FRAMELESS METHOD OF STEREOTAXIC LOCALIZATION WITH DSA

PURPOSE: To improve a method of stereotaxic localization with digital subtraction angiography that does not require use of a localization fr ame fixed to the patient's skull during examination. MATERIALS AND MET HODS: An independent, low-cost, stereotaxic computing system was devis ed. Software programs used magnetic resonance images, computed tomogra phic scans, and digitized radiographs of plastic bone implants with he ad landmarks to establish reference trihedrons in each imaging system, transpose target coordinates from one system to another, adjust surgi cal instruments, help plan radiation surgery, and compute and display isodose curves. RESULTS: The geometric distortions of the image intens ifier were corrected. Distortion problems of the conic projection were solved, and three-dimensional localization was achieved with only two associated front and lateral views. Accuracy to within 1 mm was achie ved for the three coordinates. CONCLUSION: This frameless stereotaxic localization technique is highly accurate and reliable. The system all ows maximum automation of examination procedures.