椎莖螺釘手術具有高危險性，手術中醫師不斷藉由拍攝C-arm X光影像以避免失誤，然高輻射劑量危害到病患以及醫護人員的健康，且徒手進行手術很仰賴醫師的經驗及手感，經驗不足的醫師其成功率相對的低很多。影像輔助脊椎手術導引系統可協助解決鑽孔定位的問題，但已知的市售導航系統都配備光學式定位裝置，價格昂貴使得導航系統不易普及化，因此發展一成本低兼具鑽孔導引支撐功能的脊椎手術用導引系統是有其重要性。 本研究以實驗室既有的C-arm影像輔助椎莖螺釘植入手術用的導引系統為基礎，以 高效率透視N點攝影機姿態估計方法（EPnP）取代光學式定位器的定位功能，結合特徵樣板上的特徵點影像辨識及影像中心計算，求得AP及LA方向C-arm影像與特徵樣板的座標轉換關係，並於AP及LA影像上規劃椎莖的鑽孔進入點與結束點，再利用雙角度攝影空間定位技術計算出鑽孔路徑的空間方向，將該鑽孔路徑方位轉換至導引輔具座標系上，並調整導引輔具上的鑽孔導槽方向與鑽孔路徑重合，醫師即可依循該導槽進行椎莖鑽孔手術。可跨接在手術台兩側的鑽孔導引輔具具有四自由度，兩個平移自由度用以定位鑽孔導槽位置，另兩個旋轉自由度則定位鑽孔導槽方向。 實驗以一含雙尖點的器械模擬鑽孔路徑，該兩尖點分別用來模擬鑽孔進入點以及結束點的真實空間位置。幾次實驗結果顯示進入點的位置誤差為2.92±0.76mm，結束點的位置誤差為3.41±0.99mm，方向誤差為0.73±0.33度。 ;Pedicle screw insertion is a high risk operation. Also free-hand operation is highly relied on surgeon’s clinic experience and hand feeling. The operation success rate is relatively lower for inexperienced surgeons. Image assisted surgical navigation system for spine surgery can provide position assistance of drilling. Commercially available navigation systems are equipped with an optical tracker. The high price of the navigation system makes it not easy to popularize. Therefore, development of a low cost navigation system with drill guide device for spine surgery is highly recommended. This study is based on C-arm image assisted surgical navigation system for pedicle screw insertion developed in our laboratory. Efficient perspective-n-point camera pose estimation (EPnP) method is applied to replace the optical tracker to estimate 3D pose of the featuring phantom. The transformation matrix between the AP/LA view C-arm image frames and featuring phantom frame can be determined by EPnP method with feature point image recognition and image center position calculation. Then the drill path defined by the entry point and end point selected on both AP and LA images can be determined by bi-plane method. By adjusting the guide slot of drill guide device to be coaxial with the planned drill path, then the surgeon can safely drill the pedicle just by following the guide slot. The four- degree-of-freedom drill guide device can be mounted on both sides of the operating table. Two translational degrees of freedom are for positioning the center of the guiding slot while the other two rotational degrees of freedom are for positioning the direction of the guide slot. In the experiment, a device with two cusps is used to simulate the drilling path. The two cusps are used to simulate the entry point and end point of drilling path. Several experimental results show that the position errors of the entry and end points are 2.92±0.76mm and 3.41±0.99mm respectively, and the direction error is 0.73±0.33°.
