X-ray or gamma ray systems or devices – Specific application – Absorption
Patent
1997-09-26
2000-01-25
Porta, David P.
X-ray or gamma ray systems or devices
Specific application
Absorption
378 82, G21K 106
Patent
active
060185643
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates generally to the observation of a structural feature of an object utilising penetrating radiation such as x-rays. More particularly, but not exclusively, the invention relates to x-ray phase-contrast recordal, e.g. imaging, of internal boundary features.
The present applicant's international patent publication WO95/05725 (PCT/AU94/00480) and provisional patent application PN5811/95 disclose various configurations and conditions suitable for differential phase-contrast imaging using hard x-rays. Other disclosures are to be found in Soviet patent 1402871 and in U.S. Pat. No. 5,319,694. It is desired that relatively simpler conditions and configurations more closely related, at least in some embodiments, to traditional methods of absorption-contrast radiography, may be utilised for differential phase-contrast imaging with hard x-rays.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a method of obtaining an image of a boundary of an object, said boundary representing a refractive index variation, said method including: spatial coherence and a propagation component transverse to said refraction index variation; and form said image, said radiation having been refracted by said boundary such that said boundary is represented on said image by a corresponding intensity variation.
The present invention further provides an apparatus for obtaining an image of a boundary of an object, said boundary representing a refractive index variation, said apparatus including: high lateral spatial coherence and a propagation component transverse to said refraction index variation; and said image, said radiation having been refracted by said boundary such that said boundary is represented on said image by a corresponding intensity variation.
The present invention also provides a method of deriving a phase-contrast record of an internal boundary having a sharp refractive index variation or defined by a thickness variation, comprising: direction such that there is a significant component of the propagation vector transverse to the direction of said refractive index variation or in the direction of said thickness variation, and further having a lateral spatial coherence sufficiently high for the variation in refractive index or thickness to cause a detectable change in the local direction of propagation of the radiation wavefront at the boundary; and traversed said boundary in a manner whereby an effect of said change in the local direction of propagation is observable and thereby recorded as a local diminution or rapid variation of intensity of the radiation which thereby substantially images the boundary.
The present invention further provides an apparatus for deriving a phase-contrast record of an internal boundary having a sharp refractive index variation or defined by a thickness variation, comprising: direction such that there is a significant component of the propagation vector transverse to the direction of said refractive index variation or in the direction of said thickness variation, and further having a lateral spatial coherence sufficiently high for the variation in refractive index or thickness to cause a detectable change in the local direction of propagation of the radiation wavefront at the boundary; and has traversed said boundary in a manner whereby an effect of said change in the local direction of propagation is observable and thereby recorded as a local diminution or rapid variation of intensity of the radiation which thereby substantially images the boundary.
The present invention also provides a method of obtaining an image of a boundary of an object, said boundary representing a refractive index variation, said method including: spatial coherence and a propagation component transverse to said refraction index variation; and form said image, said radiation having been Fresnel diffracted by said boundary such that said boundary is represented on said image by a corresponding intensity variation.
The present invention furt
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Davis, et al., "Phase-contrast Imaging of weakly absorbing materials using hard X-rays"; Nature, vol. 373, Feb. 16, 1995, pp. 595-598.
Dunn Drew A
Porta David P.
X-Ray Technologies Pty Ltd
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