scholarly journals Iodine vapor staining for atomic number contrast in backscattered electron and X‐ray imaging

2014 ◽  
Vol 77 (12) ◽  
pp. 1044-1051 ◽  
Author(s):  
Alan Boyde ◽  
Fergus A. Mccorkell ◽  
Graham K. Taylor ◽  
Richard J. Bomphrey ◽  
Michael Doube
Keyword(s):  
Atomic Number ◽  
Iodine Vapor ◽  
X Ray ◽  
X Ray Imaging ◽  
Backscattered Electron ◽  
Atomic Number Contrast

Thickness and composition determinations from T.E.M. specimens using both x-ray and backscattered electron data

1984 ◽  
Vol 42 ◽  
pp. 576-577
Author(s):  
M.D. Ball ◽  
H. Lagace ◽  
M.C. Thornton
Keyword(s):  
Electron Microscope ◽  
Atomic Number ◽  
Transmission Electron Microscope ◽  
Convenient Method ◽  
Flow Chart ◽  
X Ray ◽  
Intensity Measurements ◽  
Transmission Electron ◽  
Electron Intensity ◽  
Backscattered Electron

The backscattered electron coefficient η for transmission electron microscope specimens depends on both the atomic number Z and the thickness t. Hence for specimens of known atomic number, the thickness can be determined from backscattered electron coefficient measurements. This work describes a simple and convenient method of estimating the thickness and the corrected composition of areas of uncertain atomic number by combining x-ray microanalysis and backscattered electron intensity measurements.The method is best described in terms of the flow chart shown In Figure 1. Having selected a feature of interest, x-ray microanalysis data is recorded and used to estimate the composition. At this stage thickness corrections for absorption and fluorescence are not performed.

Computer reconstructed X-ray imaging

1979 ◽  
Vol 292 (1390) ◽  
pp. 223-232 ◽  
Keyword(s):  
Spatial Resolution ◽  
Atomic Number ◽  
High Sensitivity ◽  
Precise Determination ◽  
Diagnostic Methods ◽  
X Ray ◽  
X Ray Imaging ◽  
Internal Structures ◽  
Transmission Measurements

Computed tomography is a method for obtaining a series of radiographic pictures of contiguous slices through a solid object such as the human body. Each picture is computed from a set of X-ray transmission measurements and represents the distribution of X-ray attenuation in the slice. The high sensitivity of the method to changes in both density and atomic number has resulted in the development of new diagnostic methods in medicine. The limitations of the method are discussed in terms of two particular kinds of application. First, those applications in which a very precise determination of density or atomic number is required, but at low spatial resolution; an example would be the determination of the uniformity of mixture of plastics or metals. The second kind of application is that requiring high spatial resolution as in the detection of cracks and the visualization of internal structures in complicated objects.

On the Contrast of High Resolution Backscattered Electron Images

1975 ◽  
Vol 33 ◽  
pp. 206-207
Author(s):  
P. S. D. Lin
Keyword(s):  
Atomic Number ◽  
Large Angle ◽  
Backscattering Coefficient ◽  
Secondary Electrons ◽  
Backscattered Electrons ◽  
Rutherford Scattering ◽  
Electron Mode ◽  
Backscattered Electron ◽  
Atomic Number Contrast ◽  
Surface Changes

When the angle θ between the incident electron and the normal to a surface changes, the yield of secondary electrons Y varies approximately as secθ. The topographic contrast thus produced renders secondary electrons useful for surface studies. On the other hand, as the atomic number Z increases, the backscattering coefficient η increases more rapidly than Y. Therefore, backscattered electrons should be collected as signal when atomic number contrast is desired. Figs. 1 and 2 exemplify the increase of atomic number contrast as one switches from secondary to backscattered electron mode.Backscattering is not a localized process, since both single and plural/ multiple scattering are involved. In Everhart's model, incident electrons are retarded by the inelastic scattering and scattered backwards by large angle Rutherford scattering.

scholarly journals Comparison of Rhenium and Iodine as Contrast Agents in X-Ray Imaging

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
José Carlos De La Vega ◽  
Pedro Luis Esquinas ◽  
Jovan Kaur Gill ◽  
Selin Jessa ◽  
Bradford Gill ◽  
...  
Keyword(s):  
Contrast Agents ◽  
Atomic Number ◽  
Imaging Techniques ◽  
Absorbed Dose ◽  
X Rays ◽  
Micro Computed Tomography ◽  
Low Contrast ◽  
X Ray ◽  
X Ray Imaging ◽  
The Difference

Purpose. The majority of X-ray contrast agents (XCA) are made with iodine, but iodine-based XCA (I-XCA) exhibit low contrast in high kVp X-rays due to iodine’s low atomic number (Z = 53) and K-edge (33.1 keV). While rhenium is a transition metal with a high atomic number (Z = 75) and K-edge (71.7 keV), the utilization of rhenium-based XCA (Re-XCA) in X-ray imaging techniques has not been studied in depth. Our study had two objectives: (1) to compare both the image quality and the absorbed dose of I- and Re-XCA and (2) to prepare and image a rhenium-doped scaffold. Procedures. I- and Re-XCA were prepared and imaged from 50 to 120 kVp by Micro-computed tomography (µCT) and digital radiography and from 120 to 220 kVp by planar X-ray imaging. The scans were repeated using 0.1 to 1.6 mm thick copper filters to harden the X-ray beam. A rhenium-doped scaffold was prepared via electrospinning, used to coat catheters, and imaged at 90 kVp by µCT. Results. I-XCA have a greater contrast-to-noise ratio (CNR) at 50 and 80 kVp, but Re-XCA have a greater CNR at >120 kVp. The difference in CNR is increased as the thickness of the copper filters is increased. For instance, the percent CNR improvement of rhenium over iodine is 14.2% with a 0.6 mm thick copper filter, but it is 59.1% with a 1.6 mm thick copper filter, as shown at 120 kVp by µCT. Upon coating them with a rhenium-doped scaffold, the catheters became radiopaque. Conclusions. Using Monte Carlo simulations, we showed that it is possible to reduce the absorbed dose of high kVp X-rays while allowing the acquisition of high-quality images. Furthermore, radiopaque catheters have the potential of enhancing the contrast during catheterizations and helping physicians to place catheters inside patients more rapidly and precisely.

