Robert S. Ledley June 28, 1926 - July 24, 2012 Inventor of First Full-Body Ct Scanner

Article excerpt

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 on 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 Mr. 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.

Mr. Ledley was an early advocate of computer-based medical diagnostics. In 1959, he published a paper in the journal Science titled "Reasoning Foundations of Medical Diagnosis." It had a 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 Mr. Ledley's.

Robert Steven Ledley was born on June 28, 1926, 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 University. Mr. Ledley 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.

After receiving his DDS from New York University in 1948, Mr. Ledley enrolled as a graduate student at Columbia to study physics. He received his master's degree in physics in 1950.

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, Mr. Ledley was in the Army Dental Corps, assigned to a research unit at Walter Reed Army Medical Center in Washington.

Mr. Ledley set out to optimize the fitting of dentures by determining the mean slope of each tooth relative to the surface of the piece of food being chewed. …