Anatomical background noise power spectrum in differential phase contrast and dark field contrast mammograms

Purpose: In x‐ray absorption mammography, it has been found that the anatomical background noise can be characterized by a power law dependence on the spatial frequency, NPS a ( f ) ≈ αf − β . In this letter, the authors present the first experimental results of the corresponding exponents, β , for differential phase contrast ( β DPC ) and dark field contrast ( β DF ) mammography. Methods: A grating‐based x‐ray multicontrast imaging acquisition benchtop system was used to simultaneously acquire mammograms with three different contrast mechanisms from 15 cadaver breasts under the same x‐ray data acquisition conditions. The cadaver breasts were imaged in the coronal plane. The authors’ experimental implementation of the well documented method [Burgess, Jacobson, and Judy, Med. Phys. 28 , 419–437 (2001)] to extract the exponent β was first validated using anonymized clinical mammograms. Experiments were then used to determine β for the three types of mammograms for each cadaver breast acquired with our multicontrast imaging system: absorption contrast mammogram ( β Abs. ), differential phase contrast mammogram ( β DPC ), and dark‐field contrast mammogram ( β DF ). Results: The measured β values, acquired in the coronal plane with the benchtop multicontrast imaging system are β Abs. = 3.61 ± 0.49, β DPC = 2.54 ± 0.75, and β DF = 1.44 ± 0.49 for absorption, differential phase, and dark field mammogram, respectively. Conclusions: The β values for differential phase contrast and dark field mammography are significantly lower than the measured value of β for the corresponding absorption contrast mammograms. The greatly reduced β value of the anatomical background noise in differential phase contrast and dark field mammograms may suggest potentially improved diagnostic performance for certain types of breast cancer imaging tasks.