Robert Lange, a former associate clinical professor of diagnostic radiology for Yale’s Department of Diagnostic Radiology and a clinical technical director of the Magnetic Resonance Imaging Research Center, died Oct. 6 in New Haven. He was 69 years old.

Lange’s career at Yale spanned 30 years, during which he chaired the radiation safety committee and the radioactive drug research committee for Yale-New Haven Hospital, and one of the two human investigation committees at the Yale School of Medicine. He also taught the physics of diagnostic radiology and imaging to residents, faculty, and staff. He retired in 2000.

“Bob was a patient and caring teacher and scientist, as well as a wonderful friend to us all,” Medical School Dean Robert Alpern said in a notice to faculty and staff. “Even in retirement, he continued to be an incredibly valuable resource for the Department of Diagnostic Radiology, the Human Investigation Committee, and the Medical School as a whole.”

Lange served as a senior research chemist at the Monsanto Research Corporation in Ohio before coming to Yale in 1969. Lange enjoyed recounting the circumstances that led him to Yale, his wife BJ Lambert said. As the story goes, Lange found a small ad in a science journal to work in a “major Eastern university hospital.” Lange applied for the job unwittingly, not knowing that the university described was Yale.

Diagnostic Radiology professor Vicente Caride said he knew Lange when he first arrived at Yale and worked with him throughout his career at the University.

“He was the first friend I had when I came to the University,” Caride said. “He was a beautiful human being and a bright teacher.”

Coralie Shaw, who worked with Lange in her capacity as the director of the residency training diagnostic technology program at Yale, called Lange one of her heroes at the University.

“He was a man of great character, enormous intellect,” she said. “I admired him tremendously.”

Shaw said Lange’s abilities as a teacher were crucial to the success of her program’s residents, who enrolled in it to pass the American Board of Radiology certification exam.

“He was a superb teacher, able to teach the extremely complicated physics of radiology to people who did not share his background in physics,” Shaw said. “Our board pass rate has been phenomenally successful over the decades.”

Lange was so dedicated to the residents that even after his retirement he continued to instruct them, Shaw said.

Diagnostic radiology and orthopedics professor Lee Katz, who enrolled in Lange’s physics class, praised Lange’s teaching abilities.

“He’s the ultimate teacher,” Katz said. “Everyone owes him an inordinate amount of gratitude for teaching them physics.”

Lange, who considered himself a “Boston boy,” was raised in Massachusetts and attended Northeastern University and MIT. His wife said when she met Lange in 1979, she was struck by his humility.

“He was very bright, well-read but down to earth,” she said. “He had a gentle way about him.”

Lange earned a reputation as a great athlete among his colleagues. He was known for organizing squash tournaments with fellow faculty members and was also an avid downhill skier and sailor, Lambert said.

A memorial service for Lange will be held Nov. 5 at Yale’s Cushing Whitney Medical Library.