Correction in slit-scanning phase contrast imaging

Patent metadata

Field	Value
Publication number	US-2016128665-A1
Application number	US-201414896783-A
Country	US
Kind code	A1
Filing date	Jun 27, 2014
Priority date	Jun 28, 2013
Publication date	May 12, 2016
Grant date	—

Abstract

The present invention relates to calibration in X-ray phase contrast imaging. In order to remove the disturbance due to individual gain factors, a calibration filter grating ( 10 ) for a slit-scanning X-ray phase contrast imaging arrangement is provided that comprises a first plurality of filter segments ( 11 ) comprising a filter material ( 12 ) and a second plurality of opening segments ( 13 ). The filter segments and the opening segments are arranged alternating as a filter pattern ( 15 ). The filter material is made from a material with structural elements ( 14 ) comprising structural parameters in the micrometer region. The filter grating is movably arranged between an X-ray source grating ( 54 ) and an analyzer grating ( 60 ) of an interferometer unit in a slit-scanning system of a phase contrast imaging arrangement. The slit-scanning system is provided with a pre-collimator ( 55 ) comprising a plurality of bars ( 57 ) and slits ( 59 ). The filter pattern is aligned with the pre-collimator pattern ( 61 ).

First claim

1 . A calibration filter grating for transforming coherent X-ray into incoherent X-ray in a slit-scanning X-ray phase contrast imaging arrangement, comprising:
a first plurality of filter segments comprising a filter material; and a second plurality of opening segments; wherein the filter segments and the opening segments are arranged alternating as a filter pattern; wherein the filter material is made from a material with structural elements comprising structural parameters in the micrometer region; and wherein the filter grating is configured to be movably arranged between an X-ray source grating and an analyzer grating of an interferometer unit in a slit-scanning system of a phase contrast imaging arrangement; and wherein the filter pattern is configured to be aligned with a slit pattern of the slit-scanning system.

2 . Calibration filter grating according to claim 1 , wherein the structural elements are provided in a maximum range of 10 μm.

3 . Calibration filter grating according to claim 1 , wherein the filter material is provided as at least one of the group of:
fluid bubbles comprising gaseous bubbles and liquid bubbles; and fiber-based material; and wherein the filter material is made from low atomic number elements.

4 . Calibration filter grating according to claim 1 , wherein the filter is a de-coherence filter providing small angle scattering for coherent X-ray radiation provided by an X-source with a source grating for phase contrast imaging.

5 . A slit-scanning X-ray phase contrast imaging arrangement, comprising:
an X-ray source; a source grating; a pre-collimator; an interferometer unit comprising a phase grating and an analyzer grating; an X-ray detector with a plurality of detector segments displaced from each other; and a calibration device; wherein the source grating provides at least partially coherent X-ray radiation; wherein the pre-collimator comprises a plurality of bars and slits to provide an X-ray beam width with a plurality of X-ray beam sections displaced from each other by radiation-free sections; wherein the calibration device is a calibration filter grating according to one of the preceding claims; and wherein the calibration filter grating is arranged between the source grating and the analyzer grating; and wherein the calibration filter grating is movable between:
I) a first, calibrating position, in which the filter segments are arranged in the X-ray beam parts forming the plurality of X-ray beam sections; and
II) a second, scanning position, in which the filter segments are arranged out of the X-ray beam parts forming the plurality of X-ray beam sections that are detected by the detector segments.

6 . Slit-scanning X-ray phase contrast imaging arrangement according to claim 5 , wherein, the calibration filter grating is arranged:
i) between the source grating and the pre-collimator; or ii) between the pre-collimator and the phase grating; or iii) between the phase grating and the analyzer grating.

7 . Slit-scanning X-ray phase contrast imaging arrangement according to claim 5 , wherein in the scanning position, the calibration filter grating remains between the source grating and the analyzer grating; and wherein the filter segments are arranged in the radiation-free sections of the X-ray beam or in the X-ray beam parts that are blocked by bars of the pre-collimator.

8 . Slit-scanning X-ray phase contrast imaging arrangement according to claim 5 , wherein the phase grating is provided with a first period; and
wherein the structures of the structural elements are provided in a range of approximately the first period.

9 . Slit-scanning X-ray phase contrast imaging arrangement according to claim 5 , wherein a displacement device for moving the calibration filter grating between the first, calibrating position and the second, scanning position is provided.

10 . Slit-scanning X-ray phase contrast imaging arrangement according to claim 9 , wherein the displacement device is provided as at least one of the group of:
a motor driven translation stage; a electromagnetic actuation stage; and a piezoelectric translation stage.

11 . An X-ray imaging system, comprising:
an X-ray image acquisition arrangement; a processing device; and an object supporting device; wherein the X-ray image acquisition arrangement is provided as a slit-scanning X-ray phase contrast imaging arrangement according to claim 5 ; wherein the object supporting device is configured to support an object to be examined; wherein the X-ray image acquisition arrangement is configured to detect an X-ray image signal as reference signal for calibration purposes, wherein an object is arranged outside the X-ray radiation; and wherein the processing unit is configured to determine a calibration factor based on the reference signal, wherein the calibration factor represents a gain induced signal structure; and to provide the calibration factor for calibrated X-ray imaging procedures

12 . X-ray imaging system according to claim 11 , wherein the filter segments of the calibration device are configured to be arranged in the X-ray beam parts forming the X-ray beam sections for calibration purposes and outside the X-ray beams parts forming the X-ray beam sections for object and phase reference acquisition steps.

13 . A method for calibration in slit-scanning X-ray phase contrast imaging, comprising the following steps:
a) arranging a first plurality of filter segments of a calibration filter grating, for transforming coherent X-ray into incoherent X-ray, in X-ray beam parts forming X-ray beam sections of an X-ray image acquisition arrangement at a location between a source grating and an analyzer grating; the filter segments comprise a filter material made from a material with structural elements comprising structural parameters in the micrometer region; b) providing X-ray radiation; c) detecting an X-ray image signal as reference signal for calibration purposes; d) determining a calibration factor based on the reference signal, wherein the calibration factor represents a gain induced signal structure; and e) providing the calibration factor for calibrated X-ray imaging procedures

14 . A computer program element for controlling an apparatus claim 1 , which, when being executed by a processing unit, is adapted to perform the method for calibration in a slit-scanning X-ray phase contrast imaging, comprising the following steps:
a) arranging a first plurality of filter segments of a calibration filter grating, for transforming coherent X-ray into incoherent X-ray, in X-ray beam parts forming X-ray beam sections of an X-ray image acquisition arrangement at a location between a source grating and an analyzer grating; the filter segments comprises a filter material made from a material with structural elements comprising structural parameters in the micrometer region; b) providing X-ray radiation; c) detecting an X-ray image signal as reference signal for calibration purposes; d) determining a calibration factor based on the reference signal, wherein the calibration factor represents a gain induced signal structure; and e) providing the calibration factor for calibrated X-ray imaging procedures.

15 . A computer readable medium having stored the program element of claim 14 .

Assignees

• Koninkl Philips Nv

Inventors

• Roessl Ewald
• Martens Gerhard

Classifications

• A61B6/484 Primary

  involving phase contrast X-ray imaging · CPC title

• G21K1/10

  Scattering devices; Absorbing devices; Ionising radiation filters · CPC title

• G01N23/20075

  by measuring interferences of X-rays, e.g. Borrmann effect · CPC title

• A61B6/582 Primary

  Calibration · CPC title

• A61B6/5258

  involving detection or reduction of artifacts or noise · CPC title