Patent Number: 
Section: claims

1. A focus/detector system of an X-ray apparatus for generating at least one of projective and tomographic phase contrast recordings, comprising:a beam source, including a focus and a focus-side source grating, arranged in the beam path to generate a field of ray-wise coherent X-rays; anda grating/detector arrangement including a phase grating with grating lines arranged parallel to the source grating for generating an interference pattern and a detector including a multiplicity of detector elements arranged in a plane for measuring the radiation intensity behind the phase grating, wherein the detector elements are formed by a multiplicity of elongate detection strips aligned parallel to the grating lines of the phase grating. 2. The focus/detector system as claimed in claim 1, wherein the grating/detector arrangement is designed and arranged so that it satisfies the following geometrical conditions:            p      2        =          k      ×              p        DS                                p        0            =                        p          2                ×                  l          d                      ,                  ⁢                  p        1            =              2        ×                                            p              0                        ×                          p              2                                                          p              0                        +                          p              2                                                      d      =                                                  l              ×                              d                ≡                                                    l              -                              d                ≡                                              ⁢                                          ⁢          with          ⁢                                          ⁢                      d            ≡                          =                              1            2                    ×                      (                                          p                1                2                                            4                ⁢                                                                  ⁢                λ                                      )                                ,                  ⁢                  h        1            =              λ                  2          ⁢                      (                          n              -              1                        )                                ,  where:p0=grating period of the source grating G0,p1=grating period of the phase grating G1,p2=large period of the detection strips Ds, spacing of the interference lines after the analysis grating,pDS=small period of the detection strips Ds, distance from midline to midline of neighboring detection strips,d=distance from the phase grating G1 to the analysis grating G2 or to the detection strips DSx in fan beam geometry,d≡=distance from the phase grating G1 to the analysis grating G2 or to the detection strips DSx with parallel beam geometry,k=2,3,4,5, . . . ,l=distance from the source grating G0 to the phase grating G1,λ=selected wavelength of the radiation,h1=bar height of the phase grating G1 in the beam direction,n=refractive index of the grating material of the phase grating. 3. The focus/detector system as claimed in claim 1, wherein the detection strips are designed as directly converting detection strips. 4. The focus/detector system as claimed in claim 1, wherein the n detection strips of at least one detector element are connected at least one of alternately and groupwise to readout electronics via m electronics paths for reading out the radiation intensity in steps of m, where 2=m<<n. 5. The focus/detector system as claimed in claim 4, wherein precisely two electronics paths are provided. 6. The focus/detector system as claimed in claim 4, wherein at least one of precisely three electronics paths and precisely four electronics paths are provided. 7. An X-ray system for generating projective phase contrast recordings comprising at least one focus/detector system as claimed in claim 1. 8. An X-ray C-arc system for generating projective and tomographic phase contrast recordings comprising at least one focus/detector system as claimed in claim 1, arranged on a C-arc rotatable about a subject. 9. An X-ray CT system for generating tomographic phase contrast recordings comprising at least one focus/detector system as claimed in claim 1, arranged on a gantry rotatable about a subject. 10. The X-ray system as claimed in claim 7, further comprising a computation unit to control the offset of the detection strips and to calculate the phase shift from a plurality of intensity measurements of the same ray with differently offset detection strips. 11. The focus/detector system as claimed in claim 2, wherein the detection strips are designed as directly converting detection strips. 12. The focus/detector system as claimed in claim 2, wherein the n detection strips of at least one detector element are connected at least one of alternately and groupwise to readout electronics via m electronics paths for reading out the radiation intensity in steps of m, where 2=m<<n. 13. An X-ray system for generating projective phase contrast recordings comprising at least one focus/detector system as claimed in claim 2. 14. An X-ray C-arc system for generating projective and tomographic phase contrast recordings comprising at least one focus/detector system as claimed in claim 2, arranged on a C-arc rotatable about a subject. 15. An X-ray CT system for generating tomographic phase contrast recordings comprising at least one focus/detector system as claimed in claim 2, arranged on a gantry rotatable about a subject. 16. The X-ray system as claimed in claim 8, further comprising a computation unit to control the offset of the detection strips and to calculate the phase shift from a plurality of intensity measurements of the same ray with differently offset detection strips. 17. The X-ray system as claimed in claim 9, further comprising a computation unit to control the offset of the detection strips and to calculate the phase shift from a plurality of intensity measurements of the same ray with differently offset detection strips. 18. A method for generating projective X-ray recordings of a subject with a focus/detector system of an X-ray apparatus, the focus/detector system including a beam source and a grating/detector arrangement including a phase grating and a detector including a multiplicity of detector elements, wherein the detector elements are formed by a multiplicity of elongate detection strips aligned parallel to grating lines of the phase grating, the method comprising:irradiating the subject by a beam of rays, each ray in space being defined with respect to direction and extent by the focus-detector element connecting line and the extent of the detector element;measuring the average phase shift of each ray wherein, for each ray, the intensity of the radiation is measured with the aid of fine structured detection strips at detection strips connected groupwise and arranged offset with respect to one another or positioned offset from one another; andcompiling phase contrast recordings, the pixel values of which represent the average phase shift per ray, from the measured average phase shifts. 19. The method as claimed in claim 18, wherein the detection strips of a detector element are connected alternately to two measurement paths and, without an intermediate detector offset, at least two intensity measurements are carried out on the two groups of detection strips via the two measurement paths of a detector element, a spatial offset of the groups of detection strips subsequently takes place at least once, and two further measurements are carried out for the same geometrical ray. 20. The method as claimed in claim 18, wherein the spatial offset of the groups of detection strips is performed by circuit technology. 21. The method as claimed in claim 18, wherein the spatial offset of the groups of detection strips is performed physically. 22. The method as claimed in claim 18, wherein the detection strips of a detector element are connected alternately to at least three measurement paths and, without an intermediate detector offset, at least three intensity measurements are carried out on the three groups of detection strips via the three measurement paths of a detector element for a ray. 23. An X-ray system for generating projective phase contrast recordings comprising a computation and control unit including program code to carry out, when executed, the method as claimed in claim 18 during operation. 24. A storage medium at least one of for an X-ray system and of an X-ray system, the storage medium containing program code to carry out, when executed by the X-ray system, the method as claimed in claim 18 during operation of the X-ray system. 25. A computer readable medium including program segments for, when executed on a computer device of an X-ray system, causing the X-ray system to implement the method of claim 18.