An X-ray fluorescence technique for in vivo determination of lead concentration in a bone matrix

Abstract

The in vivo detection of Pb in the human skeleton by X-ray fluorescence analysis using a 740 MBq 57Co source for excitation and a 1 cm3 Ge(Li) detector for registration of the Pb K.alpha. and K.beta. radiation was previously reported. The varying geometry, density and atomic composition of the tissues of interest (mainly fingers) introduce several problems in estimation of the true concentration of a given element. A 2 component cylindrical finger phantom was constructed from silica paraffin wax and animal bone ash. The diameter of the finger bone was estimated from X-ray examinations in 2 orthogonal projections. The bone mineral concentration was estimated from the quotient of the number of coherent and Compton scattered primary photons. The Pb concentration in the finger bones was derived from a measurement on a finger phantom made of silica paraffin wax and bone ash with the same size and bone mineral concentration as the real bone. The minimum detectable Pb concentration in a finger bone was 14 .mu.g g-1 for 15 min measuring time. The Pb concentration measured in workers from a metal industry was in the range 40-100 .mu.g g-1.