Maxillofacial Surgical Planning And Simulating System Based On Three-dimensional Reconstruction Of CT Images

There are two major factors in the research of maxillofacial surgical planning and simulating systems. One is the modeling of human tissue, and the other is the simulating of surgical procedure. In the research of past decades, simulating of surgical procedure was performed mainly on the operation of human's bone, while modeling and simulating of the operation on soft tissue were implemented by idealized simple models or simple experimental procedures. Modeling and simulation incorporating realistically geometric models and properties of soft tissue from real patients and practical surgical procedures were scarce. Since Face and jaw are unveiled parts of human body, the outcome of a maxillofacial surgery may influence the appearance of patients treated. In addition to bone structure, many maxillofacial surgeries concern operations on soft tissue. Therefore, it is essential to simulate operation effect on soft tissue for better outcome prediction. This paper aims on modeling and simulation of surgical operations on soft tissue based on real patient's CT data.Because the procedure of cleft-lip repair is only involved in operation on soft tissue, which avoids the influences of other tissues, this paper concentrate on the simulation of surgical procedures for cleft lip repair. The major steps include geometric modeling of facial soft tissue based on patient's CT data, location of surgical landmarks, and buildup of a virtual scalpel for surgical simulation. For the modeling of facial soft tissue, a surface extracting method and traditional surface rendering method of Marching Cubes, were performed. Two methods were proposed for the landmark location of surgical operation. One is locating the landmarks through integration of 3D visualization with different 2D views. The other is locating landmarks directly on 3D meshes. With comparison on the maneuverability of two methods, the latter outperformed the former and was chosen in our surgical simulating system. To develop virtual scalpels in our system, we use modeling methods of 3-dimensional objects in Graphics to build the aspects of virtual scalpels, and use the 3D Widgets'framework of VTK to build behaviors of virtual scalpels. At last, we integrate those approaches into a surgical simulating system of cleft lips repair. To evaluate the developed system, surgical procedures of cleft lip repair based on thin-slice CT data from a baby patient were simulated. The simulation result indicates that the framework and implemented methods proposed in this paper are feasible. This work provides an effective means for surgical simulation of maxillofacial operations involving soft tissue.