Advanced search
1 file | 11.19 MB Add to list

Spectral X-ray computed tomography : potential and applications in geoscience

(2022)
Author
Promoter
(UGent) and Axel Renno
Organization
Project
Abstract
An accurate chemical characterization of a sample is often required in different scientific applications. This is often done by using two-dimensional analytical techniques. However, a major drawback of such methods is the loss of three-dimensional information, which is often necessary for a correct characterization of an object. Therefore, methods such as X-ray computed micro-tomography (micro-CT) are becoming more popular as they enable a high-resolution three-dimensional analysis of an object. Though, X-ray tomography is not able to provide any chemical information about a sample without any prior knowledge. There have been different approaches to obtain chemical information using X-ray computed micro-tomography. This work shows a new and emerging technique called spectral X-ray computed micro-tomography (spectral-CT). This method is based on a semiconductor detector that is able to directly detect incoming X-rays and convert them into a digital output. Therefore, it is possible to analyze the X-ray spectrum, which contains a lot of different information about the measured sample based on the interaction between X-rays and the sample itself. By using the position of absorption edges in the X-ray spectrum it is possible to identify chemical elements within the spectral range of the detector (20 -160 keV). In this work, the TESCAN PolyDet 1 was used for all measurements. It uses a CdTe crystal as a detection crystal, which offers a lot of advantages for the detection of high-energy X-rays due to its high atomic number. Therefore it is possible to identify elements with atomic numbers above 48 (Cd). To show different applications and the potential of spectral-CT in geoscience different samples were analyzed. Numerous reference materials of pure elements were measured to test the performance and the limitations of the method. Moreover, different artificial mixtures of reference materials were used to simulate rock samples containing multiple phases. In addition two different application examples of spectral-CT in geosciences are presented in this work. In the first one different platinum group minerals (PGM) from the Norilsk 1 deposit in Russia are analyzed using spectral-CT. Different PGM could be identified and their three-dimensional distribution was analyzed by combining spectral-CT with high-resolution X-ray micro-CT. Moreover, the results were compared with two-dimensional analytical techniques such as scanning electron microscopy. In the second example, spectral-CT was used to analyze different ore minerals from the Witwatersrand basin in South Africa. The three-dimensional distribution of gold and different U-minerals was analyzed by combining spectral-CT with high-resolution X-ray micro-CT. Moreover, the results were compared with scanning electron microscopy. All these examples show that spectral-CT is an evolving analytical technique, which offers a lot of advantages for the three-dimensional characterization of different materials.
Keywords
X-ray computed tomography, Spectral X-ray computed tomography, Chemical analysis, Three-dimensional

Downloads

  • (...).pdf
    • full text (Published version)
    • |
    • UGent only (changes to open access on 2027-09-28)
    • |
    • PDF
    • |
    • 11.19 MB

Citation

Please use this url to cite or link to this publication:

MLA
Sittner, Jonathan. Spectral X-Ray Computed Tomography : Potential and Applications in Geoscience. Ghent University. Faculty of Sciences, 2022.
APA
Sittner, J. (2022). Spectral X-ray computed tomography : potential and applications in geoscience. Ghent University. Faculty of Sciences, Ghent, Belgium.
Chicago author-date
Sittner, Jonathan. 2022. “Spectral X-Ray Computed Tomography : Potential and Applications in Geoscience.” Ghent, Belgium: Ghent University. Faculty of Sciences.
Chicago author-date (all authors)
Sittner, Jonathan. 2022. “Spectral X-Ray Computed Tomography : Potential and Applications in Geoscience.” Ghent, Belgium: Ghent University. Faculty of Sciences.
Vancouver
1.
Sittner J. Spectral X-ray computed tomography : potential and applications in geoscience. [Ghent, Belgium]: Ghent University. Faculty of Sciences; 2022.
IEEE
[1]
J. Sittner, “Spectral X-ray computed tomography : potential and applications in geoscience,” Ghent University. Faculty of Sciences, Ghent, Belgium, 2022.
@phdthesis{8768720,
  abstract     = {{An accurate chemical characterization of a sample is often required in different scientific applications. This is often done by using two-dimensional analytical techniques. However, a major drawback of such methods is the loss of three-dimensional information, which is often necessary for a correct characterization of an object. Therefore, methods such as X-ray computed micro-tomography (micro-CT) are becoming more popular as they enable a high-resolution three-dimensional analysis of an object. Though, X-ray tomography is not able to provide any chemical information about a sample without any prior knowledge.
There have been different approaches to obtain chemical information using X-ray computed micro-tomography. This work shows a new and emerging technique called spectral X-ray computed micro-tomography (spectral-CT). This method is based on a semiconductor detector that is able to directly detect incoming X-rays and convert them into a digital output. Therefore, it is possible to analyze the X-ray spectrum, which contains a lot of different information about the measured sample based on the interaction between X-rays and the sample itself. By using the position of absorption edges in the X-ray spectrum it is possible to identify chemical elements within the spectral range of the detector (20 -160 keV). 
In this work, the TESCAN PolyDet 1 was used for all measurements. It uses a CdTe crystal as a detection crystal, which offers a lot of advantages for the detection of high-energy X-rays due to its high atomic number. Therefore it is possible to identify elements with atomic numbers above 48 (Cd).
To show different applications and the potential of spectral-CT in geoscience different samples were analyzed. Numerous reference materials of pure elements were measured to test the performance and the limitations of the method. Moreover, different artificial mixtures of reference materials were used to simulate rock samples containing multiple phases. In addition two different application examples of spectral-CT in geosciences are presented in this work. In the first one different platinum group minerals (PGM) from the Norilsk 1 deposit in Russia are analyzed using spectral-CT. Different PGM could be identified and their three-dimensional distribution was analyzed by combining spectral-CT with high-resolution X-ray micro-CT. Moreover, the results were compared with two-dimensional analytical techniques such as scanning electron microscopy. In the second example, spectral-CT was used to analyze different ore minerals from the Witwatersrand basin in South Africa. The three-dimensional distribution of gold and different U-minerals was analyzed by combining spectral-CT with high-resolution X-ray micro-CT. Moreover, the results were compared with scanning electron microscopy.
All these examples show that spectral-CT is an evolving analytical technique, which offers a lot of advantages for the three-dimensional characterization of different materials.}},
  author       = {{Sittner, Jonathan}},
  keywords     = {{X-ray computed tomography,Spectral X-ray computed tomography,Chemical analysis,Three-dimensional}},
  language     = {{eng}},
  pages        = {{var. p.}},
  publisher    = {{Ghent University. Faculty of Sciences}},
  school       = {{Ghent University}},
  title        = {{Spectral X-ray computed tomography : potential and applications in geoscience}},
  year         = {{2022}},
}