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Projeto de investigação
Large area X-ray Fluorescence Imaging System
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Publicações
Elemental mapping of Portuguese ceramic pieces with a full-field XRF scanner based on a 2D-THCOBRA detector
Publication . Carvalho, Patrícia Miguel da Silva; Leite, Fábio; Silva, A. L. M.; Pessanha, Sofia; Carvalho, Maria Luísa; Veloso, João F. C. A.; Santos, José Paulo; DF – Departamento de Física; LIBPhys-UNL; Springer Science and Business Media Deutschland GmbH
In this work, we present a novel application of the full-field energy-dispersive X-ray fluorescence (EDXRF) imaging system based on a MicroPattern Gaseous Detector (2D-THCOBRA) in the cultural heritage field. The detector has an intrinsic imaging capability with spatial resolution of 400μmFWHM, and is energy sensitive, presenting an energy resolution of approximately 1keVFWHM at 5.9keV. The full-field XRF scanner based on the 2D-THCOBRA detector allows mapping the distribution of elements in large area samples with high detection efficiency (75 % at 5.9keV), being a very promising choice for elemental mapping analysis of large area cultural heritage samples. In this work, we have demonstrated the imaging capabilities of the full-field XRF scanner and used it to assess the restoration of a Portuguese faience piece.
Energy Dispersive X-ray Fluorescence Analysis Imaging—Development and Applications
Publication . Carvalho, Patrícia Miguel da Silva; Santos, José; Moreno, Alda; Silva, Ana
The Energy Dispersive X-ray Fluorescence (EDXRF) analysis technique presents unique
features for elemental content evaluation of varied samples, such as its non-destructive
nature, high sensitivity, or reduced costs. Many EDXRF studies have been focused on the
determination of elemental concentration variations between normal and tumour tissues,
to compare and correlate findings with factors such as the type and the stage of tumours,
or the patients’ age and sex. Mapping elemental distributions may also provide insightful
information on these types of samples, namely the identification of regions of elemental
accumulation or depletion, and the demarcation of tumour margins, thus contributing to
the unbiased differentiation between normal and abnormal tissues.
The main goals of this work are to quantitatively determine the elemental content
in paired samples of normal and tumour human tissues, and to map the corresponding
elemental distributions. An improved methodology for the quantitative analysis of biological
tissues is introduced, to surpass existing limitations (e.g., reduced number of tissue
samples) that have lead to low-accuracy quantifications and statistically irrelevant conclusions.
Moreover, a Full-field Energy Dispersive X-ray Fluorescence (FF-XRF) imaging
spectrometer based on the 2D Thick-COBRA (2D-THCOBRA) micropattern gas detector
is presented as a novel, cost-effective tool of simple instrumentation, for detection and
mapping of elements in biological tissues.
Different sample sets of normal and tumour human tissues were analysed, and it
was possible to quantify concentration variations of light (e.g., K) and heavy elements
(e.g., Fe and Zn). However, the contribution of these results to cancer studies is minimal
due to the reduced number of analysed samples. To overcome this limitation, mirror
samples of "fresh" and paraffin embedded tissues were analysed, and it was verified that
the embedding process alters the elemental content of tissues. As such, the monitoring
of the elemental content of tissues throughout the process is suggested.
The FF-XRF imaging spectrometer based on the 2D-THCOBRA detector was used to
map paired samples of normal and tumour human tissues. Elements present in small
amounts (a few μg/g) were detected and the corresponding distributions were mapped.
Overall, the detected elements are evenly distributed on the samples’ surface, with the
exception of Ca in the lung tumour tissue. Throughout the analysed sample, calcium
deposits, a possible malignancy indicator, were identified. The imaging spectrometer
was also applied in the study of Zebrafish exposed to Mn, Se, and Pb. Heavy metal accumulation in the intestinal region was identified in all the analysed fish. Despite
the suitability of the system for these studies, the need to improve detection efficiency
remains. As such, the iFluX imaging spectrometer, with a large area X-ray panel based on
a redesigned 2D-THCOBRA structure, is introduced.
Analysis of Zebrafish contamination with heavy metals using a FF-XRF imaging system based on a MPGD
Publication . Leite, F. D.; Carvalho, P. M. S.; Oliveira, R. G.; Lopes, M. C.; Domingues, I.; Correia, P. M. M.; Carramate, L. F. N. D.; Pessanha, S.; Veloso, J. F. C. A.; Silva, A. L. M.; DF – Departamento de Física; LIBPhys-UNL; Elsevier
Heavy metals have been extensively used by humans and are still present in many aspects of modern-day life. Such elements tend to accumulate, degrading the quality of air, soil, and water, negatively affecting the living organisms. As such, it is of paramount importance to understand the environmental risks of heavy metals, including their bioaccumulation capacity in organisms, since they are associated with several harmful health effects, such as neurological damages. The Zebrafish (Danio rerio) has been shown to be an excellent animal model to understand physiological responses in mammals and consequently to perform toxicological studies due to characteristics such as the high genetic and physiological similarity with humans. In this work, a Full-Field Energy Dispersive X-ray Fluorescence (FF-XRF) imaging system, based on the 2D-THCOBRA micropattern gas detector, was used to monitor heavy metal accumulation in Zebrafish during a water borne exposure bioassay. The distributions of Mn, Se, and Pb in Zebrafish, exposed to different concentrations of the heavy metal compounds during different time intervals, were mapped. The results show a preferential accumulation of Mn, Se, and Pb in the Zebrafish's visceral region and highlight the suitability of the FF-XRF imaging system for quick screening of metal accumulation in fish bioassays.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
3599-PPCDT
Número da atribuição
PTDC/FIS-AQM/32536/2017