If you are just beginning to explore iterative image reconstruction, then I recommend you begin with the Matlab image reconstruction toolbox that I have developed, and wait to get ASPIRE when you really need it. If you do not have Matlab (perhaps because it is expensive and annoyingly incompatible between versions) then checkout freemat. Work is underway to make freemat run my tomography toolbox code.
Central components of the ASPIRE code are the regularization methods described in papers by J. A. Fessler and J. W. Stayman about spatial resolution properties of image reconstruction methods. Before using the software, I recommend skimming those papers if you have not seen them already.
The ASPIRE compiled executables are available for free access to both academic and industrial users for research purposes. To access the software, you must agree to the terms of the license agreement, which prohibits selling or further distributing the software.
If you are interested, please send me a letter or plain-text email (no attachments, no html) requesting access to the software. I will then email you instructions about how to obtain the programs, and add you to an email list so that you can be informed about upgrades. (I will not distribute your email address to anyone else, and I will only very rarely send you an email about ASPIRE.)
The letter must include the following statement:
We agree to use the ASPIRE software
for non-commercial research purposes only.
We will not distribute the software
to anyone else,
and will take reasonable precautions
to prevent unintended copying.
By reasonable precautions, I mean simple things like using not world-readable file permissions, and not installing it in an ftp directory.
Companies interested in licensing portions of the software for non-research purposes should contact Jeff Fessler at the above address, or The University of Michigan's Technology Transfer Office