虚拟膝关节镜手术中保持单元质量的体网格形变方法

在虚拟膝关节手术中,需要对膝关节进行大范围形变的实时模拟。本文针对四面体网格的膝关节模型,提出了采用LSD度量建立形变能量,然后将带约束的最优化问题转化为不带约束的最优化问题,最后通过带Armijo线性查找的非精确牛顿法求解最优化问题。在求解过程中,通过预估未知点的位置,减少迭代步数,提高了算法的效率。这种方法具有较好的保体积性,同时保证形变后的四面体网格不出现体元翻转和退化。该方法也能推广应用于其它类似的关节弯曲运动的变形中。     

虚拟手术仿真中人体软组织形变技术的研究

对虚拟手术仿真中人体软组织形变技术进行深入研究,利用OpenGL三维图形标准建立了基于质点-弹簧物理模型的虚拟人体软组织形变系统。围绕虚拟手术仿真中人体软组织形变的逼真度和实时性两大要素展开研究,通过对比四边形网格结构提出了改进的基于质点-弹簧模型的正六边形几何拓扑结构,并对软组织形变动力学模型及其数值积分算法、软组织形变力反馈计算模型进行了讨论,针对以往的虚拟手术器械与软组织表面接触时作用点的最近邻质点求取算法存在的不足,提出了改进的求取算法。实验结果表明,改进的算法在模拟软组织形变时具有较好的稳定性和实时性。     

腹腔微创手术机器人末端执行机构的设计和实现

为了提高腹腔微创手术的安全性,设计了一种新型的腹腔微创手术机器人末端执行机构,用于夹持手术器械．根据腹腔微创手术的特点和技术要求,采用轴驱动和平行四杆的运动原理设计定点机构．详细介绍了末端执行机构的机械结构,应用D-H法和矢量代数法给出了各个关节的运动学解公式,研究了控制系统的硬件结构和软件系统,并进行了样机实验．实验表明所设计的末端执行机构具有很好的定点运动效果,能够较好地完成手术规划,满足腹腔微创手术要求．     

CT导航微创外科混联机器人拓扑结构分析

分析了CT导航微创外科手术环境对机器人的特殊要求,提出了一种新型串并混联机器人构型 .详细讨论了机器人的串、并联拓扑结构的设计依据,比较了多种串联微创外科机械臂的结 构类型,明确了串联部分的构型.针对传统并联机构灵活性较小的不足,提出并分析了并联 机构的结构框架,确定了并联部分的结构.基于螺旋理论重点求解了并联机构的位移输出特 征方程及其自由度,同时给出了串联部分的位移输出特征矩阵.通过灵活性仿真,验证了该 机器人可用于CT受限空间的微创外科定位手术.本文对于新型医疗机器人的构型设计提供了 一种理论参考.     

Petromyzontidae-Biomimetic Multimodal Microneedles-Integrated Bioelectronic Catheters for Theranostic Endoscopic Surgery

Current catheter devices in minimally invasive surgery still possess limited functional options, lacking multimodal integration of both sensing and therapy. Catheter devices usually operate outside the tissue, incapable to detect intra-tissue biochemical information for accurate localization and assessment of lesions during surgery. Inspired by the feature and functions of Petromyzontidae, here a multimodal core-shell microneedles-integrated bioelectronic catheter (MNIBC) for tissue-penetrating theranostics in endoscopic surgery is developed. The microneedle (MN) device possesses individually addressable functionality at single-MN tip resolution, enabling multiplex functions (a total of 11 functions distributed in three types of catheters) including biochemical sensing, myoelectric modulation, electroporation, and drug delivery in a submucosal environment. The MNIBC is prepared through hybrid fabrication and dimensionality reduction strategies, where the MN electrodes are functionalized with an MXene-carbon nanotube (MXene-CNT)-based electron mediator, addressing the challenge of reduced electrode sensitivity on ultra-small MN tip. The functionalities of MNIBC are demonstrated both ex vivo and in vivo on anesthetized rabbits via laparoscopy, simulated cystoscopy, and laparotomy. The MNIBC can effectively detect intra-tissue biochemical signals in the bladder, and offers localized electroporation and intra-tissue drug delivery for precise treatments of lesions. The versatile features of the MNIBC present a highly advanced platform for precise surgeries.     

基于姿态编码器的2D/3D脊椎医学图像实时配准方法

2D/3D医学图像配准是骨科手术三维实时导航中的一项关键技术,然而传统的基于优化迭代的2D/3D配准方法需要经过多次迭代计算,无法满足医生在手术过程中对于实时配准的要求。针对该问题,提出一种基于自编码器的姿态回归网络来通过隐空间解码捕获几何姿态信息,从而快速地回归出术中X射线图像对应的术前脊椎位置的3D姿态,并经过重新投影生成最终的配准图像。通过引入新的损失函数,以“粗细”结合配准的方式对模型进行约束,保证了姿态回归的精确度。在CTSpine1K脊椎数据集中抽取100组CT扫描图像进行10折交叉验证,实验结果表明：所提出的模型所生成的配准结果图像与X射线图像的平均绝对误差（MAE）为0.04,平均目标配准误差（mTRE）为1.16 mm,单帧耗时1.7 s。与基于传统优化的方法相比,该模型配准时间大幅缩短。相较于基于学习的方法,该模型在快速配准的同时,保证了较高的配准精度。可见,所提模型可以满足术中实时高精配准的要求。     

Photoacoustic‐Guided Surgery with Indocyanine Green‐Coated Superparamagnetic Iron Oxide Nanoparticle Clusters

