title: Frameless method of stereotaxic localization with DSA.
abstract: OBJECTIVE
  To improve a method of stereotaxic localization with digital subtraction angiography that does not require use of a localization frame fixed to the patient's skull during examination.
  
  
  METHODS
  An independent, low-cost, stereotaxic computing system was devised. Software programs used magnetic resonance images, computed tomographic scans, and digitized radiographs of plastic bone implants with head landmarks to establish reference trihedrons in each imaging system, transpose target coordinates from one system to another, adjust surgical instruments, help plan radiation surgery, and compute and display isodose curves.
  
  
  RESULTS
  The geometric distortions of the image intensifier 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 achieved for the three coordinates.
  
  
  CONCLUSIONS
  This frameless stereotaxic localization technique is highly accurate and reliable. The system allows maximum automation of examination procedures.
authors.affiliation: Biophysics Laboratory, Faculté de Médecine, Université de Lille II, France.
authors.forename: E
authors.initials: E
authors.lastname: Coste
authors.forename: J
authors.initials: J
authors.lastname: Rousseau
authors.forename: D
authors.initials: D
authors.lastname: Gibon
authors.forename: J F
authors.initials: JF
authors.lastname: Deleume
authors.forename: S
authors.initials: S
authors.lastname: Blond
authors.forename: X
authors.initials: X
authors.lastname: Marchandise
mesh_terms: D015901:Angiography, Digital Subtraction / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D002538:Intracranial Arteriovenous Malformations / Q000000981:diagnostic imaging / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008961:Models, Structural; D016634:Radiosurgery / Q000379:methods*; D013238:Stereotaxic Techniques / Q000295:instrumentation*; D014057:Tomography, X-Ray Computed