Digital tomosynthesis: phantom and patient studies with a prototype unit.

A prototype digital linear tomographic system has been developed and used in patient and phantom studies. Phantom work demonstrated 0.6 line pairs/mm of spatial resolution, a slice thickness of 5 mm to 6 mm, range of reconstruction of 1 cm to 20 cm above tabletop, reconstruction time of 2 to 45 seconds per slice depending on matrix size, and a 280 mm field of view at the tabletop. Patient studies were conducted in three categories: renal imaging in 8 patients during intravenous urography (IVU); central airways imaging in 4 patients undergoing laser resection of endobronchial tumor; the knee of one volunteer. The digital tomograms from IVU studies were similar to the conventional film tomograms, and the only parenchymal abnormality, a renal cyst, was identified by both modalities. Digital tomograms of the mediastinum were superior to the chest radiographs in determining the patency of the central airways. With further development, digital tomosynthesis could offer greater spatial resolution, faster reconstructions, and less radiation than computed tomography (CT) or conventional tomography.