A High Intensity Source of Polarized X-Rays for Fluorescent Excitation Analysis (FEA)

FEA is being used in medicine to substitute radiotracers and chemical analysis of stable tracers. Excitation with polarized x-rays reduces tracer working levels: Since they scatter at preferential angles they reduce the number of photons reaching the detector, thus decreasing system dead time and background. The use of a 160KV 19mA x-ray tube for FEA of iodine (and neighboring elements) realizes count-rates of 2.5 cts/sec/ppmI and background reductions from 11.5 ppmI (when using Am-241 excitation) to 5.7 ppmI. These early results indicate that counting time to realize constant quantitation accuracy can be reduced by 90%. Since the use of the x-ray tube results in a 50% increase in the cost of the source-excited automated system, the ten-fold reduction in analysis time makes this a practical approach.