title: Fractionated gamma knife radiosurgery for benign perioptic tumors: outcomes of 38 patients in a single institute.
abstract: BACKGROUND
  This study was performed to evaluate the efficacy and safety of fractionated Gamma Knife radiosurgery (GKRS) for perioptic lesions.
  
  
  METHODS
  Thirty-eight patients with perioptic tumors were treated at our institute from May 2004 to December 2008. All patients had a lesion in close contact with the optic apparatus. Twenty-four of these patients had undergone surgical resection before fractionated GKRS. Radiation was delivered in four sessions with 12 hours intervals between sessions. The mean target volume was 3,851 mm(3) and the median cumulative marginal dose was 20 Gy. The median follow-up was 38.2 months. Visual acuity and visual fields were analyzed according to visual impairment score using the German Ophthalmological Society guidelines.
  
  
  RESULTS
  Tumor control was achieved in 35 (94.6%) of the 37 patients with available follow-up images. Progressive tumor growth was observed in two craniopharyngioma patients (5.4%). Favorable visual outcomes in the postoperative period were achieved in 94.7% of cases (36/38). Sixteen patients showed visual function after fractionated GKRS, twenty cases were stationary, and two patients showed visual function deterioration after GKRS.
  
  
  CONCLUSIONS
  GKRS is a safe and effective alternative to either surgery or fractionated radiotherapy for selected benign lesions that are adjacent to the optic apparatus.
authors.affiliation: Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Tae Keun
authors.initials: TK
authors.lastname: Jee
authors.affiliation: Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Ho Jun
authors.initials: HJ
authors.lastname: Seol
authors.affiliation: Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yong-Seok
authors.initials: YS
authors.lastname: Im
authors.affiliation: Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Doo-Sik
authors.initials: DS
authors.lastname: Kong
authors.affiliation: Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Do-Hyun
authors.initials: DH
authors.lastname: Nam
authors.affiliation: Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Kwan
authors.initials: K
authors.lastname: Park
authors.affiliation: Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Hyung Jin
authors.initials: HJ
authors.lastname: Shin
authors.affiliation: Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jung-Il
authors.initials: JI
authors.lastname: Lee
keywords: Fractionated radiosurgery; Gamma Knife radiosurgery; Stereotactic radiosurgery; Tumor control; Visual outcome