虚拟手术环境中软组织的快速碰撞检测

针对虚拟手术中软组织碰撞检测的实时性问题,提出了一种基于延迟更新策略的快速检测方法。该方法应用层次包围盒（BVH）的思想并根据拓扑结构特征来表示手术环境中的对象,同时使用延迟更新的策略来降低更新的计算量。首先用不同的层次包围盒来表示手术工具和手术对象;然后利用包围盒的相交测试快速排除不相交部分;再对可能发生碰撞的部分使用更为精确的三角面片相交测试来确定碰撞信息,最后使用延迟更新的策略来完成软组织变形时层次包围盒的更新。实验表明,该方法相较于现有算法在保持检测精度的同时能够有效提高碰撞检测的速度。     

Tumor‐Specific Aptamer‐Conjugated Polymeric Photosensitizer for Effective Endo‐Laparoscopic Photodynamic Therapy

Recent advances in medical technology and endo‐laparoscopic devices have enabled the treatment of gastrointestinal (GI) cancers to be minimally invasive through endo‐laparoscopic photodynamic therapy (PDT). To achieve an efficient regional or endo‐laparoscopic PDT, it is necessary to develop a highly target specific photosensitizer (PS) that can be easily treated to the lesion site with endo‐laparoscopic device. Here, an ideal polymeric PS is demonstrated for effective endo‐laparoscopic PDT. In the synthetic process, conventional PS (i.e., Chlorin e6, Ce6) is conjugated with an Aptamer (i.e., AS1411) targeting nucleolin (also called C23) overexpressed on the cancer cell membrane using a water‐soluble polymeric linker (i.e., polyethylene glycol, PEG). The synthesized Aptamer‐PEG‐Ce6 could target nucleolin‐overexpressing tumor cells efficiently and visualize the tumor tissues through optical and fluorescent imaging both in vitro and ex vivo, and effectively kills cancer cells under laser irradiation. Tumor staining with Aptamer‐PEG‐Ce6 is easily accomplished through endoscopic equipment within a few minutes. Furthermore, after laser irradiation, Aptamer‐PEG‐Ce6 is found to penetrate deeply into the tumor tissue and induce apoptosis of tumor cells. Taken together, the tumor‐specific Aptamer‐conjugated polymeric PS developed in this study has great potential as an ideal photomedicine for effective tumor treatment using endo‐laparoscopic PDT.     

Hand gesture guided robot-assisted surgery based on a direct augmented reality interface

Radiofrequency (RF) ablation is a good alternative to hepatic resection for treatment of liver tumors. However, accurate needle insertion requires precise hand-eye coordination and is also affected by the difficulty of RF needle navigation. This paper proposes a cooperative surgical robot system, guided by hand gestures and supported by an augmented reality (AR)-based surgical field, for robot-assisted percutaneous treatment. It establishes a robot-assisted natural AR guidance mechanism that incorporates the advantages of the following three aspects: AR visual guidance information, surgeon's experiences and accuracy of robotic surgery. A projector-based AR environment is directly overlaid on a patient to display preoperative and intraoperative information, while a mobile surgical robot system implements specified RF needle insertion plans. Natural hand gestures are used as an intuitive and robust method to interact with both the AR system and surgical robot. The proposed system was evaluated on a mannequin model. Experimental results demonstrated that hand gesture guidance was able to effectively guide the surgical robot, and the robot-assisted implementation was found to improve the accuracy of needle insertion. This human–robot cooperative mechanism is a promising approach for precise transcutaneous ablation therapy.     

Real-time advanced spinal surgery via visible patient model and augmented reality system

This paper presents an advanced augmented reality system for spinal surgery assistance, and develops entry-point guidance prior to vertebroplasty spinal surgery. Based on image-based marker detection and tracking, the proposed camera-projector system superimposes pre-operative 3-D images onto patients. The patients’ preoperative 3-D image model is registered by projecting it onto the patient such that the synthetic 3-D model merges with the real patient image, enabling the surgeon to see through the patients’ anatomy. The proposed method is much simpler than heavy and computationally challenging navigation systems, and also reduces radiation exposure. The system is experimentally tested on a preoperative 3D model, dummy patient model and animal cadaver model. The feasibility and accuracy of the proposed system is verified on three patients undergoing spinal surgery in the operating theater. The results of these clinical trials are extremely promising, with surgeons reporting favorably on the reduced time of finding a suitable entry point and reduced radiation dose to patients.     

一种基于逐次逼近法求解软组织力平衡的方法

进行腹腔微创手术操作时,为获得软组织变形的图形反馈,需要进行软组织的力平衡求解.建立了胆囊及其附属管路的几何模型,对其赋予弹簧一质点力学模型,提出了一种基于逐次逼近法的力平衡算法求解软组织力平衡.该算法编程量较少,易于实现,仿真实时性也较好.仿真实验表明,该算法可以产生较为真实的软组织图形反馈,可以实际应用于软组织仿真...     

Surgical robotics: Reviewing the past,analysing the present,imagining the future

This paper presents an overview of the surgical robotics field, highlighting significant milestones and grouping the various propositions into cohorts. The review does not aim to be exhaustive but rather to highlight how surgical robotics is acting as an enabling technology for minimally invasive surgery. As such, there is a focus on robotic surgical solutions which are commercially available; research efforts which have not gained regulatory approval or entered clinical use are mostly omitted. The practice of robotic surgery is currently largely dominated by the da Vinci system of Intuitive Surgical (Sunnyvale, CA, USA) but other commercial players have now entered the market with surgical robotic products or are appearing in the horizon with medium and long term propositions. Surgical robotics is currently a vibrant research topic and new research directions may lead to the development of very different robotic surgical devices in the future—small, special purpose, lower cost, possibly disposable robots rather than the current large, versatile and capital expensive systems. As the trend towards minimally invasive surgery (MIS) increases, surgery becomes more technically demanding for surgeons and more challenging for medical device technologists and it is clear that surgical robotics has now an established foothold in medicine as an enabling technology of MIS.     

基于本体的智能检索及其在泌尿外科中的应用

以本体论作为指导理论,通过研究泌尿外科辅助诊断系统模型,在泌尿外科领域本体的基础上研究语义相似度、语义相关度的计算方法,并提出新的相关度计算方法。该方法可以定量地分析领域本体中的概念间相关度。并通过建立泌尿外科本体,实现基于泌尿外科本体的语义推理。     

改进的三角网格表面近似测地线算法

三角网格表面的测地线计算问题可转化为三角网格表面两点间的最短路径计算问题,为了快速地计算三角网格表面测地线,提出一种基于缩小最短路径搜索区域的三角网格表面近似测地线算法。将三角网格沿坐标系三坐标轴方向进行空间单元划分,使用A*算法求出两点间的最短路径盒子序列,进而得到新的搜索区域,计算三角网格上两点间的最短路径,迭代细分最短路径邻域内的边以构造新的网格求解测地线。实验结果表明,该算法能够快速准确地计算出三角网格表面任意两点间的近似测地线,有效解决大型三角网格上最短路径计算速度慢的问题,计算速度较改进前的算法提高了10倍~59倍。将该算法应用到虚拟肝脏手术系统的区域标定中,可满足虚拟场景中对计算实时性和效果真实性的要求。