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. 2021 Dec 1;42(10):e1513-e1517.
doi: 10.1097/MAO.0000000000003309.

Volumetric Accuracy Analysis of Virtual Safety Barriers for Cooperative-Control Robotic Mastoidectomy

Andy S Ding  1   2 , Sarah Capostagno  2 , Christopher R Razavi  1 , Zhaoshuo Li  3 , Russell H Taylor  3 , John P Carey  1 , Francis X Creighton  1
Affiliations

Volumetric Accuracy Analysis of Virtual Safety Barriers for Cooperative-Control Robotic Mastoidectomy

Andy S Ding et al. Otol Neurotol. .

Abstract

Hypothesis: Virtual fixtures can be enforced in cooperative-control robotic mastoidectomies with submillimeter accuracy.

Background: Otologic procedures are well-suited for robotic assistance due to consistent osseous landmarks. We have previously demonstrated the feasibility of cooperative-control robots (CCRs) for mastoidectomy. CCRs manipulate instruments simultaneously with the surgeon, allowing the surgeon to control instruments with robotic augmentation of motion. CCRs can also enforce virtual fixtures, which are safety barriers that prevent motion into undesired locations. Previous studies have validated the ability of CCRs to allow a novice surgeon to safely complete a cortical mastoidectomy. This study provides objective accuracy data for CCR-imposed safety barriers in cortical mastoidectomies.

Methods: Temporal bone phantoms were registered to a CCR using preoperative computed tomography (CT) imaging. Virtual fixtures were created using 3D Slicer, with 2D planes placed along the external auditory canal, tegmen, and sigmoid, converging on the antrum. Five mastoidectomies were performed by a novice surgeon, moving the drill to the limit of the barriers. Postoperative CT scans were obtained, and Dice coefficients and Hausdorff distances were calculated.

Results: The average modified Hausdorff distance between drilled bone and the preplanned volume was 0.351 ± 0.093 mm. Compared with the preplanned volume of 0.947 cm3, the mean volume of bone removed was 1.045 cm3 (difference of 0.0982 cm3 or 10.36%), with an average Dice coefficient of 0.741 (range, 0.665-0.802).

Conclusions: CCR virtual fixtures can be enforced with a high degree of accuracy. Future studies will focus on improving accuracy and developing 3D fixtures around relevant surgical anatomy.

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Conflict of interest statement

Conflicts of Interest: Under a license agreement between Galen Robotics, Inc. and the Johns Hopkins University, R.H.T. and the University are entitled to royalty distributions on technology related to technology described in the study discussed in this publication. Dr. Taylor also is a paid consultant to and owns equity in Galen Robotics, Inc. This arrangement has been reviewed and approved by the Johns Hopkins University in accordance with its conflict-of-interest policies.

Figures

Figure 1.
Figure 1.
Representation of the 2D planes that surround the allowable working space for cortical mastoidectomies. A) Visualization as seen on axial cut of the pre-operative CT scan. B) 3D reconstruction of the boundaries visualized on 3D Slicer.
Figure 2.
Figure 2.
3D rendering of experimentally drilled volumes overlaid on the temporal bone phantom used for drilling. The preplanned volume confined by the virtual fixture planes is denoted in yellow.
Figure 3.
Figure 3.
Volumetric accuracy analysis of virtual fixtures. A) maximum Hausdorff distances, B) average Hausdorff distances, and C) Dice similarity coefficients between experimentally drilled bone and the preplanned volume for each trial.
See this image and copyright information in PMC

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