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1. WO2012052881 - IMAGERIE DIFFÉRENTIELLE EN CONTRASTE DE PHASE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

CLAIMS:

1. A diffraction grating (14, 15) for X-ray differential phase-contrast imaging, comprising

- at least one portion (24) of a first sub-area (26); and

- at least one portion (28) of a second sub-area (30);

wherein the first sub-area comprises a grating structure (54) with a plurality of bars (34) and gaps (36) being arranged periodically with a first grating pitch PG1 (38); wherein the bars are arranged such that they change the phase and/or amplitude of an X-ray radiation and wherein the gaps are X-ray transparent;

wherein the second sub-area is X-ray transparent and wherein the at least one portion of the second sub-area provides an X-ray transparent aperture (40) in the grating;

wherein portions of the first and second sub-areas are arranged in an alternating manner in at least one direction (42).

2. Diffraction grating according to claim 1, wherein a number of portions of the first and/or second sub-areas are arranged adjacent as first subsets (64) and/or second subsets

(66); and wherein the first and/or second subsets are arranged across the area of the diffraction grating in a first subset-repetition pitch PSR1 and/or second subset-repetition pitch PSR2 in at least one direction.

3. Diffraction grating according to claim 1 or 2, wherein the portions of the first and second sub-areas are arranged across the area of the diffraction grating in a chess-board pattern (50).

4. Diffraction grating according to one of the preceding claims,

wherein portions of the first sub-area are arranged linearly in at least one linear grating group (76) comprising at least one line (78) of portions of first sub-area; and

wherein portions of the second sub-area are arranged linearly in at least one linear aperture group (80) comprising at least one line (82) of portions of second sub-area; wherein at least two linear grating groups (76) and at least two linear aperture groups (80) are provided; and

wherein the linear grating groups and the linear aperture groups are arranged in an alternating manner in a first line pitch PL1 (84).

5. A detector arrangement (10) of an X-ray system for generating phase-contrast images of an object comprising:

- a first diffraction grating (520);

- a second diffraction grating (522); and

- a detector (12; 514) with a sensor;

wherein the sensor comprises at least one sensor pixel (16) of a first sub-group (18) of pixels and at least one sensor pixel (20) of a second sub-group of pixels (22);

wherein the first diffraction grating is a phase grating (15);

wherein the second diffraction grating is an analyzer grating (14); wherein the analyzer grating and/or the phase grating are adapted to be stepped transversely in relation to the period of the analyzer grating;

wherein the phase grating and the analyzer grating are provided as a diffraction grating for X-ray differential phase-contrast imaging according to one of the preceding claims;

wherein the first and second diffraction gratings are each adapted to be translated in relation to the sensor from a first position (P1) to at least a second position (P2) with a first translation pitch PT1 (44);

wherein the translation pitch PT1 is adapted to the portions of the first and second sub-areas being arranged in the alternating manner in the at least one direction; and wherein in the first and second position, different fractions of the sensor are arranged behind the portions of the first and second sub-areas.

6. Detector arrangement according to claim 5, wherein the first and/or second diffraction gratings are each adapted to be phase-stepped in relation to one period of the diffraction grating structure with the first grating pitch PG1 in an acute angle a (109) to the grating structure of the first and/or second diffraction grating.

7. Detector arrangement according to claim 5 or 6, wherein the size of the pixels differs from the size of the portions of the first and/or second sub-areas of the diffraction grating.

8. An X-ray image acquisition device (510) for generating phase-contrast images of an object, with

- an X-ray source (512);

- a source grating (518);

- a phase grating (520);

- an analyzer grating (522); and

- a detector (514);

wherein the X-ray source generates an X-ray beam (536) of polychromatic spectrum of X-rays;

wherein the source grating is adapted to provide sufficient transverse coherence to illuminate (538) at least one full grating pitch of the phase grating coherently, so that interference can be observed at the location of the analyzer grating; and wherein the phase grating, the analyzer grating and the detector are provided as a detector arrangement according to one of the claims 5 to 7.

