Abstract: Stereotaxic Arc Systems are common instruments in neurosurgery for accurately directing a probe into the head and brain. Among the many types of arc concepts for such instruments is the target-centered arc. This involves an arc system which provides spherical radii from a multiplicity of directions depending on the rotation angles of the arc. All of the radii converge to the target point, thus the name target-centered arc. Prior to this invention, all such systems with two trunion bearings have an axis of arc rotation which has a fixed orientation relative to the patient's head. This causes a limitation in directions of approaches to desired targets. The present invention involves a new concept of target-centered arc, in which the access of rotation of the two trunions and their connected arc itself can be varied in orientation, leading to an unprecedented wide range of approaches to any anatomical target and great versatility of the arc system in surgery.

Abstract: The method and apparatus are presented which allow for CT guided biopsies of the body. The method is based on the finding of a reference point on the patient's body that exactly correlates to a point on the CT scan. This is accomplished by means of a localization device placed on the patient's skin which can be identified in cross section on the CT scan. Measurements of the localization device on CT scan can then be correlated to the device on the patient.