Grating-based X-ray phase contrast for biomedical imaging applications

Pfeiffer, Franz; Herzen, Julia; Willner, Marian; Chabior, Michael; Auweter, Sigrid; Reiser, Maximilian; Bamberg, Fabian

doi:10.1016/j.zemedi.2013.02.002

Cited by 88 publications

(57 citation statements)

References 29 publications

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“…The grating based Talbot-Lau interferometer made a step towards this, as the introduction of a source grating allowed for such a source to be used. 12,13 A clinical system based on this method has been developed to image articular cartilage in the hand, with this XPCi system revealing details invisible in a conventional absorption image.…”

mentioning

confidence: 99%

Monte Carlo model of a polychromatic laboratory based edge illumination x-ray phase contrast system

Millard

Endrizzi

Diémoz

et al. 2014

Review of Scientific Instruments

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A Monte Carlo model of a polychromatic laboratory based (coded aperture) edge illumination x-ray phase contrast imaging system has been developed and validated against experimental data. The ability for the simulation framework to be used to model two-dimensional images is also shown. The Monte Carlo model has been developed using the McXtrace engine and is polychromatic, i.e. results are obtained through the use of the full x-ray spectrum rather than an effective energy. This type of simulation can in future be used to model imaging of objects with complex geometry, for system prototyping, as well as providing a first step towards the development of a simulation for modelling dose delivery as a part of translating the imaging technique for use in clinical environments.

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mentioning

confidence: 99%

Monte Carlo model of a polychromatic laboratory based edge illumination x-ray phase contrast system

Millard

Endrizzi

Diémoz

et al. 2014

Review of Scientific Instruments

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“…Phase contrast imaging techniques are required in medical imaging field because of the possibility to improve the contrast of soft tissue in a body [1][2][3][4] . Applying of a Talbot interferometer into high energy radiation systems is under development and many ideas and techniques are reported 5,6 , and high energy x-ray phase contrast imaging is becoming possible.…”

Section: Introductionmentioning

confidence: 99%

Improvement of the visibility for x-ray phase contrast imaging using photon counting detector

et al. 2016

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In the case of employing Talbot interferometer to the medical imaging, a practical X-ray tube should be combined with the interferometer. Practical x-ray tubes radiate continuous X-rays and the interference intensity (so-called visibility) becomes worse because of the wide spectrum of continuous X-rays. In order to achieve high visibility, we have estimated the visibility improvement effect using the photon counting detector (PCD).The detected spectra using a 2D imaging PCD are distorted due to charge sharing and pileup, which would make visibility worse. First, we have made a model for Monte-Calro calculation to calculate the distorted spectra and point spread function (PSF) for the charge sharing. The calculation model is based on the summation of the monochromatic response function which is the detected charge on the interested pixel for one photon injection. Distortion of spectra was calculated taking into account the charge sharing effect and pulse pileup.Then we have obtained an estimation result of the visibility improvement effect using the PCD of CdTe. The visibilities of the energy integrating detector (EID) of CdTe and the PCD are calculated and compared, where the Talbot interferometer type is a fringe scanning using phase grating and absorption grating. Visibility of the EID is 36% and that of PCD is 60% without pileup effect. In high dose rate condition, the CNR decreasing ratio is remarkable. The visibility decreasing effect and quantum noise increasing effect are correlated and the both effect worsen the CNR.

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“…Phase sensitive X-ray techniques are a more sensitive method for visualizing details with similar density, as X-rays are phase-shifted much more than they are absorbed. Grating-based phase-contrast imaging enables phase measurements with high sensitivity even with conventional laboratory X-ray sources [1][2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Redefining the lower statistical limit in x-ray phase-contrast imaging

Marschner¹,

Birnbacher²,

Willner³

et al. 2015

SPIE Proceedings

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X-ray phase-contrast computed tomography (PCCT) is currently investigated and developed as a potentially very interesting extension of conventional CT, because it provides high soft-tissue contrast for weakly absorbing samples. For data acquisition, several images at different grating positions are combined to obtain a differential phase-contrast projection. At short exposure times, which are necessary for lower radiation dose, the photon counts in a single stepping position are very low. In this case, the currently used phase-retrieval does not provide reliable results for some pixels. This uncertainty results in statistical phase wrapping, which leads to a higher standard deviation in the phase-contrast projections than theoretically expected. For even lower statistics, the phase retrieval breaks down completely and the phase information is lost. New measurement procedures rely on a linear approximation of the sinusoidal phase stepping curve around the zero crossings. In this case only two images are required to obtain the differential phase-contrast projection. The approximation is only valid for small differential phase values. However, nearly all pixels lie within this regime due to the differential nature of the signal. We examine the statistical properties of a linear approximation method. We illustrate by simulation and experiment that the lower statistical limit can be redefined using this method. Thus, the differential phase signal can be retrieved even with very low photon counts and statistical phase wrapping can be avoided. This is an important step towards enhanced image quality in PCCT with very low photon counts.

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Grating-based X-ray phase contrast for biomedical imaging applications

Cited by 88 publications

References 29 publications

Monte Carlo model of a polychromatic laboratory based edge illumination x-ray phase contrast system

Monte Carlo model of a polychromatic laboratory based edge illumination x-ray phase contrast system

Improvement of the visibility for x-ray phase contrast imaging using photon counting detector

Redefining the lower statistical limit in x-ray phase-contrast imaging

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