2D/3D Image fusion for accurate target localization and evaluation of a mask based stereotactic system in fractionated stereotactic radiotherapy of cranial lesions

Jian Yue Jin, Samuel Ryu, Kathleen Faber, Tom Mikkelsen, Qing Chen, Shidong Li, Benjamin Movsas

Research output: Contribution to journalArticle

53 Scopus citations


The purpose of this study was to evaluate the accuracy of a two-dimensional (2D) to three-dimensional (3D) image-fusion-guided target localization system and a mask based stereotactic system for fractionated stereotactic radiotherapy (FSRT) of cranial lesions. A commercial x-ray image guidance system originally developed for extracranial radiosurgery was used for FSRT of cranial lesions. The localization accuracy was quantitatively evaluated with an anthropomorphic head phantom implanted with eight small radiopaque markers (BBs) in different locations. The accuracy and its clinical reliability were also qualitatively evaluated for a total of 127 fractions in 12 patients with both kV x-ray images and MV portal films. The image-guided system was then used as a standard to evaluate the overall uncertainty and reproducibility of the head mask based stereotactic system in these patients. The phantom study demonstrated that the maximal random error of the image-guided target localization was ±0.6 mm in each direction in terms of the 95% confidence interval (CI). The systematic error varied with measurement methods. It was approximately 0.4 mm, mainly in the longitudinal direction, for the kV x-ray method. There was a 0.5 mm systematic difference, primarily in the lateral direction, between the kV x-ray and the MV portal methods. The patient study suggested that the accuracy of the image-guided system in patients was comparable to that in the phantom. The overall uncertainty of the mask system was ±4 mm, and the reproducibility was ±2.9 mm in terms of 95% CI. The study demonstrated that the image guidance system provides accurate and precise target positioning.

Original languageEnglish (US)
Article number036612MPH
Pages (from-to)4557-4566
Number of pages10
JournalMedical Physics
Issue number12
StatePublished - Jan 1 2006



  • Fractionated stereotactic radiotherapy
  • Image fusion
  • Image guidance
  • Position accuracy
  • Thermal plastic mask fixation

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

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