The present invention relates to differential phase-contrast imaging of an object. For increasing spatial resolution of an X-ray imaging system (2) the size of a detector pixel element (8) may be considered a limiting factor. Accordingly, it may be beneficial to increase the resolution of an apparatus (38) for phase-contrast imaging without further reducing the area of an individual pixel element (8). Accordingly, an apparatus (38) for phase-contrast imaging with improved sampling is provided, comprising an X-ray source (4), a first grating element G1 (24), a second grating element G2 (26) and an X-ray detector element (6) comprising a plurality of detector pixel elements (8), each detector pixel element (8) having a pixel area A. An object to be imagined (14) is arrangeable between the X-ray source (4) and the X-ray detector element (6). The first grating element G1 (24) as well as the second grating element G2 (26) are arrangeable between the X-ray source (4) and the X-ray detector element (6). The X-ray source (4), the first grating element G1 (24), the second grating element G2 (26) and the X-ray detector (6) are operatively coupled for acquisition of a phase-contrast image of the object (14). At least one of the first grating element G1 (24) and the second grating element G2 (26) comprise a first area A1 having a first grating pitch p1 and a second area A2 having a second grating pitch p2 different from the first grating pitch.本発明は対象の微分位相差イメージングに関する。Ｘ線イメージングシステム２の空間分解能を増すために、検出器ピクセル素子８のサイズが制限要素とみなされ得る。従って、個別ピクセル素子８の面積をさらに減らすことなく位相差イメージング用の装置３８の分解能を増すことが有益であり得る。従って、サンプリングを改善した位相差イメージング用の装置３８が提供され、Ｘ線源４、第１の格子素子Ｇ１２４、第２の格子素子Ｇ２２６、及び複数の検出器ピクセル素子８を有するＸ線検出器素子６を有し、各検出器ピクセル素子８はピクセル面積Ａを持つ。撮像対象１４はＸ線源４とＸ線検出器素子６の間に配置可能である。第１の格子素子Ｇ１２４及び第２の格子素子Ｇ２２６はＸ線源４とＸ線検出器素子６の間に配置可能である。Ｘ線源４、第１の格子素子Ｇ１２４、第２の格子素子Ｇ２２６、及びＸ線検出器６は対象１４の位相差画像の収集のために動作可能に結合する。第１の格子素子Ｇ１２４と第２の格子素子Ｇ２２６の少なくとも一つは第１の格子ピッチｐ１を持つ第１の面積Ａ１、及び第１の格子ピッチと異なる第２の格子ピッチｐ２を持つ第２の面積Ａ２を有する。
