We present a practical approach for implementing the Projected Tetrahedra (PT) algorithm for interactive volume rendering of unstructured data using programmable graphics cards. Unlike similar works reported earlier, our method employs two fragment shaders, one for computing the tetrahedra projections and another for rendering the elements. We achieve interactive rates by storing the model in texture memory and avoiding redundant projections of implementations using vertex shaders. Our algorithm is capable of rendering over 2.0M Tet/s on current graphics hardware, making it competitive with recent ray-casting approaches, while occupying a substantially smaller memory footprint.