On November 25th, 1975, Robert S. Ledley was granted patent #3,922,522 for “diagnostic X-ray systems” known as the CAT-Scan. Dr. Ledley is best known for developing the first whole-body computerized tomography (CT or CAT) scanner in 1973, which revolutionized diagnostic medicine. Dr. Ledley’s first CT scanner [which he called the Automatic Computerized Transverse Axial, or ACTA, scanner is now owned by the Smithsonian Institution’s Museum of American History. Using his scanner, he was the first to perform three-dimensional reconstructions, the first to use CT in radiation therapy planning for cancer patients, and the creator of many other “firsts” in the application of CT in medicine. In 1990, Ledley was inducted into the National Inventors Hall of Fame. He was awarded the National Medal of Technology in 1997. He retired as president and research director of the NBRF in 2010.
