1. A method of preplanning for guided medical procedures, comprising the steps of: obtaining a first 3D diagnostic dataset for a region of interest of a subject, said first dataset being a non-stereotactic dataset, said first dataset providing sufficient contrast to identify target tissue in said region of interest; developing a treatment preplan to treat or remove said target tissue based on said first dataset exclusive of any stereotactic data, said treatment preplan including placement locations for a plurality of initial radiation beams and their respective dose intensities; obtaining a second 3D dataset for said region of interest, said second dataset being a stereotactic dataset; registering said first dataset to said second dataset, wherein a registered dataset is created, and modifying said treatment preplan using data associated with said registering step to generate a stereotactic treatment plan comprising a plurality of radiation treatment beams having respective placement positions based on said registered dataset to treat or remove said target tissue.