Stereotactic radiosurgery is used for highly focused radiation treatment of relatively small intracranial targets. Extracranial treatment systems are currently in development and used at a few centers. Approaches are image-based or image-guided, using CT and/or MR anatomical imaging. Biological imaging may provide non-invasive detection of the biological character and spatial extent of intracranial and extracranial targets. Potential uses of biological imaging in stereotactic radiosurgery include target delineation and normal tissue identification. These aspects are reviewed to explore the potential uses and impact these images may have on radiosurgery treatment.

Key words: biological imaging, molecular imaging, functional imaging, radiosurgery, radiation treatment.