声带麻痹植入手术的有限元仿真模拟

由于外科医生对于声带麻痹植入手术没有有效的预测,手术的失败率较高,因此采用有限元的方法进行术前模拟仿真。通过人体的喉部CT数据,使用Mimics软件提取声带与声门气管三维几何模型,然后导入到ANSYS-Fluent来模拟声带麻痹患者植入手术前后声带振动模式与喉部气流动态耦合特性,分析声门气管表面压力以及气流速度的变化情况。实验结果与临床统计数据进行分析与对比,推断运用有限元分析技术进行声带麻痹植入手术仿真模拟的研究方法合理可行,为手术方案提供了支持。     

人体软组织建模与实时仿真

虚拟手术系统在医学中实时仿真以建立可供手术前规划和手术时参考的虚拟环境.由于人体器官大多由软组织构成,有限元法能够精确地进行软组织几何大变形仿真.加速有限元仿真有多种方法,文章采用基于模态分析的模型约简方法,对软组织有限元模型进行模态分析,将约简子空间中的形变向量重构到原始空间,从而实现软组织实时仿真.实验结果表明,采...     

基于CT图像的肺穿刺术路径规划系统

为了解决传统肺穿刺手术路径规划方法手术并发症风险大、受医师熟练度影响大、无法量化分析手术路径风险等特有的临床问题，设计了一套肺穿刺术最优路径规划方案。首先，基于胸部 CT 图像对胸部重要器官进行图像分割。然后，将手术风险量化为 3 个约束性条件和 6 个目标性条件，用于衡量手术路径的优劣与风险。3 个约束性条件为穿刺深度、重要器官避障、入刺角度，6 个目标性条件为胸壁厚度、肺内穿刺长度、重要器官之间的距离、路径延长线与重要器官之间的距离、皮肤入刺角、胸膜入刺角。最后，设计自适应凝聚层次聚类算法将路径聚类为“簇”，并利用多目标优化方案对聚类中心点进行量化分析，确定肺穿刺最优路径。实验结果表明，自动规划得到的最优路径经医生确认均符合手术要求，且计算得到的最优路径在医生排序中排名均为前 3，证明了本文路径规划方法的合理性与有效性，满足肺穿刺手术路径规划临床需求，可以为医生提供有效的 3 维可视化穿刺路径指导。     

用于三维软组织实时切割的混合凝聚有限元模型

随着近几年来微创外科的迅速发展，虚拟内窥镜手术模拟系统作为手术训练、规划的有效手段，已逐渐成为研究的热点。根据实际手术的需要，虚拟手术系统应该不仅能够实时模拟软组织的变形，而且也同样可以对软组织的切割、缝合操作进行实时模拟。该文提出了一个用于虚拟手术模拟、三维软组织变形以及切割的有限元模型－混合凝聚有限元模型。该模型的显著优点在于其可以在当前的PC机平台上有效地对软组织变形及具有拓扑改变的切割操作进行实时模拟。     

末敏弹旋转伞系统运动建模与仿真研究

结合有限元方法研究了末敏弹旋转伞运动建模及仿真.针对降落伞具有非线性柔性变形的特点,利用粒子系统来构造伞三维模型;建立充气运动的粒子节点动力学模型;通过仿真计算,其结果与实拍伞形运动变化规律基本一致,该仿真为末敏弹旋转伞运动研究提供一种新的思路.     

基于复合模型的软组织变形模拟算法

为满足虚拟手术中软组织变形的精确性和实时性要求,提出一种基于复合模型的软组织变形模拟算法。该复合变形模型包括复合网格的建立,复合网格中粗糙体网格应用有限元模型,精细表面网格应用基于位置动力学模型,通过变形计算流程实现变形模拟。复合模型与传统的有限元模型和基于位置的动力学模型相比,变形的精确性和实时性取得了更好的平衡。通过变形实例,表明复合模型对于实例模型也具有很好的展示效果。     

基于有限元刚架模型的骨架驱动网格变形算法

借鉴刚架结构在力的作用下的变形原理,将线弹性有限元方法应用于网格的变形设计中,结合骨架驱动生物运动的机制和线弹性有限元方法,提出一种运用形函数插值计算网格变形的造型算法.首先通过创建几何模型的低分辨率骨架建立有限元刚架模型,并计算网格模型顶点与梁单元自然坐标间的映射;然后交互地添加边界条件(如固支或铰支)、施加外部载荷...     

实时交互式软组织切割与变形计算模型

为提高虚拟手术模拟的交互性与实时性,提出一种软组织实时切割与变形计算模型.该模型以混合有限元模型为基础,根据手术过程中不同区域的交互特点,利用GPU加速手术区域的切割与变形计算;同时,对非手术区域的软组织因交互而引起的实时变形可通过选择性相乘的方法快速实现.实验结果充分证明,该计算模型可以灵活有效地实现实时软组织的交互切割与变形模拟.     

填料粒子尺寸对聚合物共混体系力学性能的影响研究

聚合物填料的分布、形状、大小对冻胶的力学性能有重要影响,本文应用有限元方法对简化的微观材料结构进行力学分析,建立了聚合物和填料粒子共混的有限元模型。     

利用改进粒子群算法优化ERT有限元模型*

为了提高电阻层析成像正问题计算精度,鉴于不同拓扑结构有限元模型对应的正问题计算精度不同,针对电阻层析成像有限元模型优化的特点,提出一种改进粒子群算法。新算法首先借鉴区间算法与轮盘赌选择生成粒子初始位置,并在算法迭代过程中采取改进精英策略以克服算法早熟收敛。仿真实验结果表明,新算法具有收敛速度快、精度高、稳定性好等优点,满足电阻层析成像有限元模型优化的要求,可有效提高正问题计算精度。     

