IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Considerations on spectral determination and matrix composition for quantitative micro-XRF analysis of breast tissues
Autor/es:
MALEZAN, A.; RIBEIRO SILVA, A.; PÉREZ R.D.; POLETTI, M.
Lugar:
Beijing
Reunión:
Simposio; 13th International Symposium on Radiation Physics; 2015
Institución organizadora:
Chinese Academy of Science
Resumen:
X-ray fluorescence (XRF) quantification methodologies based on fundamental parameters, are usually limited by knowledgeof the excitation spectrum and matrix composition. Specially for the micro X-ray fluorescence (micro-XRF) technique applied tobiological samples, these factors are approximately known, or unknown. This work presents a methodology for determining theexcitation spectrum using the scattering profile of a known composition polymethyl methacrylate (PMMA) sample. In addition, itwas studied the influence of biological matrix composition in the quantification of the trace elements Ca, Fe, Cu and Zn, on breastsamples of different thickness (30 and 500 microns). The experiments were performed in X-ray Fluorescence beam line at LaboratórioNacional de Luz Síncrotron (LNLS), Campinas, Brazil. The excitation white beam was focused down to a diameter of 24 microns by aKirkpaetrick-Baez optics. Breast samples were placed on a table with three degrees of freedom (X, Y, Z) at 45 degrees with respect to theexcitation beam. Fluorescence spectra were acquired at 90 degrees to the excitation beam. The influence of the breast matrix compositionin the quantifying procedure was studied by varying the glandular fraction of the samples. Certified reference materials were usedto test the reconstructed excitation spectrum. The obtained results showed an accurate up to 7%. For 30 microns thickness samples,results from matrix composition variability showed that data deviations are limited by the matrix density variations. For 500 micronsthickness samples, changes in the linear attenuation coeffcients can deviate data in more than 35% for calcium and 14% for iron.It was possible to identify certain structures on micro-XRF maps and correlate them to neoplastic formation in tissues. The naturalvariation of trace elements in those structures are much larger than deviations introduced by the quantification procedure, whichattests that it can be applied to breast tissue analysis.