虚拟手术系统中缝合等关键模块的实现
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摘要
内窥镜下的手术操作很复杂,难度高,缺乏经验的医生很难掌握,就算是有经验的医生也会因长期没有接触而生疏技能。因此让医生进行大量精细的训练是非常重要的。大部分微创手术在内窥镜下看到的图像都是二维的,缺失三维场景的深度信息,致使不易把握操作的精确位置,这是大多数医生在接触此类手术时首先遇到的但也是最容易克服的困难。缝合是几乎每一个外科手术医生必须要掌握的技能,特别是内窥镜下的缝合,手术针极为纤细,肉眼难以辨认清楚,极大增加了缝合的难度。而且人脑中的位置信息和实际的位置信息往往不匹配,对于打结等操作更是难上加难。
虚拟现实技术是利用计算机技术对真实环境进行仿真,用户可以走进这个环境,并操纵场景中的对象进行人机交互。虚拟手术系统能够提供极为理想的手术训练平台,通过它受训医生可以观察高分辨率的三维组织,并利用力反馈设备感受到力的作用与反作用,如同在真实的人体上进行手术一样。但就目前而言,此类系统大多关注于视觉效果的虚拟,对其他感觉通道如听觉、触觉等的表现较为匮乏。
本文的主要目标是利用虚拟现实技术,并紧密结合外科理论与实践知识,对当前系统主要存在的未解难题展开讨论,并最终实现腹腔镜手术的基本训练模块。从功能上看,本文的实现模块可归结为:缝合模块和深度训练模块两大模块。具体而言,本论文的主要工作有如下几方面:
1、本文沿用弹簧模型和控制点思想对缝合线进行建模,采用Follow the leader(简称FTL)跟踪线的运动轨迹,并按照系统的需求改进算法,同时对相关力学参数及系统参数进行调整。就缝合线的真实感、物理合理性等问题,给出了大量的实验数据加以说明。采用白板技术,将缝合模块集成到虚拟手术训练系统平台中。这种集成技术减低了模块间的耦合度,大大提高系统的可扩展性和可维护性。
2、对缝合过程中使用到的碰撞检测及自碰撞检测的技术,本文从减少相交测试次数和提高检测效率两方面进行优化,不仅减少了数据存储空间,更是大大节约了检测时间,满足系统实时性要求。
3、利用软件工具对手术器械建模并集成到系统中,实现无触觉仿真人机交互操作。针对内窥镜下深度信息缺失问题,设计不同的训练任务,受训者通过练习精细物体的夹持、定位等操作加强自身在三维空间中对深度、方位、物体间相对距离关系等的判断能力。在训练过程中,若操作失误,设置系统提示并切换音效,使受训练能及时矫正错误操作。同时设计评分系统,用以衡量一次训练的合格程度。
4、实现简易的腹腔定位系统。受训者可通过系统操纵内窥镜快速定位,使目标物体准确显示于视野中央,避免了在定位过程中浪费大量时间却仍寻不到目标物的情况。
5、解决声音通道缺失的问题,并实现声音的实时听点切换,以提供一个更具沉浸感的训练环境。
Those technologies employed in endoscopic surgery are very complicated, so they are difficult to grasp for most doctors even those who have many years of surgical experiences. Therefore a long-term and rigorous training is very necessary. Almost all endoscopic images are two dimensional, which cause the loss of depth information. In this situation, most doctors can’t locate a surgical instrument to the exact position. And as one of the most common operations, suture is a basic skill that every doctor must master, especially the suture operation under the endoscope which requires doctors to clip a needle to sew the wound. However, under the endoscope, needle is too fine to be distinguished, which greatly increases the difficulties to complete the suture operation. What's more, the location information obtained from the endoscope doesn’t match the factual information, so tying a knot is even harder.
Virtual Reality(VR) is a new technology which tries to generated a kind of virtual environment and allows users to interact with the virtual objects. Based on this technology, Virtual Surgery System is developed. It will provide an ideal surgery training platform on which some high-resolution three-dimensional tissues will be observed and the sensations of force feedback will be expressed by feedback equipments. However, the studies on this kind of system just focus on a greater visual effect so far, and ignores other sensory channels.
