An enhanced sensitivity K-shell x-ray fluorescence technique for tibial lead determination

A novel irradiation-detection geometry capable of enhancing sensitivity for the measurement of tibial lead content by K-shell x-ray fluorescence (XRF) is described. The high-count-rate system comprised a small-area high-specific-activity (0.147 GBq mm-2) 109Cd source and a large-area (nominally 20 cm2) uncollimated detector, forming an axially symmetric back-scattering arrangement. Precisions in the range ±4.9 to ±14.2 μg Pb (g bone mineral)-1 have been obtained in a study of a cohort of 63 controls and 73 workers industrially exposed to lead. These precisions are comparable with those obtained in results using earlier systems, but at reduced source activities (less than 50% of the activity of other systems) and with significant reduction in measurement time (some 30% less than the measurement times of other systems). (author)