David A. Jaffray

David A. Jaffray is a Professor and Senior Scientist at Princess Margaret Cancer Centre and the University of Toronto, where he has spent his career as one of the world's foremost medical physicists in radiation oncology technology development. He is most widely recognized as the inventor and developer of kilovoltage cone-beam CT (CBCT) integrated with linear accelerators—a technology that revolutionized image-guided radiation therapy (IGRT) by enabling daily three-dimensional imaging of patient anatomy immediately before and after treatment delivery. The CBCT-on-linac system is now standard equipment on virtually every modern radiotherapy linear accelerator worldwide, directly enabling the geometric precision required for IMRT, SBRT, and stereotactic radiosurgery. Jaffray's research program at Princess Margaret has extended from CBCT development into a comprehensive program in adaptive radiotherapy, in which treatment plans are systematically modified throughout the treatment course in response to daily imaging evidence of anatomical change, tumor shrinkage, or organ motion. He was a founding scientific contributor to the MRI-linac concept, helping to establish the physical and engineering feasibility of integrating magnetic resonance imaging with therapeutic radiation delivery to achieve real-time soft-tissue image guidance. This vision has now materialized commercially in systems such as the ViewRay MRIdian and the Elekta Unity MR-linac, which are transforming adaptive radiotherapy in clinics worldwide. Beyond technology development, Jaffray has been a visionary leader in digital health and data science as applied to radiation oncology, advocating for the use of large electronic health record datasets, imaging repositories, and machine learning to optimize treatment quality and patient outcomes at the population level. He served as Chief Technology Officer of University Health Network, one of Canada's largest academic health systems, where he built cross-disciplinary programs linking radiation therapy innovation with biomedical engineering, data science, and digital pathology. He is a Fellow of both the Canadian College of Physicists in Medicine and ASTRO, and has received the ASTRO Science Council Award and numerous international prizes for medical physics innovation.