DigitalFraunhofer AWZ CTMTMaschinenbau und MechatronikZeitschriftenartikel
S. Zabler, M. Maisl, Peter Hornberger, Jochen Hiller, C. Fella, R. Hanke
X-ray imaging and computed tomography for engineering applications
tm - Technisches Messen, vol. 87, no. Online veröffentlicht: 08.04.2020
2020
DOI: 10.1515/teme-2019-0151
Abstract anzeigen
After an incremental development which took place over four decades, X-ray imaging has become an important tool for non-destructive testing and evaluation. Computed Tomography (CT) in particular beholds the power of determining the location of flaws and inclusions (e. g. in castings and composites) in three-dimensional object coordinates. Therefore, and thanks to a speed-up of the measurement, CT is now routinely considered for in-line inspection of electronics, castings and composites. When precision and not speed is important, Micro-CT (μCT) can be employed for Dimensional Measurements (DM, e. g. quality assurance and shape verification), as well as for in situ testing, and for characterizing micro-structures in metals and composites. Using appropriate image processing and analysis μCT can determine the local fibre orientation in composites, the granular morphology of battery cathodes or the inter-connectivity of certain phases in casting alloys.
Today, the large variety of X-ray instruments and methods poses an application problem which requires experience and a lot of knowledge for deciding which technique applies best to the task at hand. Application-specific guidelines exist for X-ray radiography testing (RT) only, whereas standardization has been applied to CT, unfortunately leaving out high resolution subμ CT, and nano-CT. For the latter exist an equally high number of NDT applications, however these instruments still necessitate a profound expertise. The task is to identify key industrial applications and push CT from system standardization to application specific automation.
DigitalFraunhofer AWZ CTMTMaschinenbau und MechatronikZeitschriftenartikel
A. Detterbeck, M. Hofmeister, D. Haddad, D. Weber, M. Schmid, A. Hölzing, S. Zabler, E. Hofmann, K.-H. Hiller, P. Jakob, J. Engel, Jochen Hiller, U. Hirschenfelder
Determination of the mesio-distal tooth width via 3D imaging techniques with and without ionizing radiation: CBCT, MSCT, and μCT versus MRI
European Journal of Orthodontics, vol. 39, no. 3, pp. 310-319
2016
DOI: 10.1093/ejo/cjw047
Abstract anzeigen
Objective:
The purpose of this study was to estimate the feasibility and accuracy of mesio-distal width measurements with magnetic resonance imaging (MRI) in comparison to conventional 3D imaging techniques [multi-slice CT (MSCT), cone-beam CT (CBCT), and µCT]. The measured values of the tooth widths were compared to each other to estimate the amount of radiation necessary to enable orthodontic diagnostics.
Material and Methods:
Two pig skulls were measured with MSCT, CBCT, µCT, and MRI. Three different judges were asked to determine the mesio-distal tooth width of 14 teeth in 2D tomographic images and in 3D segmented images via a virtual ruler in every imaging dataset.
Results:
Approximately 19% (27/140) of all test points in 2D tomographic slice images and 12% (17/140) of the test points in 3D segmented images showed a significant difference (P ≤ 0.05). The largest significant difference was 1.6mm (P < 0.001). There were fewer significant differences in the measurement of the tooth germs than in erupted teeth.
Conclusions:
Measurement of tooth width by MRI seems to be clinically equivalent to the conventional techniques (CBCT and MSCT). Tooth germs are better illustrated than erupted teeth on MRI. Three-dimensional segmented images offer only a slight advantage over 2D tomographic slice images. MRI, which avoids radiation, is particularly appealing in adolescents if these data can be corroborated in further studies.
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