ALIGNING SOURCE-GRATING-TO-PHASE-GRATING DISTANCE FOR MULTIPLE ORDER PHASE TUNING IN DIFFERENTIAL PHASE CONTRAST IMAGING

摘要

The present invention relates handling misalignment in an X-ray imaging system for differential phase contrast imaging. In order to provide a reduction for the pretuning and adjustment requirements for manufacture and maintenance in a differential phase contrast imaging system, an X-ray imaging system (10) for differential phase contrast imaging, is provided that comprises a differential phase contrast setup (12) with an X-ray source (14) and an X-ray detector (16), a grating arrangement (18) comprising a source grating (20), a phase grating (22) and an analyser grating (24), wherein the source grating is arranged between the X-ray source and the phase grating, and the analyser grating is arranged between the phase grating and the detector. Further, a moving arrangement for a relative movement between an object under examination and at least one of the gratings is provided, as well as a processing unit (32), and a translation arrangement (34) for translating the source grating. The phase grating, the analyser grating and the detector are provided as a rigid interferometer unit (36), in which the phase grating and the analyser grating are mounted in parallel to each other. The source grating is misaligned in respect to the interferometer unit such that moiré fringes are detectable in the plane of the detector. The processing unit is configured to detect moiré patterns in signals provided by the detector upon X-ray radiation. The processing unit is further configured to compute a translation signal (38) for translating the source grating for achieving a predetermined moiré pattern. The translation arrangement is configured to adjust the positioning of the source grating at least in the X-ray projection direction (30), based on the value of the translation signal.

主权项

1. An X-ray imaging system for differential phase contrast imaging, comprising
a differential phase contrast setup with: an X-ray source and an X-ray detector; a grating arrangement comprising a source grating, a phase grating and an analyser grating, wherein the source grating is arranged between the X-ray source and the phase grating, and the analyser grating is arranged between the phase grating and the detector; and a moving arrangement for a relative movement between an object under examination and at least one of the gratings; a processing unit; and a translation arrangement for translating the source grating; wherein the phase grating, the analyser grating and the detector are provided as a rigid interferometer unit, in which the phase grating and the analyser grating are mounted in parallel to each other; wherein the source grating is misaligned in respect to the interferometer unit such that moiré fringes are detectable in the plane of the detector; wherein the processing unit is configured to detect moiré patterns in signals provided by the detector upon X-ray radiation; and wherein the processing unit is further configured to compute a translation signal for translating the source grating for achieving a predetermined moiré pattern; and wherein the translation arrangement is configured to adjust the positioning of the source grating at least in the X-ray projection direction, based on the value of the translation signal for misaligning the source grating such that at least 2 pi of phase changes are covered with the Moiré fringes over the width of the detector array.