Digital tomosynthesis of hands using simultaneous algebraic reconstruction technique with distance driven projector

Digital tomosynthesis (DT) is an X-ray tomographic technique for producing a three-dimensional stack of crosssectional images, based on a limited number of low-dose two-dimensional projections, acquired over a limited angular range. Currently, DT has mainly been investigated for the breast and chest imaging. Another application of DT may be an orthopaedic imaging of hands. A three-dimensional reconstruction with a high in-plane resolution, a low dose and potentially low costs make DT attractive for hand imaging comparing with the planar radiography or computed tomography. However, it should be noted that an accurate image reconstruction in DT is a challenging task due to the high degree of data incompleteness. Images are affected by the residual blur of structures that are located above and below the plane of interest. A human hand consists of 27 bones and therefore the artifact problem becomes even more acute in this case, since the magnitude of artifacts is related not only to the chosen reconstruction type but also to the size and contrast of the artifact-generating object. The study presented in the current work has been performed to show a capability of Simultaneous Algebraic Reconstruction Technique (SART) for hand visualization in tomosynthesis. A distance-driven type for the projector and backprojector operator has been used to make the calculation fast and accurate. Studies have been carried out on a phantom with an uniform background and millimeter-sized balls, a dried finger bone and an in toto hand phantom. A Siemens Mammomat Inspiration device has been used to acquire the projection data. Experimental results show that SART is able to reduce out-of-plane artifacts caused by bone tissue. It provides reconstruction with acceptable quality in only one iteration with the recovered visibility of the obscured trabecular structures as well as the joint spaces and the margins. (orig.)