Author: Stephen Araujo, Jing-Tzyh Alan Chiang, Cynthia E. Davis, Eri Haneda, Andrew Karellas, Thomas C Larsen, William Ross, Hsin Wu Tseng, Srinivasan Vedantham, Pengwei Wu 👨🔬
Affiliation: Department of Biomedical Engineering, The University of Arizona, GE Aerospace Research, Department of Medical Imaging, The University of Arizona, GE HealthCare Technology & Innovation Center 🌍
Purpose: The purpose of this work is to describe the design and development of a newly developed upright-geometry dedicated breast CT system and to quantitatively and qualitatively evaluate its imaging performance characteristics.
Methods: The angular range for short-scan trajectory, where the X-ray source travels inferior to the breast, the number of projections, and X-ray beam filtration were investigated with the target of maximizing imaging performance while limiting the mean glandular dose (MGD) to 4.5 mGy for an uncompressed breast of average size and composition. Images were reconstructed to isotropic 0.22mm voxels using Feldkamp-Davis-Kress algorithm with Parker weights. Quantitative imaging performance measures including linearity, modulation transfer function and noise power spectrum were evaluated. Phantom studies were conducted to determine the minimum detectable size of low-contrast targets and calcium carbonate spheres representing soft tissue lesions and microcalcification clusters, respectively.
Results: Acquisition at 60 kV, 0.25 mm Cu and 1 mm Al added filtration (HVL: 4.23 mm of Al), 210 projections over 210 degrees resulting in 16 second scans, were found suitable for artifact-free imaging, and in conjunction with appropriate tube current and X-ray pulse width achieved 4.25 mGy for an average breast. The limiting resolution (10% MTF) was 2.7 cycles/mm and phantom studies showed the ability to visualize 1–2 mm low contrast targets and 0.24–0.27 mm calcium carbonate spheres.
Conclusion: The experimental upright breast CT system showed the ability to achieve high spatial resolution and excellent low-contrast resolution at MGD of 4.25 mGy. This indicates the potential for investigating upright breast CT for breast cancer screening and diagnosis.