Impulse response in various scanning geometries for digital tomosynthesis

Digital tomosynthesis (DTS) is a three-dimensional imaging technique to reconstruct a set of planes in the object. Opposed to the computed tomography (CT), however, DTS uses projection images obtained from limited angular scanning, hence there exist some artifacts such as blurs that are originated from depletion of data in the Fourier domain. The main advantages of DTS technique are shorter reconstruction time and less patient dose. There are various geometries for angular scanning available in DTS, and which is mainly dependent upon specific imaging task and applications, such as mammography, dental imaging, industrial laminography etc. In principle, DTS shares the same concept in imaging reconstruction with the conventional CT, and thus incorporates a back-projection operation. This backprojection operation determines the transfer function, which is mainly resulted from the scanning geometry, if we regard the image reconstruction as an inverse problem. Therefore, the investigation of impulse response with respect to various imaging geometries is valuable to identify artifacts associated with the scanning geometry and thus optimize the system performance. We investigate and compare the system-transfer functions (impulse-response functions) for various image acquisition schemes to acquire projection data by numerical simulation. This study may suggest fundamental limitations of a certain scanning geometry and provide the best geometry with least blur artifacts