ASPIRE (a sparse precomputed iterative reconstruction library) is a collection of ANSI C programs for tomographic image reconstruction developed at the University of Michigan by Jeff Fessler and his students. For novice investigators exploring iterative image reconstruction, it is recommended to begin with the Matlab-based Michigan Image Reconstruction Toolbox (MIRT) and later use ASPIRE when really needed. Central components of the ASPIRE code are regularization methods regarding spatial resolution properties of image reconstruction methods.
Tutorials: Documentation & Examples
NMMItools 