Bruce Faddegon

Bruce Faddegon, PhD is a Professor in the Department of Radiation Oncology at the University of California, San Francisco (UCSF) School of Medicine. A board-certified clinical medical physicist, Dr. Faddegon is internationally recognized for his pioneering work in developing and applying Monte Carlo methods for treatment head simulation and dose calculation in radiotherapy. His research focuses on improving the accuracy and precision of radiation therapy through innovative computational approaches, with the overarching goal of enabling more aggressive cancer treatments while minimizing side effects.

Dr. Faddegon earned his B.Sc. in Physics (honors) from the University of Victoria in 1977, followed by an M.Sc. in Physics (radiobiology) from the University of British Columbia in 1983, and completed his Ph.D. in Physics (radiotherapy) from Carleton University in 1990. His educational background provided the foundation for his subsequent contributions to medical physics and radiation oncology.

Dr. Faddegon's research program centers on the development and application of Monte Carlo simulation techniques to advance radiation therapy. His primary focus is on the Tool for Particle Simulation (TOPAS), an open-source platform built on Geant4 that he co-developed. TOPAS has evolved from its initial application in proton therapy to encompass conventional radiotherapy, imaging, and radiobiology through extensions like TOPAS-nBio. His work addresses critical challenges including dose calculation accuracy, radiobiological modeling, and the development of cost-effective solutions to improve the therapeutic ratio in cancer treatment. Dr. Faddegon's research bridges physics, biology, and clinical applications, with particular emphasis on establishing the relationship between ionization deposition details, radiation chemistry, and biological effects.

Analysis of Dr. Faddegon's most recent publications (2023-2025) reveals a strong focus on advancing Monte Carlo simulation capabilities for radiation therapy applications. His work spans from fundamental physics (track structure simulations, nanodosimetry) to clinical applications (treatment planning, secondary cancer risk assessment). A notable trend is the expansion of TOPAS capabilities into radiobiological modeling through TOPAS-nBio, which enables researchers to connect physical dose deposition with biological outcomes. His publications demonstrate increasing interdisciplinary collaboration, bridging physics, biology, and clinical oncology to address complex challenges in radiation therapy, with particular attention to improving precision in particle therapy and conventional radiotherapy.

Dr. Faddegon has secured substantial research funding as Principal Investigator on multiple NIH grants, including the current U24 grant from the NCI Informatics Technology for Cancer Research program to extend TOPAS to conventional radiotherapy and imaging. His previous NIH funding includes R01 grants focused on proton therapy and radiation biology. These grants support his team's work in developing and validating Monte Carlo simulation tools that have become widely adopted in the medical physics community for applications ranging from treatment planning system validation to fundamental radiobiological research.

Dr. Faddegon leads a research group focused on computational medical physics at UCSF that collaborates extensively with researchers at Massachusetts General Hospital, SLAC National Accelerator Laboratory, and other institutions worldwide. His team works on multiple aspects of the TOPAS simulation toolkit, including its application to clinical radiotherapy, radiobiological modeling, and medical imaging. Their work has established TOPAS as a standard tool in the field, with applications ranging from treatment planning system validation to fundamental radiobiological research, significantly advancing the precision and effectiveness of radiation therapy.