PARAMETER STUDIES FOR AN OPTIMIZED XRF-DETERMINATION OF Pb IN BONE

One of the main threats to human health from heavy metals is associated with the exposure to lead (Pb). In vivo X-ray fluorescence analysis (XRF) of human bone is a widely used technique to determine the total Pb body burden. The intention of this work was to study the feasibility of in vivo L-shell XRF measurements of Pb in bone using X-ray tubes as excitation sources. Parameter studies using direct tube excitation with various anode materials (Mo and W) and filters as well as different secondary targets and low Z polarizers were performed with regard to the lowest detection limits (LLD) achievable for Pb in bone matrix. A breakthrough for the development of a portable spectrometer was achieved using of an air cooled low power (50W) Pd anode X-ray tube, Mo secondary target and a Peltier cooled SDD detector. LLDs for Pb in bone were determined from measurements on a plaster-of-paris standard without overlying tissue equivalent material and found to be around 0.6 μg/g.