We interface a Toshiba LX-40A radiation therapy simulator with a custom designed data acquisition system and a 386-PC. The LX-40A includes a 14 inch (35.6 cm) x-ray image intensifier and a 1 inch saticon camera. Two-dimensional cone beam projections of an anthropomorphic chest/lung phantom are collected. The Feldkamp algorithm reconstructs the volume data set into a volume image of the phantom. We discuss several volume computed tomography issues including spatial distortions in the x-ray image intensifier, scatter, and veiling glare. We compare the volume computed tomography results with two-dimensional CT imaging of the same phantom scanned on the equipment.