Hello, I am currently working on a research project where we are essentially trying to create a mini CT scanner.  First we would like to do some simulations using IDL.  What we are trying to do is to rotate a user created 3D array containg at least one object, and then project through the volume onto a 2D image.  This process will be repeated for several different rotations.  Once we have a set of 2D images, we will then reconstruct them back into a 3D array, which should hopefully match our original array. We have started with project_vol, recon3, and xvolume functions, but we have not been able to completely understand the keywords associated with the functions.  Is there any better functions suited for this purpose?  If not, is there anyone who has looked at this sort of problem before and can advise us?  Thanks Fenner