https://scholars.lib.ntu.edu.tw/handle/123456789/78847
標題: | 足跟墊超音波之動態彈性影像 Dynamic Elasticity Sonogram of Plantar Heel Pad |
作者: | 許至淵 Hsu, Chin-Yuan |
關鍵字: | 足跟墊;彈性影像;超音波影像;機械特性;heel pad;elastography;sonogram;mechanical property | 公開日期: | 2005 | 摘要: | 為了探討人體足部組織在活動中,腳後跟足跟墊內組織所扮演的角色,本研究採用CL10-5 26mm超音波探頭,以亮度模式動態影像紀錄立姿下足跟墊內每一層組織的形變,並推估其機械特性。本實驗結合超音波影像系統、足底壓印量測平台、生物力學與視窗化軟體撰寫,建立一個量測腳底彈性影像的方法學,並提供兩種軟組織形變追蹤的演算法:最大色階變化法與K值比例法,以期能有更佳的影像品質。 實驗的結果顯示各組織位置的縱向應變、橫向應變、彈性係數與橫向應變與縱向應變比值,並結合一般常用的參數,如壓縮性指數、勁度、負載應變速率與卸載應變速率,來作為軟組織機械特性的考量。就正常人E值來說,若根據足跟墊內不同深度,粗分成八個區域,由淺至深分別為124.8 (19.7) kPa、119.6 (13.7) kPa、92.6 (32.1) kPa、73.0 (30.6) kPa、62.5 (15.4) kPa、62.2 (14.7) kPa、55.0 (14.1) kPa與58.4 (10.2) kPa,並計算出的足跟墊等效彈性模數為39.5 (7.401) kPa。勁度值、壓縮性指數與負載、卸載應變速率分別為247.5 (58.7) kPa、0.593 (0.008)、0.315 (0.0387) s-1與-0.292 (0.0524) s-1。 在腳足跟墊的組織形態,相較於靠近皮表的微細腔室,接近跟骨的巨腔室有較低的硬度,並以較大的應變減低地面震波對身體的衝擊力。而實驗中發現越高的負載應變速率,其組織會因為遲滯效應而整體都有較大的硬度。另外橫向應變對超音波探頭在腳後跟掃瞄方向來說,在掃瞄跟骨橫向切面時,組織會有比較大的橫向偏移,可能是足跟墊裡的膠原纖維間隔的排列方向不均,且偏移量與邊界條件有關。 A loading-unloading apparatus that combined clinical ultrasound and load cell was built to investigate the mechanical properties of the plantar heel pad tissues in living activities. A 5-10 MHz 26mm compact linear array transducer was used to record the continuous B-mode images of the deformation of the plantar heel pad, and then derive their mechanical properties. Elastography of the plantar heel pad were constructed to investigate the biomechanics during normal walking condition. The boundaries of each layer of the soft tissue were estimated by tracking either by the maximum gradient of gray scale or by the k-value of correlative deformation. Axial strain, lateral strain, elastic modulus, and the ratio of axial strain to lateral strain were computed in various layers of tissues. Compressive index, stiffness, loading and unloading strain rate were taken into account for the quantification of mechanical properties of soft tissues. The elastic modulus of heel pad, at eight different depths calculated, were 124.8 (19.7) kPa, 119.6 (13.7) kPa, 92.6 (32.1) kPa, 73.0 (30.6) kPa, 62.5 (15.4) kPa, 62.2 (14.7) kPa, 55.0 (14.1) kPa and 58.4 (10.2) kPa respectively, which resulted in an equivalent elastic modulus of 39.5 (7.401) kPa. Moreover, the overall stiffness, compressive index, loading and unloading strain rate measured were about 247.5 (58.7) kPa, 0.593 (0.008), 0.315 (0.0387) s-1 and -0.292 (0.0524) s-1 respectively. The macro-chamber near the calcaneus has a lower stiffness than the micro-chamber next to the plantar skin. Under the action of larger strain rate, the macro-chamber reduces shock from ground effectively. Because of hysteresis, the larger loading strain rate, results a steeper slope in stress-strain curve. There is a large lateral deformation in the transverse scanning plane of the calcaneus, and the amount of lateral distortion is affected by boundary condition and the collagen fibrous spacing. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/62367 | 其他識別: | zh-TW |
顯示於: | 應用力學研究所 |
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ntu-94-R92543033-1.pdf | 23.53 kB | Adobe PDF | 檢視/開啟 |
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