Performance speedups are dependent mostly on possible parallelism and implementation Schiwietz et al report in mr image reconstruction using the gpu an 128x improvement in using a GPU instead of a CPU for CT reconstruction However Kachelreiss et al s has a version of the same reconstruction algorithm which runs twice as fast on an intel CPU as Schiwietz et al s gpu version even though he was optimising for the CBE Hyperfast parallel beam and cone beam backprojection using the cell general purpose hardware