CONRAD is a software framework for cone-beam imaging in radiology. The software package includes different simulation tools that are able to generate 4-D projection and volume data and respective vector motion fields. Well known reconstruction algorithms such as FBP, DBP, and ART are included. It is based on platform-independent technologies. Special libraries offer access to hardware acceleration such as CUDA and OpenCL. There is an easy interface for parallel processing.
Source Code: Link 1 & Link 2 (GitHub)
Tutorial: Documentation & Demos
NMMItools 