Guillem Pratx, PhD is an Associate Professor of Radiation Oncology and Medical Physics at Stanford University. Originally from France, he studied engineering at Ecole Centrale Paris, then went on to pursue a Ph.D. in Electrical Engineering from Stanford University, during which time he developed several innovative instruments and algorithms for in vivo cancer imaging. The Physical Oncology Laboratory, which he now leads, investigates how novel physical approaches can solve longstanding problems in oncology. For instance, they use single-cell radionuclide imaging to measure the uptake of clinical PET tracers in heterogeneous cell populations and thus derive a biological interpretation of PET scans that accounts for factors such as cell diversity, microenvironmental factors and cell metabolism. They are also working to develop methods capable of tracking cell migration in vivo at the whole body level. Finally, they are involved in research to elucidate the radiochemical underpinnings of ultra-high dose rate (FLASH) radiotherapy. Prof. Pratx was named a Damon Runyon Innovator and a Society of Nuclear Medicine Young Investigator. He has published over 90 papers and been principal investigator on grants from the NIH, DoD and CIRM.