Pylimitics

"Simplicity" rearranged


Robert Ledley

Good morning! Computers are now an inextricable part of medicine. It wasn’t always that way, though. One of the leaders in using computers in medicine and biomedical research was Robert Ledley who was born June 28 in New York City. You may have heard of him; he was “the only physicist who could pull your tooth.” 

Ledley was born into a typical middle-class family; his father was an accountant and his mother had been a schoolteacher. He graduated high school in 1943 and enrolled in Columbia University, where he majored in physics. He was taking graduate courses by his second year, and told his parents he wanted to become a physicist. His parents, though, reacted in horror, picturing an unemployable son because they didn’t see many jobs calling for a physicist. They urged him to go into dentistry instead. 

Ledley was a dutiful son, so he enrolled in the New York University College of Dentistry. But he didn’t give up on physics. He studied dentistry during the day, then took the subway to Columbia and study physics in the evening. He graduated from the College of Dentistry in 1948, but instead of opening a practice he became a full-time graduate student in physics at Columbia. He studied with Enrico Fermi and Hans Bethe, and earned an MS degree in 1950. The joke about him being the only physicist who could pull your tooth came from I. I. Rabi, another Nobel Prize-winning physicist Ledley studied with. 

In 1950 the Korean War intervened; Ledley was given the choice of joining the US Army Dental Corps or being drafted as an infantry private. He took the dental option, and was assigned to do dental research at Walter Reed Hospital in Washington, D.C. He used his physics training to optimize the way dentists fit dentures to mouths — his project caught some popular attention in 1952 when the Associated Press wrote a story printed in newspapers nationwide: Mathematics Used to Keep False Teeth in Place.

Ledley was discharged from the Army in 1952 and got another research job, this time at the Bureau of Standards Dental Materials Research Section (bet you never heard of that before). And that’s where computers intervened; the Bureau of Standards had an early electronic digital computer called SEAC (the Standards Eastern Automatic Computer). Luckily for Ledley, his wife was one of the programmers for SEAC, and she helped Ledley learn programming. Operating SEAC was an important moment for Ledley; he later said “I had previously realized that although, conceptually, physics equations could be written to describe any biomedical phenomenon, such equations would be so complex that they could not feasibly be solved in closed form. Thus SEAC would be my panacea, because the equations would become tractable to numerical methods of solutions. Or so I truly believed at the time. That was to be my field, application of computers to biomedical problems.”

In 1954, thanks to another of the constant changes in US politics, the budget for the National Bureau of Standards was cut and Ledley and many of his colleagues lost their jobs. IBM offered to hire all of them on the spot, but Ledley demurred and instead went to Johns Hopkins University where he was an “Operations Research Analyst.” One of his colleagues was George Gamow, a theoretical physicist. Gamow was captivated by the possibilities that opened up when the double helix structure of DNA had been discovered the previous year, and offered Ledley the chance to work with him on studying how a DNA sequence translates into proteins. This amounted to an invitation to join the RNA Tie Club, an informal club of elite scientists interested in DNA and RNA. Other members, besides Gamow, included Richard Feynman and Edward Teller. 

Ledley developed a way to write a computer program that could (theoretically) determine the correspondence between any triplet of nucleotide bases and any amino acid. he published the work in 1955, but also worked out that actually running his program, at least on 1955-era computers, would require several thousand years. After that he drifted away from the RNA Tie Club and became a professor of electrical engineering at George Washington University. He developed and taught some of the earliest computer programming courses, and wrote his first book, Digital Computer and Control Engineering. He also tried to talk the school into acquiring two electronic computers, Florida Automatic Computer I and II. The computers at the time were cheap because they were military surplus, having been discarded by the Air Force. But the school was wary of the expense and effort involved in installing and supporting two whole computers — in the 1950s the things required their own buildings. So Ledley’s “computer center” was never built. This put Ledley into a bit of a bind, since without telling the school, he’d already purchased the surplus computers! He never actually took delivery, though. They wouldn’t fit in his garage. 

In 1956 Ledley really began to work toward his dream of integrating computing with medicine, and collaborated extensively with Lee Lusted, a radiologist who shared Ledley’s vision. In 1959 they published Reasoning Foundations of Medical Diagnosis in Science magazine, and the article became enormously popular. It remained influential in the field for several decades, and brought Ledley and Lusted into the public sphere. They were profiled in national magazines and newspapers. But no matter how hard they tried to explain to reporters that their idea was that computers could help doctors and researchers, most of the stories were about computers replacing doctors instead. Dr. Univac Wanted in Surgery was a New York Post headline, and A Metal Brain for Diagnosis was featured in the New York World Telegram

Ledley went on to found the National Biomedical Research Foundation in 1960, which he led until he retired in 2010. The NBRF pioneered optical pattern recognition and digitization systems, both of which became widely adopted. They also developed the Film Input to Digital Automatic Computer (FIDAC) in the mid-1960s and sold a number of the systems to medical research facilities. Ledley also founded the journal Pattern Recognition and was the editor until 2010. 

In the 1970s Ledley was the leader in developing CAT scanners, the work he’s most remembered for. NBRF built the first prototype of a modern CAT scanner after researchers at Georgetown University complained about the price of a scanning machine from the EMI company. Ledley said NBRF could make a better system for half the cost. In just a year, NBRF delivered a full-body scanner (the EMI device could only scan your head) that was faster, less expensive, and scanned at higher resolution. Just after delivery, a neurosurgeon used the NBRF scanner to save the life of a child who’d received a head injury in a bike accident. Ledley wasn’t told about the neurosurgeon’s use, but the dramatic story put him in the national news again. The original prototype scanner is now on display in the Smithsonian. 

Ledley accomplished a lot more in biomedical computing, especially in imaging systems, and had dozens of publications and awards, but this is getting pretty long. He passed away in 2012 at 86, but should be remembered any time a patient needs a CAT scan.



About Me

I’m Pete Harbeson, a writer located near Boston, Massachusetts. In addition to writing my own content, I’ve learned to translate for my loquacious and opinionated pup Chocolate. I shouldn’t be surprised, but she mostly speaks in doggerel. You can find her contributions tagged with Chocolatiana.