Table 1. Contrast-to-noise-ratio (CNR) of selected regions of the absorption and dark-field images of a tumor-like mass (test object 15).

As the exposure time of each phase step remained unchanged during the experiment, a reduction in number of processed phase steps results in a lower dose to the phantom. Note that the low contrast-to-noise-ratio (CNR_amp < 1) of the absorption signal corresponds to a noise level that is higher than the difference in mean pixel values and therefore does not allow for tissue discrimination in the image.

Number of phase steps	CNRamp	CNRDCI
4	0.1	4.7
8	0.1	6.5
16	0.1	9.2
32	0.1	12.8