Two-dimensional single grating phase contrast system

Phase contrast X-ray not only provides attenuation of tissue, but two other modalities (phase and scatter) in same scan. Scatter (dark-field) images provided by the technology are far more sensitive to structural and density changes of tissue such as lungs and can identify lung disease where conventional X-ray fails. Other areas poised to benefit greatly are mammography and bone joint imaging (eg. imaging arthritis). Of the various interferometer techniques, the two at the forefront are: Far-field Interferometry (FFI) (Miao et al, Nat. Phy . 2015) and Talbot-Lau interferometry (TLI) (Momose JJAP 2005 , Pfeiffer Nature 2006 ). While the TLI has already made clinical strides, the newer FFI has advantage of not requiring an absorption grating (“analyzer”) and provides few-fold higher scatter sensitivity. In this work, a novel 2D single phase-grating (not requiring the analyzer), near-field phase contrast system was simulated using Sommerfeld- Rayleigh diffraction integrals. We observed 2D fringe patterns (pitch 800nm) at 50mm distance from the grating. Such a pattern period of 0.05mm, can be imaged by the LSU-interferometers with CT detector resolution (0.015mm) or Philips mammography detector resolution (0.05mm) making this practical system. Our design has a few advantages over Miao et al FFI system. We accomplish in one X-ray grating the functionality that requires 2-3 phase-grating in their design. And our design can also provide a compact system (source to detector distance < 1m) with control over the fringe pattern by fine tuning grating structure. We retain all the benefits of far-field systems -- of not requiring analyzer and high scatter sensitivity over Talbot-Lau interferometers.