Research On Key Technologies Of Virtual Training And Navigation For Cranio-maxillofacial Surgery And Development For The Application Systems

Computer Assisted Surgery (CAS), as an interdiscipline betweeninformation technology and modern medicine, is a hot topic ininternational research. CAS, which breaks through the limitation oftraditional surgery, greatly increases the surgery accuracy and success rate,and also has a significant impact on improving the life and health level ofhuman being. This article presented the key technologies of virtual surgerytraining and image guided surgery, which were the two most importantcomponents of CAS, with the relevant application systems developed forcranio-maxillofacial surgery.As for the virtual surgery training part, this article showed the relatedalgorithms and technologies. In particular, collision detection and hapticforce calculation were involved. In order to realize the fast and accurateinteraction detection between the virtual surgical instrument and thecranio-maxillofacial model, an algorithm based on Axis Aligned BoundingBox (AABB) and multiple points was proposed in this article, and theresult confirmed the effectiveness of this method. Based on regressionequations, the realistic haptic force was calculated and fed back to traineesin real time. On basis of the above-mentioned algorithms, a VirtualTraining System for Cranio-Maxillofacial Surgery (VR-CMFS) wasdeveloped, with the utilization of VS2008, as well as some other toolkits,such as Qt, OpenGL, Chai3D, etc. Further, by the use of a haptic device(Omega.6) and an immersive workbench (Display300), the realistic senseof tactile, visual and aural could be realized in VR-CMFS. A test for VR-CMFS has been carried out by clinicians and experts. Result of theassessment indicated that the visual simulation environment and the tactilefeedback were well-matched with the real clinic, which was helpful forsurgery preparation and novices training.As for the image guided surgery part, this article involved severalresearches listed as follows:1) the data interface between the surgerypreplanning system and navigation system was designed based onencapsulated STL files and regular XML files.2) In order to realize thecalibration for surgical instrument’s tip, axis and norm, we designed acalibration device, as well as the related algorithms.3) A registrationstrategy based on points and surface was proposed in this article. Withnoninvasive markers selected as the registration points, it could achieve theeffect of patient-friendly and high registration accuracy at the same time.4)The Cranio-Maxillofacial Surgery Navigation System (CMFSNS) wasdeveloped with the use of VS2008, and some other toolkits, such as Qt,VTK, ITK, CTK, IGSTK, etc.In order to validate the accuracy of CMFSNS, a precision measuredevice has been designed. Further, several experiments were carried out,and consequently, the result showed that the precisions of point-basedregistration and surface-based registration were respectively within1mmand1.2mm, which could well meet the requirements of clinicalcranio-maxillofacial surgery.