Image-Space Sheet-Buffered Splatting is a popular high quality volume-rendering technique specially suitable for zoomed views of the data. On the contrary to other splatting approaches, it processes the voxels in slabs perpendicular to the viewing direction. Recently, a GPU design of this method has been proposed that considerably accelerates the rendering stage. However, the bottleneck of the method is the computation of the buckets, i.e the structure handling the voxels to be rendered in each slab. This stage of the method is done on the CPU. In this paper, we propose a new design of the method that creates and manages the buckets on the GPU. The proposed method is more than twice faster than the previous ones.