The Experts below are selected from a list of 168 Experts worldwide ranked by ideXlab platform
Nicholas M. Spyrou - One of the best experts on this subject based on the ideXlab platform.
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3D quantitative elemental mapping using simultaneous proton induced X-Ray Emission tomography and scanning transmission ion microscopy tomography
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2007Co-Authors: Daniel Beasley, Nicholas M. SpyrouAbstract:Abstract A technique has been implemented that could produce sub-micron resolution quantitative elemental mapping of cells in an acceptable time frame. A new experimental set-up was installed to produce 3D quantitative elemental maps of biological samples by combining simultaneous proton induced X-Ray Emission tomography (PIXE-T), on/off-axis scanning transmission ion microscopy tomography (STIM-T) and Rutherford backscattering spectrometry (RBS). Combined with a high efficiency Si(Li) detector, 3D quantitative maps of Cl, S, Ca, K, Fe and Zn in a section of a hair were produced with an analytical time of 3 h.
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Determination of the elemental homogeneity of selected biological organs by 2MeV proton induced X-Ray Emission analysis
Journal of Radioanalytical and Nuclear Chemistry, 1995Co-Authors: A. C. Beach, Nicholas M. SpyrouAbstract:The use of finite size sub-samples to derive elemental concentrations which are representative of a tissue or organ as a whole are subject to errors arising from the heterogeneous nature of biological specimens. Proton induced X-Ray Emission (PIXE) analysis is employed to identify element variances in porcine liver, kidney and heart and sampling factors, which are the minimum mass of sample required to reduce concentration variability to a given level, are calculated. This analysis highlights the inhomogeneous nature of biological specimens and the need for clearly defined sampling protocols.
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Elemental concentrations in nigerians with affective disorders using Proton-Induced X-Ray Emission.
Biological Trace Element Research, 1994Co-Authors: M. A. Durosinmi, A. F. Oluwole, A. F. Ononye, O. A. Akanle, Nicholas M. SpyrouAbstract:The concentrations of a number of elements are determined in the plasma and erythrocytes of 21 Nigerians (11 females, 10 males) with symptomatic affective disorders (11 depressives, 10 manics) and in 40 normal controls using Proton-Induced X-Ray Emission (PIXE) analysis. The study shows that there is significant elevation of plasma K and Zn, as well as the erythrocyte S in the patients relative to the controls. The plasma and erythrocyte Cu, and the erythrocyte P, Ca, Fe, and Zn are significantly lower in the patients compared to the controls. However, the plasma levels of Ca, S, Fe, and Br are similar in both the patients and the controls. Similarly, the concentrations of K, Br, and Rb show no significant difference in the erythrocytes of patients and controls
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Study of trace elements in blood of cancer patients by Proton-Induced X-Ray Emission (PIXE) analysis.
Biological trace element research, 1994Co-Authors: M. A. Durosinmi, A. F. Oluwole, O. A. Akanle, Nicholas M. SpyrouAbstract:Proton-Induced X-Ray Emission (PIXE) analysis was employed to determine the concentrations of six elements in the plasma and erythrocytes of 18 cancer subjects (15 males and 3 females) with neoplastic disorders and in 70 controls (35 males and 35 females). It was found that the concentrations of Br, K, and Zn were significantly elevated in the erythrocytes of the cancer subjects compared to the controls, whereas the concentration of Fe was significantly depressed, but with no difference observed in the concentration of Ca. In the plasma, the concentrations of Br, Cu, Ca, and K were significantly elevated, whereas the concentrations of Fe and Zn were found to be significantly depressed compared to the controls.
Jehan Akbar - One of the best experts on this subject based on the ideXlab platform.
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Standardization of proton induced X-Ray Emission for analysis of trace elements in thick samples
Canadian Journal of Physics, 2019Co-Authors: Muhammad Haneef, Azhar Muhammad Naeem, Jehan AkbarAbstract:This paper presents the standardization of proton induced X-Ray Emission (PIXE) technique for the analysis of trace elements in thick, standard samples. Three standard reference materials, titanium...
