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  • 學位論文

多層板導波應用於骨質疏鬆症之探討

An Investigation on Osteoporosis Based on Guided Waves Propagation in Multilayered Media

指導教授 : 楊哲化

摘要


人口老化問題日漸嚴重,其中以骨質疏鬆症最為普及。當骨質流失會導致皮質骨(cortical)厚度減薄與海綿骨(cancellous)孔隙率上升。目前仰賴雙能量x光吸收儀與定量超音波儀器檢測,雙能量x光吸收儀的x光是放射線,對於人體會造成輻射傷害,此外機器昂貴且龐大導致量測費用高和機動性不佳。定量超音波儀器只用於篩檢,精準度低,原因可能為軟組織(soft tissue)影響,降低準確度。   故本研究透過多層結構模擬骨質流失之情況,利用導波傳遞於雙層結構仿體骨板,分別為皮質骨與海綿骨仿體,利用水模擬軟組織層,建立多層結構的理論解,獲得多層結構的頻散曲線關係。皮質骨以橫向等向性材料模擬,海綿骨與軟組織以等向性材料模擬,理論利用遞迴近似勁度矩陣法(recursive asymptotic stiffness matrix method, RASM)建立多層結構。實驗部分以雷射超音波激發導波與探頭接收的方式。   研究結果中以部分波分析法(partial wave analysis)和實驗驗證遞迴近似勁度矩陣法的正確性,觀察軟組織對於頻散關係曲線的影響。在實驗接收的部分利用雙層結構的位移場對於實驗值的訊號接收做探討,位移量變化大,訊號接收佳。 之後對於骨質疏鬆症做參數探討,皮質骨減薄,頻散關係曲線模態朝向高頻且低相速度方向偏移;海綿骨密度下降,頻散關係曲線模態往高頻且高相速度方向偏移。進一步探討孔隙率,從實驗試片發現孔隙率上升,頻散關係曲線模態往低頻且低相速度方向偏移。透過軟組織的加入以及針對參數同步變化,期望在未來能夠在判別骨質疏鬆症中高準確性,應用於骨質疏鬆症的檢測。

並列摘要


Age population is more and more serious, and the most popular disease is Osteoporosis. Bone gradually reduces faster than grows as increment of age, and reducing of bone mass is thickness of cortical bone and increase the porosity of cancellous bone. Dual-energy x-ray absorptiometry and quantitative ultrasonic Instrument are used to examine, but x-ray affects people’s health. The Dual-energy x-ray absorptiometry is also expensive and huge. Quantitative ultrasonic Instrument only use for screening and accuracy is low. Maybe effect by the “ Soft tissue ” Therefore, this study is focused in the modeling with Multilayers to simulation on reduction of bone mass. Double layer bones phantoms with guided wave and using water to modeling soft tissue layer to discuss the dispersion relation. Cortical is transverse isotropic material, cancellous is isotropic material. The theoretical model is based on recursive asymptotic stiffness matrix method with Multilayers guided wave’s boundary conditions is used to provide numerical calculations. A laser ultrasound technique is used to measure the experiment data. The results verify experiment and partial wave analysis are identical trends in recursive asymptotic stiffness matrix method, obverse the soft tissue influence on dispersion relation. Double layers displacement field is discussion for the experiment data receiving. More displacement is getting more experiment data. As a result, this study uses this parameter variable in model to predict the change of osteoporosis. Hope that this research in the study can use on Osteoporosis and have the high accuracy in the future.

參考文獻


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