Grating-based x-ray phase-contrast imaging with a multi energy-channel photon-counting pixel detector

Pelzer, Georg; Weber, Thomas; Anton, G.; Ballabriga, R.; Bayer, Florian; Campbell, M.; Gabor, T; Haas, Wilhelm; Horn, Florian; Llopart, X.; Michel, Norbert; Mollenbauer, Uwe; Rieger, Jens; Ritter, André; Ritter, I.; Sievers, P.; Wolfel, S.; Wong, Winnie; Zang, Andrea; Michel, Thilo

doi:10.1364/oe.21.025677

Cited by 15 publications

(14 citation statements)

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“…Furthermore, energy resolved detection, [25][26][27] as supported by the next generation MicroDose system, can further improve the SNR. [28][29][30] Since our ultimate goal is phase-contrast mammography, future work will also include the imaging of breast samples.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

confidence: 99%

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

et al. 2015

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“…The optimal k of −0.77 is not a very strong weight. In comparison, weighting factors proportional to E −3 are found in attenuation imaging [17,18] and proportional to E −2 for phase-contrast imaging [21]. Also in this measurement the index of k = −0.77 had to be determined iteratively.…”

Section: Discussionmentioning

confidence: 99%

“…In previous publications, Talbot-Lau interferometers were combined with energy-resolving x-ray detectors for phase-contrast imaging only. It was shown that artifacts can be removed [19] and that the image quality can be improved by setting optimized energy thresholds [20] or by appropriate energy-weighting [21]. Here, we evaluate the benefit of an energy-resolving detector in x-ray dark-field imaging.…”

Section: Introductionmentioning

confidence: 99%

Energy weighted x-ray dark-field imaging

Pelzer¹,

Zang²,

Anton³

et al. 2014

Opt. Express

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Abstract:The dark-field image obtained in grating-based x-ray phasecontrast imaging can provide information about the objects' microstructures on a scale smaller than the pixel size even with low geometric magnification.In this publication we demonstrate that the dark-field image quality can be enhanced with an energy-resolving pixel detector. Energy-resolved x-ray dark-field images were acquired with a 16-energy-channel photon-counting pixel detector with a 1 mm thick CdTe sensor in a Talbot-Lau x-ray interferometer. A method for contrast-noise-ratio (CNR) enhancement is proposed and validated experimentally. In measurements, a CNR improvement by a factor of 1.14 was obtained. This is equivalent to a possible radiation dose reduction of 23%. x-ray dark-field imaging using a grating interferometer," Nat. Mater. 7, 134-137 (2008). 5. A. Momose, T. Takeda, Y. Itai, and K. Hirano, "Phasecontrast xray computed tomography for observing biological soft tissues," Nat. Med. 2(4), 473-475 (1996). 6. F. Pfeiffer, T. Weitkamp, O. Bunk, and C. David, "Phase retrieval and differential phase-contrast imaging with low-brilliance x-ray sources," Nat. Phys. 2(4), 258-261 (2006). 7. T. Weitkamp, C. David, O. Bunk, J. Bruder, P. Cloetens, and F. Pfeiffer, "X-ray phase radiography and tomography of soft tissue using grating interferometry," Eur. J. Radiol. 68(3), 13-17 (2008

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“…In the case of small variances with σ 2 w 1.3 it has been shown [32], [33], that the concentration κ w can be approximated with 1…”

Section: B Maximum Likelihood Estimation Of the Unwrapped Phasementioning

confidence: 99%

“…With regularization (continuous curve) a preference is added for small values of ϕ * which leads to an estimated value ofφ * reg = −1.9 rad. In view of other related work, in particular the work by Pelzer et al [33] on optimal energy weighting of spectral phase contrast data, it is also instructive to investigate the case where the variances σ 2 w = κ −1 w are small and the true phase shifts are so small that no phase wrapping occurs. In this limiting case, we can drop the regularization and (12b) becomes a weighted least square optimization problem.…”

Section: B1 Regularizationmentioning

confidence: 99%

Phase Unwrapping in Spectral X-Ray Differential Phase-Contrast Imaging With an Energy-Resolving Photon-Counting Pixel Detector

Epple

Ehn

Thibault

et al. 2015

IEEE Trans. Med. Imaging

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Grating-based differential phase-contrast imaging has proven to be feasible with conventional X-ray sources. The polychromatic spectrum generally limits the performance of the interferometer but benefit can be gained with an energy-sensitive detector. In the presented work, we employ the energy-discrimination capability to correct for phase-wrapping artefacts. We propose to use the phase shifts, which are measured in distinct energy bins, to estimate the optimal phase shift in the sense of maximum likelihood. We demonstrate that our method is able to correct for phase-wrapping artefacts, to improve the contrast-to-noise ratio and to reduce beam hardening due to the modelled energy dependency. The method is evaluated on experimental data which are measured with a laboratory Talbot-Lau interferometer equipped with a conventional polychromatic X-ray source and an energy-sensitive photon-counting pixel detector. Our work shows, that spectral imaging is an important step to move differential phase-contrast imaging closer to pre-clinical and clinical applications, where phase wrapping is particularly problematic.

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Grating-based x-ray phase-contrast imaging with a multi energy-channel photon-counting pixel detector

Cited by 15 publications

References 20 publications

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

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

Energy weighted x-ray dark-field imaging

Phase Unwrapping in Spectral X-Ray Differential Phase-Contrast Imaging With an Energy-Resolving Photon-Counting Pixel Detector

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