title: Beam hardening effects in grating-based x-ray phase-contrast imaging.
abstract: OBJECTIVE
  In this work, the authors investigate how beam hardening affects the image formation in x-ray phase-contrast imaging and consecutively develop a correction algorithm based on the results of the analysis.
  
  
  METHODS
  The authors' approach utilizes a recently developed x-ray imaging technique using a grating interferometer capable of visualizing the differential phase shift of a wave front traversing an object. An analytical description of beam hardening is given, highlighting differences between attenuation and phase-contrast imaging. The authors present exemplary beam hardening artifacts for a number of well-defined samples in measurements at a compact laboratory setup using a polychromatic source.
  
  
  RESULTS
  Despite the differences in image formation, the authors show that beam hardening leads to a similar reduction of image quality in phase-contrast imaging as in conventional attenuation-contrast imaging. Additionally, the authors demonstrate that for homogeneous objects, beam hardening artifacts can be corrected by a linearization technique, applicable to all kinds of phase-contrast methods using polychromatic sources.
  
  
  CONCLUSIONS
  The evaluated correction algorithm is shown to yield good results for a number of simple test objects and can thus be advocated in medical imaging and nondestructive testing.
authors.affiliation: Siemens AG Corporate Technology, 80200 München, Germany. michael.chabior.ext@siemens.com
authors.forename: Michael
authors.initials: M
authors.lastname: Chabior
authors.forename: Tilman
authors.initials: T
authors.lastname: Donath
authors.forename: Christian
authors.initials: C
authors.lastname: David
authors.forename: Oliver
authors.initials: O
authors.lastname: Bunk
authors.forename: Manfred
authors.initials: M
authors.lastname: Schuster
authors.forename: Christian
authors.initials: C
authors.lastname: Schroer
authors.forename: Franz
authors.initials: F
authors.lastname: Pfeiffer
mesh_terms: D007091:Image Processing, Computer-Assisted; D007368:Interferometry; D014057:Tomography, X-Ray Computed / Q000379:methods*