Real-Space x-ray tomographic reconstruction of randomly oriented objects with sparse data frames

Opt Express. 2014 Feb 10;22(3):2403-13. doi: 10.1364/OE.22.002403.

Abstract

Schemes for X-ray imaging single protein molecules using new x-ray sources, like x-ray free electron lasers (XFELs), require processing many frames of data that are obtained by taking temporally short snapshots of identical molecules, each with a random and unknown orientation. Due to the small size of the molecules and short exposure times, average signal levels of much less than 1 photon/pixel/frame are expected, much too low to be processed using standard methods. One approach to process the data is to use statistical methods developed in the EMC algorithm (Loh & Elser, Phys. Rev. E, 2009) which processes the data set as a whole. In this paper we apply this method to a real-space tomographic reconstruction using sparse frames of data (below 10(-2) photons/pixel/frame) obtained by performing x-ray transmission measurements of a low-contrast, randomly-oriented object. This extends the work by Philipp et al. (Optics Express, 2012) to three dimensions and is one step closer to the single molecule reconstruction problem.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Algorithms*
  • Data Interpretation, Statistical
  • Imaging, Three-Dimensional / methods*
  • Protein Conformation
  • Proteins / chemistry*
  • Proteins / ultrastructure*
  • Radiographic Image Interpretation, Computer-Assisted / methods*
  • Tomography, X-Ray Computed / methods*
  • X-Ray Diffraction / methods*

Substances

  • Proteins