STIR: Software for Tomographic Image Reconstruction. STIR is Open Source software for use in tomographic imaging. Its aim is to provide a Multi-Platform Object-Oriented framework for all data manipulations in tomographic imaging. Currently, the emphasis is on (iterative) image reconstruction in PET and SPECT, but other application areas and imaging modalities can and might be added. STIR is the successor of the PARAPET software library which was the result of a (European Union funded) collaboration between 6 different partners (see the CREDITS file). Please check the STIR web-site at http://STIR.sourceforge.net for more information. This software is distributed under an open source license, see LICENSE.txt for details.