時域有限差分法分析漏溢聲波之針定位

FDTD Analysis of Leaky Acoustic Waves for Needle Positioning

蘇虹瑜(Hong-Yu Su)

指導教授 ： 曾雪峰

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202001257

摘要

臨床醫學中由於人體組織非肉眼可透視，因此經常使用超聲波作為輔助來判斷醫療針在體內的位置，然而超聲波在針體表面的反射作用限制了超聲波探頭與針之間的角度，進而影響手術的自由度以及誤差。本論文以一種利用雷射誘發漏溢聲波的針定位方式作為基礎進行時域有限差分法模型建構，其原理為使用超聲波導波在針體與組織邊界由於介質不匹配產生的漏溢聲波進行針體位置的計算。模擬中利用聲波控制方程式模擬超聲波之傳遞，使用不同型號之醫療針進行定位誤差運算後，更改針壁厚度與針內徑大小與誤差結果進行對比，觀測針體幾何條件對於定位之影響。研究結果顯示使用的針其針壁厚度較厚時，得到的針定位計算誤差值減小，且針與探測器夾角達26∘時計算誤差值上升幅度增加。

關鍵字

時域有限差分法 ； 超聲波 ； 漏溢聲波 ； 完美匹配層

並列摘要

Here we model a needle visualization method based on laser-induced leaky acoustic waves. Guided acoustic waves propagate through the needle and leak into the surrounding medium as leaky acoustic waves which can be detected by the ultrasound (US) transducer. The needle position can be calculated with characteristics of leaky acoustic waves. We analyze the relationship of needle position error and different parameters of needles by employing the two-dimensional finite-difference time domain (FDTD) simulation. It is shown that we get lower needle position error with thicker wall thickness of needle and the insertion angle is up to 26∘.

並列關鍵字

finite-difference time-domain (FDTD) ； ultrasound ； leaky acoustic waves ； perfectly matched layers

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