臺灣博碩士論文加值系統

　　本篇論文主要在提供一種新的模擬思維應用在腹腔鏡手術模擬中，以建構曲面的方式取代原本建立實體模的方式。藉由提供新的建構斯維應用在模擬器上，期進一步能應用在醫學教育上，讓醫師更能接受好的訓練。

　　建構曲面的方式來做內視鏡手術模擬有許多優點；其一，更貼近於實際內視鏡手術的狀況。實際內視鏡手術時，因為人體內被灌入了CO2，從內視鏡中並不容易看到器官的全貌。在個手術過程中，醫師憑著經驗切開一層層的組織，而運用多層次的曲面來模擬人體內一層層的薄膜，更貼近於實際手術運作的情形；其二，曲面建構可以降低電腦的運算，增進模擬的即時性。實體模在運算上會耗費龐大的電腦資源，故一般都是在專門電腦上做運算。而改用曲面建購的方式來做模擬，可以降低電腦運算量。

　　在本篇論文中，以單層的曲面做模擬，達到碰撞與裂開的物理呈現。過程中，使用者可藉由滑鼠的控制，操控手術刀的動；在3D的虛擬空間中，以手術刀觸碰網格，並可對網格進行切割的動作。整個過程中，碰撞的反應以即時地呈現在螢幕上，而修剪的動作礙於運算問題採取觸發式的運作。

　　在將來，單層的網格曲面可延伸為多層次的網格曲面，如此更貼近於真實腹腔鏡手術的情形，而修剪的裂口更可進一步地呈現不同器具的刀痕。

　The objective of this research is to develop an algorithm to simulate the mesh cutting procedure in Laparoscope Surgeries. The new idea is to use mesh to simulate the membranes which surround organs. It is different from some conventional methods, which use solid models to represent organs. However, the virtual solid models are suppressed by the pressure of CO2, which is used to inflate the abdominal wall to generate a dome-shape space for laparoscope surgery. That means doctors cannot see entire organs most of time during the surgical procedures. Therefore, we plan to use mesh to simulate membranes and some surfaces of organs instead of building and simulating entire organ models.

　We use a mesh with 29x29 vertices on the top of several spherical obstacles to model part of human abdominal environment. Vertices of the mesh are affected by four different forces such as spring force, gravity force, damping force, and force from CO2 pressure respectively. Several vertices of the mesh are fixed to avoid the mesh slip away. And then we simulate the cutting procedures by adding extra same vertices at the cutting position. Repeat the same steps along the cutting path until the process stops.

　The algorithm is successfully implemented and proved to be very efficient and fast in laparoscope surgical simulation. It also provides a new way for modeling organs inside human abdominal. The algorithm can be further improved to clothes design and consumer product form design, etc.

　　 　　 　　 　　 　　 　　 　　 　　 LIST
Chapter 1 INTRODUCTION------------------------------------------------------- 1
　　 1.1 Application of the mesh cutting------------------------------------- 1
　　 1.2 Condition of the laparoscope surgical operation--------------------- 2
　　 1.3 Medical education--------------------------------------------------- 3
　　 1.4 Simulators---------------------------------------------------------- 4
　　 1.5 Comparison between simulator and laparoscope operation ------------- 6
　　 1.6 Purpose and idea---------------------------------------------------- 7
Chapter 2 OVERVIEW----------------------------------------------------------- 8
　　 2.1 Mesh cutting-------------------------------------------------------- 8
　　 2.1-1 Cutting methods--------------------------------------------------- 8
　　 2.1-2 Theory----------------------------------------------------------- 15
　　 2.2 Structure of mesh-------------------------------------------------- 17
　　 2.2-1 Physical forces-------------------------------------------------- 18
　　 2.3 Surgical simulator------------------------------------------------- 23
　　 2.3-1 Apprenticeship in medicine--------------------------------------- 23
　　 2.3-2 The function of surgical simulator------------------------------- 23
　　 2.3-3 The classification of simulator---------------------------------- 24
Chapter 3 METHODOGY--------------------------------------------------------- 27
　　 3.1 Idea development--------------------------------------------------- 27
　　 3.2 Internal forces in physical simulation----------------------------- 29
　　 3.3 External forces in physical simulation----------------------------- 29
　　 3.3-1 Pressure computation--------------------------------------------- 30
　　 3.3-2 Force buffer----------------------------------------------------- 31
　　 3.4 Collision detection------------------------------------------------ 33
　　 3.5 Cutting algorithm-------------------------------------------------- 36
　　 3.6 Discussion -------------------------------------------------------- 42
Chapter 4 Simulation program------------------------------------------------ 43
　　 4.1 Program structure-------------------------------------------------- 45
　　 4.1-1 3DMAX output type------------------------------------------------ 45
　　 4.1-2 Reading ASE files------------------------------------------------ 46
　　 4.1-3 Particle structure----------------------------------------------- 48
　　 4.1-4 The stretch spring’s structure---------------------------------- 49
　　 4.1-5 The shear spring’s structure------------------------------------ 49
　　 4.1-6 The bending spring’s structure---------------------------------- 50
　　 4.1-7 Physical force computation--------------------------------------- 51
　　 4.1-8 Stretch force computation---------------------------------------- 52
　　 4.1-9 Shear force computation------------------------------------------ 53
　　 4.1-10 Bending force computation--------------------------------------- 54
　　 4.1-11 Pressure computation-------------------------------------------- 56
　　 4.1-12 Action force computation---------------------------------------- 57
　　 4.1-13 Collision detection--------------------------------------------- 59
　　 4.1-14 Cutting--------------------------------------------------------- 62
　　 4.2 Simulation system ------------------------------------------------- 69
　　 4.2-1 Software--------------------------------------------------------- 69
　　 4.2-2 Hardware--------------------------------------------------------- 69
　　 4.3 Computer graphics simulation--------------------------------------- 70
　　 4.3-1 Tool model------------------------------------------------------- 70
　　 4.3-2 Effect of the pressure------------------------------------------- 71
　　 4.3-3 The collision detection------------------------------------------ 74
　　 4.3-4 Cutting slash---------------------------------------------------- 77
Chapter 5 Conclusion and discussion----------------------------------------- 79
　　 5.1 Results------------------------------------------------------------ 79
　　 5.2 The contribution of the research----------------------------------- 79
　　 5.3 Question and discussion-------------------------------------------- 80
　　 5.4 Future work-------------------------------------------------------- 81
　　 5.4-1 Numerical method------------------------------------------------- 81
　　 5.4-2 Collision detection---------------------------------------------- 81
　　 5.4-3 Cutting slash---------------------------------------------------- 82
　　 5.4-4 Mesh------------------------------------------------------------- 82

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