Ultrasound imaging is one of the most preferred modalities for image-guided procedures due to its low-cost, non-ionizing nature, and real-time capability. However, if patient-specific ultrasound images can be simulated before the actual procedure, it may aid in better implementation of the procedure planned using pre-planning image data. For this reason, ultrasound simulations from CT data have gained much interest over the past few years. Recent approaches combine ultrasound echo reflection image, intensity transmission map, and scatter image of the region of interest to form the final ultrasound image. However, the scatter image is simulated from Field II, which is computationally very intensive. In this paper, we propose combining the traditional convolution model for scatter map simulation with ray tracing approaches to simulate an ultrasound image. The obtained results suggest that using convolution model instead of Field II reduces significantly the computational time without affecting the image quality. © 2018 IEEE.