Homogenization of sample absorption for the imaging of large and dense fossils with synchrotron microtomography

Nat Protoc. 2013 Sep;8(9):1708-17. doi: 10.1038/nprot.2013.098. Epub 2013 Aug 8.

Abstract

Propagation phase-contrast synchrotron radiation microtomography (PPC-SRμCT) has proved to be very successful for examining fossils. Because fossils range widely in taphonomic preservation, size, shape and density, X-ray computed tomography protocols are constantly being developed and refined. Here we present a 1-h procedure that combines a filtered high-energy polychromatic beam with long-distance PPC-SRμCT (sample to detector: 4-16 m) and an attenuation protocol normalizing the absorption profile (tested on 13-cm-thick and 5.242 g cm(-3) locally dense samples but applicable to 20-cm-thick samples). This approach provides high-quality imaging results, which show marked improvement relative to results from images obtained without the attenuation protocol in apparent transmission, contrast and signal-to-noise ratio. The attenuation protocol involves immersing samples in a tube filled with aluminum or glass balls in association with a U-shaped aluminum profiler. This technique therefore provides access to a larger dynamic range of the detector used for tomographic reconstruction. This protocol homogenizes beam-hardening artifacts, thereby rendering it effective for use with conventional μCT scanners.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Absorption
  • Fossils*
  • Signal-To-Noise Ratio
  • Synchrotrons*
  • X-Ray Microtomography / methods*