In the treatment of neurosurgical disease, we should have much detail information about neurological micro-anatomy. Additionally, Gamma knife surgery, which can provide intracranial lesions to cure or control without any craniotomy, also needs for precisely neurological imaging on MRI/CT. Particularly, '3D Image' is able to make detail neurological knowledge to us quickly. We usually use special software, which was dedicated for Gamma knife, 'Gamma Plan(ELEKTA Instrument AB) 'to easily make dose planning for '3D Image' in not only brain tumors, vascular malformations, in but also functional disease such as intractable pain, epilepsy, and movement disorders. In this article, our purpose is to show each case illustration to demonstrate why '3D Image' is very useful in Gamma knife surgery.