title: Experiences on two different stereotactic radiosurgery modalities of Gamma Knife and Cyberknife in treating brain metastases.
abstract: In this study, we compared the dosimetric properties between Gamma Knife (GK) and Cyberknife (CK), and investigated the clinical implications in treating brain metastases (BMs).
  
  
  
  Between 2011 and 2013, 77 patients treated with either single-fraction GK for small BMs (n = 40) or fractionated CK for large BMs >3 cm (n = 37) were analyzed. Among a total of 160 lesions, 81 were treated with GK (median, 22 Gy) and 38 (large lesions) with three- or five-fraction CK (median, 35 Gy). The median tumor volume was 1.0 cc (IQR, 0.12-4.4 cc) for GK and 17.6 cc (IQR, 12.8-23.7 cc) for fractionated CK. A lesion-to-lesion dosimetric comparison was performed using the identical contour set in both systems.
  
  
  
  The mean dose to tumor was significantly higher in GK by 1.25-fold (P < 0.001), whereas normal tissue volume receiving 90-10 % of prescription dose was significantly larger in CK by 1.26-fold (P < 0.001). Nevertheless, no differences were observed in local tumor control (rates at 1 year, 89.7 % vs 87.0 %; P = 0.594) and overall survival (median, 14 vs 16 months; P = 0.493) between GK and fractionated CK groups. The incidences of radiation necrosis were also not different (12.3 % vs 15.8 %; P = 0.443).
  
  
  
  Despite slightly inferior dosimetric properties of CK, fractionated CK for large BMs appears to be as effective and safe as single-fraction GK for small BMs, representing fractionation as an effective strategy for enhancing efficacy and moderating toxicity in stereotactic radiosurgery for BMs.
authors.affiliation: Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro-43-gil, Songpa-gu, Seoul, 138-736, Republic of Korea. yhyunc@amc.seoul.kr.|Radiosurgery Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea. yhyunc@amc.seoul.kr.
authors.forename: Young Hyun
authors.identifier: 0000-0002-3274-5096
authors.initials: YH
authors.lastname: Cho
authors.affiliation: Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro-43-gil, Songpa-gu, Seoul, 138-736, Republic of Korea.
authors.forename: Jung Min
authors.initials: JM
authors.lastname: Lee
authors.affiliation: Radiosurgery Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Doheui
authors.initials: D
authors.lastname: Lee
authors.affiliation: Radiosurgery Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Jae Hong
authors.initials: JH
authors.lastname: Park
authors.affiliation: Radiosurgery Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: KyoungJun
authors.initials: K
authors.lastname: Yoon
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Seon Ok
authors.initials: SO
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro-43-gil, Songpa-gu, Seoul, 138-736, Republic of Korea.
authors.forename: Do Hoon
authors.initials: DH
authors.lastname: Kwon
authors.affiliation: Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro-43-gil, Songpa-gu, Seoul, 138-736, Republic of Korea.
authors.forename: Jeong Hoon
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro-43-gil, Songpa-gu, Seoul, 138-736, Republic of Korea.|Radiosurgery Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Chang Jin
authors.initials: CJ
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro-43-gil, Songpa-gu, Seoul, 138-736, Republic of Korea.|Radiosurgery Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Sung Woo
authors.initials: SW
authors.lastname: Roh
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000556:secondary / Q000601:surgery*; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011829:Radiation Dosage; D016634:Radiosurgery / Q000379:methods*; D016896:Treatment Outcome; D047368:Tumor Burden
keywords: Brain metastases; Cyberknife; Fractionation; Gamma Knife; Stereotactic radiosurgery