title: Noise in x-ray grating-based phase-contrast imaging.
abstract: OBJECTIVE
  Grating-based x-ray phase-contrast imaging is a fast developing new modality not only for medical imaging, but as well for other fields such as material sciences. While these many possible applications arise, the knowledge of the noise behavior is essential.
  
  
  METHODS
  In this work, the authors used a least squares fitting algorithm to calculate the noise behavior of the three quantities absorption, differential phase, and dark-field image. Further, the calculated error formula of the differential phase image was verified by measurements. Therefore, a Talbot interferometer was setup, using a microfocus x-ray tube as source and a Timepix detector for photon counting. Additionally, simulations regarding this topic were performed.
  
  
  RESULTS
  It turned out that the variance of the reconstructed phase is only dependent of the total number of photons used to generate the phase image and the visibility of the experimental setup. These results could be evaluated in measurements as well as in simulations. Furthermore, the correlation between absorption and dark-field image was calculated.
  
  
  CONCLUSIONS
  These results provide the understanding of the noise characteristics of grating-based phase-contrast imaging and will help to improve image quality.
authors.affiliation: ECAP-Erlangen Centre for Astroparticle Physics, University of Erlangen-Nuremberg, Erwin-Rommel-Str. 1, 91058 Erlangen, Germany. thomas.weber@physik.uni-erlangen.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Weber
authors.forename: Peter
authors.initials: P
authors.lastname: Bartl
authors.forename: Florian
authors.initials: F
authors.lastname: Bayer
authors.forename: Jürgen
authors.initials: J
authors.lastname: Durst
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Haas
authors.forename: Thilo
authors.initials: T
authors.lastname: Michel
authors.forename: André
authors.initials: A
authors.lastname: Ritter
authors.forename: Gisela
authors.initials: G
authors.lastname: Anton
mesh_terms: D000465:Algorithms; D016477:Artifacts; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*