title: Image-guided radiosurgery in the treatment of spinal metastases.
abstract: OBJECTIVE
  The authors describe a new method for treating metastatic spinal tumors in which noninvasive, image-guided, frameless stereotactic radiosurgery is performed. Stereotactic radiosurgery delivers a high dose of radiation in a single or limited number of fractions to a lesion while maintaining delivery of a low dose to adjacent normal structures.
  
  
  METHODS
  Image-guided radiosurgery was developed by coupling an orthogonal pair of real-time x-ray cameras to a dynamically manipulated robot-mounted linear accelerator that guides the radiation beam to treatment sites associated with radiographic landmarks. This procedure can be conducted in an outpatient setting without the use of framebased skeletal fixation. The system relies on skeletal landmarks or implanted fiducial markers to locate treatment targets. Four patients with spinal metastases underwent radiosurgery with total prescription doses of 1000 to 1600 cGy in one or two fractions. Alignment of the treatment dose with the target volume was accurate to within 1.5 mm. During the course of each treatment fraction, patient movement was less than 0.5 mm on average. Dosimetry was highly conformal, with a demonstrated ability to deliver 1600 cGy to the perimeter of an irregular target volume while keeping exposure to the cord itself below 800 cGy.
  
  
  CONCLUSIONS
  These experiences indicate that frameless radiosurgery is a viable therapeutic option for metastatic spine disease.
authors.affiliation: Department of Neurosurgery, Stanford University School of Medicine, Stanford, California 94305, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Murphy
authors.forename: S
authors.initials: S
authors.lastname: Chang
authors.forename: I
authors.initials: I
authors.lastname: Gibbs
authors.forename: Q T
authors.initials: QT
authors.lastname: Le
authors.forename: D
authors.initials: D
authors.lastname: Martin
authors.forename: D
authors.initials: D
authors.lastname: Kim
mesh_terms: D000368:Aged; D000556:Ambulatory Surgical Procedures; D001943:Breast Neoplasms / Q000473:pathology; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery; D003199:Computer Systems; D019583:Dose Fractionation, Radiation; D004938:Esophageal Neoplasms / Q000473:pathology; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology; D008297:Male; D008545:Melanoma / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery; D008875:Middle Aged; D010315:Particle Accelerators; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D012371:Robotics; D013125:Spinal Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary* / Q000601:surgery*; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed