Affecting approximately 80,000 Canadians, Parkinson's disease is characterized by the lack of the neurotransmitter dopamine in the brain. Symptoms include progressive impairment of motor function and a significant impact on quality of life. Dr. Vesna Sossi is a medical physicist who brings her expertise in the physics of nuclear imaging to advance understanding of the pathogenesis, progression and specific manifestations of Parkinson's disease, as well as the biochemical results of therapeutic interventions. Currently, she is developing a new method for using Positron Emission Tomography (PET) to study the dopaminergic system (the brain's production and use of dopamine) at varying stages of the disease. PET is a non-invasive diagnostic imaging technique for measuring the metabolic activity of cells in the human body. In addition to providing information about disease progression, this work may provide important insights into how the brain compensates for decreased dopamine levels during early stages of Parkinson's.