Precipitates in GaN epilayers grown on sapphire substrates

1998 ◽  
Vol 13 (8) ◽  
pp. 2100-2104 ◽  
Author(s):  
Junyong Kang ◽  
Tomoya Ogawa
Keyword(s):  
Grain Boundaries ◽  
Atomic Number ◽  
Luminescence Intensity ◽  
Energy Dispersive Spectrometry ◽  
Deep Levels ◽  
Energy Dispersive ◽  
Yellow Luminescence ◽  
X Ray ◽  
Sapphire Substrates ◽  
Atomic Number Contrast

Precipitates in GaN epilayers grown on sapphire substrates were investigated by atomic number contrast (ANC), wavelength-dispersive x-ray spectrometry (WDS), energy-dispersive spectrometry (EDS), and cathodoluminescence (CL) techniques. The results showed that the precipitates are mainly composed of gallium and oxygen elements and distribute more sparsely and inhomogeneously in directions in the sample grown on substrate nitridated for a longer period. Yellow luminescence intensity was imaged to be stronger in the precipitates. The results suggest that the precipitates are formed on dislocations and grain boundaries by substituting oxygen onto the nitrogen site, and result in the formations of deep levels nearby.

Calculation of effective atomic numbers using a rational polynomial approximation method with a dual-energy X-ray imaging system

2021 ◽  
pp. 1-14
Author(s):  
Chia-Hao Chang ◽  
Yu-Ching Ni ◽  
Sheng-Pin Tseng
Keyword(s):  
Atomic Number ◽  
Polynomial Approximation ◽  
Approximation Method ◽  
Imaging System ◽  
Effective Atomic Number ◽  
Dual Energy ◽  
Calibration Model ◽  
X Ray ◽  
Rational Polynomial ◽  
X Ray Imaging

The study aims to develop a rational polynomial approximation method for improving the accuracy of the effective atomic number calculation with a dual-energy X-ray imaging system. This method is based on a multi-materials calibration model with iterative optimization, which can improve the calculation accuracy of the effective atomic number by adding a rational term without increasing the computation time. The performance of the proposed rational polynomial approximation method is demonstrated and validated by both simulated and experimental studies. The twelve reference materials are used to establish the effective atomic number calibration model, and the value of the effective atomic numbers are between 5.444 and 22. For the accuracy of the effective atomic number calculation, the relative differences between calculated and experimental values are less than 8.5%for all sample cases in this study. The average calculation accuracy of the method proposed in this study can be improved by about 40%compared with the conventional polynomial approximation method. Additionally, experimental quality assurance phantom imaging result indicates that the proposed method is compliant with the international baggage inspection standards for detecting the explosives. Moreover, the experimental imaging results reveal that the difference of color between explosives and the surrounding materials is in significant contrast for the dual-energy image with the proposed method.

Mean Atomic Number Quantitative Assessment in Backscattered Electron Imaging

2012 ◽  
Vol 18 (6) ◽  
pp. 1355-1361 ◽  
Author(s):  
E. Sánchez ◽  
M. Torres Deluigi ◽  
G. Castellano
Keyword(s):  
Atomic Number ◽  
Mineral Phase ◽  
Experimental Conditions ◽  
Backscattered Electron Imaging ◽  
X Ray ◽  
Unknown Sample ◽  
Mineral Phases ◽  
Backscattered Electron ◽  
The Mean ◽  
Electron Imaging

AbstractA method for obtaining quantitative mean atomic number images in a scanning electron microscope for different kinds of samples has been developed. The backscattered electron signal is monotonically increasing with the mean atomic number Z, and accordingly Z can be given as a function of the image gray levels. From results obtained from Monte Carlo simulations, an exponential function is fitted to convert the backscattered registered gray levels into a Z image map. Once this fitting was performed, the reproducibility of the Z determination was checked through the acquisition of backscattered electron images from metal and mineral standards. The developed method can be applied to any unknown sample, always controlling the experimental conditions, as shown here for a thin section of a rock in which several unknown mineral phases are present; the results obtained herein are compared to quantitative assessments performed with X-ray spectra from each mineral phase.

Defects of Platelet Function Recognized by X-Ray Imaging and Scanning Electron Microscopy

1985 ◽  
Vol 43 ◽  
pp. 610-613
Author(s):  
M.G. Baldini ◽  
S. Morinaga ◽  
D. Minasian ◽  
R. Feder ◽  
D. Sayre ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Biology ◽  
Imaging Technique ◽  
Human Platelets ◽  
X Rays ◽  
X Ray ◽  
X Ray Imaging ◽  
Complex Phenomena ◽  
Scanning Electron

Contact X-ray imaging is presently developing as an important imaging technique in cell biology. Our recent studies on human platelets have demonstrated that the cytoskeleton of these cells contains photondense structures which can preferentially be imaged by soft X-ray imaging. Our present research has dealt with platelet activation, i.e., the complex phenomena which precede platelet appregation and are associated with profound changes in platelet cytoskeleton. Human platelets suspended in plasma were used. Whole cell mounts were fixed and dehydrated, then exposed to a stationary source of soft X-rays as previously described. Developed replicas and respective grids were studied by scanning electron microscopy (SEM).

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