J Korean Assoc Maxillofac Plast Reconstr Surg.  2012 Jan;34(1):41-52.

Accuracy Verification of Optical Tracking System for the Maxillary Displacement Estimation by Using of Triangulation

Affiliations
  • 1Department of Dentistry, School of Dentistry, Seoul National University, Korea. myungkim@snu.ac.kr
  • 2Department of Oral and Maxillofacial Surgery, Dental Research Institute, School of Dentistry, Seoul National University, Korea.

Abstract

PURPOSE
Triangulation is the process of determining the location of a point by measuring angles to it from known points at either end of a fixed baseline. This point can be fixed as the third point of a triangle with one known side and two known angles. The aim of this study was to find a clinically adaptable method for applying an optical tracking navigation system to orthognathic surgery and to estimate its accuracy of measuring the bone displacement by use of triangulation methods.
METHODS
In orthognathic surgery, the head position is not fixed as in neurosurgery, so that a head tracker is needed to establish the reference point on the head surface byusing an optical tracking system. However, the operation field is interfered by its bulkiness that makes its clinical use difficult. To solve this problem, we designed a method using an Aquaplast splinting material and a mini-screw in applying a head tracker on a patient's forehead. After that, we estimated the accuracy of measuring displacements of the ball marker by an optical tracking system with a conventional head tracker (Group A) and with a newly designed head tracker (Group B). Measured values of ball markers' displacements by each optical tracking system were compared with values obtained from fusion CT images for an estimation of accuracy.
RESULTS
The accuracy of the optical tracking system with a conventional head tracker (Group A) is not suitable for clinical usage. Measured and predictable errors are larger than 10 mm. The optical tracking system with a newly designed head tracker (Group B) shows 1.59 mm, 6.34 mm, and 9.52 mm errorsin threeclinical cases.
CONCLUSION
Most errors were brought on mainly from a lack of reproducibility of the head tracker position. The accuracy of the optical tracking system with a newly designed head tracker can be a useful method in further orthognathic navigation surgery even though the average error is higher than 2.0 mm.

Keyword

Accuracy; Head tracker; Optical tracking system; Orthognathic surgery; Triangulation

MeSH Terms

Carboxymethylcellulose Sodium
Displacement (Psychology)
Forehead
Head
Neurosurgery
Orthognathic Surgery
Splints
Track and Field
Carboxymethylcellulose Sodium
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