Improved reconstruction of phase-stepping data for Talbot–Lau x-ray imaging

Sebastian Kaeppler; Jens Rieger; Georg Pelzer; Florian Horn; Thilo Michel; Andreas Maier; Gisela Anton; Christian Riess

doi:10.1117/1.JMI.4.3.034005

5 September 2017 Improved reconstruction of phase-stepping data for Talbot–Lau x-ray imaging

Sebastian Kaeppler, Jens Rieger, Georg Pelzer, Florian Horn, Thilo Michel, Andreas Maier, Gisela Anton, Christian Riess

Author Affiliations +

Journal of Medical Imaging, Vol. 4, Issue 3, 034005 (September 2017). https://doi.org/10.1117/1.JMI.4.3.034005

Abstract

Grating-based Talbot–Lau x-ray interferometry is a popular method for measuring absorption, phase shift, and small-angle scattering. The standard acquisition method for this modality is phase stepping, where the Talbot pattern is reconstructed from multiple images acquired at different grating positions. We review the implicit assumptions in phase-stepping reconstruction, and find that the assumptions of perfectly known grating positions and homoscedastic noise variance are violated in some scenarios. Additionally, we investigate a recently reported estimation bias in the visibility and dark-field signal. To adapt the phase-stepping reconstruction to these findings, we propose three improvements to the reconstruction. These improvements are (a) to use prior knowledge to compute more accurate grating positions to reduce moiré artifacts, (b) to utilize noise variance information to reduce dark-field and phase noise in high-visibility acquisitions, and (c) to perform correction of an estimation bias in the interferometer visibility, leading to more quantitative dark-field imaging in acquisitions with a low signal-to-noise ratio. We demonstrate the benefit of our methods on simulated data, as well as on images acquired with a Talbot–Lau interferometer.

Citation Download Citation

Sebastian Kaeppler, Jens Rieger, Georg Pelzer, Florian Horn, Thilo Michel, Andreas Maier, Gisela Anton, and Christian Riess "Improved reconstruction of phase-stepping data for Talbot–Lau x-ray imaging," Journal of Medical Imaging 4(3), 034005 (5 September 2017). https://doi.org/10.1117/1.JMI.4.3.034005

Received: 7 April 2017; Accepted: 9 August 2017; Published: 5 September 2017

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