支持力反馈的个性化膝关节置换虚拟手术仿真系统的研究与构建

应用传统外科手术培训模式发展的医师队伍无法满足当前日益激增的膝关节病患就医需求,研究构建一套基于虚拟现实和力反馈技术的个性化膝关节置换手术仿真系统。采用医学影像三维重构技术创建膝关节解剖组织几何模型,应用正向CAD参数化建模技术建立手术器械的几何模型,研究三角网格体素化算法,并基于此生成组织和器械的物理体素模型;通过设备接口和虚拟代理点的坐标匹配映射建立手术器械的力触觉模型,AABB包围盒层次树作为碰撞检测模型,空间重叠相交模拟组织的切割变形,基于单点约束的力触觉渲染方法建立组织和器械的虚拟操作过程;以力反馈设备Phantom Omni和计算机为硬件平台,基于触觉引擎CHAI 3D和OpenGL等软件接口,开发构建虚拟膝关节置换手术仿真系统;将专业医学人员体验系统后实际手术操作训练时间与对照组的作比较,并采用问卷调查的形式对系统作出等级评估。结果表明,仿真系统可实现个性化膝关节置换手术沿规划路径钻孔和截骨操作的组织形变和力触觉反馈的仿真模拟,并且系统仿真的实时性能良好,视触觉刷新频率维持在60~1 000 Hz左右;统计结果显示,两组成员的实际手术操作时间存在显著性统计学差异(P< 0.04),问卷结果皆在平均优良水平(8分)之上(P＜0.05)。仿真系统为个性化膝关节置换手术提供一种安全、可靠、有效的医学培训和术前演练方式。

Research and Development of Virtual Surgery Simulation System with Haptic Feedback for Personalized TKA

Physicians educated with traditional surgical training modes cannot meet the current surge in demand for knee joint patients. The aim of this work is to develop a simulation system based on virtual reality technology for the personalized knee replacement surgery. The virtual geometric models of knee joint and instruments were established by 3D reconstruction and CAD modeling technology respectively. We studied the voxelization algorithm and applied it to generate the virtual physical models. By using coordinate match method, the force model of the instrument was established between the device interface and the proxy. The AABB bounding box hierarchy tree was used as the collision detection model, we applied the overlapped intersect way to simulate deformation of tissue and the single point constraint force rendering to simulate the operation process. By setting up the hardware platform consisting of Phantom Omni and computer, and configuring the software environment CHAI 3D and OpenGL, the virtual knee replacement surgery simulation system was constructed. We compared the training time of the actual surgical operation of the professionals who experienced system with that of the control group, and used a questionnaire survey to make assessment of the system. Results showed that the system achieved the simulation of tissue deformation and force haptic feedback of drilling and osteotomy along the planned path in TKA, and the real-time performance of the system was excellent, the visual and haptic update frequency was maintained at 60 Hz and 1000 Hz respectively. The statistical results illustrated that there was a statistically significant difference (P=0.04) in the actual operation time between the two groups, the questionnaire results were all above the average excellent level (P<0.05). The constructed simulation system provides a safe, reliable and effective mode for medical training and preoperative drilling of TKA.