title: Multisession gamma knife radiosurgery: a preliminary experience with a noninvasive, relocatable frame.
abstract: OBJECTIVE
  To evaluate preliminary outcomes for a cohort of patients who were treated with multisession Gamma Knife radiosurgery (GKRS) using the new noninvasive vacuum-assisted immobilization system.
  
  
  METHODS
  A retrospective review was performed of 15 consecutive cases treated with multisession GKRS. Radiosurgical targets included 12 meningiomas, 1 nonfunctioning pituitary adenoma, 1 growth hormone-secreting pituitary adenoma, and 1 pilocytic astrocytoma. GKRS was delivered in 3-5 sessions to a mean tumor volume of 8.55 mL (median, 7.3 mL; range, 1.24-22.7 mL) with a mean margin dose of 19.7 Gy (median, 20 Gy; range, 15-25 Gy). The optic nerves, chiasm, and tracts received mean doses of 3.5 Gy (range, 0.7-5.7 Gy), 3.1 Gy (range, 1-4.4 Gy), and 2.6 Gy (range, 0.83-5.45 Gy) per session. Mean biologic equivalent dose (α/β = 2.5) was 60.9 Gy (median, 60 Gy; range, 45-79.8 Gy). Follow-up examinations were performed at 3- to 6-month intervals.
  
  
  RESULTS
  Mean follow-up was 17.7 months (median, 13.8 months; range, 4-44.3 months), and tumor control was noted in all patients, with regression in 5 patients and stability in 10 patients. New neurologic deficits developed in 3 patients after treatment, but none of these deficits were permanent. Resection was performed in 1 patient with expressive aphasia with worsening of peritumoral T2 signal but a stable tumor on follow-up magnetic resonance imaging. The other 2 patients were managed conservatively for minor complications (ptosis, taste dysfunction), and their symptoms resolved. No patients developed deterioration in vision during the follow-up period.
  
  
  CONCLUSIONS
  Preliminary experience with multisession GKRS appears promising, with reasonable tumor control and complication rates. Multisession stereotactic radiosurgery may expand the treatment envelope for intracranial pathologies, including targets with larger volumes and locations in close proximity to radiosensitive structures.
authors.affiliation: Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia, USA.
authors.forename: James H
authors.initials: JH
authors.lastname: Nguyen
authors.affiliation: Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia, USA.
authors.forename: Ching-Jen
authors.initials: CJ
authors.lastname: Chen
authors.affiliation: Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia, USA.
authors.forename: Cheng-Chia
authors.initials: CC
authors.lastname: Lee
authors.affiliation: Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia, USA.
authors.forename: Chun-Po
authors.initials: CP
authors.lastname: Yen
authors.affiliation: Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia, USA.
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia, USA; Department of Radiation Oncology, University of Virginia Health System, Charlottesville, Virginia, USA.
authors.forename: David
authors.initials: D
authors.lastname: Schlesinger
authors.affiliation: Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia, USA; Department of Radiation Oncology, University of Virginia Health System, Charlottesville, Virginia, USA. Electronic address: jsheehan@virginia.edu.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Sheehan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007103:Immobilization / Q000295:instrumentation / Q000379:methods; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D011829:Radiation Dosage; D016634:Radiosurgery / Q000295:instrumentation* / Q000379:methods*; D012189:Retrospective Studies; D055815:Young Adult
keywords: Gamma Knife Extend; Hypofractionated Gamma Knife; Multisession Gamma Knife; Multisession stereotactic radiosurgery