骨板材料參數量測與反算

Measurement and Inversion Calculation of Material and Geometrical Properties of Bone Plate

謝季軒(Chi-Hsuan Hsieh)

指導教授 ： 楊哲化

國立臺北科技大學/機電學院/製造科技研究所/碩士(2013年)

摘要

骨質疏鬆症是一種普遍和日益嚴重的臨床問題，骨質疏鬆症發生會導致在皮質骨(cortical bone)的厚度減薄與海綿骨(cancellous bone)的密度下降，此疾病會造成患者容易因為些微的外力導致骨折。但是骨質疏鬆症的患者多半無法自己得知，只能藉由儀器的檢測來得知。現今的量測儀器主要以雙能量X光吸收儀及超音波骨質密度偵測儀為主。雙能量X光吸收儀雖精確度高，但受測者會受到X光的照射進而吸收到輻射劑量；超音波骨質密度偵測儀無此疑慮，但是此檢測技術主要以時域訊號的變化來判別是否有骨質的流失，所以精確度還無法普遍被信任。此兩種為目前廣泛應用的骨質檢驗技術並無法深入探討骨頭機械性質，因此已有大量的研究投入在骨頭的材料及幾何性質上，本研究主要目的在建立一個骨頭材料機械性質量測技術，本技術主要以超音波導波為基礎，使用遞迴近似勁度矩陣法模擬骨頭之頻散關係，並結合全域最佳化粒子群演算法反算骨頭仿體及骨板之材料及幾何參數。本技術之量測精度經由測試皆能在5%的誤差值以內且穩定度高。
研究中所開發的骨頭機械性質量測技術，其主要特性包括：以非侵入式的情況下進行量測；橫向等向性材料特性適合用於骨頭仿體；全域性粒子群演算法則具有快速收斂與反算多個變數的特性。在研究結果中，比較理論模擬與實驗量測的結果十分吻合，反算結果可以正確的表現出皮質骨仿體厚度減薄的情形以及海綿骨密度的變化影響表現在勁度矩陣係數上。在真實牛骨試片實驗中，反算結果也可明顯得知其材料和幾何參數。未來可以將此非侵入式量測技術，實際應用於骨質疏鬆症的檢測系統中，並且將所得到的結果回饋至骨質疏鬆症的研究中。也期望本量測技術未來不僅能應用在骨質疏鬆的檢測，也能提供實質的幫助在各領域需獲得材料與幾何參數的研究上。

關鍵字

雷射超音波技術 ； 粒子群演算法 ； 骨質疏鬆症 ； 遞迴近似勁度矩陣法

並列摘要

Osteoporosis is a widespread and growing clinical problem, when the osteoporosis happened, the thickness of cortical bone will become thinning; and the porosity of cancellous bone become larger. This disease could make the patient fracture easily, but most of osteoporosis patients wouldn’t know the osteoporosis happened, they just can get the information from detection equipments. Dual Energy X-ray Absorptiometry (DEXA) and Broadband Ultrasound Attenuation (BUA) are the most common detection equipments in the world. The DEXA has high accuracy, but the patient will be contaminated by X-ray. The BUA doesn’t has this disadvantage but it detected from time domain, so it has lower accuracy than DEXA.
The purpose of this study is building a material characterization elevated platform. This platform based on the laser ultrasonic technique. It uses recursive approximate stiffness matrix method to simulate the dispersion of bone phantoms, and combines the particle swarm optimization method to inversion calculate for different material parameters of bone phantoms. Through the accuracy testing, the several times of inversion calculates from the same data, comparing the inversed results with the measuring results are under the 8% from Decrease.
Through the platform, the dispersion of bone phantoms are totally consistent. In different thickness of cortical bone phantoms, the variations of thickness are shown on the inversed results. The elastic modulus of cancellous bone phantoms increasing accompany with the density increasing. The material property of the specimens from the same bovine bone are similarly by the platform. The density of raw bovine bone increases by cooking, caused the longitudinal and transverse elastic modulus decreased, but there aren’t effect on the longitudinal and transverse Poisson's ratio. This measuring platform is building on the transversely isotropic material, the researcher can get the material and geometry property by non-contact and non-destructive measurement. This platform is potentially useful to probe the material characterization in a nondestructive way.

並列關鍵字

Laser-ultrasonic ； Particle swarm optimization ； Osteoporosis ； Recursive approximate stiffness matrix method

參考文獻

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