超音波導波技術於骨頭性質之模擬

Application of Guided Acousitc Waves for Modeling of Bone Properties

陳致諺(Chih-Yen Chen)

指導教授 ： 楊哲化

國立臺北科技大學/機電學院/機電整合研究所/碩士(2013年)

摘要

骨質疏鬆為一種伴隨人口老化所帶來的疾病，當骨質流失時，對於人體骨頭內部將造成皮質骨厚度減薄且海綿骨密度下降的影響，僅有仰賴儀器的檢測才能得知。目前主要以放射線為原理的儀器來檢測，因此會受到輻射汙染的缺點；另一種安全的檢測方式則是利用超音波，不過目前精確度不足。在近年來文獻中指出，導波對於骨質疏鬆變化的量測上，具有良好效果。
故本研究將以雙層平板理論和雷射超音波技術的實驗方式來相互驗證，將模擬皮質骨厚度減薄與海綿骨密度下降時，探討頻散關係曲線以及附近區域的模態位移場變化。理論將以部分波分析法來推導，獲得等向性與橫向等向性所組成的雙層平板。試片為單層皮質骨與海綿骨的骨頭仿體，和相互組成的雙層結構。實驗則以雷射超音波技術，以雷射激發與超音波縱波探頭接收的方式。
研究結果中，理論模擬與實驗量測的結果趨勢相同。進一步探討當皮質骨厚度減薄時，對於頻散關係曲線中的各個模態將朝向高頻且低相速度方向變化；當海綿骨密度下降時，則各個模態朝向高頻且高相速度方向移動。另外，模態位移場能提供頻散關係曲線上，指定座標軸時的物體內部振動情形，以便用於選擇相對應的探頭達到較佳的量測方式。因此將可依照要量測的皮質骨或海綿骨，針對頻散關係曲線上相對應的單一參數探討，並且選取有變化的區域，觀察其模態位移場來獲得較佳的頻段以及量測方式。藉由這個流程，可提供導波在骨質檢上測量測頻段的選取。

關鍵字

骨質疏鬆 ； 皮質骨 ； 海綿骨 ； 雷射超音波技術 ； 頻散關係 ； 導波

並列摘要

Osteoporosis is the one of diseases with population aging. Bone gradually reduces faster than grows as increment of age, and reducing of bone mass is thickness of cortical bone and density of cancellous bone. Currently, dual-energy x-ray absorptiometry is used to examine, but x-ray affects people’s health. Fortunately, another technique can be provided more safe inspective technique is ultrasound, but accuracy is low, now. Recently, some research find guided wave can measure different bones with osteoporosis.
Therefore, this study is focused in the modeling with single layer and double layer bones phantoms with guided wave on reduction of bone mass. The theoretical model is based on a partial wave analysis with double layer guided wave’s boundary conditions is used to provide numerical calculations. A laser ultrasound technique is used to measure the experiment data.
The results indicate experiment and theory are identical trends in dispersion relations. As a result, this study uses this model to predict the change of osteoporosis. In the other hand, displacement fields provide the vibration of object is much important, too. Hence, Dispersion relations and displacement field can be applied to provide the range of measurement on reduction of bone mass with ultrasonic guided wave technique.

並列關鍵字

Osteoporosis ； Cortical bone ； Cancellous bone ； Laser ultrasound technique ； Dispersion relation ； Guided wave

參考文獻

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