血流流速是一評估健康程度的重要指標，而光聲顯微鏡(Photoacoustic Microscopy)為量測活體內血管影像及血流流速之新興工具。光聲顯微鏡之測量訊號的方法:使用脈衝雷射加熱目標物，如紅血球等，因此，相較於傳統之光學顯微鏡，光聲顯微鏡顯然較適合用於活體內觀測。目前文獻中基於光學解析度光聲顯微鏡的流速演算法僅能估算軸向或是橫向單一方向流速，且光聲訊號具有寬頻且無中心頻率的特性，使用傳統運用在M-mode下的都卜勒軸向流速演算法，或是在時域上的使用其正交相行交相關的演算法等皆不適合。在本論文中，我們針對光學解析度光聲顯微鏡光聲訊號的特性，提出了使用蝶狀搜尋(Buttefly Search)之光聲血流流速估計演算法，可同時量測軸向、橫向流速及都卜勒流速方向。透過依據光學解析度光聲訊號數學模型模擬的M-mode訊號來驗證所提出演算法的可行性，並與目前主要的橫向流速以及軸向流速演算法分別比較。此外，我們亦探討包括雷射、超音波探頭等系統端的選擇對所提出流速演算法之影響以及驗證了演算法的抗雜訊能力。

In the litereature, flow estimation algorithms for optical resolution photoacoustic microscopy (ORPAM) only provide single-axis flow velocity estimation – either lateral or axial velocity estimation. In this study, according to the charcteristics of ORPAM photoacoustic flow signals, we propose a novel photoacoustic flow estimation algorithm using the butterfly search technique which allows the simultaneous estimation of both axial flow velocity and lateral flow rate. Here, the feasibility of the proposed method is verified via the M-mode simulation based on OR-PAM photoacoustic signal model, and the performance of the proposed method is compared with that of the conventional axial and lateral velocity estimators. The influence of the ORPAM system parameters such as the number of laser pulses and types of the ultrasound transducers on the performance of the proposed method is also discussed. In addition, the insusceptibility of the proposed method to the noise is also demonstrated.

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