Gerd Muehllehner, former professor of radiologic physics in radiology at the University of Pennsylvania’s Perelman School of Medicine, died at his farm in Baraboo Hills, Wisconsin, in late June, a few days after his 81st birthday.

Dr. Muehllehner was born in Germany and educated in Jesuit boarding schools, Georgetown University and the University of Michigan, where he graduated in 1966 with a PhD in nuclear physics. He came to Penn in 1979 as a lecturer in the department of radiology. He went on to become a research associate professor in the same department while also serving as an associate professor in neurology. In 1981 he became an associate professor of radiologic physics. He earned tenure in 1983, and then became a full professor in 1988. He used his time at Penn to create, together with his team, the modern generation of Positron Emission Tomography (PET) imaging devices. Following his ten years on the faculty at Penn, he and his wife, Ursula (WEV’87), started UGM Medical Systems to commercialize PET technology developed at Penn. He remained an adjunct professor at Penn until 2011.

Dr. Muehllehner, along with his wife and friends, established the Gerd Muehllehner Professorship of Radiology at Penn. The Professorship was originally begun as a PET research fund. To broaden the application of the fund, it was converted into the Professorship, which was supported with additional funding from Joel and Janet J. Karp.

When Dr. Muehllehner retired to his farm, he became involved in solar energy generation, conservation and restoration of the environment, and he became an ardent supporter of Planned Parenthood, The International Crane Foundation and The Nature Conservancy.

He is survived by his wife, Ursula; and children and grandchildren, Donya, Tessa, Nancy Muehllehner and their families.