title: Frameless image-guided intracranial stereotactic radiosurgery: clinical outcomes for brain metastases.
abstract: OBJECTIVE
  After preclinical investigations confirming the accuracy of target localization by frameless image-guided radiosurgery, we report the clinical outcomes of patients with brain metastases who underwent frameless radiosurgery.
  
  
  METHODS
  Between 2005 and 2006, 53 patients underwent frameless stereotactic radiosurgery using a linear accelerator equipped with on-board image guidance for the treatment of 158 brain metastases. The radiation doses were delivered in a single fraction (dose range, 12-22 Gy; median, 18). Patients were followed with magnetic resonance imaging scans at 2-3-month intervals. Progression-free survival was the primary study endpoint.
  
  
  RESULTS
  With a median follow-up of 38 weeks (range, 14-112), the overall survival rate was 70% at 6 months, 44% at 1 year, 29% at 18 months, and 16% at 24 months. Local control was achieved in 90% of 168 treated lesions at 6 months, 80% at 12 months, 78% at 18 months, and 78% at 24 months. Local control tended to be improved in lesions treated with >or=18 Gy and for lesions <0.2 cm(3). Adverse events occurred in 5 patients (9.6%). No evidence of imaging changes on post-stereotactic radiosurgery scans was found to suggest mistargeting of a radiation isocenter.
  
  
  CONCLUSIONS
  The clinical outcomes after frameless stereotactic radiosurgery were comparable to those after frame-based radiosurgery techniques. Given its significant advantages in terms of patient comfort, ability to use fractionated treatment regimens, and convenience in scheduling of personnel and equipment resources, frameless radiosurgery will likely become a common technique for intracranial radiosurgery.
authors.affiliation: Department of Radiation Oncology, Brain Tumor Center at the University of Cincinnati Neuroscience Institute, Cincinnati, OH, USA. brenemjc@healthall.com
authors.forename: John C
authors.initials: JC
authors.lastname: Breneman
authors.forename: Ryan
authors.initials: R
authors.lastname: Steinmetz
authors.forename: Aaron
authors.initials: A
authors.lastname: Smith
authors.forename: Michael
authors.initials: M
authors.lastname: Lamba
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Warnick
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000401:mortality / Q000556:secondary* / Q000601:surgery*; D005260:Female; D006801:Humans; D007103:Immobilization / Q000295:instrumentation; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D011832:Radiation Injuries / Q000473:pathology; D016634:Radiosurgery / Q000295:instrumentation / Q000379:methods* / Q000401:mortality; D011879:Radiotherapy Dosage; D015996:Survival Rate; D016896:Treatment Outcome