OPTIMIZATION OF IN-VIVO X-RAY-FLUORESCENCE ANALYSIS-METHODS FOR BONE LEAD BY SIMULATION WITH THE MONTE-CARLO CODE CEARXRF

In the design of X-ray fluorescence (XRF) systems for in vivo Measurem ents of lead in human bone, the most important considerations are the minimum detectable concentration (MDC), and accuracy and precision. Po ssible design optimizations can be investigated much more easily and e conomically by Monte Carlo simulation than by experiment. The specific purpose Monte Carlo code CEARXRF has been used in the present study f or: (1) improving the MDC of a hypothesized in vivo Cd-109 source-base d KXRF system and a Cd-109 source or X-ray tube source-based LXRF syst em by investigating the effects of source polarization and source-bone -detector geometry modification on reducing the scattering background, and (2) investigating the effects of sample variables, such as overly ing skin thickness on the MDC and the lead XRF intensity precision. In addition, the feasibility of the Monte Carlo-Library Least-Squares (M CLLS) approach has been investigated in a preliminary fashion for Cd-1 09-based KXRF spectroscopy analysis. (C) 1997 Elsevier Science Ltd. Al l rights reserved.