In vivo X-ray fluorescence (XRF) measurement of uranium in bone

This study investigates the applicability of X-ray fluorescence (XRF) to measuring bone uranium concentrations, using a Co-57 source to excite the uranium X-rays, with the source and detector in an approximate 180 degrees backscatter geometry relative to the sample position. It is demonstrated, by experiment and Monte Carlo simulation that the X-ray to coherent peak ratio is linearly related to concentration and is independent of variations in source-sample geometry, thickness of overlying tissue and tibia size. Preliminary in vivo measurements indicate a minimum detectable concentration (MDC) of approximately 20 mu g/g, which may not be sufficiently sensitive for monitoring occupational workers. However, a larger study of occupationally exposed individuals as well as work with subjects with known significant accidental uranium exposures is necessary to assess the clinical usefulness of this system. (C) 1997 Elsevier Science Ltd (C) 1998 Elsevier Science Ltd. All rights reserved.