scholarly journals Comparative Study of the Measurement of Enamel Demineralization and Remineralization Using Transverse Microradiography and Electron Probe Microanalysis

2014 ◽  
Vol 20 (3) ◽  
pp. 937-945 ◽  
Author(s):  
Nathan J. Cochrane ◽  
Youichi Iijima ◽  
Peiyan Shen ◽  
Yi Yuan ◽  
Glenn D. Walker ◽  
...  
Keyword(s):  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Mineral Content ◽  
Atomic Ratio ◽  
Variable Density ◽  
X Rays ◽  
Mineral Density ◽  
Dental Tissues ◽  
Human Enamel ◽  
Dental Hard Tissues

AbstractTransverse microradiography (TMR) and electron probe microanalysis (EPMA) are commonly used for characterizing dental tissues. TMR utilizes an approximately monochromatic X-ray beam to determine the mass attenuation of the sample, which is converted to volume percent mineral (vol%min). An EPMA stimulates the emission of characteristic X-rays from a variable volume of sample (dependent on density) to provide compositional information. The aim of this study was to compare the assessment of sound, demineralized, and remineralized enamel using both techniques. Human enamel samples were demineralized and a part of each was subsequently remineralized. The same line profile through each demineralized lesion was analyzed using TMR and EPMA to determine vol%min and wt% elemental composition and atomic concentration ratio information, respectively. The vol%min and wt% values determined by each technique were significantly correlated but the absolute values were not similar. This was attributable to the complex ultrastructural composition, the variable density of the samples analyzed, and the nonlinear interaction of the EPMA-generated X-rays. EPMA remains an important technique for obtaining atomic ratio information, but its limitations in determining absolute mineral content indicate that it should not be used in place of TMR for determining the mineral density of dental hard tissues.

Electron Probe Microanalysis and Transverse Microradiography Studies of Artificial Lesions in Enamel and Dentin: A Comparative Study

1997 ◽  
Vol 11 (4) ◽  
pp. 426-432 ◽  
Author(s):  
H. Ngo ◽  
J. Ruben ◽  
J. Arends ◽  
D. White ◽  
G.J. Mount ◽  
...  
Keyword(s):  
Comparative Study ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Mineral Content ◽  
Local Density ◽  
Mineral Distribution ◽  
Dental Hard Tissues ◽  
Hard Tissues ◽  
Restorative Materials ◽  
Compositional Information

In cariology and research involving the interactions between restorative materials and dental hard tissues, it is important for small changes in tooth mineral content to be measurable. Currently, transverse microradiography (TMR) is the most accepted tool for the above purpose. Electron Probe Microanalysis (EPMA) can yield both qualitative identification of elements and quantitative compositional information. The purpose of this study was to compare the mineral distribution in well-defined artificial lesions, in dentin and enamel, by the use of both TMR and EPMA on the same sample. The good correlation between the two sets of data validates EPMA as a technique and helps in the interpretation of its results. The data from TMR analysis are expressed as vol% of mineral, while EPMA gives the levels of Ca and phosphate in wt%. The conversion between the two sets of data is complicated by the fact that local density is, as yet, unknown.

Absorption of primary x-rays in electron probe microanalysis

1975 ◽  
Vol 47 (14) ◽  
pp. 2408-2411 ◽  
Author(s):  
Kurt F. J. Heinrich ◽  
Harvey. Yakowitz
Keyword(s):  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
X Rays

Monte Carlo Simulation of Characteristic Secondary Fluorescence in Electron Probe Microanalysis of Homogeneous Samples Using the Splitting Technique

2015 ◽  
Vol 21 (3) ◽  
pp. 753-758 ◽  
Author(s):  
Mauricio Petaccia ◽  
Silvina Segui ◽  
Gustavo Castellano
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Variance Reduction ◽  
Fluorescence Enhancement ◽  
Radiation Transport ◽  
X Rays ◽  
X Ray ◽  
Secondary Fluorescence

