title: Targeting Accuracy of Image-Guided Radiosurgery for Intracranial Lesions: A Comparison Across Multiple Linear Accelerator Platforms.
abstract: OBJECTIVE
  To evaluate the overall positioning accuracy of image-guided intracranial radiosurgery across multiple linear accelerator platforms.
  
  
  METHODS
  A computed tomography scan with a slice thickness of 1.0 mm was acquired of an anthropomorphic head phantom in a BrainLAB U-frame mask. The phantom was embedded with three 5-mm diameter tungsten ball bearings, simulating a central, a left, and an anterior cranial lesion. The ball bearings were positioned to radiation isocenter under ExacTrac X-ray or cone-beam computed tomography image guidance on 3 Linacs: (1) ExacTrac X-ray localization on a Novalis Tx; (2) cone-beam computed tomography localization on the Novalis Tx; (3) cone-beam computed tomography localization on a TrueBeam; and (4) cone-beam computed tomography localization on an Edge. Each ball bearing was positioned 5 times to the radiation isocenter with different initial setup error following the 4 image guidance procedures on the 3 Linacs, and the mean (µ) and one standard deviation (σ) of the residual error were compared.
  
  
  RESULTS
  Averaged overall 3 ball bearing locations, the vector length of the residual setup error in mm (µ ± σ) was 0.6 ± 0.2, 1.0 ± 0.5, 0.2 ± 0.1, and 0.3 ± 0.1 on ExacTrac X-ray localization on a Novalis Tx, cone-beam computed tomography localization on the Novalis Tx, cone-beam computed tomography localization on a TrueBeam, and cone-beam computed tomography localization on an Edge, with their range in mm being 0.4 to 1.1, 0.4 to 1.9, 0.1 to 0.5, and 0.2 to 0.6, respectively. The congruence between imaging and radiation isocenters in mm was 0.6 ± 0.1, 0.7 ± 0.1, 0.3 ± 0.1, and 0.2 ± 0.1, for the 4 systems, respectively.
  
  
  CONCLUSIONS
  Targeting accuracy comparable to frame-based stereotactic radiosurgery can be achieved with image-guided intracranial stereotactic radiosurgery treatment.
authors.affiliation: Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, USA yhuang2@hfhs.org.
authors.forename: Yimei
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhao
authors.affiliation: Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Indrin J
authors.initials: IJ
authors.lastname: Chetty
authors.affiliation: Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Brown
authors.affiliation: Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, USA.
authors.forename: James
authors.initials: J
authors.lastname: Gordon
authors.affiliation: Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Ning
authors.initials: N
authors.lastname: Wen
mesh_terms: D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D002138:Calibration; D006801:Humans; D019047:Phantoms, Imaging; D016634:Radiosurgery; D011880:Radiotherapy Planning, Computer-Assisted
keywords: CBCT; ExacTrac; image guided; intracranial radiosurgery; setup accuracy