title: Analysis of translational errors in frame-based and frameless cranial radiosurgery using an anthropomorphic phantom.
abstract: OBJECTIVE
  To evaluate three-dimensional translational setup errors and residual errors in image-guided radiosurgery, comparing frameless and frame-based techniques, using an anthropomorphic phantom.
  
  
  METHODS
  We initially used specific phantoms for the calibration and quality control of the image-guided system. For the hidden target test, we used an Alderson Radiation Therapy (ART)-210 anthropomorphic head phantom, into which we inserted four 5mm metal balls to simulate target treatment volumes. Computed tomography images were the taken with the head phantom properly positioned for frameless and frame-based radiosurgery.
  
  
  RESULTS
  For the frameless technique, the mean error magnitude was 0.22 ± 0.04 mm for setup errors and 0.14 ± 0.02 mm for residual errors, the combined uncertainty being 0.28 mm and 0.16 mm, respectively. For the frame-based technique, the mean error magnitude was 0.73 ± 0.14 mm for setup errors and 0.31 ± 0.04 mm for residual errors, the combined uncertainty being 1.15 mm and 0.63 mm, respectively.
  
  
  CONCLUSIONS
  The mean values, standard deviations, and combined uncertainties showed no evidence of a significant differences between the two techniques when the head phantom ART-210 was used.
authors.affiliation: MSc, Radiologic Technologist, Doctoral Student at the Faculdades Pequeno Príncipe, Curitiba, PR, Brazil.
authors.forename: Taynná Vernalha Rocha
authors.initials: TV
authors.lastname: Almeida
authors.affiliation: MD, Radiotherapist at the Centro de Radioterapia São Sebastião, Florianópolis, SC, Brazil.
authors.forename: Arno Lotar
authors.initials: AL
authors.lastname: Cordova Junior
authors.affiliation: MD, Physicist at the Centro de Radioterapia São Sebastião, Florianópolis, SC, Brazil.
authors.forename: Pedro Argolo
authors.initials: PA
authors.lastname: Piedade
authors.affiliation: Radiology Technologist, Dosimetrist at the Centro de Radioterapia São Sebastião, Florianópolis, SC, Brazil.
authors.forename: Cintia Mara
authors.initials: CM
authors.lastname: da Silva
authors.affiliation: Radiology Technologist, Masters Student at the Universidade Tecnológica Federal do Paraná (UTFPR), Curitiba, PR, Brazil.
authors.forename: Priscila
authors.initials: P
authors.lastname: Marins
authors.affiliation: MD, Radiotherapist at the Centro de Radioterapia São Sebastião, Florianópolis, SC, Brazil.
authors.forename: Cristiane Maria
authors.initials: CM
authors.lastname: Almeida
authors.affiliation: MD, Imaging Physicist at the Centro de Diagnóstico Médico Imagem, Florianópolis, SC, Brazil.
authors.forename: Gabriela R Baseggio
authors.initials: GR
authors.lastname: Brincas
authors.affiliation: PhD, Professor in the Physics Department, Universidade Tecnológica Federal do Paraná (UTFPR), Curitiba, PR, Brazil.
authors.forename: Danyel Scheidegger
authors.initials: DS
authors.lastname: Soboll
keywords: Frame cranial radiosurgery; Frameless cranial radiosurgery; IGRT; Phantoms, imaging; Residual errors; Setup errors