本文選題：微創(chuàng)虛擬血管手術(shù)　切入點：血管三維重建　出處：《大連理工大學》2015年碩士論文

【摘要】：微創(chuàng)虛擬血管手術(shù)仿真系統(tǒng)結(jié)合了計算機圖形學、現(xiàn)代醫(yī)學和虛擬仿真技術(shù),通過對微創(chuàng)血管手術(shù)的模擬,為很多臨床醫(yī)生和實習生再現(xiàn)出了一個真實的手術(shù)場景,不但提高了用戶的手術(shù)技能,同時大大減少手術(shù)誤差。在保證安全的基礎上,微創(chuàng)虛擬手術(shù)系統(tǒng)應為手術(shù)過程提供足夠真實性的同時,還應使醫(yī)生能自然和本能地控制工具的運動,充分利用其固有的感覺和反應能力,發(fā)揮其熟練手術(shù)技能。這就要求系統(tǒng)具有高臨場感。為了解決仿真逼真性低、行為模型不夠完善以及實時性和準確性相矛盾的問題,本文以腹主動脈血管為研究對象,對微創(chuàng)虛擬血管手術(shù)仿真系統(tǒng)中的三維模型重建、幾何模型的優(yōu)化、物理形變模型仿真、實時碰撞檢測等關鍵技術(shù)進行了研究,研究主要內(nèi)容概括如下：(1)血管的三維幾何構(gòu)建是微創(chuàng)虛擬血管手術(shù)系統(tǒng)的基礎,本文針對血管造影圖像對比度不均衡和血管邊界模糊的問題,采用Mimics 15.0 (Materialise公司,比利時)軟件對血管CT數(shù)據(jù)進行了分割、編輯和三維重建,同時對模型進行了相應的優(yōu)化和檢驗。通過Mimics軟件,采用混合自動分割的方式將血管組織分割出來,并通過空腔填充解決因造影圖像對比度不均勻造成的血管蒙版信息丟失的問題,同時,通過蒙版編輯對血管進行邊界增強并去噪。(2)針對血管壁復雜的組織構(gòu)成,本文采用基于四面體網(wǎng)格的粘彈性有限元模型來模擬血管的形變。由于有限元模型在形變過程中需要進行大量的計算,在保證腹主動脈血管形變模型的精度的同時,結(jié)合真實血管的形變數(shù)據(jù),本文將血管分為線性彈性形變部分和非線性形變部分。同時,本文利用Mimics軟件對有限元的四面體網(wǎng)格進行分析和優(yōu)化,獲得高質(zhì)量的體網(wǎng)格。(3)血管的有限元模型比較復雜,致使其碰撞檢測計算量和計算時間相對較大。為了減少相交測試時間,提高檢測精度,本文提出了基于軸向包圍盒(Aligned Axis Bounding Box, AABB)和離散方向包圍盒(Discrete Orientation Polytopes, K-DOPs)的混合雙層包圍盒碰撞檢測算法。該方法分為粗糙檢測和精確檢測兩個階段,上層(外層)采用AABB快速排出不可能發(fā)生碰撞檢測的幾何集,下層(內(nèi)層)采用K-DOPs較精確地測試可能發(fā)生碰撞的幾何集并檢測出碰撞點。本文通過模擬微創(chuàng)虛擬血管手術(shù)過程中血管與手術(shù)刀相接觸的場景,對血管的形變模型和碰撞檢測進行了檢驗。實驗表明,通過Mimics進行三維重建和模型優(yōu)化,不但提高了重建模型的精度,還極大地提高了建模的速度。改進的血管形變模型以及用Mimics優(yōu)化后的體網(wǎng)格,不但減少了有限元形變求解計算量,同時較精確地描述了血管的形變模型。采用AABB-K-DOPs混合包圍盒有效地減少了計算量,提高了碰撞檢測速率。這為建立高臨場感的微創(chuàng)虛擬手術(shù)系統(tǒng)奠定了堅實的基礎。
[Abstract]:The minimally invasive virtual vascular surgery simulation system combines computer graphics, modern medicine and virtual simulation technology. Through the simulation of minimally invasive vascular surgery, it reproduces a real operation scene for many clinicians and interns.Not only improve the user's surgical skills, but also greatly reduce the surgical error.While ensuring safety, the minimally invasive virtual surgery system should provide sufficient authenticity for the surgical process, while also allowing doctors to control the movement of the tool naturally and instinctively and to take full advantage of their inherent senses and responsiveness,Give play to their skilled surgical skills.This requires that the system has a high sense of presence.In order to solve the problems of low lifelike simulation, imperfect behavior model and contradiction between real-time and accuracy, the three-dimensional model reconstruction in the minimally invasive virtual vascular surgery simulation system is studied in this paper.The key technologies such as geometric model optimization, physical deformation model simulation, real-time collision detection and so on are studied. The main contents of the research are summarized as follows: Three-dimensional geometry construction of blood vessel is the foundation of minimally invasive virtual vascular surgery system.In this paper, aiming at the problems of uneven contrast and blurred boundary of angiography images, Mimics 15.0 Materialise Corporation (Belgium) is used to segment, edit and reconstruct the CT data of blood vessels.At the same time, the model is optimized and tested.By using Mimics software, the vascular tissue is segmented by mixed automatic segmentation, and the problem of missing information of vascular mask caused by uneven contrast of angiography image is solved by cavity filling. At the same time,Aiming at the complex tissue structure of vascular wall, a viscoelastic finite element model based on tetrahedron mesh is used to simulate the deformation of blood vessel.Since the finite element model needs a lot of calculation in the process of deformation, the accuracy of the model is guaranteed, and the deformation data of the real blood vessel are combined.In this paper, blood vessels are divided into linear elastic deformation and nonlinear deformation.At the same time, using Mimics software to analyze and optimize the finite element tetrahedron mesh, the finite element model of high quality volume mesh.In order to reduce the intersecting test time and improve the detection accuracy, a hybrid double-layer bounding box collision detection algorithm based on axial bounding Axis Bounding box (AABB) and discrete bounding box concrete Orientation polytopes (K-DOPs) is proposed.The method can be divided into two stages: rough detection and accurate detection. The upper layer (outer layer) uses AABB to quickly remove the geometric sets which cannot be detected by collision.The lower layer (inner layer) uses K-DOPs to accurately test the geometric set of possible collisions and to detect collision points.In this paper, the deformation model and collision detection of blood vessels were tested by simulating the contact scene between blood vessels and scalpel during minimally invasive virtual vascular surgery.Experimental results show that 3D reconstruction and model optimization through Mimics not only improve the accuracy of the reconstruction model, but also greatly improve the speed of modeling.The improved vascular deformation model and the volume mesh optimized by Mimics not only reduce the computational complexity of finite element deformation solution, but also accurately describe the vascular deformation model.The AABB-K-DOPs hybrid bounding box can effectively reduce the computation and improve the collision detection rate.This has laid a solid foundation for the establishment of a high-sense minimally invasive virtual surgery system.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：R654;TP391.9

【參考文獻】

相關碩士學位論文 前1條

1 王晨;基于物理的柔性管形變建模實時仿真[D];浙江大學;2008年

，

本文編號：1730625