Evaluating the imaging performance of a next-generation digital breast tomosynthesis prototype

A next generation tomosynthesis (NGT) prototype was designed to investigate alternative scanning geometries for digital breast tomosynthesis (DBT). The NGT system uses a 2D plane as an address space for the x-ray source, and one-dimensional linear detector motion to determine an acquisition geometry. This design provides myriad acquisition geometries for investigation. This system is also capable of magnification DBT. We performed image quality measurements to evaluate performance of the NGT system for both contact and magnification imaging in 2D and 3D. The modulation transfer function (MTF) was computed using the slanted-edge method to evaluate spatial resolution. The first zero of the MTF was observed to increase by a factor of the magnification. In-plane spatial resolution performance for 3D was measured using an in-house metric, and was found to be commensurate to the MTF. This metric uses a star pattern as an input object to produce the contrast transfer function (CTF). The 2D noise power spectra (NPS) were calculated to evaluate the degradation of image quality due to noise. 3D NPS were also calculated for various 3D image reconstructions. 3D renditions of the NPS show how the NGT can sample a broader range of frequencies in the Fourier domain than conventional DBT. The system's lag was measured and found not to affect 3D image reconstructions significantly. A wax calcification phantom was constructed and imaged using the NGT system. The performance of this system has been evaluated and the results suggest that image quality is sufficient for clinical investigation.