title: Preliminary experience with frameless stereotactic radiotherapy.
abstract: OBJECTIVE
  To report initial clinical experience with a novel high-precision stereotactic radiotherapy system.
  
  
  METHODS
  Sixty patients ranging in age from 2 to 82 years received a total of 1426 treatments with the University of Florida frameless stereotactic radiotherapy system. Of the total, 39 (65%) were treated with stereotactic radiotherapy (SRT) alone, and 21 (35%) received SRT as a component of radiotherapy. Pathologic diagnoses included meningiomas (15 patients), low-grade astrocytomas (11 patients), germinomas (9 patients), and craniopharyngiomas (5 patients). The technique was used as means of dose escalation in 11 patients (18%) with aggressive tumors. Treatment reproducibility was measured by comparing bite plate positioning registered by infrared light-emitting diodes (IRLEDs) with the stereotactic radiosurgery reference system, and with measurements from each treatment arc for the 1426 daily treatments (5808 positions). We chose 0.3 mm vector translation error and 0.3 degrees rotation about each axis as the maximum tolerated misalignment before treating each arc.
  
  
  RESULTS
  With a mean follow-up of 11 months, 3 patients had recurrence of malignant disease. Acute side effects were minimal. Of 11 patients with low grade astrocytomas, 4 (36%) had cerebral edema and increased enhancement on MR scans in the first year, and 2 required steroids. All had resolution and marked tumor involution on follow-up imaging. Bite plate reproducibility was as follows. Translational errors: anterior-posterior, 0.01 +/- 0.10; lateral, 0.02 +/- 0.07; axial, 0.01 +/- 0.10. Rotational errors (degrees): anterior-posterior, 0.00 +/- 0.03; lateral, 0.00 +/- 0.06; axial, 0.01 +/- 0.04. No patient treatment was delivered beyond the maximum tolerated misalignment. Daily treatment was delivered in approximately 15 min per patient.
  
  
  CONCLUSIONS
  Our initial experience with stereotactic radiotherapy using the infrared camera guidance system was good. Patient selection and treatment strategies are evolving rapidly. Treatment accuracy was the best reported, and the treatment approach was practical.
authors.affiliation: Department of Radiation Oncology, University of Florida College of Medicine, Gainesville 32610, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Buatti
authors.forename: F J
authors.initials: FJ
authors.lastname: Bova
authors.forename: W A
authors.initials: WA
authors.lastname: Friedman
authors.forename: S L
authors.initials: SL
authors.lastname: Meeks
authors.forename: R B
authors.initials: RB
authors.lastname: Marcus
authors.forename: J P
authors.initials: JP
authors.lastname: Mickle
authors.forename: T L
authors.initials: TL
authors.lastname: Ellis
authors.forename: W M
authors.initials: WM
authors.lastname: Mendenhall
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001254:Astrocytoma / Q000601:surgery; D001932:Brain Neoplasms / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D003397:Craniopharyngioma / Q000601:surgery; D019583:Dose Fractionation, Radiation; D005260:Female; D018237:Germinoma / Q000601:surgery; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000601:surgery*; D008579:Meningioma / Q000601:surgery; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods*; D011881:Radiotherapy, Computer-Assisted