Phase-contrast imaging using polychromatic hard X-rays

Wilkins, S. W.; Gureyev, T. E.; Gao, Dachao; Pogany, A.; Stevenson, Andrew W.

doi:10.1038/384335a0

Cited by 1,675 publications

(1,168 citation statements)

References 10 publications

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“…This may include radiologically thin threat material. During the last decade, a number of novel methods have been developed in the field of X-ray imaging that are based on wave properties of X-rays (see for instance, Wilkins, 1996;Fitzgerald, 2000;Gundogdu et al, 2007). In order to perform X-ray phase contrast imaging, the coherence of the X-ray beam used is an important factor in determining the quality of the images obtained, since it is the coherence that allows the wave phenomena of interference and diffraction to be utilised for high energy X-ray photons.…”

Section: Phase Contrast Imagingmentioning

confidence: 99%

“…Temporal coherence or monochromaticity is not essential and as such phase contrast imaging can also be performed with polychromatic radiation (Wilkins et al 1996). The employing of a microfocal spot x-ray tube places the greatest limitation on performance, the system being relatively slow and only suitable for radiologically thin media, a situation in which multiple scattering dominated by inelastic scattering is limited.…”

Section: Phase Contrast Imagingmentioning

confidence: 99%

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A review of X-ray explosives detection techniques for checked baggage

Wells

Bradley

2012

Applied Radiation and Isotopes

221

116

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Section: Phase Contrast Imagingmentioning

confidence: 99%

Section: Phase Contrast Imagingmentioning

confidence: 99%

A review of X-ray explosives detection techniques for checked baggage

Wells

Bradley

2012

Applied Radiation and Isotopes

221

116

View full text Add to dashboard Cite

“…5 is that an edge enhancement or phase contrast can be observed with a polychromatic X-ray beam. This fact has been discussed in a number of papers also in connection with the interplay between refraction and diffraction [5,19]. The general features of refraction contrast imaging will be discussed by means of fig.…”

Section: Discussionmentioning

confidence: 99%

“…For a polycarbonate foil of 10 µm thickness and a photon energyhω = 12 keV, for which the complex refraction index parameters are δ = 1.826 · 10 −6 and β = 1.573 · 10 −9 , the phase shift is φ = 1.11 rad while the intensity attenuation is only 1 − exp[(−2ω/c) · β · d] = 1.91 · 10 −3 . These considerations lead to the important conclusion that a high contrast combined with a low absorbed dose could be achieved by using the phase shift mechanism to produce a radiograph [5]. In the next section the question will be addressed how the phase shift can be exploited for radiography.…”

Section: Absorption Versus Phase Shiftmentioning

confidence: 99%

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X-ray phase contrast imaging at MAMI

El-Ghazaly

Backe

Lauth

et al.

Many Body Structure of Strongly Interacting Systems

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Abstract. Experiments have been performed to explore the potential of the low emittance 855 MeV electron beam of the Mainz Microtron MAMI for imaging with coherent X-rays. Transition radiation from a microfocused electron beam traversing a foil stack served as X-ray source with good transverse coherence. Refraction contrast radiographs of low absorbing materials, in particular polymer strings with diameters between 30 and 450 µm, were taken with a polychromatic transition radiation X-ray source with a spectral distribution in the energy range between 8 and about 40 keV. The electron beam spot size had standard deviation σ h = (8.6 ± 0.1) µm in the horizontal and σv = (7.5 ± 0.1) µm in the vertical direction. X-ray films were used as detectors. The source-to-detector distance amounted to 11.4 m. The objects were placed in a distance of up to 6 m from the X-ray film. Holograms of strings were taken with a beam spot size σv = (0.50 ± 0.05) µm in vertical direction, and a monochromatic X-ray beam of 6 keV energy. A good longitudinal coherence has been obtained by the (111) reflection of a flat silicon single crystal in Bragg geometry. It has been demonstrated that a direct exposure CCD chip with a pixel size of 13 × 13 µm 2 provides a highly efficient on-line detector. Contrast images can easily be generated with a complete elimination of all parasitic background. The on-line capability allows a minimization of the beam spot size by observing the smallest visible interference fringe spacings or the number of visible fringes. It has been demonstrated that X-ray films are also very useful detectors. The main advantage in comparison with the direct exposure CCD chip is the resolution. For the Structurix D3 (Agfa) X-ray film the standard deviation of the resolution was measured to be σ f = (1.2 ± 0.4) µm, which is about a factor of 6 better than for the direct exposure CCD chip. With the small effective X-ray spot size in vertical direction of σv = (1.2±0.3) µm and a geometrical magnification of up to 7.4 high-quality holograms of tiny transparent strings were taken in which the holographic information is contained in up to 18 interference fringes.PACS. 87.59.Bh X-ray radiography -52.59.Px Hard X-ray sources -41.50.+h X-ray beams and X-ray optics -07.85.Fv X-and gamma-ray sources, mirrors, gratings, and detectors -07.85.Nc X-ray and gamma-ray spectrometers

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Theory of Imaging a Perfect Crystal under the Conditions of X-Ray Spherical Wave Dynamical Diffraction

Kohn¹,

Snigireva²,

Snigirev³

2000

phys. stat. sol. (b)

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A theory of the formation of interference patterns due to X-ray spherical wave two-beam dynamical diffraction in a perfect crystal is presented. An asymmetrical Laue case is analyzed in detail, when a polychromatic focus is realized with different distances in front of and behind the crystal. Such a property is essential for high-energy X-rays produced by synchrotron radiation sources of the third generation because of the long distance between source and object. It is shown that a monochromatic X-ray spherical wave is focused due to dynamical diffraction when a definite relation between distances and crystal thickness is held. An X-ray beam of less than 10 mm width may be obtained. A two-dimensional intensity distribution (topograph) may be registered with a wedge-shaped crystal. It shows interference fringes of different kinds depending on crystal thickness and asymmetry rate. It is also discussed how a slit in front of the crystal influences the interference pattern. An example of an interference pattern is presented under the condition of highly asymmetrical diffraction which was obtained by a computer simulation technique. Fringes of a new kind are observed and their physical nature is discussed.

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Phase-contrast imaging using polychromatic hard X-rays

Cited by 1,675 publications

References 10 publications

A review of X-ray explosives detection techniques for checked baggage

A review of X-ray explosives detection techniques for checked baggage

X-ray phase contrast imaging at MAMI

Theory of Imaging a Perfect Crystal under the Conditions of X-Ray Spherical Wave Dynamical Diffraction

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