April 2010
Volume 51, Issue 13
ARVO Annual Meeting Abstract  |   April 2010
Comparision of Fiducial Placement for Image Guided Orbital Surgery
Author Affiliations & Notes
  • L. A. Mawn
    Dept of Ophthalmology,
    Vanderbilt University, Nashville, Tennessee
  • L. Blackwell
    Dept of Neurological Surgery,
    Vanderbilt University, Nashville, Tennessee
  • R. Thompson
    Dept of Neurological Surgery,
    Vanderbilt University, Nashville, Tennessee
  • R. L. Galloway
    Dept of Biomedical Engineering,
    Vanderbilt University, Nashville, Tennessee
  • Footnotes
    Commercial Relationships  L.A. Mawn, Patent 60/488,758, P; L. Blackwell, None; R. Thompson, None; R.L. Galloway, Patent 60/488,758, P.
  • Footnotes
    Support  NIH 1R21RR025806
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 18. doi:
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    • Get Citation

      L. A. Mawn, L. Blackwell, R. Thompson, R. L. Galloway; Comparision of Fiducial Placement for Image Guided Orbital Surgery. Invest. Ophthalmol. Vis. Sci. 2010;51(13):18.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : In a previous project we compared fiducial placement for image guided with traditional placement of fiducials to a mathematically optimized periorbital configuration and showed improved target registration error with the optimized fiducial placement. To translate this finding to surgical applications we compared the optimized fiducial placement to traditional placement in the commercially available Stealthstation/S7.

Methods: : A replica of the human skull with was created. A mathematical algorithm, simulated annealing, was used to determine optimal fiducial placement. External skin fiducials were placed by both the traditional random method and based on the optimized placement. Preprocedural computed tomographic (CT) images of the phantom were loaded into a commercially available navigation system. The registration was then determined 20 times for both fiducial arrangements. The accuracy number that the Stealth Station/S7 rendered was then compared with both arrangements of fiducials. An accustar bone marker secured at the orbital apex was located with image guidance with both registration methods.

Results: : The traditional neurosurgery placement method rendered an accuracy number of 0.970 mm + 0.208 compared to the optimized position of 1.13 + 0.98 (p= 0.017). The CT scan position of the accustar position within the phantom was accurately determined with both arrangements of fiducials.

Conclusions: : With a mathematically rigorous process of simulated annealing, we have previously shown that improved registration results for image guidance are achieved by optimizing fiducial placement. We urge caution when drawing conclusions from the accuracy numbers produced from the commercially available image guidance systems as they are not true target registration calculations.1. Atuegwu NC, Mawn L, Galloway R. Transorbital endoscopic image guidance.Conf Proc IEEE Eng Med Biol Soc. 4663-6, 2007.2. Ateugwu NC, Galloway R. Volumetric characterization of the Aurora magnetic tracker system for image-guided transorbital procedures. Phys Med Biol 53(16):4355-68, 2008;

Keywords: orbit • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anatomy 

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