Evaluation of the effect of acquisition parameters on image quality in digital breast tomosynthesis: Simulation studies

摘要

In Digital Tomosynthesis the reconstruction algorithms as well as the acquisition arc and the number of projections per arc are critical for the quality of tomosynthetic slices containing features of different sizes and contrast. This paper presents the results from a simulation study aiming to investigate the effect of these parameters. For this purpose, sixteen acquisition sets of simulated projections from a tissue equivalent breast phantom containing masses and groups of calcifications of gradually increasing dimensions are generated using an in-house developed XRay Imaging Simulator. For all acquisition schemes, the mean glandular dose to the breast phantom is set to 2.5 mGy. Breast tomosynthetic images are reconstructed from these projections using a simple and a filtered multiple projection algorithm. The quality of reconstructed breast tomograms is evaluated using contrast (C) and contrast to noise ratio (CNR) as figures of merit. Both evaluations show superior visibility of all reconstructed features using the filtered algorithm. CNR values increase with extending the arc for the studied mass. In case of high contrast features, the CNR trend with the arc length demonstrates an opposite behavior. The optimal increment angle between projections for calcifications of large size (0.4 mm) is found equal to 2° and for calcifications of smaller size (0.230-0.165 mm), the optimal step is increased to 4°-6°.