With the aid of VR Technology and other important theories, we try to find out some solutions for the existing problems. On functions, all should be solved in this paper fall into two parts: suture simulation and depth training. The main achievements and work of this paper is listed following:
1. We still use Mass-spring Model and“control points”method to simulate the suture. Meanwhile, the trajectory of the suture is configured by a constraint-based technique -“follow-the-leader”(FTL). To get better performance, some algorithms will be further modified. And a mass of experimental data obtained prove the feasibility and validity of such improvements. Finally, a technology named”Whiteboard Mode”will be introduced to integrate the suture module into our virtual surgery system. This kind of technology can help to reduce the coupling of modules and promote the scalability of the system greatly.
2. The Collision Detection Algorithm mentioned will be optimized, which includes two aspects: reducing the times of intersection testing and improving the detection efficiency. These optimizations not only reduce the storage, but also largely short the computational time.
3. Surgical instruments will be modeled to realize the interaction between the users and our system. As to the problem of losing the depth information under endoscope, we design several training programs which require users to do some practices such as clipping and orientating to strength their sense of spacing. Once there is a mistake during a training, the system will give some attentions to help users correct their mistakes.
4. We also design a simple orientation system to help users locate objects to the center of screen quickly.
5. Audio rendering is applied to enhance the immersion of virtual environment.
虚拟现实技术是利用计算机技术对真实环境进行仿真,用户可以走进这个环境,并操纵场景中的对象进行人机交互。虚拟手术系统能够提供极为理想的手术训练平台,通过它受训医生可以观察高分辨率的三维组织,并利用力反馈设备感受到力的作用与反作用,如同在真实的人体上进行手术一样。但就目前而言,此类系统大多关注于视觉效果的虚拟,对其他感觉通道如听觉、触觉等的表现较为匮乏。
本文的主要目标是利用虚拟现实技术,并紧密结合外科理论与实践知识,对当前系统主要存在的未解难题展开讨论,并最终实现腹腔镜手术的基本训练模块。从功能上看,本文的实现模块可归结为:缝合模块和深度训练模块两大模块。具体而言,本论文的主要工作有如下几方面:
1、本文沿用弹簧模型和控制点思想对缝合线进行建模,采用Follow the leader(简称FTL)跟踪线的运动轨迹,并按照系统的需求改进算法,同时对相关力学参数及系统参数进行调整。就缝合线的真实感、物理合理性等问题,给出了大量的实验数据加以说明。采用白板技术,将缝合模块集成到虚拟手术训练系统平台中。这种集成技术减低了模块间的耦合度,大大提高系统的可扩展性和可维护性。
2、对缝合过程中使用到的碰撞检测及自碰撞检测的技术,本文从减少相交测试次数和提高检测效率两方面进行优化,不仅减少了数据存储空间,更是大大节约了检测时间,满足系统实时性要求。
3、利用软件工具对手术器械建模并集成到系统中,实现无触觉仿真人机交互操作。针对内窥镜下深度信息缺失问题,设计不同的训练任务,受训者通过练习精细物体的夹持、定位等操作加强自身在三维空间中对深度、方位、物体间相对距离关系等的判断能力。在训练过程中,若操作失误,设置系统提示并切换音效,使受训练能及时矫正错误操作。同时设计评分系统,用以衡量一次训练的合格程度。
4、实现简易的腹腔定位系统。受训者可通过系统操纵内窥镜快速定位,使目标物体准确显示于视野中央,避免了在定位过程中浪费大量时间却仍寻不到目标物的情况。
5、解决声音通道缺失的问题,并实现声音的实时听点切换,以提供一个更具沉浸感的训练环境。
Those technologies employed in endoscopic surgery are very complicated, so they are difficult to grasp for most doctors even those who have many years of surgical experiences. Therefore a long-term and rigorous training is very necessary. Almost all endoscopic images are two dimensional, which cause the loss of depth information. In this situation, most doctors can’t locate a surgical instrument to the exact position. And as one of the most common operations, suture is a basic skill that every doctor must master, especially the suture operation under the endoscope which requires doctors to clip a needle to sew the wound. However, under the endoscope, needle is too fine to be distinguished, which greatly increases the difficulties to complete the suture operation. What's more, the location information obtained from the endoscope doesn’t match the factual information, so tying a knot is even harder.
