Author: John M. Boone, Andrew M. Hernandez, Paul Schwoebel, Jeffrey H. Siewerdsen, Alejandro Sisniega, Wojciech B. Zbijewski 👨🔬
Affiliation: Johns Hopkins University, University of California, UT MD Anderson Cancer Center, University of New Mexico Albuquerque, UC Davis Health 🌍
Purpose: To significantly improve image quality relative to clinically deployed digital breast tomosynthesis (DBT) systems, which use a 1D acquisition geometry (an arc), with a 2D image acquisition geometry via a planar Multiple X-ray-source Array (MXA) in a clinically practical, high speed DBT system.
Methods: Published data from an emulated 2D MXA DBT system demonstrated significant improvements in image quality relative to the 1D image acquisition geometry used in commercial DBT systems. These data combined with detectability index modeling showed that when populating a rectangular plane above the detector plane with an array of X-ray focal spots, image quality improved as the focal spots were located at the periphery of the rectangle in both dimensions.
Results: Using the aforementioned analysis, a 2D MXA DBT source with 22 individually addressable, grid pulsed X-ray sources in a planar, 8 cm x 32 cm rectangular array was constructed. The 2D MXA uses a rotating anode which provides up to 200 mA operation, allowing exposures of 100 mAs to be acquired in < 2 s. This is important because mammography studies have shown that patient motion artifacts increase significantly with longer acquisition times. With a Varex 2520 detector operating at 30 fps (2 x 2 binning) acquisition times will be 0.7 s at 200 mA/source. With a Varex 3024MX mammography detector operating at 16 frames/second (2x2 binning) acquisition times will be limited by the detector frame rate to 1.4 s for currents greater than 100 mA/source.
Conclusion: Design and construction of the 2D MXA source is complete, and testing is underway, offering image acquisition times ranging 0.7 – 1.4 s (compared to 3.7 – 25 s for conventional DBT). Measurements of spatial resolution, noise, sampling, and reduction of out-of-plane anatomical clutter will quantify the performance gains associated with the 2D MXA geometry.