X-ray interferometer with bent gratings: Towards larger fields of view

Revol, Vincent; Kottler, Christian; Kaufmann, R.; Jerjen, Iwan; Lüthi, T.; Cardot, F.; Niedermann, Philippe; Straumann, U.; Sennhauser, U.; Urban, Claus

doi:10.1016/j.nima.2010.11.040

Cited by 58 publications

(49 citation statements)

References 22 publications

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“…For the design of the compact gantry, one has to particularly consider shadowing effects of the X-ray absorbing bars in the gratings due to the diverging X-ray beam. Moreover, phase-contrast cone-beam reconstruction schemes have to be implemented in the reconstruction algorithms used with this prototype (15)(16)(17).In this work we report on the mechanical challenges imposed by the translation to a compact rotating gantry system and present the first results of phase-contrast CT using an advanced phase recovery method that corrects for the occurring phase drifts. Using this method, we show in particular that the scanner performs quantitatively accurate with respect to phase and absorption Hounsfield units.…”

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confidence: 99%

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Experimental results from a preclinical X-ray phase-contrast CT scanner

Tapfer

Bech

Velroyen

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

145

114

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To explore the future clinical potential of improved soft-tissue visibility with grating-based X-ray phase contrast (PC), we have developed a first preclinical computed tomography (CT) scanner featuring a rotating gantry. The main challenge in the transition from previous bench-top systems to a preclinical scanner are phase artifacts that are caused by minimal changes in the grating alignment during gantry rotation. In this paper, we present the first experimental results from the system together with an adaptive phase recovery method that corrects for these phase artifacts. Using this method, we show that the scanner can recover quantitatively accurate Hounsfield units in attenuation and phase. Moreover, we present a first tomography scan of biological tissue with complementary information in attenuation and phase contrast. The present study hence demonstrates the feasibility of gratingbased phase contrast with a rotating gantry for the first time and paves the way for future in vivo studies on small animal disease models (in the mid-term future) and human diagnostics applications (in the long-term future).differential X-ray phase contrast | grating interferometer | X-ray imaging O ne of the main shortcomings of existing biomedical X-ray imaging systems is their weak contrast in soft tissue. This limitation can be addressed by phase-sensitive imaging methods that rely on the phase shift that X-rays undergo when passing through matter (1). The resultant refraction angle can be utilized as contrast mechanism in a grating-based interferometer in radiographic (2, 3) and tomographic acquisition mode (4, 5). In a computed tomography scan, quantitative information about the sample's composition can be extracted-i.e., the linear attenuation coefficient μ and decrement of the refractive index δ can be reconstructed (6-8). Because the grating-based phase-contrast imaging method is compatible with X-ray tube sources, when operated as Talbot-Lau interferometer (9), a translation to a clinical application scenario is currently discussed with great enthusiasm in the research community. Recent studies with laboratory X-ray sources have shown excellent imaging results with respect to softtissue contrast (10)(11)(12)(13)(14). In order to explore the envisioned clinical potential, we have developed a first preclinical phase-contrast CT scanner. This development represents an important milestone in the translation of phase-contrast imaging to clinical settings, as all grating-based phase-contrast setups, which are reported in the literature so far, use a rotating sample for tomographic scans. Because this mode of operation is obviously not preferable for intended in vivo animal studies, we have explored with this work the step from rotating sample to rotating gantry. The main challenge in this translation process was mechanical stability regarding the required precise alignment of the X-ray optical components (gratings). Even mechanical movements of either grating of only fractions of a micrometer during gantry rotation already c...

