title: Image-guided hypo-fractionated stereotactic radiosurgery to spinal lesions.
abstract: OBJECTIVE
  This article demonstrates the technical feasibility of noninvasive treatment of unresectable spinal vascular malformations and primary and metastatic spinal tumors by use of image-guided frameless stereotactic radiosurgery.
  
  
  METHODS
  Stereotactic radiosurgery delivers a high dose of radiation to a tumor volume or vascular malformation in a limited number of fractions and minimizes the dose to adjacent normal structures. Frameless image-guided radiosurgery was developed by coupling an orthogonal pair of x-ray cameras to a dynamically manipulated robot-mounted linear accelerator that guides the therapy beam to treatment sites within the spine or spinal cord, in an outpatient setting, and without the use of frame-based fixation. The system relies on skeletal landmarks or implanted fiducial markers to locate treatment targets. Sixteen patients with spinal lesions (hemangioblastomas, vascular malformations, metastatic carcinomas, schwannomas, a meningioma, and a chordoma) were treated with total treatment doses of 1100 to 2500 cGy in one to five fractions by use of image-guided frameless radiosurgery with the CyberKnife system (Accuray, Inc., Sunnyvale, CA). Thirteen radiosurgery plans were analyzed for compliance with conventional radiation therapy.
  
  
  RESULTS
  Tests demonstrated alignment of the treatment dose with the target volume within +/-1 mm by use of spine fiducials and the CyberKnife treatment planning system. Tumor patients with at least 6 months of follow-up have demonstrated no progression of disease. Radiographic follow-up is pending for the remaining patients. To date, no patients have experienced complications as a result of the procedure.
  
  
  CONCLUSIONS
  This experience demonstrates the feasibility of image-guided robotic radiosurgery for previously untreatable spinal lesions.
authors.affiliation: Department of Neurosurgery, Stanford University Medical Center, 300 Pasteur Drive, Stanford, CA 94304, USA. seoulman@stanford.edu
authors.forename: S I
authors.initials: SI
authors.lastname: Ryu
authors.forename: S D
authors.initials: SD
authors.lastname: Chang
authors.forename: D H
authors.initials: DH
authors.lastname: Kim
authors.forename: M J
authors.initials: MJ
authors.lastname: Murphy
authors.forename: Q T
authors.initials: QT
authors.lastname: Le
authors.forename: D P
authors.initials: DP
authors.lastname: Martin
authors.forename: J R
authors.initials: JR
authors.lastname: Adler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001165:Arteriovenous Malformations / Q000601:surgery*; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000295:instrumentation*; D012371:Robotics / Q000295:instrumentation*; D013116:Spinal Cord / Q000098:blood supply*; D013120:Spinal Cord Neoplasms / Q000556:secondary / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*; D016896:Treatment Outcome; D014584:User-Computer Interface