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PACEA — De la Préhistoire à l’Actuel : Culture, Environnement et Anthropologie. UMR 5199, Université de Bordeaux, CNRS.


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X-Ray micro-tomography

par Frédéric Santos - publié le

In December 2013 PACEA acquired a micro-CT scanner dedicated for use in the bio-anthropological and archaeological sciences. This instrument was bought with financing from Aquitaine Regional Council (organising committee chaired by Olivier Dutour) and the Cluster of Excellence in archaeology (“LabEx LaScArBx”) from the universities of Bordeaux and Bordeaux Montaigne.

The scanner, housed at PLACAMAT (“Plateforme de Caractérisation des Matériaux”, UMS 3626) on the University of Bordeaux campus, can produce micro-CT images of different types of archaeological material, including biological tissue (human, animal or vegetal – mineralised, fossilised or mummified), ceramics, stone (stone tools and mineral material), glass, and metal. The high performance of this next generation scanner is due to its dual-tube construction.

While priority access is accorded to research carried out within the framework of the LabEx LaScArBx and projects developed as part of the IdEx Bordeaux, external projects with a cultural heritage focus or those form the scientific and industrial sector are also possible (see examples below).

Manufacturer : General Electric
Model : V|tome|x s
Date of acquisition : 1 juillet 2014
Cost : 370 000 € HT
Financing : 50% Aquitaine Region, 50% LabEx
Location : PLACAMAT : PLateforme Aquitaine de CAractérisation des MATériaux, UMS 3626

Main technical specifications

  • Detectability : > 10 µm (directional tube), > 2 µm (transmission tube)
  • Max power : 180kV (15W) to 240 kV (320W)
  • Max sample size : up to 250 mm in diameter and 400 mm in length
  • Max sample weight : 10kg
  • Rotation precision : 0.1°

Scientific objectives

X-ray microtomography is a non-destructive tomography technique used to create 3D visual models of objects.

The 3D images of the internal structure of objects combine a series of 2D radiographs taken at different angles. The grey levels of each projection reflect the absorption coefficient and thickness of the object. A reconstruction algorithm applied to all the 2D x-ray images is then used to recalculate the absorption coefficient for each point on the objects volume. This produces a quantified representation of density variations and atomic composition of the internal structure of the micro-scanned object.

Examples of micro-CT scans produced by members of the LabEx LaScArBx

A : Decorated eye-hafted axe in cooper alloy, 20th century Hungary – identification of structural defects (© Michel Pernot, IRMAT CRP2A).

B : Human fibula embedded with a fragment of a projectile point, Grotte de l’Orage, Neolithic (© Delphine Linard, Patrice Courtaud, PACEA).

C : Reindeer antler Pressure-flaker, experiments M. Baumann, S. Maury – identification of fissuring during manufacture (© Malvina Baumann, Hugues Plisson, PACEA).

D : Roman amphora studied during the doctoral research Pierre Machut – identification of heterogenous componants and porosities (© Rémy Chapoulie, IRAMAT CRP2A).

E : Coralloid from the Grotte de Leye (Dordogne) studied during the doctoral research of Léna Bassel – identification of porosities and the interface between the cave wall and the concretion (© Catherine Ferrier, PACEA).

F : Child vertebra from the pre-ceramic Neolithic of the Near East (Early PPNB, Syria) – identification of a stage of vertebral infection representing the earliest evidence for tuberculosis in the world (© Olivier Dutour, Hélène Coqueugniot, PACEA).