The Use of In Vivo X-Ray Fluorescence Measurement in the Analysis of Cadmium Toxicology

Abstract

Cadmium (Cd) is a highly toxic metallic element to the human body such that prolonged occupational or environmental exposure produces renal, hepatic, pneumonic, and neurological disorders. Thus, as a consequence it is important to have a way of monitoring cadmium exposure as it has the potential to become an occupational health hazard. The primary uses of this element are in the mining and smelting industry in the manufacture of cadmium alloys and the manufacture of alkaline accumulators. Since the discovery of X-rays in 1895 by Wilhelm Conrad Roentgen, the science of X-ray analysis has become a cardinal tool in all domains of chemical identification and classification. X-ray fluorescence (XRF) has been shown to be an effectual technique for measuring trace quantities of heavy metals such as lead in various tissues within the body. This thesis stud:r elucidates a means of measuring Cadmium in bone. The study assesses the feasibility and practicality of the polarised XRF and source excited techniques. In the polarised cadmium concentration measurements, a gain in sensitivity due to improved background characteristics was perused by increasing the x-ray tube operating voltage of the system. It was found that an operating voltage of 175 kV, and a copper filter resulted in a significant gain in sensitivity for which a minimum detection limit (MDL) of 3.5 ± 1.4 ppm was determined with 3 mm of tissue equivalent overlay. Using the source-based technique, a MDL of 3.5 ± 0.2 ppm was estimated for the corresponding tissue equivalent overlay.