Reconstruction method for grating-based x-ray phase-contrast images without knowledge of the grating positions

Pelzer, Georg; Rieger, Jens; Hauke, Christian; Horn, Florian; Michel, Thilo; Seifert, Maria; Anton, G.

doi:10.1088/1748-0221/10/12/p12017

Cited by 24 publications

(21 citation statements)

References 20 publications

(28 reference statements)

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“…Using principle component analysis (PCA), all step positions can be retrieved in a single, fast computation step. It has been adapted for gbPC imaging by Pelzer et al [26], but does not perform well for low numbers of moiré fringes and strongly attenuating samples. A combination of this method with the one given in [23] was presented in [27], which combines the applicability of PCA for arbitrary step positions with the high quality of results achieved with the method from [23].…”

Section: Discussionmentioning

confidence: 99%

Analysis and correction of bias induced by phase stepping jitter in grating-based X-ray phase-contrast imaging

et al. 2018

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Grating-based X-ray phase-contrast (gbPC) is an X-ray phase-contrast imaging method involving optical gratings that typically employs the Talbot self-imaging effect. X-ray phase contrast is known to provide significant benefits for biomedical imaging. To investigate these benefits for gbPC, a high-sensitivity gbPC micro-CT setup for small biological samples has been constructed. A gbPC projection measurement simultaneously retrieves the transmittance, differential-phase and dark-field modalities of a sample. Phase stepping, the most common gbPC acquisition technique, involves several acquisitions at different lateral positions of one of the gratings. The three modalities can then be retrieved by least-squares- or FFT-based methods. Unfortunately, increasing differential-phase sensitivity also leads to an increased magnitude of artifacts introduced during retrieval of the modalities from the phase-stepping data, which limits image quality. Most importantly, processing of phase-stepping data with incorrect stepping positions (i.e., spatial sampling jitter) can introduce artifacts to the modalities. Using data from the high-sensitivity gbPC setup, as well as simulations, we show that an artifact is introduced by the jitter which is correlated with the phase of the stepping curve. We present a theoretical explanation for this correlation by introducing small deviations to an equidistant sampling of a stepping curve and approximating the effect on the calculation of the three gbPC modalities with a first-order Taylor approximation. Finally, we present an algorithm for the detection and removal of these artifacts that exploits these correlations. We show that this algorithm is able to eliminate these artifacts without degrading true image information.

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Section: Discussionmentioning

confidence: 99%

Analysis and correction of bias induced by phase stepping jitter in grating-based X-ray phase-contrast imaging

et al. 2018

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“…In particular, we want to point out that the presented full‐body scan of the pig demonstrates that the phase‐stepping method is feasible for dark‐field imaging of human‐sized objects under clinical conditions. In addition, the system's acquisition speed and robustness toward external influences could be even further increased by implementing single‐shot dark‐field imaging techniques, using motionless phase‐stepping, or refining the image reconstruction …”

Section: Discussionmentioning

confidence: 99%

A preclinical Talbot–Lau prototype for x‐ray dark‐field imaging of human‐sized objects

et al. 2018

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We demonstrated that a dedicated design of a Talbot-Lau interferometer can be applied to medical imaging by constructing a preclinical Talbot-Lau prototype. We experienced that the system is feasible for imaging human-sized objects and the phase-stepping approach is suitable for clinical practice. Hence, we conclude that Talbot-Lau x-ray imaging has potential for clinical use and enhances the diagnostic power of medical x-ray imaging.

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“…The noise properties of this algorithm were later investigated by Weber et al 24 Yang et al 25 developed a phase-stepping reconstruction method for nonideal gratings, which may exhibit a phase-stepping curve with twin peaks. The problem of estimating the position of misaligned phase steps was considered by Pelzer et al 26 and Seifert et al 27 They showed that an algorithm known in optics 28 can be used to retrieve the correct phase-stepping positions, if the Talbot-Lau interferometer is detuned by rotation of either G1 or G2, such that sufficient moiré fringes appear in the reference phase, and if a sufficient number of phase steps are available. However, detuning the interferometer reduces visibility.…”

Section: Prior Workmentioning

confidence: 99%

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

et al. 2017

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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.

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Reconstruction method for grating-based x-ray phase-contrast images without knowledge of the grating positions

Cited by 24 publications

References 20 publications

Analysis and correction of bias induced by phase stepping jitter in grating-based X-ray phase-contrast imaging

Analysis and correction of bias induced by phase stepping jitter in grating-based X-ray phase-contrast imaging

A preclinical Talbot–Lau prototype for x‐ray dark‐field imaging of human‐sized objects

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

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