title: Image-guided and intensity-modulated radiosurgery for patients with spinal metastasis.
abstract: BACKGROUND
  Radiosurgery can deliver a single, large radiation dose to a localized tumor using a stereotactic approach and hence, requires accurate and precise delivery of radiation to the target. Of the extracranial organ targets, the spine is considered a suitable site for radiosurgery, because there is minimal or no breathing-related organ movement. The authors studied spinal radiosurgery in patients with spinal metastases to determine its accuracy and precision.
  
  
  METHODS
  The spinal radiosurgery program was based on an image-guided and intensity-modulated, shaped-beam radiosurgical unit. It is equipped with micromultileaf collimators for beam shaping and radiation intensity modulation and with a noninvasive, frameless positioning device that uses infrared, passive marker technology together with corroborative image fusion of the digitally reconstructed image from computed tomography (CT) simulation and orthogonal X-ray imagery at the treatment position. These images were compared with the port films that were taken at the time of treatment to determine the accuracy of the isocenter position. Clinical feasibility was tested in 10 patients who had spinal metastasis with or without spinal cord compression. The patients were treated with fractionated external beam radiotherapy followed by single-dose radiosurgery as a boost (6-8 grays) to the most involved portion of the spine or to the site of spinal cord compression.
  
  
  RESULTS
  The accuracy for the isocenter was within 1.36 mm +/- 0.11 mm, as measured by image fusion of the digitally reconstructed image from CT simulation and the port film. Clinically, the majority of patients had prompt pain relief within 2-4 weeks of treatment. Complete and partial recovery of motor function also was achieved in patients with spinal cord compression. The radiation dose to the spinal cord was minimal. The maximum dose of radiation to the anterior edge of the spinal cord within a transverse section, on average, was 50% of the prescribed dose. There was no acute radiation toxicity detected clinically during the mean follow-up of 6 months.
  
  
  CONCLUSIONS
  Image-guided, shaped-beam spinal radiosurgery is accurate and precise. Rapid clinical improvement of pain and neurologic function also may be achieved. The results indicate the potential of spinal radiosurgery in the treatment of patients with spinal metastasis, especially those with solitary sites of spine involvement, to increase the prospects of long-term palliation.
authors.affiliation: Department of Radiation Oncology, Henry Ford Hospital, Detroit, Michigan 48202, USA. sryu1@hfhs.org
authors.forename: Samuel
authors.initials: S
authors.lastname: Ryu
authors.forename: Fang
authors.initials: F
authors.lastname: Fang Yin
authors.forename: Jack
authors.initials: J
authors.lastname: Rock
authors.forename: Jingeng
authors.initials: J
authors.lastname: Zhu
authors.forename: Archie
authors.initials: A
authors.lastname: Chu
authors.forename: Eduard
authors.initials: E
authors.lastname: Kagan
authors.forename: Lisa
authors.initials: L
authors.lastname: Rogers
authors.forename: Munther
authors.initials: M
authors.lastname: Ajlouni
authors.forename: Mark
authors.initials: M
authors.lastname: Rosenblum
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Kim
mesh_terms: D005240:Feasibility Studies; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy; D016634:Radiosurgery / Q000379:methods*; D013125:Spinal Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery*; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome