Determination of elemental concentrations in a thin lamb bone slice from x-ray fluorescence measurements at the Canadian Light Source synchrotron

In vitro x-ray fluorescence (XRF) studies using synchrotron radiation (SR) can probe microscopic two-dimensional (2D) elemental distributions in tissues by employing raster scanning techniques. In SR studies, however, elemental concentrations are not measured; 2D distribution of elements are obtained after corrections for variations of photon fluence rate and detector’s dead time. Elemental concentrations are important in comparative studies and a model computing elemental concentrations from SR data is presented in this study. The model implemented as a C++ code linked concentrations to measured ratios between the sum of Kα and Kβ peak areas and the sum of coherent and Compton scatter peak areas. Experimentally, a 0.38-mm thick semicircular slice (~150 mm²) was cut from a lamb bone and analyzed at the VESPERS beamline at the Canadian Light Source synchrotron. Two rectangular areas (0.4 mm 0.6 mm) of the inner and the outer regions of the bone slice were examined by a 10- m step 2D XRF raster scan using a 6- m width x-ray beam. 2D maps of P, Ca, Fe, Ni, Cu, and Zn distributions in the bone slice were obtained for each region at 12, 15, 18.6, and 20 keV photon energies. 2D spatial distribution of Zn was also obtained for 18.6 and 20 keV photon energies. Computed elemental concentrations were within the expected ranges and their 2D maps agreed with cortical bone histology.