David Kirsch, MD, PhD, is the Peter and Shelagh Godsoe Chair in Radiation Medicine, Head of the Radiation Medicine Program, and Head of the Department of Radiation Oncology at the Princess Margaret Cancer Centre, University Health Network.  He is also a Professor in the Departments of Radiation Oncology and Medical Biophysics at the University of Toronto.  Dr. Kirsch is an expert in the use of radiation therapy to care for patients with bone and soft tissue sarcomas. As a Senior Scientist at Princess Margaret Cancer Centre, he leads a research lab utilizing sophisticated genetically engineered mouse models and human cancer cell lines to study mechanisms of tumor development and the response of cancer and normal tissues to radiation.