A new method to extract angle of refraction in diffraction enhanced imaging computed tomography

Wang, Min; Zhu, Ping; Zhang, Kai; Hu, Xiaofang; Huang, Wanxia; Cen, Yuwan; Qin, Yuan; Yu, Xiaoliu; Wang, Jun-Yue

doi:10.1088/0022-3727/40/22/010

Cited by 20 publications

(16 citation statements)

References 17 publications

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“…In fact, according to the aforementioned analogy, the intensity recorded by a detector positioned after the grating interferometer can be expressed (see equation 1 in ref. 18) as:…”

Section: Resultsmentioning

confidence: 99%

Low-dose, simple, and fast grating-based X-ray phase-contrast imaging

Zhu

Zhang²,

Wang³

et al. 2010

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

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218

156

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Phase sensitive X-ray imaging methods can provide substantially increased contrast over conventional absorption-based imaging and therefore new and otherwise inaccessible information. The use of gratings as optical elements in hard X-ray phase imaging overcomes some of the problems that have impaired the wider use of phase contrast in X-ray radiography and tomography. So far, to separate the phase information from other contributions detected with a grating interferometer, a phase-stepping approach has been considered, which implies the acquisition of multiple radiographic projections. Here we present an innovative, highly sensitive X-ray tomographic phase-contrast imaging approach based on grating interferometry, which extracts the phase-contrast signal without the need of phase stepping. Compared to the existing phase-stepping approach, the main advantages of this new method dubbed "reverse projection" are not only the significantly reduced delivered dose, without the degradation of the image quality, but also the much higher efficiency. The new technique sets the prerequisites for future fast and low-dose phase-contrast imaging methods, fundamental for imaging biological specimens and in vivo studies.X-ray imaging | differential phase contrast | grating interferometer | tomography O ver the last few decades X-ray imaging has experienced a true revolution. The most striking advancement has been the production of coherent X-ray beams with their intrinsic capability of generating interference signals and, as a consequence, providing access to phase information within the investigated sample. This fact has been very stimulating for the X-ray-imaging community, which had been continually challenged by the frustrating question of how to increase the contrast in X-ray images without increasing the dose imparted to a specimen. It is well known that, different from conventional visible light, the refractive index in X-ray optics is very close to and smaller than unity. In first approximation, for a small and negligible anisotropy in the medium, the index of refraction characterizing the optical properties of a tissue can be expressed-including X-ray absorptionwith its complex form: n ¼ 1-δ-iβ where δ is the decrement of the real part of the refractive index, responsible for the phase shift, while the imaginary part β describes the absorption property of the tissue. In conventional absorption-based radiography, the X-ray phase shift information is usually not used for image reconstruction. However, at photon energies greater than 10 keV and for soft tissues (made up of low-Z elements), the phase shift term plays a more prominent role than the attenuation term because δ is typically three orders of magnitude larger than β (1). As a consequence, phase-contrast modalities can generate significantly greater image contrast compared to conventional, absorptionbased radiography. In fact, far from absorption edges, δ is inversely proportional to the square of the X-ray energy while β decreases as the fourth power of it. Conseq...

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“…In fact, according to the aforementioned analogy, the intensity recorded by a detector positioned after the grating interferometer can be expressed (see equation 1 in ref. 18) as:…”

Section: Resultsmentioning

confidence: 99%

Low-dose, simple, and fast grating-based X-ray phase-contrast imaging

Zhu

Zhang²,

Wang³

et al. 2010

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

Self Cite

218

156

View full text Add to dashboard Cite

show abstract

“…This contribution demonstrated that several differential phase imaging methods can employ the same principle as DEI to extract the refraction angle information. In addition, the decrement of the real part of the refractive index and its derivatives in the X-Z plane can be reconstructed by x-ray phase tomography [20,21] with the projection data set recorded by the detector with only a set of sample rotation data of 360° [14][15][16], according to Eqs. (13), (24), (46), and (51).…”

Section: Resultsmentioning

confidence: 99%

“…Although these imaging methods are very different in configurations, they share a common imaging principle by extracting differential phase information through evaluating the refraction angles. This paper focuses on the discussion of the common physics principles, and investigates common characteristics [12][13][14][15][16] shared by these differential phase contrast imaging methods.…”

Section: Introductionmentioning

confidence: 99%

Common characteristics shared by different differential phase contrast imaging methods

Zhu

et al. 2014

Appl. Opt.

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“…This is realized by repositioning the sample mask between the two projections, therefore adding "dead time" to the acquisition. The reverse projection concept, first described by Wang et al for diffraction enhanced imaging, 25 removes the need for mask movement between projections, therefore reducing scan time. Here, instead of acquiring two frames per angular position over a 180 • range, the sample is rotated over 360 • , while the sample mask is kept in the same position throughout the scan.…”

Section: Reverse Projectionmentioning

confidence: 99%

Increased robustness and speed in low-dose phase-contrast tomography with laboratory sources

et al. 2016

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In this article we discuss three different developments in Edge Illumination (EI) X-ray phase contrast imaging (XPCi), all ultimately aimed at optimising EI computed tomography (CT) for use in different environments, and for different applications. For the purpose of reducing scan times, two approaches are presented; the "reverse projection" acquisition scheme which allows a continuous rotation of the sample, and the "single image" retrieval algorithm, which requires only one frame for retrieval of the projected phase map. These are expected to lead to a substantial reduction of EI CT scan times, a prospect which is likely to promote the translation of EI into several applications, including clinical. The last development presented is the "modified local" phase retrieval. This retrieval algorithm is specifically designed to accurately retrieve sample properties (absorption, refraction, scattering) in cases where high-resolution scans are required in non-ideal environments. Experimental results, using both synchrotron radiation and laboratory sources, are shown for the various approaches.

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A new method to extract angle of refraction in diffraction enhanced imaging computed tomography

Cited by 20 publications

References 17 publications

Low-dose, simple, and fast grating-based X-ray phase-contrast imaging

Low-dose, simple, and fast grating-based X-ray phase-contrast imaging

Common characteristics shared by different differential phase contrast imaging methods

Increased robustness and speed in low-dose phase-contrast tomography with laboratory sources

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