A Dedicated On-Board Dual-Energy Computer Tomograph
A dedicated on-board dual energy computer tomograph able to generate both tomographic and digital radiographic images of unconsolidated sediments cores with a diameter up to 12 cm and a height up to 1 m was built and tested on-board of the R/V Mare Nigrum. This instrument, designed to be used on-board of any oceanographic research vessel with minimum adaptations, can work very well on stationary laboratory too, provided that there is adequate protection against hard X-rays. The tomograph has a single 160 kV X-ray tube and two set of 240 in-line X-ray detectors separated by a copper attenuator (dual-energy arrangement) allowing one to obtain tomographic as well as digital radiographic images depicting the distribution of both density and effective atomic number of the objects. In tomographic and radiographic mode, the spatial resolution of reconstructed images of the linear attenuation coefficient is about 0.5 mm while in dual-energy mode, when reconstructed images depict the distribution of densities and effective atomic numbers that requires an additional smoothing filtering, the spatial resolution is about 1 mm.
By using a set of standard samples with known values of densities and effective atomic numbers we have estimated the precision in calculating the local values of these parameters to a maximum of 8%.
By its performance and by its ability to work on-board, the tomograph could be useful not only for oceanographic researches but also for any exploratory tests performed on open sea.
KeywordsTomography Radioscopy Digital radiography Dual-energy X-ray Nondestructive testing Atomic effective number Density Sediments On-board
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