INTERACTIVE INTRAOPERATIVE LOCALIZATION USING AN INFRARED-BASED SYSTEM

We discuss new methods of localizing and treating brain lesions for bo th the conventional method of a base-ring fixed to the patient's skull (referred to as frame-based procedures) and the new method of framele ss procedures (no base ring). Frame-based procedures are used for find ing a precise instrument position during neurosurgical procedures, suc h as stereotactic biopsy of deep-seated lesions, placing electrodes fo r functional stereotaxis or catheters with radioactive seeds for brach ytherapy, or even the placement of a stereotactic retractor or endosco pe for removal or internal decompression of lesions. In such procedure s, the intraoperative image localization of instruments becomes useful as it tracks instruments as they travel through the preplanned trajec tory. Additional intraoperative digitization of surgical instruments, e.g, bipolar suction, biopsy forceps, microscope, ultrasound probe, et c, can be achieved during the stereotactic resection of eloquent areas or deep intracranial lesions by adding an infrared-based system. Fram eless procedures broaden the range of surgical approaches, image guida nce planning, and operative procedures, since no ring is attached to t he patient's head which might interfere with the surgical approach, an d offers logistic advantages in scheduling diagnostic studies. Framele ss diagnostic studies employ anatomical markers and/or surface matchin g techniques for data registration in the computer software surgical p replanning program. This simplifies scheduling of the procedures since the image study does not need to be acquired the same day as surgery. Frameless diagnostic studies allow for the use of more than one type of imaging data for planning and optimization of surgical procedures, and greatly improve patient tolerance and comfort during these procedu res and during surgery, as compared with frame-based procedures. The i nfrared digitizer can be used in frameless neurosurgical procedures fo r intraoperative instrument tracking as it is in frame-based neurosurg ery. It tracks almost any component of the surgical armamentarium such as suction, bipolar, biopsy forceps, surgical microscope, the ultraso und probe, even the patient and the surgeon.