author is supported by a Faculty Sponsored Student Research Award (FSSRA) from the CSM.
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