Design And Development Of A Surgical Navigation System With A Real-time Warning System For Otologic Surgery

Background; Surgical navigation system plays an increasingly important role in modern surgery. It helps ensuring surgical safety by minimizing the risk of unnecessary injuries. While surgical navigation is becoming a standard surgical tool in the Operating Room in developed countries, hospitals in our country have financial problems purchasing these systems due to the price. Moreover, the mainstream products on the market only provide surgeons with a basic navigational function. Few modules were developed tailoring to the demand of surgeons in any specific types of surgery in practice.Objective: To develop a surgical navigation system with our own patent and add to it a warning module specifically designed for otologic surgeries.Methods: We developed our own surgical navigation software and added to it the real time warning modules concerning the safe distance from the drill tip to important structures such as the sigmoid sinus, the facial nerve, the meninges, the external auditory canal and the semicircular canal. When the drill tip gets too close to the above structures during the surgery, the system will give a visual as well as an auditory warning to the surgeon. To minimize the error produced by the registration process, we chose titanium screws as our markers of fiducial registration. To evaluate the effectiveness of the system, we studied the fiducial registration error and target registration error on two phantoms and a cadaver. We also performed a navigated mastoidectomy on the cadaver with the warning module activated. We then res-canned the cadaver and measured the thickness of different regions of the temporal bone on the image and measured the actual thickness of the corresponding spots with a caliper.Result: The accuracy of the navigation system we developed reached sub millimeter level. In the phantom-experiment, the Target Registration Error in4-point registration,6-point registration and8-point registration were0.81±0.05mm,0.56±0.04mm and0.40±0.04mm, respectively (P<0.05). The application error in the cadaver surgery was0.43±0.20mm. Regarding the measurement result of the bone thickness with different methods, the difference between that of caliper measurement and CT image measurement ΔDimg=0.45±0.54mm. The difference between that of caliper measurement and navigation estimation ΔDnav=0.47±0.89mm. We successfully finished the design and development of the3D model construction, distance measurement and alarming module of the navigation system. The system proved helpful in our experimental surgery.Conclusion: The navigation system we developed may provide useful functions tailored to the demand of otologic surgeons, assisting them in protecting the important structures during surgery and thus help improving operation safety.