Improved quantitation of low level tracers in X-ray fluorescent excitation analysis

Abstract

FEA in medicine combines the ease and accuracy of quantitation with radiotracers with the convenience and safety associated with the use of stable tracers. A major limitation in the utility of FEA is its comparatively low sensitivity. We address three techniques for improving quantitation accuracy: polarized excitation sources; pulse rise-time discrimination; and a third technique now under investigation: Anticoincidence shielding similar in concept to that used in low-level radionuclide counting. The techniques described here may permit extension of quantitation by FEA to 50–100 ppb tracer levels in unprepared biologic samples.