A scaled head frame positioner and tabletop adapter are provided. The positioner may be employed for any neurosurgical procedure that requires fixed positioning of the stereotactic head frame or ring onto a patients skull. The positioner employs a generally triangular shaped member with Velcro tapes fixed at each corner. The tapes have measurement markings, such as measurement tapes. The positioner supports the head frame with the tapes engaging means on the frame and fastened back to themselves, with markings indicating distances to adjust the position of the frame about the patients head. Furthermore, the tabletop adapter clamps the patient with a stereotactic head frame onto a CT or treatment table. The tabletop adapter includes a generally U-shaped bracket secured to a support to be placed on the tabletop. The bracket is attachable to the head frame of the patient to hold his head in a desired position.