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Standardization of Proton-Induced X-Ray Emission technique for analysis of thick samples
Chinese Physics B, 2015Co-Authors: Abdul Ahad, Muhammad Haneef, Ishfaq Ahmad, Jehan AkbarAbstract:This paper describes the standardization of the Proton-Induced X-Ray Emission (PIXE) technique for finding the elemental composition of thick samples. For the standardization, three different samples of standard reference materials (SRMs) were analyzed using this technique and the data were compared with the already known data of these certified SRMs. These samples were selected in order to cover the maximum range of elements in the periodic table. Each sample was irradiated for three different values of collected beam charges at three different times. A proton beam of 2.57 MeV obtained using 5UDH-II Pelletron accelerator was used for excitation of X-Rays from the sample. The acquired experimental data were analyzed using the GUPIXWIN software. The results show that the SRM data and the data obtained using the PIXE technique are in good agreement.
R.c. Da Silva - One of the best experts on this subject based on the ideXlab platform.
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GPU-accelerated reconstruction methods for Proton Induced X-Ray Emission Tomography
Radiation Physics and Chemistry, 2014Co-Authors: D.g. Beasley, Ana C. Marques, Luís Alves, R.c. Da SilvaAbstract:Abstract A combination of simultaneous Proton Induced X-Ray Emission Tomography (PIXE-T), Scanning Transmission Ion Microscopy Tomography (STIM-T) and Rutherford Backscattering Spectrometry (RBS) can produce 3D quantitative elemental maps with a resolution on the micron scale. This combination is being developed at the Instituto Tecnologico e Nuclear-Instituto Superior Tecnico (ITN-IST) nuclear microprobe facility. To reconstruct complex datasets, iterative procedures are usually applied. GPU-accelerated PIXE-T/STIM-T simulation software has been developed and used in conjunction with an iterative reconstruction software DISRA and an MLEM algorithm to reconstruct data produced by simulating a PIXE-T experiment of a phantom.
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Fast simulation of Proton Induced X-Ray Emission Tomography using CUDA
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2013Co-Authors: D.g. Beasley, Ana C. Marques, Luís Alves, R.c. Da SilvaAbstract:Abstract A new 3D Proton Induced X-Ray Emission Tomography (PIXE-T) and Scanning Transmission Ion Microscopy Tomography (STIM-T) simulation software has been developed in Java and uses NVIDIA™ Common Unified Device Architecture (CUDA) to calculate the X-Ray attenuation for large detector areas. A challenge with PIXE-T is to get sufficient counts while retaining a small beam spot size. Therefore a high geometric efficiency is required. However, as the detector solid angle increases the calculations required for accurate reconstruction of the data increase substantially. To overcome this limitation, the CUDA parallel computing platform was used which enables general purpose programming of NVIDIA graphics processing units (GPUs) to perform computations traditionally handled by the central processing unit (CPU). For simulation performance evaluation, the results of a CPU- and a CUDA-based simulation of a phantom are presented. Furthermore, a comparison with the simulation code in the PIXE-Tomography reconstruction software DISRA (A. Sakellariou, D.N. Jamieson, G.J.F. Legge, 2001) is also shown. Compared to a CPU implementation, the CUDA based simulation is approximately 30× faster.
Roland Akselsson - One of the best experts on this subject based on the ideXlab platform.
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Non-Linear Least Squares Analysis of Proton-Induced X-Ray Emission Data
Advances in x-ray analysis, 2019Co-Authors: H. C. Kaufmann, Roland AkselssonAbstract:A Fortran program for analysis of spectra obtained in proton induced X-Ray Emission spectroscopy is under development. The first version is working and some results are shown. The program uses a model which describes the physics involved in the analysis. The continuum is described by an exponentially decreasing function representing secondary electron induced bremsstrahlung and a constant approximating different Compton scattering processes. Absorption effects are also included. All parameters in the model are fitted simultaneously. About 100 test runs have been made with good results. The continuum was accurately fitted for each spectrum. Other advantages are reliability, speed, and the fact that the program is easily adaptable to a small computer with 16K memory. (Less)
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Geophysical Applicability of Aerosol Size Distribution Measurements Using Cascade Impactors and Proton Induced X-Ray Emission
Atmospheric Environment, 2003Co-Authors: René Van Grieken, Thomas B Johansson, John W. Winchester, Roland Akselsson, J William Nelson, K.r. ChapmanAbstract:Proton Induced X-Ray Emission, (PIXE), is capable of high precision analysis for trace element components of aerosol particle size fractions sampled by cascade impactor. A statistical evaluation of data quality has been carried out in order to distinguish between analytical uncertainties in the PIXE procedure, errors caused by cascade impactor performance and by other factors in the sampling procedure, and geophysical causes of differences in composition and particle size distributions of the elements in aerosols. Replicate analyses and simultaneous samplings taken in north Florida and St. Louis have been used for the data evaluation. In addition to the analytical error the sampling procedure contributes an error of ~ 10% to be added quadratically. The resulting precision is sufficient to evaluate the data in geophysical terms. This is illustrated by means of sample sets taken simultaneously in an urban, forest and coastal environment of the same region. (Less)
Luís Alves - One of the best experts on this subject based on the ideXlab platform.