A common cause of local tumor recurrence in brain tumor surgery results from incomplete surgical resection. Adjunctive technologies meant to facilitate gross total resection have had limited efficacy to date. Contrast agents used to delineate tumors preoperatively cannot be easily or accurately used in the real‐time operative setting. Although multimodal imaging contrast agents are developed to help the surgeon discern tumor from normal tissue in the operating room, these contrast agents are not readily translatable. This study has developed a novel contrast agent comprised solely of two Food and Drug Administration approved components, indocyanine green (ICG) and superparamagnetic iron oxide (SPIO) nanoparticles—with no additional amphiphiles or carrier materials, to enable preoperative detection by magnetic resonance (MR) imaging and intraoperative photoacoustic (PA) imaging. The encapsulation efficiency of both ICG and SPIO within the formulated clusters is ≈100%, and the total ICG payload is 20–30% of the total weight (ICG + SPIO). The ICG–SPIO clusters are stable in physiologic conditions; can be taken up within tumors by enhanced permeability and retention; and are detectable by MR. In a preclinical surgical resection model in mice, following injection of ICG–SPIO clusters, animals undergoing PA‐guided surgery demonstrate increased progression‐free survival compared to animals undergoing microscopic surgery.     

一种具有力检测机制的新型血管介入手术机器人

为了在机器人辅助远程介入手术中实现向医生提供高精度的力反馈,设计了一种具有力检测机制的新型血管介入手术机器人,其是一个主从控制系统,包括一个操作方便的主端装置和一个递送导丝/导管的从端装置。首先,设计了血管介入手术机器人的力检测机制,以实现轴向近端力的精准测量和径向夹紧力的感知。然后,基于血管介入手术机器人的动力学分析,设计了具有在线整定参数功能的模糊PID (proportional integral derivative,比例积分微分)控制器,以提高从端装置的递送精度和抗干扰能力,同时选择阶跃信号对所设计的模糊PID控制器进行仿真验证。最后,搭建血管介入手术机器人物理样机,并开展主从运动跟踪实验和轴向近端力、径向夹紧力检测评估实验。实验结果表明,该血管介入手术机器人具有[-0.31, 0.25] mm的运动跟踪误差,可检测平均误差为0.12 N的轴向近端力以及可感知0.47～4 N的径向夹紧力。研究结果验证了所设计血管介入手术机器人的鲁棒性以及其力检测机制的可行性,可为同类产品的设计和改进提供参考依据。     

Hands-free administration of subjective workload scales: Acceptability in a surgical training environment

Introduction

Subjective workload measures are usually administered in a visual-manual format, either electronically or by paper and pencil. However, vocal responses to spoken queries may sometimes be preferable, for example when experimental manipulations require continuous manual responding or when participants have certain sensory/motor impairments. In the present study, we evaluated the acceptability of the hands-free administration of two subjective workload questionnaires - the NASA Task Load Index (NASA-TLX) and the Multiple Resources Questionnaire (MRQ) - in a surgical training environment where manual responding is often constrained.

Method

Sixty-four undergraduates performed fifteen 90-s trials of laparoscopic training tasks (five replications of 3 tasks - cannulation, ring transfer, and rope manipulation). Half of the participants provided workload ratings using a traditional paper-and-pencil version of the NASA-TLX and MRQ; the remainder used a vocal (hands-free) version of the questionnaires. A follow-up experiment extended the evaluation of the hands-free version to actual medical students in a Minimally Invasive Surgery (MIS) training facility.

Results

The NASA-TLX was scored in 2 ways - (1) the traditional procedure using participant-specific weights to combine its 6 subscales, and (2) a simplified procedure - the NASA Raw Task Load Index (NASA-RTLX) - using the unweighted mean of the subscale scores. Comparison of the scores obtained from the hands-free and written administration conditions yielded coefficients of equivalence of r = 0.85 (NASA-TLX) and r = 0.81 (NASA-RTLX). Equivalence estimates for the individual subscales ranged from r = 0.78 (“mental demand”) to r = 0.31 (“effort”). Both administration formats and scoring methods were equally sensitive to task and repetition effects. For the MRQ, the coefficient of equivalence for the hands-free and written versions was r = 0.96 when tested on undergraduates. However, the sensitivity of the hands-free MRQ to task demands (η_partial² = 0.138) was substantially less than that for the written version (η_partial² = 0.252). This potential shortcoming of the hands-free MRQ did not seem to generalize to medical students who showed robust task effects when using the hands-free MRQ (η_partial² = 0.396). A detailed analysis of the MRQ subscales also revealed differences that may be attributable to a “spillover” effect in which participants’ judgments about the demands of completing the questionnaires contaminated their judgments about the primary surgical training tasks.

Conclusion

Vocal versions of the NASA-TLX are acceptable alternatives to standard written formats when researchers wish to obtain global workload estimates. However, care should be used when interpreting the individual subscales if the object is to make comparisons between studies or conditions that use different administration modalities. For the MRQ, the vocal version was less sensitive to experimental manipulations than its written counterpart; however, when medical students rather than undergraduates used the vocal version, the instrument’s sensitivity increased well beyond that obtained with any other combination of administration modality and instrument in this study. Thus, the vocal version of the MRQ may be an acceptable workload assessment technique for selected populations, and it may even be a suitable substitute for the NASA-TLX.     

基于影像引导的计算机辅助肝癌微波消融

为了方便临床医生使用医学影像进行手术的规划和引导,提出了一种新颖的计算机辅助肝癌微波消融手术方法.采用基于GPU加速的三维可视化技术实时重构影像的三维模型,显示出患者器官的解剖关系;采用基于生物传热学的三维热场计算技术,规划手术路径及消融设备的作用时间和功率.经过大量的临床应用以及手术影像对比,表明该方法能够有效计算消融手术的作用效果,并在手术的引导过程中发挥了重要的作用,提高了手术的临床精度和效果.