PET and SPECT imaging for stereotactic localization

Stereotactic localization using PET and SPECT has been used together with the Leksell stereotactic frame and the other imaging tools routinely provided to Gamma Knife radiosurgery sites. The accuracy of the measurements has been confirmed with CT and MR using a Radiation Analog Dosimetry phantom. The activity of the radionuclide solution placed in the tubes of Elekta Radiosurgery's MR imaging box is somewhat critical because the window levels chosen for the scan will affect the apparent size of the lesion. A technique is presented to resolve areas of activity more than about 12-14 mm apart, and it may prove useful in targeting epileptogenic sites in patients with medically intractable epilepsy.