Professor George Sgouros, PhD

It is with great sadness that we inform you of the passing of Professor George Sgouros — a pioneer in the field of radiopharmaceutical therapy (RPT) physics and dosimetry, and one of the most consequential figures in modern nuclear medicine physics. George passed away on June 25, 2026, in the presence of his family, from the sequelae of recurrent glioblastoma.

Recently, George was honoured with the Society of Nuclear Medicine and Molecular Imaging (SNMMI) Loevenger-Berman Award, where his son Theodore accepted the award on his behalf and spoke eloquently of George's two passions: his family and his research.

Both of these aspects of his life began at Columbia University, where George earned his undergraduate degree in applied physics — and where he also met his wife, Shirley. He later obtained his PhD from Weill Cornell Medical College and performed a fellowship in medical physics at Memorial Sloan-Kettering Cancer Center in New York. In 2003, the Sgouros family moved to Baltimore, where George joined the Johns Hopkins Medical Institute, founded and led the Radiopharmaceutical Therapy and Dosimetry (RTD) laboratory, and earned the titles of Professor and Chair of the Radiological Physics Division of the Department of Radiology.

George's research career was defined by an unshakeable belief in the potential of radiopharmaceutical therapy and in the use of patient-specific dosimetry to optimise clinical outcomes — a conviction that, for much of his career, placed him ahead of the field. He developed the first three-dimensional internal dosimetry software package, 3D-ID (later known as 3D-RD), which became a template for numerous subsequent internal dosimetry platforms and laid the conceptual groundwork for the dosimetry-guided RPT paradigm now embraced globally.

His particular expertise and passion lay in alpha-particle therapy and dosimetry. Over the course of his career, he became one of the world's leading advocates and recognised authorities in this domain. His advice and expertise were consistently sought by international scientific and regulatory bodies, including the International Atomic Energy Agency (IAEA), the International Commission on Radiation Units and Measurements (ICRU), and the National Institutes of Health (NIH). He himself initiated several landmark educational and scientific ventures where he saw unaddressed needs: the MIRD Primer 2022, the MIRD Alpha Monograph, and the creation of the Radiopharmaceutical Therapy Normal Tissue Effects in the Clinic (RPT-TEC) group.

His prominence in the field was further recognised by additional major honours from the SNMMI: the Saul Hertz Award, the Presidential Distinguished Service Award, and the Paul C. Aebersold Award. He also served as President of the Medical Internal Radiation Dose (MIRD) Committee for more than ten years — half of his twenty-plus years as a member.

George also founded a Master's degree programme in radiopharmaceutical physics at Johns Hopkins — the only such programme in Maryland — reflecting his deep commitment to training the next generation of specialists in this rapidly growing field. His influence on the field extends far beyond his publications and inventions; it lives in the students, post-doctoral fellows, and mentees he trained, many of whom now lead the field themselves.

He is survived by his wife Shirley and their children Theodore, Helen, and Marie. May his soul rest in peace.