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International Bulletin of Otorhinolaryngology

Accuracy assessment of a novel optical image guided system for trans-nasal sinus and skull base surgeries

Yerasimos Kyriakides


Purpose: Many studies have been conducted on assessment of navigation accuracy on cadaver head using pre-installed CT fiducials. However, there are fewer studies on assessing accuracy on real patient due to its complexity in measuring Target Registration Error (TRE). In this paper we propose a new approach for quantifying navigation accuracy on the real patients. This paper summarizes the results of navigation accuracy of a novel optical image guided navigation system evaluated on over 20 patients.
Method: Commercially available optical navigation system (Navient Image guided navigation system - ClaroNav Kolahi Inc., Toronto, Canada) was used on over 20 patients from 2017 to 2019. Navient employs both landmarks based and trace based registration. Since mounting CT fiducials on the real patients is invasive and impractical, we developed a new approach to measure the distance from the navigation probe to the patient’s skin as a new metric to quantify navigation accuracy. The measurement was conducted in dozens of locations including patient’s forehead, temples and base of the nose. These anatomical locations were chosen very carefully to represent navigation accuracy in coronal, sagittal and axial directions respectively. Furthermore, our method also eliminates human errors involved in the TRE measurements which is the main source of error in TRE studies.
Results: The average Euclidian distance from skin on 23 patients were 1.47(mm). the standard deviation of the accuracy was 0.28(mm). Low STD demonstrates consistent accuracy during the two year course of the study.
Conclusion: A new noninvasive approach for accuracy assessment
of image guided navigation systems on real patient was proposed and
validated using a novel optical navigation system. The low STD of
navigation accuracy indicates its reliable accuracy.

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