PURPOSE: To study image quality in filtered digital tomosynthesis (FDTS) tomograms as a function of their reconstruction arc, using isocentrically acquired, fluoroscopic projection data. MATERIAL AND METHODS: Both digital tomosynthesis (DTS) and cone beam CT (CBCT) reconstruction algorithms are based on backprojection and use cone beam projection data as input. Under limited angle conditions, CBCT is reduced to FDTS, where only a subset of projection