The advent of DirectX Shader Model 3 and comparable OpenGL extensions has led to graphics processors providing an ideal platform for efficiently mapping ray casting-based volume rendering to hardware. This fragment-program based ray casting does not suffer from any flexibility issues and, therefore, offers an optimal volume visualizing tool. Moreover, new graphics hardware designs encourage the use of novel fragment program features with much faster current and planned generations of graphics hardware. Hence, our goal in this work is to take advantage of this new direction and utilize recent commercial graphics hardware technology of GPUs to speed up the volume reconstruction time while increasing the quality of visualization. The target is to achieve high-quality volume rendering using ray casting at frame rates suitable for present 4D ultrasound imaging applications.