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confidence: 99%

mentioning

confidence: 99%

Experimental results from a preclinical X-ray phase-contrast CT scanner

Tapfer

Bech

Velroyen

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

145

114

View full text Add to dashboard Cite

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“…• , see Revol et al 20 for details. In our system, the visibility drops to 11% at the outermost detector lines.…”

Section: A Stability and Image Qualitymentioning

confidence: 99%

“…19 Realizing such a large, gap-less FOV with a two-dimensional detector fully covered by gratings is relatively challenging due to the necessary tiling and focusing of gratings toward the xray focal spot, although considerable progress has also been made in this area. 20 Compared to FFDM systems with twodimensional detectors, a slit-scanning system is at an advantage when large FOVs are to be realized. 17 Since the scanning method facilitates phase retrieval for this platform, we pursued this approach in this work.…”

Section: Introductionmentioning

confidence: 99%

Slit‐scanning differential x‐ray phase‐contrast mammography: Proof‐of‐concept experimental studies

et al. 2015

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Purpose: The purpose of this work is to investigate the feasibility of grating-based, differential phase-contrast, full-field digital mammography (FFDM) in terms of the requirements for field-ofview (FOV), mechanical stability, and scan time. Methods: A rigid, actuator-free Talbot interferometric unit was designed and integrated into a state-of-the-art x-ray slit-scanning mammography system, namely, the Philips MicroDose L30 FFDM system. A dedicated phase-acquisition and phase retrieval method was developed and implemented that exploits the redundancy of the data acquisition inherent to the slit-scanning approach to image generation of the system. No modifications to the scan arm motion control were implemented. Results: The authors achieve a FOV of 160 × 196 mm consisting of two disjoint areas measuring 77 × 196 mm with a gap of 6 mm between them. Typical scanning times vary between 10 and 15 s and dose levels are lower than typical FFDM doses for conventional scans with identical acquisition parameters due to the presence of the source-grating G 0 . Only minor to moderate artifacts are observed in the three reconstructed images, indicating that mechanical vibrations induced by other system components do not prevent the use of the platform for phase contrast imaging. Conclusions: To the best of our knowledge, this is the first attempt to integrate x-ray gratings hardware into a clinical mammography unit. The results demonstrate that a scanning differential phase contrast FFDM system that meets the requirements of FOV, stability, scan time, and dose can be build. C 2015 American Association of Physicists in Medicine. [http://dx

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“…Hence, for linear gratings, the twodimensional detection systems will suffer from inhomogeneous visibility over the FOV, whereas the slit-scanning approach limits the loss in visibility owing to oblique incidence onto the trench planes by the limited spatial coverage of the detector in the scan direction. To avoid visibility inhomogeneities in the two-dimensional approach and extend the FOV with homogeneous phase sensitivity, bending of the gratings was considered [33] but appears challenging in practice. The loss of visibility owing to the oblique incidence of X-rays onto the gratings is illustrated in a simulation in figure 4.…”

Section: (F) Phase Sensitivitymentioning

confidence: 99%

Clinical boundary conditions for grating-based differential phase-contrast mammography

Roessl

Daerr

Kœhler

et al. 2014

Phil. Trans. R. Soc. A.

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Research in grating-based differential phase-contrast imaging (DPCI) has gained increasing momentum in the past couple of years. The first results on the potential clinical benefits of the technique for X-ray mammography are becoming available and indicate improvements in terms of general image quality, the delineation of lesions versus the background tissue and the visibility of microcalcifications. In this paper, we investigate some aspects related to the technical feasibility of DPCI for human X-ray mammography. After a short introduction to state-of-the-art fullfield digital mammography in terms of technical aspects as well as clinical aspects, we put together boundary conditions for DPCI. We then discuss the implications for system design in a comparative manner for systems with two-dimensional detectors versus slit-scanning systems, stating advantages and disadvantages of the two designs. Finally, focusing on a slit-scanning system, we outline a possible concept for phase acquisition.

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X-ray interferometer with bent gratings: Towards larger fields of view

Cited by 58 publications

References 22 publications

Experimental results from a preclinical X-ray phase-contrast CT scanner

Experimental results from a preclinical X-ray phase-contrast CT scanner

Slit‐scanning differential x‐ray phase‐contrast mammography: Proof‐of‐concept experimental studies

Clinical boundary conditions for grating-based differential phase-contrast mammography

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