X-ray interferometer
AssigneeCsem Centre Suisse D'Electronique Et De Microtechnique SA—Recherche Et DéVeloppement
InventorsChristian Kottler, Vincent Revol
Life of this patent
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Abstract
Embodiments relate to an X-ray interferometer for imaging an object comprising: a phase grating for effecting in correspondence with the phase grating geometry a phase shift to at least a part of X-ray incident onto the phase grating; and an absorption grating for effecting in correspondence with the absorption grating geometry absorption to at least a part of X-ray incident onto the absorption grating. The grating period of the phase grating, and the grating period of the absorption grating may be dimensioned such that a detector for X-rays can be placed at a relatively large distance away from the absorption grating such the phase contrast sensitivity of the image of the object detected by the detector remains substantially unaffected.
Claims16
A method for performing phase contrast imaging with an X-ray interferometer that is operative to irradiate an object with X-ray at a given radiation energy, the X-ray interferometer having a total setup length Ltot, the method comprising:
- a detector detecting radiation emitted by an X-ray source with a projection magnification M greater than 1 and having a sensor plane, wherein the total setup length Ltot is a distance from a focal spot of the X-ray source to a plane of the detector;
- a phase grating phase-shifting X-ray emanating from the object and which is incident onto the phase grating;
- an absorption grating intensity modulating the phase-shifted X-ray from the phase grating;
- positioning the phase grating between the X-ray source and the absorption grating at a distance I from the X-ray source;
- positioning the absorption grating between the phase grating and the detector at a distance d from the phase grating;
- positioning the detector at a distance dM from the absorption grating, the distance dM being at least 5 cm and up to 2 meters, and the distance d being less than half the total setup length Ltot, where
- M
- =
- d
- M
- +
- d
- +
- 1
- 1
- -
- d
- s
- ;
- positioning the object between the X-ray source and the phase grating at a distance ds from the phase grating, the distance ds being a distance between the phase grating and the plane which is perpendicular to an optical axis and intersects a geometric center of the object;
- dimensioning the grating period of the phase grating and the grating period of the absorption grating such that,
- d
- =
- n
- .
- η
- .
- p
- 1
- .
- p
- 2
- 8.
-
- λ
-
-
- and
- l
- =
- d
- .
- p
- 1
- η
- .
- p
- 2
- -
- p
- 1
- where λ denotes a wavelength of the X-ray emitted by the X-ray source, n denotes a fractional Talbot order, η denotes a symmetry parameter, p1 denotes the grating period of the phase grating and p2 denotes the grating period of the absorption grating;
- and
- dimensioning ds and dm so that a phase contrast sensitivity of an image of the object detected by the detector is not reduced with M greater than 1.
Dependencies are inferred from the claim text.