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Castanea sativa shells and fruits: Compositional analysis by proton induced X-Ray Emission
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2020Co-Authors: V. Corregidor, Luís Alves, Amilcar L. Antonio, Sandra Cabo VerdeAbstract:Abstract Chestnut fruits, from Castanea sativa Miller species, have been previously characterized mainly to study the nutritional and biochemical parameters, with mineral contents receiving less attention from the researchers, although these minerals are essential for several mechanisms in human body. In this study, a detailed elemental compositional analysis was performed using Proton Induced X-Ray Emission (PIXE) to characterize two varieties of Castanea sativa Miller chestnuts (Longal and Judia). This study comprises the composition of the outer shells (pericarp), inner shells (episperm) and the edible fruits. From our knowledge, this is the first time that the presence of up to 20 elements on the shells and the fruits are reported. Furthermore, by PIXE it was possible to quantify them, allowing significant improvements in the assessment of chestnuts composition. Essential and non-essential elements were quantified on a food item that is used mainly for human consumption but it is also incorporated in animal feeding.
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GPU-accelerated reconstruction methods for Proton Induced X-Ray Emission Tomography
Radiation Physics and Chemistry, 2014Co-Authors: D.g. Beasley, Ana C. Marques, Luís Alves, R.c. Da SilvaAbstract:Abstract A combination of simultaneous Proton Induced X-Ray Emission Tomography (PIXE-T), Scanning Transmission Ion Microscopy Tomography (STIM-T) and Rutherford Backscattering Spectrometry (RBS) can produce 3D quantitative elemental maps with a resolution on the micron scale. This combination is being developed at the Instituto Tecnologico e Nuclear-Instituto Superior Tecnico (ITN-IST) nuclear microprobe facility. To reconstruct complex datasets, iterative procedures are usually applied. GPU-accelerated PIXE-T/STIM-T simulation software has been developed and used in conjunction with an iterative reconstruction software DISRA and an MLEM algorithm to reconstruct data produced by simulating a PIXE-T experiment of a phantom.
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Fast simulation of Proton Induced X-Ray Emission Tomography using CUDA
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2013Co-Authors: D.g. Beasley, Ana C. Marques, Luís Alves, R.c. Da SilvaAbstract:Abstract A new 3D Proton Induced X-Ray Emission Tomography (PIXE-T) and Scanning Transmission Ion Microscopy Tomography (STIM-T) simulation software has been developed in Java and uses NVIDIA™ Common Unified Device Architecture (CUDA) to calculate the X-Ray attenuation for large detector areas. A challenge with PIXE-T is to get sufficient counts while retaining a small beam spot size. Therefore a high geometric efficiency is required. However, as the detector solid angle increases the calculations required for accurate reconstruction of the data increase substantially. To overcome this limitation, the CUDA parallel computing platform was used which enables general purpose programming of NVIDIA graphics processing units (GPUs) to perform computations traditionally handled by the central processing unit (CPU). For simulation performance evaluation, the results of a CPU- and a CUDA-based simulation of a phantom are presented. Furthermore, a comparison with the simulation code in the PIXE-Tomography reconstruction software DISRA (A. Sakellariou, D.N. Jamieson, G.J.F. Legge, 2001) is also shown. Compared to a CPU implementation, the CUDA based simulation is approximately 30× faster.
