NDTnet 1998 Aug, Vol.3 No.8

Abstract

X and gamma-ray computed tomography (CT) is a non-destructive technique for the visualisation of internal parts of a sample. In CT a well collimated radiation beam crosses the object to be studied in a variety of positions and the attenuation of the beam is measured. After a mathematical process called reconstruction, the distribution of the linear attenuation coefficient (generally equivalent to the density) along the section of the object crossed by the radiation is determined. Various X and gamma-ray scanners have been designed and constructed for various types of industrial applications. A typical CT-scanner is composed by the following main parts:
1) a source that may be a radioisotope emitting X or gamma rays, or X-ray tube or synchrotron radiation. The energy of the emitted radiation should be modulated as a function of the sample (size and composition);
2) a detector or detectors system, that may be a single one (for X or gamma-rays) or an array of detectors, or an Image Intensifier. The last solution is very useful in the energy interval between about 10 and 100 keV; at higher energies (gamma rays) a single gamma - ray detector is perhaps the best solution;
3) a mechanics for the translation and rotation of the sample;
4) a reconstruction algorithm, generally based on back-projection.
CT was applied to various types of samples, such as: a) concrete; b) asphalt; c) wood and trees; d) soil samples; e) ceramic materials; f) works of art.
Various computed tomography CT- scanners for industrial applications have been designed and constructed) They use as radiation sources X-ray tubes or gamma emitting radioisotopes and as detectors Nal(Tl)-scintillators for gamma rays and image intensifiers for X-rays.The CT-scanners have been employed to various industrial samples such as concrete, asphalt, wood, ceramics and so on.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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