M.J. Anjos

Elemental mapping of teeth using μSRXRF

Human teeth were analysed by X-ray microfluorescence analysis using synchrotron radiation (μSRXRF). The aim of this work was to study the elemental distribution for Ca, Zn and Sr along the dental regions, enamel, dentine and pulp from patterns of relative fluorescence intensities. The measurements were performed in standard geometry of 45° incidence, exciting with a white beam and using a conventional system collimation (orthogonal slits) in the XRF beamline at the Synchrotron Light National Laboratory (Campinas, Brazil). The results show that Ca distribution is quite constant and it is independent of the tooth type and individuals characteristics. An increase of the Zn concentration was found for the pulp region and for untreated carious areas. Ca and Sr distributions show a similar behavior.

Elemental distribution mapping on breast tissue samples

The main of this work is to determine the elemental and absorption distribution map in breast tissue samples by X-ray fluorescence and X-ray transmission microtomography. The experiments were performed at the X-ray fluorescence beamline (D09B-XRF) in the Brazilian Synchrotron Light Source (LNLS), Campinas, Brazil. A quasi-monochromatic beam produced by a multilayer monochromator was used as an incident beam. The sample was placed on a high precision goniometer and translation stages that allow rotating as well as translating it perpendicularly to the beam. The fluorescence photons were collected with an energy dispersive HPGe detector placed at 90 degrees to the incident beam, while transmitted photons were detected with a fast Na(Tl) scintillation counter () placed behind the sample on the beam direction. All the tomographic images were reconstructed using a filtered-back projection algorithm. In the breast tissue samples, it was possible to determine the distribution of Zn, Cu and Fe in healthy tissue and tumor.

Bone diagnosis by X-ray techniques

In this work, two X-ray techniques used were 3D microcomputed tomography (micro-CT) and X-ray microfluorescence (micro-XRF) in order to investigate the internal structure of the bone samples. Those two techniques work together, e.g. as a complement to each other, to characterize bones structure and composition. Initially, the specimens were used to do the scan procedure in the microcomputer tomography system and the second step consists of doing the X-ray microfluorescence analysis. The results show that both techniques are powerful methods for analyzing, inspecting and characterizing bone samples: they are alternative procedures for examining bone structures and compositions and they are complementary.

X-ray transmission microtomography using synchrotron radiation

This work reports the feasibility of a non-destructive synchrotron radiation X-ray transmission imaging technique development at Brazilian synchrotron light source. The quality control image parameters (spatial and density resolution and noise) are given and microtomograms presented. Microtomograms of biomedical samples are presented. The tomography system was mounted into the XRF beamline that uses a high-intensity white beam with 12 keV effective energy, and maximum width and height equals to 11 and 1 mm, respectively. The detector used to collect the data was a 512-pixel Hamamatsu linear array with width of 50 μm (36 μm of sensitivity length) and cooled by a Peltier junction, causing the temperature falling down to 15°C. The samples were placed over a computer controlled table with 0.5° angular resolution and turned around the center covering 360°. To reconstruct the sample a parallel beam filtered back-projection algorithm was used.

Determination of Cu/Zn and Fe in human serum of patients with sickle cell anemia using radiation synchrotron.

In this work we analyzed serum samples from patients with Sickle Cell Anemia (SCA) using Total Reflection X-Ray Fluorescence using Synchrotron Radiation (SRTXRF). The SRTXRF measurements were performed at the X-Ray Fluorescence Beamline at the Brazilian National Synchrotron Light Laboratory (LNLS). We studied forty-three patients aged 18-50 suffering from SCA and sixty healthy volunteers aged 18-60. It was possible to determine the concentrations of the following elements: P, S, Cl, K, Ca, Fe, Cu, Zn, Br and Rb. Moreover, there are evidences of an association among Fe, Cu, Zn and Cu/Zn in the SCA pathogenesis process. The concentrations of Fe and Cu in the serum samples of patients with SCA were larger, 120% and 20%, respectively, when compared with the CG. The serum level Cu/Zn ratio was significantly higher (60%) in the serum samples from patients suffering from SCA than from the CG. Therefore, the Cu/Zn ratio can be used as an adjuvant index in enhancement for diagnosis of SCA.

