Grating‐based x‐ray differential phase contrast imaging with twin peaks in phase‐stepping curves—phase retrieval and dewrapping

Abstract

Using the phase retrieval and dewrapping methods proposed to deal with the phenomenon of twin peaks in PSCs and phase wrapping, the performance of grating-based x-ray differential phase contrast radiography and CT can be significantly improved.

Reducing radiation dose in grating based x‐ray phase contrast CT with twin‐peaks in its phase stepping curves

“…13 Due to imperfections, such as nonuniform gold layer thickness, in the absorption grating induced in the fabrication process, 14 it has been reported that twin-peaks at significant different heights may exist in the PSCs. 8,15,16 In general, as noted in Ref. 17, the polychromatic X-ray spectrum is another important factor that may cause the twin-peaks phenomenon in the PSCs.…”

“…[1][2][3] Initially, this imaging method can only be implemented with highly brilliant synchrotron x-ray sources. 1,2 Recently, the requirement for an x-ray source with complete spatial coherence has been relaxed via the adoption of Talbot interferometry, 4 which can be implemented with a micro-focus tube [5][6][7][8] or a multi-slit source grating in front of an x-ray tube with a finite focal spot. [9][10][11] By fulfilling the requirement for partial spatial coherence, the grating based differential phase contrast CT is compatible with polychromatic x-ray sources that are readily available in practice.…”

“…In order to improve the accuracy of Fourier phase retrieval, it has been proposed that the shearing grating should be shifted over twice the period of absorption grating G 2 . 15,16 A theoretical framework 8 has been previously developed by us to characterize the Fourier components of the PSCs distorted by the twin-peaks phenomenon. Based on this theoretical framework, we have proposed an approach to extract the differential phase contrast signals from the secondorder Fourier component, which improves the accuracy of the Fourier phase retrieval substantially.…”

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

“…Modregger et al 23 proposed a deconvolution-based approach for information retrieval, which does not depend on the assumption of a sinusoidal phase-stepping curve. 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.…”

Quantitative evaluation on 3D fetus morphology via X‐ray grating based imaging technique

“…Currently, the synchrotron‐based XPCI techniques, propagation phase‐contrast imaging (PPI) and X‐ray grating interferometry (XGI), have dominated the nondestructive 3D visualization of biological tissues in hard X‐ray domain. Both techniques perform well over a large energy range in imaging application without requiring a strictly monochromatic or collimated X‐ray wave and display different characteristics of intensity distribution recorded on detectors, and different physical quantity in raw data determines different phase retrieval method.…”