In Memoriam: George S. Sgouros, PhD (1963–2026)

The Society of Nuclear Medicine and Molecular Imaging (SNMMI) mourns the passing of George S. Sgouros, PhD, an internationally recognized medical physicist whose work helped transform the field of radiopharmaceutical therapy. Dr. Sgouros died on June 25, 2026, surrounded by his family, after a long and courageous battle with glioblastoma.

Dr. Sgouros’s contributions reshaped how radionuclide therapies are developed and delivered, advancing a more precise and individualized approach to treating cancer. Over the course of his career, he became one of the world’s foremost authorities on dosimetry and a leading advocate for tailoring therapies to the specific needs of individual patients. His work played a central role in establishing the scientific foundations of modern radiopharmaceutical therapy and precision nuclear oncology, influencing clinical practice and improving outcomes for patients worldwide.

He earned his undergraduate degree in applied physics from Columbia University and his PhD degree from Weill Cornell Medical College. He completed a fellowship in medical physics at Memorial Sloan-Kettering Cancer Center, where he began work in internal radionuclide dosimetry that would define his career. He joined the Johns Hopkins faculty in 2003, where he rose to professor of radiology, oncology, and radiation oncology and later became director of the Radiological Physics Division in the Department of Radiology.

Dr. Sgouros’s work also helped pioneer targeted alpha-emitter therapy. His laboratory conducted foundational preclinical and modeling studies, and he provided physics and dosimetry support for the first FDA-approved human trial of this approach in the early 1990s. These efforts contributed to the development of a powerful new class of cancer therapies. In 2015, he authored the MIRD monograph on radiobiology and dosimetry for radiopharmaceutical therapy with alpha-particle emitters, reviewing pioneering research and establishing guidance for human dosimetry.

George S. Sgouros, PhD

A prolific scholar, Dr. Sgouros authored more than 200 peer-reviewed publications as well as numerous review articles, monographs, and book chapters. He contributed to key scientific and regulatory efforts, including committees and advisory groups associated with the International Commission on Radiation Units and Measurements, the National Council on Radiological Protection and Measurements, the National Institutes of Health, and the International Atomic Energy Agency.

His service to SNMMI spanned nearly three decades. He was an active member of the Medical Internal Radiation Dose (MIRD) Committee for more than 20 years and served as its chair for nearly a decade. More recently, he co-chaired the SNMMI Dosimetry Task Force, helping guide initiatives that advanced the understanding and application of radiopharmaceutical dosimetry.

His contributions were widely recognized. In 2026, he received the Loevinger-Berman Award for excellence in internal dosimetry. He was also honored with the SNMMI Paul C. Aebersold Award in 2024, the Presidential Distinguished Service Award in 2022, and the Saul Hertz, MD, Award in 2017. In 2023, he was named a Fellow of the American Association of Physicists in Medicine.

Throughout his career, Dr. Sgouros advanced the field through research, teaching, scientific presentations, and mentorship. His enthusiasm for science was contagious, and his commitment to improving the lives of patients remained at the center of everything he did.

SNMMI extends its sincere condolences to Dr. Sgouros’s family, friends, and colleagues. His loss is deeply felt across the nuclear medicine and molecular imaging community.

SNMMI is awaiting further details regarding memorial arrangements and will share them as they become available.