Here is an overview of PET (polarized emission tomography), a brain scanning technique. The web page offers a description of how PET scans are conducted and an example of the kind of image they can produce. The science behind PET's ability to document levels of brain activity is also briefly addressed. As part of a set of materials about brain scanning technologies, this overview also points out how PET differs from earlier types of brain scans. Copyright 2005 Eisenhower National Clearinghouse