Arboleda Carolina, Wang Zhentian, Stampanoni Marco
Opt Express. 2014 Jun 30;22(13):15447-58. doi: 10.1364/OE.22.015447.
Among the existent X-ray phase-contrast modalities, grating interferometry appears as a very promising technique for commercial applications, since it is compatible with conventional X-ray tubes and is robust from a mechanical point of view. However, since applications such as medical imaging and homeland security demand covering a considerable field of view, the fabrication of large-area gratings, which is known to be challenging and expensive, would be needed. A scanning setup is a good solution for this issue, because it uses cheaper line instead of large-area 2D detectors and, therefore, would require smaller gratings. In such a setup, the phase-retrieval using the conventional phase-stepping approach would be very slow, so having a faster method to record the signals becomes fundamental. To tackle this problem, we present a scanning-mode grating interferometer design, in which a grating is tilted to form Moiré fringes perpendicular to the grating lines. The sample is then translated along the fringes, so each line detector records a different phase step for each slice of the sample. This new approach was tested both in a simulated scenario and in an experimental setting, and its performance was quantitatively satisfactory compared to the traditional phase-stepping method and another existing scanning-mode technique.
在现有的X射线相衬成像技术中，光栅干涉术似乎是一种非常有前景的商业应用技术，因为它与传统X射线管兼容，并且从机械角度来看很坚固。然而，由于医学成像和国土安全等应用需要覆盖相当大的视场，因此需要制造大面积光栅，而这已知具有挑战性且成本高昂。扫描装置是解决此问题的一个好办法，因为它使用更便宜的线探测器而非大面积二维探测器，因此所需的光栅尺寸更小。在这样的装置中，使用传统相移方法进行相位恢复会非常缓慢，所以拥有一种更快的信号记录方法变得至关重要。为了解决这个问题，我们提出了一种扫描模式光栅干涉仪设计，其中光栅倾斜以形成垂直于光栅线的莫尔条纹。然后将样品沿着条纹平移，这样每个线探测器为样品的每个切片记录不同的相移步长。这种新方法在模拟场景和实验环境中都进行了测试，与传统相移方法和另一种现有的扫描模式技术相比，其性能在定量上令人满意。
