Medical images hold a wealth of information, much of it invisible to the naked eye. Dr. Rebecca Thornhill (Medicine/OHRI), a medical imaging physicist, collaborates with radiologists and cardiologists to deliver safe, high-quality cardiac MRI while pushing the boundaries of what these images can reveal. Her research focuses on radiomics—quantitative features extracted from images—and how these features can feed AI models to detect disease or tissue states. As models grow increasingly powerful, her team is developing explainable AI tools to make complex decisions interpretable for clinicians and patients alike, ensuring that cutting-edge technology can be trusted and effectively integrated into clinical care.
An unconventional path to imaging physics
Dr. Thornhill’s route into imaging physics was far from typical. With an undergraduate degree in biomedical sciences, she never imagined her love of mathematics could be applied to medicine—until her honours project at Guelph, analyzing heart-rate variability in horses. That first encounter with Fourier theory and digital signal processing sparked a fascination that led her to graduate studies in medical biophysics and cardiac MRI. Over nearly three decades, her focus shifted from producing beautiful images of the beating heart to extracting meaningful diagnostic information, inspiring work in radiomics and explainable AI—a space where she draws on insights from psychology, management studies, and human factors. She says she remains perpetually humbled by how much there is still to learn and how much collaboration shapes discovery.