Robust Phase Integration

Our phase-based methods (edge-illumination and beam tracking) are differential phase contrast methods, i.e. they are sensitive to the first derivative of the phase shift imposed by the object on the x-ray beam. While the phase shift can be obtained through integration, this is known to lead to strong “stripe” artifacts if simple, direct integration is applied. In the past, this problem was solved through iterative methods which are computationally very expensive: typically, tens of minutes are required to integrate a single 2D image, which makes applications to CT prohibitive. We have developed a non-iterative algorithm based on the Wiener filter, which achieves the same results as iterative approaches with computational times well below 1 second per image, fully compatible with CT.

Differential phase contrast image of a beetle (a) integrated with direct integration (b), the new method we developed (c) and the much more computationally expensive iterative approach (d).