Virtual Reality(VR) is a new technology which tries to generated a kind of virtual environment and allows users to interact with the virtual objects. Based on this technology, Virtual Surgery System is developed. It will provide an ideal surgery training platform on which some high-resolution three-dimensional tissues will be observed and the sensations of force feedback will be expressed by feedback equipments. However, the studies on this kind of system just focus on a greater visual effect so far, and ignores other sensory channels.
With the aid of VR Technology and other important theories, we try to find out some solutions for the existing problems. On functions, all should be solved in this paper fall into two parts: suture simulation and depth training. The main achievements and work of this paper is listed following:
1. We still use Mass-spring Model and“control points”method to simulate the suture. Meanwhile, the trajectory of the suture is configured by a constraint-based technique -“follow-the-leader”(FTL). To get better performance, some algorithms will be further modified. And a mass of experimental data obtained prove the feasibility and validity of such improvements. Finally, a technology named”Whiteboard Mode”will be introduced to integrate the suture module into our virtual surgery system. This kind of technology can help to reduce the coupling of modules and promote the scalability of the system greatly.
2. The Collision Detection Algorithm mentioned will be optimized, which includes two aspects: reducing the times of intersection testing and improving the detection efficiency. These optimizations not only reduce the storage, but also largely short the computational time.
3. Surgical instruments will be modeled to realize the interaction between the users and our system. As to the problem of losing the depth information under endoscope, we design several training programs which require users to do some practices such as clipping and orientating to strength their sense of spacing. Once there is a mistake during a training, the system will give some attentions to help users correct their mistakes.
4. We also design a simple orientation system to help users locate objects to the center of screen quickly.
5. Audio rendering is applied to enhance the immersion of virtual environment.
引文
[1]周炎勋. "虚拟现实技术综述".计算机仿真, 1996, 13(1): p2-7
[2] John Waterworth. "Virtual Reality in Medicine: A Survey of the State of the Art". Report RR-98.02, Department of Informatics, Umea University, Sweden,1998
[3] Satava R.M, Jones S.B. "Current and future application of virtual reality for medicine". In: Proceedings of the IEEE, March, 1998, 86(3), p484- 489
[4] Ursino M, Tasto JL, Nguyen BH, et al. "The first low-cost Intravascular Catheterization Simulator on a PC". In: Proceeding of Medicine Meets Virtual Reality, January, 1999, p360-366
[5] N.Ayache, S.Cotin, et al. "Simulation of endoscopic surgery". Journal of Minimally Invasive Therapy and Allied Technologies(MITAT), July 1998, 17(2): p71-77
[6] Joel Brown et al. "Real-time simulation of deformable objects: tools and application". The Fourteenth Conference on Computer Animation. Proceedings ,2001, p228-258
[7] Nienhuys HW, Frank A. "Supporting cuts and finite element deformation in interactive surgery simulation". In MICCAI 2001, Berlin, 2001, p1458-152
[8] Bruyns C, Montgomery K. "Generalized interactions using virtual tools within the spring framework:Cutting". In Medicine Meets Virtual Reality 2002(MMVR2002), 2001, p23-26
[10]熊岳山,徐帆,王彦臻,谭珂,郭光友. "虚拟膝关节镜手术仿真系统的关键技术研究".国防科技大学学报, 2007, 01期
[11]李晓波,顾力栩,张少霆,郑广超,张静思. "一个用于腹腔镜训练的虚拟手术系统".首届上海研究生学术论坛论文集生物制造与数字化临床工程, 2007, p111-119
