It is very challenging to measure the chemical composition of hetero nanostructures in a reliable and quantitative manner. Here, we propose a novel and straightforward approach that can be used to quantify energy dispersive X-ray spectra acquired in a transmission electron microscope. Our method is based on a combination of electron tomography and the so-called ζ-factor technique. We will demonstrate the reliability of our approach as well as its applicability by investigating Au-Ag and Au-Pt hetero nanostructures. Given its simplicity, we expect that the method could become a new standard in the field of chemical characterization using electron microscopy.
The overall importance of x-ray phase contrast (XPC) imaging has grown substantially in the last decades, in particular with the recent advent of compact lab-based XPC systems. For optimizing the experimental XPC setup, as well as benchmarking and testing new acquisition and reconstruction techniques, Monte Carlo (MC) simulations are a valuable tool. GATE, an open source application layer on top of the Geant4 simulation software, is a versatile MC tool primarily intended for various types of medical imaging simulations. To our knowledge, however, there is no GATE-based academic simulation software available for XPC imaging. In this paper, we extend the GATE framework with new physics-based tools for accurate XPC simulations. Our approach combines Monte Carlo simulations in GATE for modelling the x-ray interactions in the sample with subsequent numerical wave propagation, starting from the GATE output.
Laboratory based X-ray micro-CT is a non-destructive testing method that enables three dimensional visualization and analysis of the internal and external morphology of samples. Although a wide variety of commercial scanners exist, most of them are limited in the number of degrees of freedom to position the source and detector with respect to the object to be scanned. Hence, they are less suited for industrial X-ray imaging settings that require advanced scanning modes, such as laminography, conveyor belt scanning, or time-resolved imaging (4DCT). We introduce a new X-ray scanner FleXCT that consists of a total of ten motorized axes, which allow a wide range of non-standard XCT scans such as tiled and off-centre scans, laminography, helical tomography, conveyor belt, dynamic zooming, and X-ray phase contrast imaging. Additionally, a new software tool ‘FlexRayTools’ was created that enables reconstruction of non-standard XCT projection data of the FleXCT instrument using the ASTRA Toolbox, a highly efficient and open source set of tools for tomographic projection and reconstruction.
One of the most commonly used correction methods in X-ray imaging is flat field correction, which corrects for systematic inconsistencies, such as differences in detector pixel response. In conventional X-ray imaging, flat fields are acquired by exposing the detector without any object in the X-ray beam. However, in edge illumination Xray CT, which is an emerging phase contrast imaging technique, two masks are used to measure the refraction of the X-rays. These masks remain in place while the flat fields are acquired and thus influence the intensity of the flat fields. This influence is studied theoretically and validated experimentally using Monte Carlo simulations of an edge illumination experiment in GATE.
The overall importance of x-ray phase-contrast imaging techniques has grown substantially due to their ability to generate contrast in a range of situations where traditional absorption imaging falls short. Monte Carlo simulations are a valuable tool for benchmarking and testing new acquisition and reconstruction techniques, as well as optimisation of the system and components design. GATE, an open source application layer on top of the Geant4 simulation software, is a versatile Monte Carlo tool for various types of medical imaging simulations. Currently, however, tools intended for phase-contrast imaging are not yet available within GATE. In this work, we introduce grating-based x-ray phase-contrast simulations in GATE, with specific focus on phantoms with fibrous microstructures. The simulations are based on a combination of Monte Carlo simulations in GATE for modelling the x-ray interactions in the sample, and subsequent numerical wave propagation in the interferometer, modelled in MATLAB. We show simulated computed tomography results for grating interferometry.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.