9. A medical X-ray imaging system (500) for differential phase contrast imaging, with:

- an X-ray image acquisition device (510) for generating phase-contrast images of an object according to claim 8;

- a processing unit (526);

- an interface unit (528); and

- an object receiving device (524);

wherein the processing unit is adapted to control the X-ray source as well as the phase-stepping of the analyzer grating and/or the phase grating and the translation of the phase grating and the analyzer grating;

wherein the interface unit is adapted to provide the recorded first and second raw image data to the processing unit; and

wherein the object receiving device is adapted to receive the object of interest for the phase contrast image acquisition.

10. A method (400) for differential phase contrast imaging, comprising the steps of:

- a1) applying (410) coherent X-ray radiation to an interferometer with two diffraction gratings in a first position (PI); which diffraction gratings each comprise at least one grating part and at least an aperture part; wherein a first diffraction grating is a phase grating and wherein a second diffraction grating is an analyzer grating;

a2) phase stepping (412) the analyzer grating; and

a3) recording (414) first raw image data (416) with a sensor with at least two parts; wherein a first and a second part are recording phase contrast image information and density information;

- b) translating (420) the analyzer grating and the phase grating to a second position (P2); and

- c1) applying (422) coherent X-ray radiation to the interferometer in the second position;

c2) phase stepping (424) the analyzer grating; and

c3) recording (426) second raw image data (428) with a sensor with at least two parts; wherein the first and second part are recording density information and phase contrast image information; and

- d) providing (432) the recorded first and second raw image data as raw image data (434).

11. Method according to claim 10,

wherein the phase-stepping is performed in an acute angle a (109) to the diffraction grating.

12. Method according to claim 10 or 11,

wherein the phase grating and the analyzer grating each comprise at least one portion of a first sub-area, which first sub-area comprises a grating structure with a plurality of bars and gaps being arranged periodically with a first grating pitch PGi; wherein the bars are arranged such that they change the phase and/or amplitude of an X-ray radiation and wherein the gaps are X-ray transparent; and at least one portion of a second sub-area, which is X-ray transparent and wherein the at least one portion of the second sub-area provides an X-ray

transparent aperture in the grating; wherein portions of the first and second sub-areas are arranged in an alternating manner in at least one direction;

wherein step a3) comprises recording the first raw image data with the sensor in the first position, wherein the sensor comprises at least one sensor pixel of a first sub-group of pixels and at least one sensor pixel of a second sub-group of pixels; wherein in the first position, the first sub-areas of the analyzer grating and the phase grating are each arranged at least partially in front of the first sub-group of pixels and the second sub-areas are arranged at least partially in front of the second sub-group of pixels; and wherein the first and second sub-groups are recording phase contrast image information and density information;

wherein step b) comprises translating the phase grating and the analyzer grating in relation to the sensor from the first position to at least the second position with a first translation pitch PT1; wherein the translation pitch is adapted to the portions of the first and second sub-areas of the diffraction gratings being arranged in the alternating manner in the at least one direction; and wherein in the second position, the first sub-areas of the analyzer grating and the phase grating are each arranged at least partially in front of the second sub-group of pixels and the second sub-area at least partially in front of the first sub-group of pixels; and

wherein step c3) comprises recording the second raw image data with the sensor in the second position; wherein the first and second sub-group are recording density information and phase contrast image information.

13. Method according to claim 12, wherein in the first and second position, the first and second sub-areas of the analyzer grating are each arranged at least partially in front of the first sub-group of pixels and at least partially in front of the second sub-group of pixels;

wherein in the first and second position, different first (94a, 96a) and second parts (96a, 96a ) of the first and second sub-group of pixels are covered by the portions of the first sub-area of the analyzer grating respectively;

wherein following step c), a third position (P3) and at least a further position

(PF) are provided into which the diffraction gratings are translated (438, 448) and in which third and further raw image data is recorded (444, 454) while applying (440, 450) coherent X-ray radiation and phase-stepping (442, 452) the analyzer grating;

wherein in the third and further position, the first and second sub-areas of the analyzer grating and the phase grating are each arranged at least partially in front of the first sub-group of pixels and at least partially in front of the second sub-group of pixels; wherein in the third and further position, different third (94a, 96a) and further parts (94a, 96a) of the first and second sub-group of pixels are covered by the portions of the first sub-area of the analyzer and phase grating respectively; which third and further parts partially overlap with the first and second parts respectively.

14. Computer program element for controlling an apparatus according to one of the claims 1 to 9, which, when being executed by a processing unit, is adapted to perform the method steps of one of the claims 10 to 13.

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