Abstract
A Monte Carlo program has been written to model the in vivo X-ray fluorescence of lead in the kidney, to aid the choice of one of four candidate fluorescing source/measurement geometry combinations: 109Cd/180', 57Co/90' and 99Tcm at both 180' and 90'. Computational studies and practical considerations led to the choice of 99Tcm in a backscatter geometry for the measurement system.