Traditional Fuzzy C-Means (FCM) clustering algorithm only considers the characteristics of a single pixel when applied to liver CT image segmentation, and it can not overcome the influence of uneven gray scale and the problem of boundary leakage caused by blurred liver boundary. In order to solve the problems, a Spatial Fuzzy C-Means (SFCM) clustering segmentation algorithm combined with spatial constraints was proposed. Firstly, the convolution kernel was constructed by using two-dimensional Gauss distribution function, and the feature matrix could be obtained by using the convolution kernel to extract the spatial information of the source image. Then, the penalty term of spatial constraint was introduced to update and optimize the objective function to obtain a new iteration equation. Finally, the liver CT image was segmented by using the new algorithm. As shown in results, the shape of liver contour splited by SFCM is more regular when segmenting liver CT images with gray unevenness and boundary leakage. The accuracy of SFCM reaches 92.8%, which is 2.3 and 4.3 percentage points higher than that of FCM and Intuitionistic Fuzzy C-Means (IFCM). Also, over-segmentation rate of SFCM is 4.9 and 5.3 percentage points lower than that of FCM and IFCM.

Concerning the problem that too many transitional links and complex parameter solving process existed in camera calibration of the surgical navigation based on C-arm, a new method that completely ignored the camera model was proposed. In this method, the camera model was completely ignored, and the transition link in the process of solving mapping parameters was simplified, which increased the efficiency. In addition, the camera calibration was achieved by distinguishing the projection data from the calibration target which has double-layer metal ball. In the calibration point verification experiment, it can be proved that the residual error of each test point was no more than 0.002 pixels; in the navigation validation experiment, probe point and perforation test were successfully implemented with the established preliminary experiment platform. The experimental results verify that the proposed camera calibration method can meet the accuracy requirements of surgical navigation system.