Dr. Robert Ledley, 86, inventor of modern CT scanning

July 27, 2012 by  
Filed under Every thing you Need to Know

NEW YORK — Robert S. Ledley, a dentist turned biomedical researcher and computing trailblazer who invented the first CT scanner capable of producing cross-sectional images of any part of the ­human body, died Tuesday in Kensington, Md. He was 86.

The cause was Alzheimer’s disease, his son Fred said.

Nearly every field of medicine has been affected by the whole-body CT scanner, short for computerized tomography. ‘‘Many of the CT scanners we see in hospitals are based on the Ledley design,’’ said Joseph A. November, a professor of history at the University of South Carolina, who is writing a biography of Dr. Ledley.

Before the advent of CT scanning in the early 1970s, radiologists had limited tools. CT scanning gave them not only a far higher resolution than traditional X-rays, but also three-dimensional, cross-sectional images to work with, significantly reducing the need for exploratory surgery and its attendant risks. it also changed the way physicians follow cancers and their response to therapy.

Dr. Ledley was an early advocate of computer-based medical diagnostics, a half-century before medical residents began punching patients’ symptoms into online programs.

In 1959, he published a ­paper in the journal Science, ‘‘Reasoning Foundations of Medical Diagnosis.’’ it had broad impact in the medical field.

‘‘in the summer before I started medical school, I read that paper, and it was eye-opening,’’ said Dr. Alan N. Schechter, chief of the molecular medicine branch at the National Institutes of Health and a longtime colleague of Dr. Ledley’s. ‘‘The idea that computers could assist physicians in diagnosis and choice of therapy was a totally new understanding of the process of medical diagnosis.’’

Robert Steven Ledley was born in Flushing, Queens, N.Y. His father, Joseph, was an accountant; his mother, Kate, was a teacher. He attended the Horace Mann School and studied physics at Columbia. He hoped to pursue a career in physics, but his parents, worried about the scarcity of jobs in the field, urged him to become a dentist.

‘’His family said he could study physics as long as he also became a licensed dentist, so he could ­always make a living doing dentistry,’’ November said.

After receiving his DDS from new York University in 1948, Dr. Ledley enrolled as a graduate student at Columbia to study physics. He received his master’s degree in physics in 1950. His professors ­included Nobel Prize winners Enrico Fermi, Hans Bethe, and I.I. Rabi. ‘‘Rabi joked that Ledley was the only physicist who could pull a man’s tooth,’’ November said.

The year before, he had married Terry Wachtell, a music major at Queens College. At his urging, she switched to math, earned a master’s degree in the subject, and became a mathematics teacher.

In 1951, during the Korean War, Dr. Ledley was in the US Army Dental Corps, assigned to a research unit at Walter Reed Army Medical Center in Washington, where he worked on improving prosthetic dental devices.

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