基于图像形态学的软组织变形测量方法研究

为了准确测量针穿刺过程中的软组织变形,提出了一种基于图像形态学的软组织形 变测量方法。阐述了边缘检测、图像膨胀和腐蚀等算法,获取组织内标识物增强图像。提取标识 物重心位移,并存入测量矩阵M 中。搭建了包括精密运动装置、工业相机、光源和嵌入标识物的 水凝胶假体等组成的组织形变测量平台。实时采集了穿刺过程图像,并利用形态学算法测量了组 织内标识物的位移。经误差补偿后,组织形变测量误差小于0.7 mm。该方法可提高机器人辅助针 穿刺手术精度。     

Simultaneous estimation of elasticity for multiple deformable bodies

Material property has great importance in deformable body simulation and medical robotics. The elasticity parameters, such as Young's modulus of the deformable bodies, are important to make realistic animations. Further, in medical applications, the (recovered) elasticity parameters can assist surgeons to perform better pre‐op surgical planning and enable medical robots to carry out personalized surgical procedures. Previous elasticity parameters estimation methods are limited to recover one elasticity parameter of one deformable body at a time. In this paper, we propose a novel elasticity parameter estimation algorithm that can recover the elasticity parameters of multiple deformable bodies or multiple regions of one deformable body simultaneously from (at least two sets of) images. We validate our algorithm with both synthetic test cases and real patient computed tomography images. Copyright © 2015 John Wiley & Sons, Ltd.     

MRI脑部图像头骨剥离方法研究

头骨剥离是脑组织分割过程中的关键环节.针对传统的MRI脑组织分割中头骨剥离速度较慢,分割精度不高的问题,提出一种基于水平集的头骨剥离方法.首先根据脑部图像灰度特征确定初始分割曲线,然后将曲线看成高维函数的零水平集,最后利用灰度和形态特征控制高维函数水平集演化,通过高维函数的演化确定曲线的演化,使曲线达到待分割图像边缘.对基于水平集的方法和现有的典型方法进行仿真,仿真结果表明该方法在分割精度上有明显提高.实验证明方法可精确地将脑部组织和非脑组织分离,达到头骨剥离的目的.     

生物工程人工生命的科学技术基础

生物工程人工生命的科学技术基础包括材料技术型生物医学工程和组织工程等。文章着重论述材料技术型生物医学工程、组织工程与生物工程人工生命BEAL的关系,并对材料技术型生物医学工程、组织工程、人工组织、人工器官做扼要评述。     

骨组织支架的计算机辅助设计方法综述

随着先进的计算机辅助设计和增材制造技术的快速发展,使得制造具有复杂几何结构的骨组织支架成为可能。根据骨组织支架功能设计要求,从几何形态的角度出发将其结构分为规则性多孔结构和不规则多孔结构两大类,并综述了骨组织支架的设计方法,特别强调了两种适合增材制造的设计方法,即三周期极小曲面(TPMS)和拓扑优化。针对骨组织支架结构设计面临的技术挑战,展望了骨组织支架设计方法的可能发展趋势。     

A polynomial alternative to unbounded environment for tissue P systems with cell division

The standard definition of tissue P systems includes a special alphabet whose elements are assumed to appear in the initial configuration of the system in an arbitrarily large number of copies. These objects reside in a distinguished place of the system, called the environment. Such potentially infinite supply of objects seems an unfair tool when designing efficient solutions to computationally hard problems in the framework of membrane computing, by performing a space–time trade-off. This paper deals with computational aspects of tissue P systems with cell division where there is no environment having the property mentioned above. Specifically, we prove that the polynomial complexity classes associated with tissue P systems with cell division and with or without environment are actually identical. As a consequence, we conclude that it is not necessary to have infinitely many copies of some objects in the initial configuration in order to solve NP–complete problems in an efficient way.     

Wavelets approach for optimal boundary control of cellular uptake in tissue engineering

The control of the uptake of growth factors in tissue engineering is mathematically modelled by a partial differential equation subject to boundary and initial conditions. The main objective is to regulate cellular processes for the growth or regeneration of a tissue within an assigned terminal time. The techniques of basis function expansion and direct state parameterization were employed to yield efficient computational methods for this problem. Using Legendre and Chebyshev wavelets, the optimal control of the lumped-parameter system was transformed into a system of algebraic equations. The computational efficiency and effectiveness of the proposed method are illustrated by numerical examples.     

Differential valine metabolism in adipose tissue of low and high fat-oxidizing obese subjects

Differences in fat metabolism are of importance in relation to energy balance. Low fat‐oxidizers (LFO) are thought to be more prone for developing obesity. We studied whether LFO have different fasting adipose tissue (AT) protein profiles than high fat‐oxidizers (HFO). Six LFO and six HFO subjects were selected from an obese group (n = 99, body mass index>30 kg/m²) taking part in a multi‐center study (Nutrient‐Gene interaction in human obesity) based on the postprandial fat oxidation capacity after a high fat load. AT protein profiles were studied by 2‐DE. Differential proteins were clustered with MAPPfinder according to their function. Protein profiles of purified blood cells and adipocytes served to confine the comparison to adipocyte‐specific proteins in AT profiles of LFO and HFO subjects. LFO had increased mitochondrial ROS scavengers possibly related to long‐chain unsaturated fatty acid‐induced increases in mitochondrial ROS‐production. Carbohydrate oxidation seemed to be reduced since expression of several proteins from the glycolysis pathway was lower in LFO. Up‐regulation of the valine catabolism at the level of methylmalonate‐semialdehyde dehydrogenase appeared to be (part of) the compensatory mechanism. In conclusion, the fasting AT protein profile of LFO and HFO differ at the level of ROS scavenging, the glycolysis pathway and valine metabolism.