[12] J Zhang, L Gu, X Li, et al. "A minimal invasive surgery simulator employing a novel hybrid cutting method". IEEE 6th International Special Topic Conference on ITAB, Tokyo, 2007, p135-138
[13] J Zhang, L Gu, X Li, M Fang. "An Advanced Hybrid Cutting Method with an Improved State Machine for Surgical Simulation". Computerized Medical Imaging and Graphics, 2008, 33: p63-71
[14] J Zhang, L Gu, B Zhu, et al. "A Novel laparoscopic surgery simulator: System and Evaluation". In: Proceedings of the 5th International Conference on Information Technology and Application in Biomedicine, 2008, p467-470
[15] F Xia, S Xiao, L Gu, L Huang, et al. "Real-time and Haptic Suture Simulation". International Symposium on Bioelectronics and Bioinformatics, in press
[16] J Zhang, L Gu, F Huang, et al. "Real-time Cutting and Suture Simulation Using Hybrid Elastic Model". In: Proceedings of the 29th Annual International Conference of the IEEE EMBS Cite International, Lyon, France, August23-26, 2007, p3646-3649
[17] Lin M.C., Canny J.F. "Efficient algorithms for incremental distance computation ". In:Proceedings of the IEEE International Conference on Robotics and Automation ,1991, p1008-1014
[18] Ehmann S.A, Lin M.C. "Accelerated proximity queries between convex polyhedra by multi-level voronoi marching". In: Proceedings IEEE IROS, 2000, 3: p1201-1207
[19] Ehmann S.A.,Lin M.C.. "Accurate and fast proximity queries between polyhedral using convex surface decomposition". In: Proceedings of the Eurographics Conference, Manchester, 2001, p500-510
[20] Gilbert E.G, Johnson D.W, Keerthi S.S. "A fast procedure for computing the distance between objects in three-dimensional space". IEEE Journal on Robotics and Automation, 1988, 4: p193-203
[21] Cohenor D., Solomovic A., Levin D. "Three-dimensional distance field metamorphosis". ACM Transactions on Graphics(TOG), 1998, 17(2): p116-141
[22] Poutrain K, Contensin M. "Dual Brep-CSG Collision Detection for General Polyhedra". In Ninth Pacific Conference on Computer Graphics and Applications, 2001, p124-128
[23] Miller J, Goldman R, "Combining algebraic rigor with geometric robustness for the detection and calculation of conic sections in the intersection of two quadric surfaces". In: Proceedings of ACM Solid Mode ling, 1991, p221-233
[24] Lane J.M., Riesenfeld R.F., "A theoretical development for the computer generation and display of piecewise polynomial surfaces". IEEE Transactions on Pattern Analysis and Machine Intelligence, 1980, 2(1): p150-159
[25] Boyles M., Fang SF. "Slicing-based volumetric collision detection". Journal of Graphics Tools, 1999, 4(4): p23-32
[26] Gibson S.F. "Beyond Volume Rendering: Visualization, Haptic Exploration, and Physical Modeling of Voxel-based Objects". Visualization in Scientific Computing, 1995, p10-24
[27] Moore, Matthew, Wilhelms, Jane. "Collision Detection and ResPonse for Computer Animation". Computer Graphics (SIGGRAPH 88proc.), Aug 1988, 22: p289-298
[28] Bradshow G., Osullivan C.. "Sphere-tree construction using dynamic medial-axis approximation". In: Proceedings of the ACM SIGGRAPH Symposium on Computer Animation, 2002, p33-40
[29] Van den Bergen G. "Efficient collision detection of complex deformable models using AABB trees". Journal of Graphics Tools, 1997, 4(2): p1-14
[30] Ar Sigal, Chazelle B. "Self-customized BSP trees for collision detection". Computational Geometry: Theory and Applications, Feb 2000, 15(1): p91-102
[31] James T.K., Martin H., Joseph S.B., et al. "Efficient collision detection using bounding volume hierarchies of k-DOPs". IEEE Tansactions on Visualization and Computer Graphics, 1998, 4(1): p21-36
[32]魏迎梅,吴泉涌,石教英. "碰撞检测中的固定方向凸包包围盒的研究".软件学报, 2001, 12(7): p1056-1063
[33] Hubbard P.M. "Collision detection for interactive graphics applications". IEEE Transactions on Visualization and Computer Graphics, 1995, 1(3): p218-230
