E.F.O. de Jesus

Quantitative analysis of metals in soil using X-ray fluorescence☆

Abstract Using energy dispersive X-ray fluorescence analysis with an X-ray tube filtered with Ti, it was possible to determine the concentration at ppm level of several elements (K, Ca, Ti, Mn, Fe, Cu, Zn, Ga, Br, Rb, Sr, Zr, Y and Pb) in soil treated with organic compounds of urban garbage. It was possible to observe a significant increase in the contents of K, Ca, Zn, Rb, Sr, Zr and Pb in the soil treated in comparison with the soil control.

X-ray diffraction microtomography using synchrotron radiation

Abstract The X-ray diffraction computed tomography technique is based on the interference phenomena of the coherent scatter. For low-momentum transfer, it is most probable that the scattering interaction will be coherent. A selective discrimination of a given element in a scanned specimen can be realized by fixing the Bragg angle which produces an interference peak and then, to carry out the computed tomography in the standard mode. The image reconstructed exalts the presence of this element with respect to other ones in a sample. This work reports the feasibility of a non-destructive synchrotron radiation X-ray diffraction imaging technique. This research was performed at the X-ray Diffraction beam line of the National Synchrotron Light Laboratory (LNLS) in Brazil. The coherent scattering properties of different tissue and bone substitute materials were evaluated. Furthermore, diffraction patterns of some polycrystalline solids were studied due to industrial and environmental human exposure to these metals. The obtained diffraction patterns form the basis of a selective tomography technique. Preliminary images are presented.

Electron spin resonance dosimetry of teeth of Goiânia radiation accident victims

Electron spin resonance (ESR) spectroscopy is used to assess absorbed doses of six teeth belonging to victims of the highly irradiated group of Goiânia accident. The influence of the broad background signal at g = 2.0040 as well as of the unstable fraction of CO2- radicals was taken into account in dose estimates. Three victims teeth showed absorbed doses comparable to those estimated by chromosomal analysis. For the other three teeth, the doses were higher by a factor of 1.3, 1.8 and 2.2.

Identification and dose determination using ESR measurements in the flesh of irradiated vegetable products

The international commerce of vegetable products is often dependent on the quarantine protections that are imposed by the importing countries because of the fear of contamination by fruit flies. The use of ionizing radiation as a treatment for these products can be used to remove this problem and a real proof of irradiation can contribute to the implementation of the international commerce. ESR measurement on the pulp of vegetable products can be used as a proof of irradiation using the species introduced in cellulose that are found uniquely in irradiated products. The stability of these species are compatible with the life of the products analyzed. The pulp signal intensity is sufficient to identify products irradiated with doses as low as 100 Gy for some fruits.

Computed tomography with monochromatic bremsstrahlung radiation

The use of filters with appropriate thickness of different elements produces a method to quasi-monochromatize X-ray beams. In the present study the filters were produced in a boric acid matrix, using the elements Mo, Sb, Cs, Ce and Gd. The thickness of the filters varied from 50 to 300 microm for a high voltage tube operating from 30 to 70 kVp. The parameters analyzed were the beam resolution, measured by its FWHM as a function of filter thickness, and the reduction of beam intensity. The results show a comparison between conventional tomographies obtained with different filters and application in the technique of differential tomography, with double energy for identification of elements such as Zr, Nd, Ba and Sm.

Synchrotron radiation X-ray fluorescence analysis of trace elements in Nerium oleander for pollution monitoring☆

Abstract This works describes the use of synchrotron radiation fluorescence analysis as a technique for monitoring trace elements in bio-indicators for environmental pollution control. The analyses were performed on leaves of Nerium oleander collected in streets with different levels of traffic flow in Rio de Janeiro, Brazil, with one sample from a rural zone. The leaves were collected from adult trees in December and April. The measurement was made with a white beam of synchrotron radiation calibrated with thin samples from MicroMatter. The results indicate that some metals such as Ti, V, Fe and Zn have major content in samples that were collected in places with a high traffic flow, even in the leaves that have been washed. The levels of Mn, Co, Cu and Ni did not show significant differences between the samples. The Pb level also did not vary significantly. This was expected because in Brazil gasoline without Pb has been used for many years. The results seem to indicate that the leaves from Nerium oleander absorb metals from the atmosphere and may be used as an environmental indicator.

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.

Angle-dispersive diffraction with synchrotron radiation at Laboratório Nacional de Luz Sı́ncrotron (Brazil): potential for use in biomedical imaging

At low angles the scattering of X-rays in the diagnostic energy range (low-momentum transfer), it is probable that the scattering interaction will be coherent. This coherence gives rise to interference effects resulting in X-ray diffraction patterns that are characteristic of the scattering material. The usefulness of coherent scattering is not limited to crystallography. It can provide information about biological material as well. The interatomic and intermolecular co-operative effects which modify the free-atom coherent scattering process are well known for highly ordered structures such as crystalline materials but are important for amorphous solids and liquids where short-range ordering occurs. X-ray diffraction using synchrotron radiation has became a well established technique. This work introduces a non-destructive synchrotron radiation X-ray diffraction imaging technique. The feasibility of the X-ray diffraction computed microtomography using synchrotron radiation has been investigated. This research was carried out at the X-ray diffraction beam line of the National Synchrotron Light Laboratory supported by the National Council for Scientific and Technological Development (LNLS/CNPq) in Brazil. These experimental patterns were carried out with a 500 microm slit in front of the detector and an 11.101 keV beam (lambda = 1.117 A) monochromatic beam from the double crystal monochromator. The diffracted beam was detected by a fast scintillation detector (10(6) counts s(-1)) designed specifically to meet the needs of high quality X-ray diffraction and synchrotron radiation experiments. The data were recorded at rates of one second per degree of 2theta (angular steps equal to 0.05 +/- 0.01 degrees) and registered by a multichannel analyzer. These experimental data could be used to evaluate the scattering properties of different tissue-substitute (water, lucite, nylon, plastic and polystyrene) and bone-substitute (hydroxyapatite and aluminum) materials. The data are in good agreement with those obtained by other authors, indicating the feasibility of the imaging technique.

Detection of paraffin deposition inside a draining tubulation by the Compton Scattering Technique

Abstract This work shows an application of the Compton Scattering Technique (CS) in the detection of the problem produced by the formation of paraffin (condensed petrol) inside the petrol draining pipeline in deep-water exploration (off-shore). This study was made using an inspection system by CS. The measurements were made with two types of beam, punctual and fan-beam, by analysing a pipeline cross-section or small elements of volume through a transversal line. The punctual system can detect a minimum of 10% paraffin. This value is about 20% with a fan-beam system.

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.