A Two-Dimensional K-Shell X-ray Fluorescence (2D-KXRF) Model for Soft Tissue Attenuation Corrections of Strontium Measurements in a Cortical Lamb Bone Sample

Abstract

Human bones store elements such as calcium, phosphorus, and strontium, and accumulate toxic elements such as lead. In vivo measurements of elemental bone concentration can be done using X-ray fluorescence (XRF) techniques. Monte Carlo (MC) simulations of X-ray interactions were predominantly employed in this field to develop calibration methods that linked XRF measurements to concentrations. A simple and fast two-dimensional K-shell X-ray fluorescence model was developed to compute the KXRF signal of elements in bone and overlying soft tissue samples. The model is an alternative to MC methods and can guide future bone XRF studies. Contours of bone and soft tissue cross sections were elliptical and only KXRF signals from absorption of primary photons were considered. Predictions of the model were compared to Sr KXRF measurements using the bare lamb bone (LB) and the LB with overlying leather. XRF experiments used a small X-ray beam, silicon X-ray detector, and three positioning stages. Linear attenuation coefficients of the leather and LB were measured and used in the model. Measured and model-derived values of the Sr X-rays leather attenuation and Sr Kβ/Kα ratio agreed, but estimated bone Sr concentrations were likely overestimated. Results, approximations, future work directions, and applications were discussed.