[34] Hubbard,P.M. "Approximating polyhedra with spheres for time-critical collision detection". ACM Transactions on Graphics(TOG), 1996, 15(3): p179-210
[35]潘振宽,崔树娟,张继萍等. "基于层次包围盒的碰撞检测方法".青岛大学学报, 2005, 18(1): p71-76
[36] M.LeDuc, S.Payandeh, J Dill. "Toward modeling of a suturing task". Graphics Interface Proceedings, 2003, p273-279
[37] Andrew Ladd. "Simulated Knot tying". In: Proceedings of the 2002 IEEE International Conference on Robotics and Automation, Washington DC, 2002, 1: p841-846
[38] J Lenoir, P Meseure, L Grisoni, C Chaillou. "A suture Model for surgical Simulation". ISMS 2004, LNCS 3078, 2004, p105-113
[39] J Lenoir, P Meseure, L Grisoni, C Chaillou. "Surgical thread simulation". Modelling and Simulation for Computer-aided Medicine and Surgery(MS4CMS), November 2002, 12(3): p102-107
[40] J Brown, et al. "Real-Time Simulation of Deformable Objects: Tools and Application". The 4th Conference on Computer Animation, 2001, p228-258
[41] J Brown, et al. "Real-Time knot-tying simulation". The Visual Computer, 2004, 20: p165-197
[42] J Brown, S Sorkin, JC Latombe, K Montgometry et al. "Algorithmic tools for real-time microsurgery simulation". Medical Image Analysis, 2002, 6(3): 289-300
[43] J Brown, K Montgometry, JC Latombe, M Stephanides. "A Microsurgery Simulation System". Medical Image Computing and Computer-Assisted Intervention-MICCAI, 2001, 2208/2008: p137-144
[44]董士海. "人机交互的进展及面临的挑战".计算机辅助设计与图形学学报, 2004, 16(1): p1-13
[45] Y.J. Kim, M.A. Otaduy, M.C. Lin, and D. Manocha, Fast penetration depth computation for physically-dased animation. Pro.of the 2002 ACM Siggraph/ Eurographics symposium on Computer Animation, 2002, p23-31
[46]黄鹏飞,顾力栩,张静思,邹岩岩,宋佳思. "虚拟手术中的软组织建模及切割缝合仿真".上海研究生学术论坛, 2007
[2] John Waterworth. "Virtual Reality in Medicine: A Survey of the State of the Art". Report RR-98.02, Department of Informatics, Umea University, Sweden,1998
[3] Satava R.M, Jones S.B. "Current and future application of virtual reality for medicine". In: Proceedings of the IEEE, March, 1998, 86(3), p484- 489
[4] Ursino M, Tasto JL, Nguyen BH, et al. "The first low-cost Intravascular Catheterization Simulator on a PC". In: Proceeding of Medicine Meets Virtual Reality, January, 1999, p360-366
[5] N.Ayache, S.Cotin, et al. "Simulation of endoscopic surgery". Journal of Minimally Invasive Therapy and Allied Technologies(MITAT), July 1998, 17(2): p71-77
[6] Joel Brown et al. "Real-time simulation of deformable objects: tools and application". The Fourteenth Conference on Computer Animation. Proceedings ,2001, p228-258
[7] Nienhuys HW, Frank A. "Supporting cuts and finite element deformation in interactive surgery simulation". In MICCAI 2001, Berlin, 2001, p1458-152
[8] Bruyns C, Montgomery K. "Generalized interactions using virtual tools within the spring framework:Cutting". In Medicine Meets Virtual Reality 2002(MMVR2002), 2001, p23-26
[10]熊岳山,徐帆,王彦臻,谭珂,郭光友. "虚拟膝关节镜手术仿真系统的关键技术研究".国防科技大学学报, 2007, 01期
[11]李晓波,顾力栩,张少霆,郑广超,张静思. "一个用于腹腔镜训练的虚拟手术系统".首届上海研究生学术论坛论文集生物制造与数字化临床工程, 2007, p111-119
[12] J Zhang, L Gu, X Li, et al. "A minimal invasive surgery simulator employing a novel hybrid cutting method". IEEE 6th International Special Topic Conference on ITAB, Tokyo, 2007, p135-138
[13] J Zhang, L Gu, X Li, M Fang. "An Advanced Hybrid Cutting Method with an Improved State Machine for Surgical Simulation". Computerized Medical Imaging and Graphics, 2008, 33: p63-71
[14] J Zhang, L Gu, B Zhu, et al. "A Novel laparoscopic surgery simulator: System and Evaluation". In: Proceedings of the 5th International Conference on Information Technology and Application in Biomedicine, 2008, p467-470
