title: Initial clinical experience with frameless optically guided stereotactic radiosurgery/radiotherapy in pediatric patients.
abstract: OBJECTIVE
  The objective of this study is to report our initial experience treating pediatric patients with central nervous system tumors using a frameless, optically guided linear accelerator.
  
  
  METHODS
  Pediatric patients were selected for treatment after evaluation by a multidisciplinary neuro-oncology team including neurosurgery, neurology, pathology, oncology, and radiation oncology. Prior to treatment, all patients underwent treatment planning using magnetic resonance imaging (MRI) and treatment simulation on a standard computed tomography scanner (CT). For CT simulation, patients were fitted with a customized plastic face mask with a bite block attached to an optical array with four reflective markers. After ensuring adequate reproducibility, these markers were tracked during treatment by an infra-red camera. All treatments were delivered on a Varian Trilogy linear accelerator. The follow-up period ranges from 1-18 months, with a median follow-up of 6 months.
  
  
  RESULTS
  Nine patients, ages ranging from 12 to 19 years old (median age 15 years old), with a variety of tumors have been treated. Patients were treated for juvenile pilocytic astrocytoma (JPA; n = 2), pontine low-grade astrocytoma (n = 1), pituitary adenoma (n = 3), metastatic medulloblastoma (n = 1), acoustic neuroma (n = 1), and pineocytoma (n = 1). We followed patients for a median of 12 months (range 3-18 months) with no in-field failures and were able to obtain encouraging toxicity profiles.
  
  
  CONCLUSIONS
  Frameless stereotactic optically guided radiosurgery and radiotherapy provides a feasible and accurate tool to treat a number of benign and malignant tumors in children with minimal treatment-related morbidity.
authors.affiliation: Department of Surgery, Division of Neurosurgery, University of California, San Diego, 200 W. Arbor Drive, Suite 8893, San Diego, CA 92103-8893, USA. skeshavarzi@ucsd.edu
authors.forename: Sassan
authors.initials: S
authors.lastname: Keshavarzi
authors.forename: Hal
authors.initials: H
authors.lastname: Meltzer
authors.forename: Sharona
authors.initials: S
authors.lastname: Ben-Haim
authors.forename: Charles Benjamin
authors.initials: CB
authors.lastname: Newman
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Lawson
authors.forename: Michael L
authors.initials: ML
authors.lastname: Levy
authors.forename: Kevin
authors.initials: K
authors.lastname: Murphy