Distribution of Fe, Cu and Zn in Cellular Spheroid Derived Human Prostate Tumor Cells by Synchrotron X-Ray Fluorescence

The formation of three-dimensional cell microspheres such as spheroids has attracted attention as a useful culture technique. In this study, we investigated the distribution (mapping) of Fe, Cu and Zn in cellular spheroid derived human prostate tumor cells. The measurements were performed in standard geometry of 45° incidence, exciting with a white beam collimated with the help of a 20 μm diameter optical capillary in the XRF beam line at the Synchrotron Light National Laboratory (Campinas, Brazil). The results showed that all the elements analyzed presented non-uniform distribution. The spheroids analyzed showed different elemental distribution of Fe and Cu. Zinc concentrations were higher in the central regions of the spheroids analyzed.

Evaluation of osteoporotic bone structure through synchrotron radiation X-ray microfluorescence images

The abnormal accumulation or deficiency of trace elements may theoretically impair the formation of bone and contribute to osteoporosis. In this context, the knowledge of major and trace elements is very important in order to clarify many issues regarding diseases of the bone, such as osteoporosis, that remain unresolved. Several kinds of imaging techniques can be useful to access morphology and the minerals present in osteoporotic bones. In this work, synchrotron radiation X-ray microfluorescence was used as an X-ray imaging technique to investigate bone structures. Therefore, this research aims to improve the knowledge about some aspects of bone quality. The measurements were carried out at the Brazilian Synchrotron Laboratory Light Laboratory, in Brazil. A white beam with an energy range of 4-23 keV, a 45 degrees /45 degrees geometry and a capillary optics were used. It was demonstrated that bone quality can and must be evaluated not only by considering the architecture of bones but also by taking into account the concentration and the distribution of minerals. Our results showed that the elemental distributions in bone zones on a micron scale were very helpful to understand functions in those structures.

Evaluation of scatter-to-primary ratio in soil CT-imaging

Radiation scatter leads to error in measurement of a projection that limits the image quality. The present work focuses on reconstruction error due to scattering in various types of soils and analysis was used to examine the spatial properties of scattered radiation in pencil beam geometry. EGS4 has been used (Electron–Gamma Shower), a general purpose Monte Carlo simulation package for coupled transport of electrons and photons in an arbitrary geometry. Scatter is measured in terms of the scatter-to-primary ratio (S/P). For a cylindrical geometry, the distribution of S/P was calculated for several thicknesses of each soil type, the intend being to determine the significance of detected scattered radiation in tomographic image. Two different photon energies were used: 60 keV and 662 keV. The dependence of S/P on soil diameter, chemical composition, bulk density and energy photon is presented. r 2001 Elsevier Science Ltd. All rights reserved.

Compton scattering of gamma-rays as surface inspection technique

Abstract A system for surface inspection based on the physical principle of Compton scattering of gamma-rays is presented here. Our system consists of a collimated 137 Cs source and a NaI(Tl) detector. An experimental search was carried out to determine the best layout of the array. A set of aluminium blocks with different surface conditions has been tested, and imperfections up to 1.6 mm were detected.

Analysis of matrix characterization by X-ray diffraction and synchrotron radiation

Abstract X-ray spectrometry is a non-destructive and multi-elemental technique widely used for elemental analysis. This technique has inherent complexities for quantitative analysis because of matrix effects. Matrix absorption is the most important factor when measurements are carried out using thick samples. Therefore, new methods have to be developed in order to evaluate matrix effects. In this work, the feasibility of using the synchrotron X-ray diffraction for matrix characterization has been investigated. All measurements were performed at the Laboratorio Nacional de Luz Sincrotron (LNLS), in Campinas, Brazil. The diffraction patterns of boric acid and cellulose matrix with different oxides were carried out. The preliminary results encourage us to examine further the application of X-ray diffraction analysis combined with energy-dispersive X-ray fluorescence technique for the characterization of thick samples.