Computerized Tomography for Nondestructive Testing
Ricardo T. Lopes, COPPE, UFRJ, Rio de Janeiro, RJ, Brasil
ABSTRACT Various apparatus for x and gamma ray computed tomography (CT) have been constructed by us during the last 15 years, with the aim of producing simple and low-cost systems for non-destructive testing. The first one was constructed in 1985 and used an 137Cs radioactive source emitting 662 keV gamma - rays and a single NaI(Tl) x-ray detector. Successively the radioactive source was substituted during the years by others sources (different energy) and x-ray tubes, and the single detector by multidetection system such as arrays of detectors and image intensifiers. The last CT scanner employs a 160 kV x-ray tube and a 6"x 6" image intensifier coupled through a lens to a cooled CCD-camera. At the same time, also gamma CT-scanners were constructed for big size and/or high-density samples. These are based on Ir192 or Cs 137 radioactive sources coupled to a single NaI(Tl) gamma ray detector. The characteristics and properties of the CT-scanners based on the use of x-ray tubes, emitting x-rays in the energy range 20-100 keV, and on g emitting radioisotopes (192Ir and 137Cs) have been studied and will be described in this paper. Various types of applications have been studied: among them test objects and common objects such asphaltic mixtures, aluminum casting, solid propellant.
Publication Source: NDTISS '99 - International Symposium on NDT Contribution to the Infrastructure Safety Systems, Nov 1999 in Tores Brazil.
Publisher: Center of Tecnology, Federal University of Santa Maria (UFSM) - [Homepage]
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