[15] F Xia, S Xiao, L Gu, L Huang, et al. "Real-time and Haptic Suture Simulation". International Symposium on Bioelectronics and Bioinformatics, in press
[16] J Zhang, L Gu, F Huang, et al. "Real-time Cutting and Suture Simulation Using Hybrid Elastic Model". In: Proceedings of the 29th Annual International Conference of the IEEE EMBS Cite International, Lyon, France, August23-26, 2007, p3646-3649
[17] Lin M.C., Canny J.F. "Efficient algorithms for incremental distance computation ". In:Proceedings of the IEEE International Conference on Robotics and Automation ,1991, p1008-1014
[18] Ehmann S.A, Lin M.C. "Accelerated proximity queries between convex polyhedra by multi-level voronoi marching". In: Proceedings IEEE IROS, 2000, 3: p1201-1207
[19] Ehmann S.A.,Lin M.C.. "Accurate and fast proximity queries between polyhedral using convex surface decomposition". In: Proceedings of the Eurographics Conference, Manchester, 2001, p500-510
[20] Gilbert E.G, Johnson D.W, Keerthi S.S. "A fast procedure for computing the distance between objects in three-dimensional space". IEEE Journal on Robotics and Automation, 1988, 4: p193-203
[21] Cohenor D., Solomovic A., Levin D. "Three-dimensional distance field metamorphosis". ACM Transactions on Graphics(TOG), 1998, 17(2): p116-141
[22] Poutrain K, Contensin M. "Dual Brep-CSG Collision Detection for General Polyhedra". In Ninth Pacific Conference on Computer Graphics and Applications, 2001, p124-128
[23] Miller J, Goldman R, "Combining algebraic rigor with geometric robustness for the detection and calculation of conic sections in the intersection of two quadric surfaces". In: Proceedings of ACM Solid Mode ling, 1991, p221-233
[24] Lane J.M., Riesenfeld R.F., "A theoretical development for the computer generation and display of piecewise polynomial surfaces". IEEE Transactions on Pattern Analysis and Machine Intelligence, 1980, 2(1): p150-159
[25] Boyles M., Fang SF. "Slicing-based volumetric collision detection". Journal of Graphics Tools, 1999, 4(4): p23-32
[26] Gibson S.F. "Beyond Volume Rendering: Visualization, Haptic Exploration, and Physical Modeling of Voxel-based Objects". Visualization in Scientific Computing, 1995, p10-24
[27] Moore, Matthew, Wilhelms, Jane. "Collision Detection and ResPonse for Computer Animation". Computer Graphics (SIGGRAPH 88proc.), Aug 1988, 22: p289-298
[28] Bradshow G., Osullivan C.. "Sphere-tree construction using dynamic medial-axis approximation". In: Proceedings of the ACM SIGGRAPH Symposium on Computer Animation, 2002, p33-40
[29] Van den Bergen G. "Efficient collision detection of complex deformable models using AABB trees". Journal of Graphics Tools, 1997, 4(2): p1-14
[30] Ar Sigal, Chazelle B. "Self-customized BSP trees for collision detection". Computational Geometry: Theory and Applications, Feb 2000, 15(1): p91-102
[31] James T.K., Martin H., Joseph S.B., et al. "Efficient collision detection using bounding volume hierarchies of k-DOPs". IEEE Tansactions on Visualization and Computer Graphics, 1998, 4(1): p21-36
[32]魏迎梅,吴泉涌,石教英. "碰撞检测中的固定方向凸包包围盒的研究".软件学报, 2001, 12(7): p1056-1063
[33] Hubbard P.M. "Collision detection for interactive graphics applications". IEEE Transactions on Visualization and Computer Graphics, 1995, 1(3): p218-230
[34] Hubbard,P.M. "Approximating polyhedra with spheres for time-critical collision detection". ACM Transactions on Graphics(TOG), 1996, 15(3): p179-210
[35]潘振宽,崔树娟,张继萍等. "基于层次包围盒的碰撞检测方法".青岛大学学报, 2005, 18(1): p71-76
[36] M.LeDuc, S.Payandeh, J Dill. "Toward modeling of a suturing task". Graphics Interface Proceedings, 2003, p273-279
[37] Andrew Ladd. "Simulated Knot tying". In: Proceedings of the 2002 IEEE International Conference on Robotics and Automation, Washington DC, 2002, 1: p841-846
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