A prototype voluiie CT irnager has been tested using a vascular phantom. This systen consists of a fixed x-ray tube a conventional image intensifier coupled to a chargecoupled device (CCD) camera a computer-controlled turntable on which phantons are placed and a digital computer with a graphics station. To explore the imaging performance of the system for reconstructing a three-dimensional (3D) vascular structure a set of subtraction projections of a vascular phantom acquired over 25 projection angles with two different sizes of image intensifiers were digitized. Then these data were reconstructed using two iterative algorithms specially designed for 3D vascular structures. The quality of the reconstructed vascular images indicates that the system can offer adequate signal-to-noise ratio (SNR) for direct 3D vascular reconstruction when only a few subtraction projections are used assuming intraarterial injection of contrast. The results also suggest that the iterative vascular reconstruction algorithms work well for direct 3D vascular reconstruction. 1.