StevenRainwater: Don't bother trying to scan CT tranparencies, it is very difficult without a backlit scanner. You are better off calling the medical imaging lab and asking for them on CD-R. A while ago I got a CD-R of my MRI images (my brain on a CD, cool!). Be prepared to deal with funky medical imaging formats, but you are most likely to get DICOM. DICOM can be converted to PNM using the GPL'd DICOM Toolkit. You'll also be able to dump out the slice coordinates and lots more information.