IN VIVO TOTAL BODY LEAD ANALYSIS BY X-RAY FLUORESCENCE

THERE ARE AN ESTIMATED 600,000 CHILDREN UNDER SIX YEARS OLD WITH ELEVATED BLOOD LEAD LEVELS AND ONLY 5,000 PER YEAR UNDERGOING TREATMENT; AS YET, NO TECHNIQUE IS AVAILABLE TO MEASURE TOTAL BODY LEAD BURDEN. THIS PROPOSAL DESCRIBES A TECHNIQUE WHICH USES X-RAY FLUORESCENCE IN A TRANSMISSION GEOMETRY TO MEASURE THE TOTAL BODY-BURDEN OF LEAD, IN VIVO, NONINVASIVELY. A SYSTEM USING A GOLD CALIBRATION TARGET, A RADIOACTIVE SOURCE, AND A GERMANIUM X-RAY DETECTOR IS PRESENTED. TO PROVE FEASIBILITY, PHASE I RESEARCH WILL USE THIS SYSTEM TO MEASURE THE LEAD CONTENT OF A PHANTOM CONTAINING A KNOWN QUANTITY OF LEAD. EXPERIMENTS WILL ESTABLISH THE ACCURACY OF THIS TECHNIQUE IN THE FACE OF VARIATIONS IN BODY COMPOSITION (E.G., CA, NA, FE), IN THE RATIO OF BONE TO BODY WEIGHT, AND IN THE PRESENCE OF HEAVY METALS. IF PHASE I IS SUCCESSFUL, PROTOTYPE MACHINES FOR ANIMAL AND HUMAN TESTS WILL BE BUILT DURING PHASE II. THE ULTIMATE MACHINE WILL BE USEFUL AS (1) A DIAGNOSTIC TOOL IN DETERMINING THE PRESENCE OF LEAD POISONING AND ELEVATED LEVELS OF BODY LEAD; (2) A MONITORING DEVICE IN FOLLOWING THE PROGRESS OF CHELATION TREATMENT; AND (3) A MASS SCREEN- ING DEVICE TO COMPLEMENT OR REPLACE ERYTHROCYTE PROTOPORPHYRIN SCREENING.