AbstractElectron probe microanalysis (EPMA) is based on the comparison of characteristic intensities induced by monoenergetic electrons. When the electron beam ionizes inner atomic shells and these ionizations cause the emission of characteristic X-rays, secondary fluorescence can occur, originating from ionizations induced by X-ray photons produced by the primary electron interactions. As detectors are unable to distinguish the origin of these characteristic X-rays, Monte Carlo simulation of radiation transport becomes a determinant tool in the study of this fluorescence enhancement. In this work, characteristic secondary fluorescence enhancement in EPMA has been studied by using the splitting routines offered by PENELOPE 2008 as a variance reduction alternative. This approach is controlled by a single parameter NSPLIT, which represents the desired number of X-ray photon replicas. The dependence of the uncertainties associated with secondary intensities on NSPLIT was studied as a function of the accelerating voltage and the sample composition in a simple binary alloy in which this effect becomes relevant. The achieved efficiencies for the simulated secondary intensities bear a remarkable improvement when increasing the NSPLIT parameter; although in most cases an NSPLIT value of 100 is sufficient, some less likely enhancements may require stronger splitting in order to increase the efficiency associated with the simulation of secondary intensities.

Absorption Correction Curves Obtained from Measurements of the Production of X-Rays as a Function of Depth

1972 ◽  
Vol 16 ◽  
pp. 198-205
Author(s):  
J.D. Brown ◽  
L. Parobek
Keyword(s):  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
X Rays ◽  
Matrix Elements ◽  
X Ray ◽  
Absorption Correction ◽  
Correction Equations

AbstractMeasurements of x-ray production as a function of depth in a sample (ϕ(ρz) curves) are fundamental to the determination of the quantitative equations for relating x-ray intensity to composition in electron probe microanalysis. These ϕ(ρz) curves have been measured for four different voltages and a number of different tracers in aluminum, copper, silver arid gold as matrix elements. From these ϕ(ρz) curves the absorption correction curves (f(x) curves) can be calculated. Such curves have been obtained and comparison is made with the absorption correction equations of Philibert. The effect of a tilted sample on the absorption correction is also discussed.

Microstructure and Compound Developed from La-As-Fe System at 1223K

2013 ◽  
Vol 702 ◽  
pp. 145-148 ◽  
Author(s):  
Xiao Dong Liu ◽  
Jin Zhu Zhang ◽  
Si Si Zhu
Keyword(s):  
Optical Microscopy ◽  
Ternary Compound ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Binary Compound ◽  
Atomic Ratio ◽  
X Ray Diffraction ◽  
Gray Phase ◽  
X Ray

The interaction among Lanthanum, Arsenic and Iron at 1223K were studied by means of electron probe microanalysis, optical microscopy and X-ray diffraction. The result shows that the gray phase might be a ternary compound La10Fe50As40, and the binary compound LaAs and the ternary compound La10Fe50As40 are the main interaction products when the atomic ratio of La to As is 1:3. The eutectic compound Fe2As can be precipitated from ferrite with the temperature decreasing.

scholarly journals A Model for Characteristic X-Ray Emission in Electron Probe Microanalysis based on the Spherical Harmonic (PN) Method for Electron Transport

2021 ◽  
Author(s):  
Jonas Buenger ◽  
Silvia Richter ◽  
Manuel Torrilhon
Keyword(s):  
Monte Carlo ◽  
Electron Transport ◽  
Electron Probe Microanalysis ◽  
Spherical Harmonic ◽  
Electron Probe ◽  
Material Structure ◽  
X Rays ◽  
Minimum Entropy ◽  
Promising Alternative ◽  
X Ray

Classical k-ratio models, e.g. ZAF and phi(rho z), used in electron probe microanalysis (EPMA) assume a homogeneous or multi-layered material structure, which essentially limits the spatial resolution of EPMA to the size of the interaction volume where characteristic x-rays are produced. We present a new model for characteristic x-ray emission that avoids assumptions on the material structure to not restrict the resolution of EPMA a-priori. Our model bases on the spherical harmonic (PN) approximation of the Boltzmann equation for electron transport in continuous slowing down approximation. PN models have a simple structure, are hierarchical in accuracy and well-suited for efficient adjoint-based gradient computation, which makes our model a promising alternative to classical models in terms of improving the resolution of EPMA in the future. We present results of various test cases including a comparison of the PN model to a minimum entropy moment model as well as Monte-Carlo (MC) trajectory sampling, a comparison of PN-based k-ratios to k-ratios obtained with MC, a comparison with experimental data of electron backscattering yields as well as a comparison of PN and Monte-Carlo based on characteristic X-ray generation in a three-dimensional material probe with fine structures.

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