Monte Carlo simulations and measurement of DNA damage from x-ray-triggered Auger cascades in iododeoxyuridine (IUdR)

2001 ◽  
Vol 40 (3) ◽  
pp. 199-206 ◽  
Author(s):  
S. J. Karnas ◽  
V. V. Moiseenko ◽  
E. Yu ◽  
P. Truong ◽  
J. J. Battista
Keyword(s):  
Dna Damage ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
X Ray

Low-voltage EDS of magnesium ferrite Dendrites in a FEG-SEM

1996 ◽  
Vol 54 ◽  
pp. 478-479
Author(s):  
Matthew T. Johnson ◽  
Ian M. Anderson ◽  
Jim Bentley ◽  
C. Barry Carter
Keyword(s):  
Monte Carlo ◽  
Quantitative Analysis ◽  
Monte Carlo Simulations ◽  
Cross Section ◽  
Spatial Resolution ◽  
Low Voltage ◽  
Magnesium Ferrite ◽  
X Ray ◽  
Interaction Volume ◽  
Ferrite Spinel

Energy-dispersive X-ray spectrometry (EDS) performed at low (≤ 5 kV) accelerating voltages in the SEM has the potential for providing quantitative microanalytical information with a spatial resolution of ∼100 nm. In the present work, EDS analyses were performed on magnesium ferrite spinel [(MgxFe1−x)Fe2O4] dendrites embedded in a MgO matrix, as shown in Fig. 1. spatial resolution of X-ray microanalysis at conventional accelerating voltages is insufficient for the quantitative analysis of these dendrites, which have widths of the order of a few hundred nanometers, without deconvolution of contributions from the MgO matrix. However, Monte Carlo simulations indicate that the interaction volume for MgFe2O4 is ∼150 nm at 3 kV accelerating voltage and therefore sufficient to analyze the dendrites without matrix contributions.Single-crystal {001}-oriented MgO was reacted with hematite (Fe2O3) powder for 6 h at 1450°C in air and furnace cooled. The specimen was then cleaved to expose a clean cross-section suitable for microanalysis.

scholarly journals Modular MA-XRF Scanner Development in the Multi-Analytical Characterisation of a 17th Century Azulejo from Portugal

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1913
Author(s):  
Sergio Augusto Barcellos Lins ◽  
Marta Manso ◽  
Pedro Augusto Barcellos Lins ◽  
Antonio Brunetti ◽  
Armida Sodo ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
17Th Century ◽  
Scanning System ◽  
X Ray ◽  
Portable Instruments ◽  
Complementary Techniques ◽  
Non Destructive ◽  
Suitable Technique ◽  
Cobalt Blue

A modular X-ray scanning system was developed, to fill in the gap between portable instruments (with a limited analytical area) and mobile instruments (with large analytical areas, and sometimes bulky and difficult to transport). The scanner has been compared to a commercial tabletop instrument, by analysing a Portuguese tile (azulejo) from the 17th century. Complementary techniques were used to achieve a throughout characterisation of the sample in a complete non-destructive approach. The complexity of the acquired X-ray fluorescence (XRF) spectra, due to inherent sample stratigraphy, has been resolved using Monte Carlo simulations, and Raman spectroscopy, as the most suitable technique to complement the analysis of azulejos colours, yielding satisfactory results. The colouring agents were identified as cobalt blue and a Zn-modified Naples-yellow. The stratigraphy of the area under study was partially modelled with Monte Carlo simulations. The scanners performance has been compared by evaluating the images outputs and the global spectrum.

scholarly journals A hydroxyapatite phantom material for the calibration of in vivo x-ray fluorescence systems of bone strontium and lead quantification

2021 ◽  
Author(s):  
Eric Da Silva
Keyword(s):  
Monte Carlo ◽  
Soft Tissue ◽  
Monte Carlo Simulations ◽  
Calibration Procedure ◽  
X Rays ◽  
X Ray ◽  
Total Phosphate Concentration ◽  
High Concentrations ◽  
Phantom Material

A hydroxyaptite [HAp; Ca5(PO4)3OH] phantom material was developed with the goal of improving the calibration protocol of the 125I-induced in vivo X-ray fluorescence (IVXRF) system of bone strontium quantification with further application to other IVXRF bone metal quantification systems, particulary those associated with bone lead quantification. It was found that calcium can be prepared pure of inherent contamination from strontium (and other elements) through a hydroxide precipitation producing pure Ca(OH)2, thereby, allowing for the production of a blank phantom which has not been available previously. The pure Ca(OH)2 can then be used for the preparation of pure CaHPO4 ⋅ 2H2O. A solid state pure HAp phantom can then be prepared by reaction of Ca(OH)2 and CaHPO4 ⋅ 2H2O mixed as to produce a Ca/P mole ratio of 1.67, that in HAp and the mineral phase of bone, in the presence of a setting solution prepared as to raise the total phosphate concentration of the solution by increasing the solubility CaHPO4 ⋅ 2H2O and thereby precipitating HAp. The procedure can only be used to prepare phantoms in which doping with the analyte does not disturb the Ca/P ratio substantially. In cases in which phantoms are to be prepared with high concentrations of strontium, the cement mixture can be modified as to introduce strontium in the form of Sr(OH)2 ⋅ 8H2O as to maintain a (Ca + Sr)/P ratio of 1.67. It was found by both X-ray diffraction spectrometry and Raman spectroscopy studies that strontium substitutes for calcium as in bone when preparing phantoms by this route. The necessity for the blank bone phantoms was assessed through the first blank bone phantom measurement and Monte Carlo simulations. It was found that for the 125I-induced IVXRF system of bone strontium quantification, the source, 125I brachytherapy seeds may be contributing coherently and incoherently scattered zirconium X-rays to the measured spectra, thereby requiring the use of the blank bone phantom as a means of improving the overall quantification methodology. Monte Carlo simulations were employed to evaluate any improvement by the introduction of HAp phantoms into the coherent normalization-based calibration procedure. It was found that HAp phantoms remove the need for a coherent conversion factor (CCF) thereby potentially increasing accuracy of the quantification. Further, it was found that in order for soft tissue attenuation corrections to be possible using spectroscopic information alone, HAp along with a suitable soft tissue surrogate material need to be employed. The HAp phantom material was used for the evaluations of portable X-ray analyzer systems for their potential for IVXRF quantification of lead and strontium with a focus on a comparison between tungsten, silver and rhodium target systems. Silver and rhodium target X-ray tube systems were found to be comparable for this quantification.

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