Massachusetts Institute of Technology
Mit: Invention of the Week: Albert Macovski: Medical Imaging Systems
Learn about the work done by Albert Macovski, which included the development of digital radiography, ultrasound, and magnetic resonance imaging (MRI), and learn how these inventions impact the medical world.
University of Colorado
University of Colorado: Physics 2000: Cat Scans
This highly interactive animated site does a thorough job describing CAT scans. You can even produce your own CAT scan with one of the simulations.