X-ray detection efficiencies for 103Pd in lungs: synthesis of data from two laboratories

Phoswich counters viewing the frontal surfaces of the thorax were used to detect 20-keV X-rays from inhaled 103Pd, present in the lungs of volunteers in independently known quantities. The inhaled activity was incorporated in polystyrene microspheres, with three size distributions: (i) monodisperse 5 μm. (ii) polydisperse with AMAD approximately 2 μm and σsub(g) approximately 2 and (iii) essentially monodisperse approximately 1 μm. There were no major changes in the X-ray detection efficiency attributable to differences in particle size in the range 1-5 μm. The detection efficiencies are compared with values previously recorded for 103Pd deposited in the lungs of a realistic phantom thorax. (author)