title: Early decreased tumor volume following fractionated Gamma Knife Radiosurgery for metastatic melanoma and the role of "adaptive radiosurgery": case report.
abstract: OBJECTIVE
  We report a case in which fractionated gamma knife radiosurgery was used to treat a metastatic melanoma lesion. The tumor demonstrated a rapid response to radiosurgery with an observable reduction in tumor volume between the second and third treatments, requiring a favorable modification in the third fractionated treatment.
  
  
  METHODS
  A 61-year-old woman presented with a frontal floor metastatic melanoma lesion that was located adjacent to the optic apparatus.
  
  
  METHODS
  Gamma knife radiosurgery was administered in three fractionated treatments of 6.5 Gy to the 50% isodose line in each case. Repeat imaging for the purpose of planning demonstrated that tumor volume at the time of the third treatment, 9 days following the first treatment, had decreased by 31%, resulting in a 21% decrease in the dose administered to the optic chiasm.
  
  
  CONCLUSIONS
  A case of metastatic melanoma treated with fractionated GKRS is presented, in which a significant reduction in tumor volume was noted 9 days following the initial treatment. This case provides insight into the rate with which malignant neoplasms may respond to intermediate-dose hypofractionated GKRS, and lends support to the concept of "adaptive radiosurgery" as a means of optimizing radiation to an evolving target while minimizing collateral radiation to surrounding structures.
authors.affiliation: Department of Neurosurgery, Keck School of Medicine, University of Southern California, Los Angeles, California 90089, USA. gzada@usc.edu
authors.forename: Gabriel
authors.initials: G
authors.lastname: Zada
authors.forename: Cheng
authors.initials: C
authors.lastname: Yu
authors.forename: Paul G
authors.initials: PG
authors.lastname: Pagnini
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Khalessi
authors.forename: Vladimir
authors.initials: V
authors.lastname: Zelman
authors.forename: Michael L J
authors.initials: ML
authors.lastname: Apuzzo
mesh_terms: D001932:Brain Neoplasms / Q000473:pathology* / Q000556:secondary / Q000601:surgery*; D005123:Eye / Q000473:pathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008545:Melanoma / Q000473:pathology* / Q000556:secondary / Q000601:surgery*; D008875:Middle Aged; D009897:Optic Chiasm / Q000473:pathology / Q000601:surgery; D016634:Radiosurgery