A Lightweight Integrated Positioning System With Occlusion-Aware Region-Based Pose Tracking for Oral and Maxillofacial Surgery

The development of an accurate and robust positioning system for oral and maxillofacial surgery (OMS) is a challenging task, primarily due to the oral space limitations and line-of-sight occlusions. This paper presents a novel lightweight integrated positioning system for OMS, which can provide practical guidance utilizing only a micro camera installed on the end of the surgical instrument. An efficient region-based pose tracking method for texture-less teeth is proposed, which can use search lines around the object contour and simple local region partitioning strategy to improve pose accuracy. Besides, to deal with the possible partial occlusions of target during surgery, an occlusion-aware weight function is presented and utilized seamlessly in the pose optimization pipeline. This function calculates the pixel-wise occlusion probability using object contour and distance constraint, helping to improve the tracking robustness. Pivot calibration evaluation reveals that the tracking accuracy of the proposed camera-based handpiece is higher than the marker-based handpieces. Comparative experiments demonstrate that proposed pose tracking method has higher accuracy than existing state-of-the-art methods and ablation study confirms the effectiveness of the occlusion handling strategy. The overall positioning experiment indicates that the proposed system has satisfactory static poses stability and positioning accuracy. Furthermore, the main advantage of our system is that it is lighter and more integrated than other systems, which can reduce the system complexity, decrease the risk of line-of-sight occlusion, and lower the surgery cost.Note to Practitioners—This paper is motivated by the problem of restricted oral space constraints and partial occlusions during positioning for OMS. Compared with traditional OMS navigation systems, the designed system is more lightweight and more integrated without other external cameras and additional fiducial markers. Our system can provide practical guidance utilizing only a micro camera installed on the end of the surgical instrument. In addition, an efficient region-based pose tracking method for texture-less teeth is proposed to increase pose accuracy. Since the target can partially be occluded during the procedure, we present a novel occlusion-aware strategy to improve the tracking performance of partial occlusions. Our proposed system achieves a decent balance between positioning accuracy and hardware cost, and can easily be integrated into various dental surgical tools, thus it has tremendous potential for commercialization.