Beyond current guided bronchoscopy: a robust and real-time bronchoscopic ultrasound navigation system.

This paper develops a new bronchoscopic ultrasound navigation system that fuses multimodal sensory information including preoperative images, bronchoscopic video sequences, ultrasound images, and external position sensor measurements. To construct such a system, we must align these information coordinate systems. We use hand-eye calibration to align the video camera and its attached external sensor and introduce a phantom-free method to calibrate the ultrasonic probe and its fixed external sensor. More importantly, we propose a marker-free registration method that uses the bronchoscope and the bronchial tree center information to register the sensor and the pre-operative coordinate systems. We constructed a bronchial phantom to validate our system, whose navigation accuracy was about 2.6 mm. Furthermore, compared to the current navigated bronchoscopy, the main advantage of our system is that it navigates the bronchoscope and the ultrasonic mini probe simultaneously and provides bronchial structures inside and outside the bronchial walls, particularly lymph node structures in ultrasonic images.