To decrease the calculation time of iterative tomographic reconstruction, this study proposes and investigates the uses of the "dot-projection" algorithm, which uses smooth basis functions for data representation. Basis functions give an approximation to the basis functions of blobs, which provide a more accurate reconstruction at the same resolution than for traditional "ray-driven" projection algorithms with voxels. This study evaluates the calculation time decrease and obtained errors from the algorithm for reconstruction, as well as its response to spatial frequencies. Finally, we compare the dot-projection for several basis functions and the ray-driven projection with respect to accuracy. (C) 2001 John Wiley & Sons, Inc.