EDXRS MODELING FOR IN-VIVO TRACE-ELEMENT ANALYSIS BY USING THE SHAPE CODE

The validity of the SHAPE code, a computer package able to simulate ED XRS spectra, was tested to model the in vivo XRF determination of cadm ium concentrations in the kidney by choosing the best source-measureme nt geometry combination. Accurate measurements were performed in order to validate the results of this code in the energy interval involved in in vivo XRF analysis. In addition, a comparison was made with Monte Carlo results including thrid-order contributions and polarization. V ery good agreement was found with the experimental and Monte Carlo res ults. In spite of the fact that, at present, this code does not includ e higher order multiple scattering, modelling results using the SHAPE code agree very well with the expensive Monte Carlo solutions and the empirical values recently predicted for this technique.