Repositioning accuracy of a noninvasive head fixation system for stereotactic radiotherapy

Russell J. Hamilton, Franca T. Kuchnir, Charles A. Pelizzari, Patrick J. Sweeney, Steven J. Rubin

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


We report on the repositioning accuracy of patient setup achieved with a noninvasive head fixation device for stereotactic radiotherapy. A custom head mask which attaches to our stereotactic radiosurgery head ring assembly is fabricated for each patient. The position and orientation of a patient in the stereotactic space at the time of treatment are determined from analyzing portal films containing images of radio-opaque spheres embedded in a custom mouthpiece. From analysis of 104 setups of 12 patients, we find that the average distance between the treated isocenter and its mean position is 1.8 mm, and that the standard deviations of the position of the treated isocenter in stereotactic coordinate space about its mean position are less than 1.4 mm in translation in any direction and less than 1° of rotation about any axis.

Original languageEnglish (US)
Pages (from-to)1909-1917
Number of pages9
JournalMedical physics
Issue number11
StatePublished - Nov 1996


  • immobilization
  • localization
  • positioning
  • stereotactic radiotherapy

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging


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