1. A method of determining a position of a deep brain stimulation (DBS) electrode, the method locating the position of said DBS electrode with respect to a targeted region in a deep brain of a living subject, by using a first volume data set including information on said targeted region and a second volume data set including information on said DBS electrode implanted toward said targeted region, the method comprising the steps of: generating a subvolume of said targeted region from said first volume data set, and also generating a subvolume of said DBS electrode from said second volume data set; overlapping and displaying said subvolume of said targeted region and said subvolume of said DBS electrode to determine said position of said DBS electrode with respect to said targeted region, with said first volume data set and said second volume data set aligned; and determining the position of the DBS electrode with respect to said target region from viewing the overlapping of the subvolumes of said targeted region and said DBS electrode, wherein said first volume data set is acquired before the implantation of said DBS electrode, and said second volume data set is acquired after the implantation of said DBS electrode and, wherein said first volume data set is an MRI image and said second volume data set is a CT image.