A quantitative metrology for performance characterization of breast tomosynthesis systems based on an anthropomorphic phantom
Purpose: Common methods for assessing image quality of digital breast tomosynthesis (DBT) devices currently utilize simplified or otherwise unrealistic phantoms, which use inserts in a uniform background and gauge performance based on a subjective evaluation of insert visibility. This study proposes a different methodology to assess system performance using a three-dimensional clinically-informed anthropomorphic breast phantom. Methods: The system performance is assessed by imaging the phantom and computationally characterizing the resultant images in terms of several new metrics. These include a contrast index (reflective of local difference between adipose and glandular material), a contrast to noise ratio index (reflective of contrast against local background noise), and a nonuniformity index (reflective of contributions of noise and artifacts within uniform adipose regions). Indices were measured at ROI sizes of 10mm and 37 mm, respectively. The method was evaluated at fixed dose of 1.5 mGy AGD. Results: Results indicated notable differences between systems. At 10 mm, vendor A had the highest contrast index, followed by B and C in that. The performance ranking was identical at the largest ROI size. The non-uniformity index similarly exhibited system-dependencies correlated with visual appearance of clutter from out-of-plane artifacts. Vendor A had the greatest NI at all ROI sizes, B had the second greatest, and C the least. Conclusions: The findings illustrate that the anthropomorphic phantom can be used as a quality control tool with results that are targeted to be more reflective of clinical performance of breast tomosynthesis systems of multiple manufacturers.
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