X-Ray Fluorescence Microtomography Investigates the Elemental Distribution in Breast Tissue Samples

The X-ray fluorescence microtomography (XR-FCT) is a non-destructive technique, based on the detection of X-ray fluorescence emitted by the elements in the sample, and it is used to complement other techniques for sample characterization. In this work human breast tissues samples have been analyzed in order to verify the efficiency of the system in the determination of the elemental distribution in these kind of samples. The experiments were performed at the X-ray fluorescence beamline (D09B-XRF) of the Brazilian Synchrotron Light Source (LNLS), Campinas, Brazil. A quasi-monochromatic beam produced by a multilayer monochromator was used for the excitation of the elements and the fluorescence photons have been detected by a HPGe detector, placed at 90deg to the incident beam. The beam was monitored by an ionization chamber and a fast scintillator detector was used to detect the transmitted radiation. In one projection, samples were positioned in steps of 200 mum (actual beam size) perpendicularly to the beam direction covering the whole transversal section of the sample proof. Each single value in a projection is obtained by measuring the fluorescent radiation emitted by all pixels along the beam. The object is then rotated, and another projection is measured. Projections are obtained in steps of 3deg until the object has completed 180deg. The selected measuring for each scanned point was evaluated separately for each sample. All the tomographies have been reconstructed using a filtered-back projection algorithm. In the breast tissue samples, the elements of higher concentration were Zn, Cu and Fe.