L-shell x-ray fluorescence measurements of lead in bone: system development

This paper reports on the development of an L-shell x-ray fluorescence (XRF) bone lead measurement system. A secondary target gave greater lead x-ray peak signal-to-background ratios than partially plane polarized XRF. Filtration did not improve the lead x-ray peak signal-to-background ratio: the gains in spectrum quality were outweighed by the losses caused by attenuation. There was a substantial matrix effect: the signal from a calcium-rich matrix was far lower than that from a calcium-free matrix. The effect of attenuation was, as expected, profound for the lead L x-rays: detection limits ranged from 18 to 217 microg Pb/g plaster with attenuation equivalent to 0-2.1 mm of skin or 0-3.7 mm of adipose tissue for the Pb Lalpha x-ray group (10.5 keV), and from 16 to 184 microg Pb/g plaster with attenuation equivalent to 0-1.3 mm of skin or 0-2.3 mm of adipose tissue for the Pb Lbeta x-ray group (12.6 keV).