Medical ultrasound interpretation requires a great deal of experience. Real-time simulation of medical ultrasound provides a cost-effective tool for training and easy access to a variety of cases and exercises. However, fully synthetic and realistic simulation of ultrasound is complex and extremely time-consuming. In this paper, we present a novel method for simulation of ultrasound images from 3D CT scans by breaking down the computations into a preprocessing and a run-time phase. The preprocessing phase produces detailed fixed-view 3D scattering images and the run-time phase generates view-dependent ultrasonic artifacts for a given aperture geometry and position within a volume of interest. We develop a simple acoustic model of the ultrasound for the run-time phase, which produces realistic ultrasound images in real-time when combined with the previously computed scattering image.