Pre-clinical evaluation and optimization of image quality for a Next Generation Tomosynthesis prototype.

A next generation tomosynthesis (NGT) prototype has been developed 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 to define an acquisition geometry. In previous work, tests of physics have been used as objective metrics to evaluate image quality for NGT. In this work, the performance of custom NGT acquisition geometries is evaluated for mastectomy specimens to validate previous phantom experiments. Two custom acquisition geometries - incorporating T- and K-shaped source motion paths in the posteroanterior direction - were compared with a conventional DBT acquisition geometry. Noise power spectra (NPS) are calculated using 3D image reconstructions of the three acquisition geometries to evaluate the degradation of image quality due to noise and to visualize NGT sampling properties in the Fourier domain. NPS are used to describe features of the specimen image reconstructions and compare acquisition geometries. NGT acquisition geometries were found to improve high-frequency performance with isotropic super resolution, reduce out-of-plane reconstruction artifacts, and improve overall image reconstruction quality. The T-geometry combines the benefits of narrow- and wide-angle tomosynthesis in a single scan improving high-frequency spatial resolution and out-of-plane blurring, respectively.