This directory has filter-backproject (FBP) routines for image reconstruction. Run fbp2_example.m or fbp_fan_arc_example.m to see a complete example. For the notation, see this book chapter: http://dx.doi.org/10.1016/B978-0-444-53632-7.00212-4 If you can't access it, email me. It is also in a book chapter hidden on my web site - ask me.