A Graphic Method for Estimating Equivalent Dipole of Localized EEG Discharge

Location, orientation, and magnitude of a dipole in spherical conducting media are estimated by using a nomograph. No iterative numerical process on a computer is necessary for each dipole estimation. The estimation method was applied to computer generated dipoles. The difference between true and estimated locations was within 0.8 percent of the sphere radius, and the difference between true and estimated moments was within 3.3 percent of true dipole magnitude. It was also applied to pathological discharges from three patients. Estimated locations nearly agreed with abnormal regions observed in CT images.