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

Kaeppler, Sebastian; Rieger, Jens; Pelzer, Georg; Horn, Florian; Michel, Thilo; Maier, Andreas; Anton, G.; Rieß, Christian

doi:10.1117/1.jmi.4.3.034005

Cited by 30 publications

(23 citation statements)

References 40 publications

(37 reference statements)

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“…In case of large objects usually small regions of interest of some square centimeters are separately acquired and are combined afterwards to a large image. Furthermore, the phase-stepping procedure 16 which is necessary in grating-based interferometric methods to resolve the sub-pixeled information is time-consuming and has high mechanical requirements to move the gratings very precisely 30 , 42 – 45 . To bring x-ray phase-contrast imaging to clinics and non-destructive testing workflows, a highly stable system with a large field of view and a fast acquisition time has to be available.…”

Section: Introductionmentioning

confidence: 99%

Talbot-Lau x-ray phase-contrast setup for fast scanning of large samples

Seifert

Ludwig

Kaeppler

et al. 2019

Sci Rep

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Compared to conventional attenuation x-ray radiographic imaging, the x-ray Talbot-Lau technique provides further information about the scattering and the refractive properties of the object in the beam path. Hence, this additional information should improve the diagnostic process concerning medical applications and non-destructive testing. Nevertheless, until now, due to grating fabrication process, Talbot-Lau imaging suffers from small grating sizes (70 mm diameter). This leads to long acquisition times for imaging large objects. Stitching the gratings is one solution. Another one consists of scanning Talbot-Lau setups. In this publication, we present a compact and very fast scanning setup which enables imaging of large samples. With this setup a maximal scanning velocity of 71.7 mm/s is possible. A resolution of 4.1 lines/mm can be achieved. No complex alignment procedures are necessary while the field of view comprises 17.5 × 150 cm2. An improved reconstruction algorithm concerning the scanning approach, which increases robustness with respect to mechanical instabilities, has been developed and is presented. The resolution of the setup in dependence of the scanning velocity is evaluated. The setup imaging qualities are demonstrated using a human knee ex-vivo as an example for a high absorbing human sample.

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Section: Introductionmentioning

confidence: 99%

Talbot-Lau x-ray phase-contrast setup for fast scanning of large samples

Seifert

Ludwig

Kaeppler

et al. 2019

Sci Rep

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“…On the contrary, Fig. 3(d–f) proves the removal of the artifacts using an improved reconstruction algorithm, which adjusts the phase-step positions 51 .…”

Section: Resultsmentioning

confidence: 97%

“…However, signal extraction remains challenging taking in mind the small grating periods, typically in the range of a few microns. Hence, the mechanical robustness of the interferometer is key together with sophisticated image retrieval algorithms that correct for artifacts caused by mismatches in grating alignment 40 and phase-step position 48 – 51 . An alternative to phase-stepping is especially important for CT-measurements, as a continuously rotating gantry is a requirement for clinical applications.…”

Section: Introductionmentioning

confidence: 99%

Implementation of a Talbot-Lau interferometer in a clinical-like c-arm setup: A feasibility study

Horn

Leghissa

Kaeppler

et al. 2018

Sci Rep

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X-ray grating-based phase-contrast imaging has raised interest regarding a variety of potential clinical applications, whereas the method is feasible using a medical x-ray tube. Yet, the transition towards a clinical setup remains challenging due to the requirement of mechanical robustness of the interferometer and high demands applying to medical equipment in clinical use. We demonstrate the successful implementation of a Talbot-Lau interferometer in an interventional c-arm setup. The consequence of vibrations induced by the rotating anode of the tube is discussed and the prototype is shown to provide a visibility of 21.4% at a tube voltage of 60 kV despite the vibrations. Regarding clinical application, the prototype is mainly set back due to the limited size of the field of view covering an area of 17 mm × 46 mm. A c-arm offers the possibility to change the optical axis according to the requirements of the medical examination. We provide a method to correct for artifacts that result from the angulation of the c-arm. Finally, the images of a series of measurements with the c-arm in different angulated positions are shown. Thereby, it is sufficient to perform a single reference measurement in parking position that is valid for the complete series despite angulation.

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“…Improvements were discussed to further optimize these results including phase stepping methods [36,37] and optimizations of the debris shield before the source grating. Other adjustments to the physical setup, such as x-ray source adjustments and a more efficient imaging device, could provide further enhancements.…”

Section: Discussionmentioning

confidence: 99%

“…This is achieved by laterally shifting the grating positions by a fraction of their period and recording reference images for each configuration. This gives a database of background images that may be used when comparing reference images to probe images [36,37]. Doing so eliminates any phase offsets, which would have otherwise been compensated for through numerical techniques, thereby reducing numerical artefacts and improving the precision of the final results [38,39].…”

Section: Use For High-repetition-rate Facilities a Resolution Of Recmentioning

confidence: 99%

Proof-of-concept Talbot–Lau x-ray interferometry with a high-intensity, high-repetition-rate, laser-driven K-alpha source

Bouffetier¹,

Ceurvorst²,

Valdivia³

et al. 2020

Appl. Opt.

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Talbot-Lau x-ray interferometry is a grating-based phase-contrast technique, which enables measurement of refractive index changes in matter with micrometric spatial resolution. The technique has been established using a variety of hard x-ray sources, including synchrotron, free-electron lasers, and x-ray tubes, and could be used in the optical range for low-density plasmas. The tremendous development of table-top high-power lasers makes the use of high-intensity, laser-driven K-alpha sources appealing for Talbot-Lau interferometer applications in both high-energy-density plasma experiments and biological imaging. To this end, we present the first, to the best of our knowledge, feasibility study of Talbot-Lau phase-contrast imaging using a high-repetition-rate laser of moderate energy (100 mJ at a repetition rate of 10 Hz) to irradiate a copper backlighter foil. The results from up to 900 laser pulses were integrated to form interferometric images. A constant fringe contrast of 20% is demonstrated over 100 accumulations, while the signal-to-noise ratio continued to increase with the number of shots. Phase retrieval is demonstrated without prior ex-situ phase stepping. Instead, correlation matrices are used to compensate for the displacement between reference acquisition and the probing of a PMMA target rod. The steps for improved measurements with more energetic laser systems are discussed. The final results are in good agreement with the theoretically predicted outcomes, demonstrating the applicability of this diagnostic to a range of laser facilities for use across several disciplines.

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

Cited by 30 publications

References 40 publications

Talbot-Lau x-ray phase-contrast setup for fast scanning of large samples

Talbot-Lau x-ray phase-contrast setup for fast scanning of large samples

Implementation of a Talbot-Lau interferometer in a clinical-like c-arm setup: A feasibility study

Proof-of-concept Talbot–Lau x-ray interferometry with a high-intensity, high-repetition-rate, laser-driven K-alpha source

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