Effect of geometric variations on image characteristics in digital tomosynthesis

Digital tomosynthesis (DTS) has been used in diagnosis and radiation therapy due to its performance and benefits. DTS is able to provide 3D images with good depth resolution comparing to conventional radiography and reduce radiation dose comparing to computed tomography (CT). However, DTS scans with limited scan angles and a few projections lead to the insufficiency in data acquisition. Such a drawback causes the alteration of image characteristics and the distortion of image quality in DTS imaging. These issues can be magnified by the geometric variations of the DTS systems and the imaging strategies. In this study, the effect of geometric variations on image characteristics was evaluated by the DTS systems simulated with various X-ray source scan trajectories and angles. The DTS images were analyzed in terms of noise property, contrast-to-noise ratio (CNR), and spatial resolution. The results showed that the quality of DTS images was highly dependent on X-ray source scan trajectories and angles, and the characteristics of DTS images varied according to their acquisition geometries. Therefore, the geometries and strategies for DTS imaging should be appropriately determined for optimizing their systems and applications.