title: Multisession Gamma Knife surgery for benign orbital tumors.
abstract: OBJECTIVE
  The goal of this study was to investigate the safety and efficacy of multisession Gamma Knife surgery (GKS) in the treatment of benign orbital tumors.
  
  
  METHODS
  Twenty-three patients who retained their vision despite having tumors touching their optic nerve were treated with multisession (4-fraction) GKS. The median tumor volume was 2800 mm(3) (range 211-10,800 mm(3)), and the median cumulative margin dose was 20 Gy (range 18-22 Gy).
  
  
  RESULTS
  The median clinical follow-up duration in these patients was 38 months (range 9-74 months). No patient experienced tumor progression in this study. In particular, a higher degree of tumor shrinkage was found in the 7 patients with cavernous hemangiomas than in patients with other types of lesions (p < 0.05). Of the 23 patients whose preoperative vision was preserved, 11 showed improvement in visual acuity and/or visual field and 12 showed stable visual acuity. No GKS-related adverse events were noted during or after treatment.
  
  
  CONCLUSIONS
  Multisession radiosurgery using the Gamma Knife may be a good strategy for tumors in direct contact with the optic nerve. A cumulative margin dose of up to 22 Gy delivered in 4 sessions is safe for preservation of visual function with a high probability of tumor control.
authors.affiliation: Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Kyung-Il
authors.initials: KI
authors.lastname: Jo
authors.forename: Yong Seok
authors.initials: YS
authors.lastname: Im
authors.forename: Doo-Sik
authors.initials: DS
authors.lastname: Kong
authors.forename: Ho Jun
authors.initials: HJ
authors.lastname: Seol
authors.forename: Do-Hyun
authors.initials: DH
authors.lastname: Nam
authors.forename: Yoon-Duck
authors.initials: YD
authors.lastname: Kim
authors.forename: Jung-Il
authors.initials: JI
authors.lastname: Lee
mesh_terms: D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D016586:Granular Cell Tumor / Q000601:surgery; D006392:Hemangioma, Cavernous / Q000601:surgery; D006801:Humans; D008297:Male; D008579:Meningioma / Q000601:surgery; D008875:Middle Aged; D009442:Neurilemmoma / Q000601:surgery; D009918:Orbital Neoplasms / Q000601:surgery*; D016634:Radiosurgery / Q000295:instrumentation* / Q000379:methods; D054364:Solitary Fibrous Tumors / Q000601:surgery; D016896:Treatment Outcome; D047368:Tumor Burden