Geometric dependence of image quality in digital tomosynthesis: Simulations of X-ray source trajectories and scan angles

Abstract

Digital tomosynthesis (DTS) is able to provide the 3-dimensional (3D) images of an object, while reducing radiation dose compared to computed tomography (CT). Despite these benefits, DTS has a geometric sensitivity because only a few dozen projections obtained with limited scan angles are used for DTS imaging. In this study, we evaluated the effects of X-ray source scan trajectories and angles on DTS images for investigating the geometric dependence in DTS. The DTS systems were simulated with linear, rotational and circular scan trajectories, and 54 projections were obtained from each of the four scan angle intervals of ±17, ±27, ±37 and ±47 degrees. The obtained projections were reconstructed by using a model-based filtered back-projection (FBP) technique. The characteristics of reconstructed DTS images were analyzed in terms of quantitative accuracy, noise property, contrast-to-noise ratio (CNR) and spatial resolution. The results showed that the quality of DTS images was highly dependent on the geometric variations, and the characteristics of DTS images differed according to the X-ray source scan trajectories and angles. In conclusion, the DTS geometries should be determined by considering image quality and characteristic in order to optimize their systems and applications.