北京生物醫(yī)學(xué)工程

一種新的X-wave仿真方法

A novel algorithm of simulation based on X-wave

作者：李雅琴花少炎丁明躍尉遲明

單位：華中科技大學(xué)圖像識(shí)別與人工智能研究所圖像信息處理與智能控制教育部重點(diǎn)實(shí)驗(yàn)室(武漢430074)

關(guān)鍵詞：非衍射波；X-wave；矩形波；三角波

分類號(hào)：

出版年·卷·期（頁(yè)碼）：2012·31·6（586-590）

摘要：

目的 X-wave作為一種典型的非衍射波，具有很強(qiáng)的潛在價(jià)值，在使用有限孔徑傳感器的情況下，能夠在較深的場(chǎng)域內(nèi)保持不發(fā)散的優(yōu)點(diǎn)，比傳統(tǒng)的超聲系統(tǒng)節(jié)省了動(dòng)態(tài)聚焦的計(jì)算過程，能有效提高超聲成像的速度。但X-wave的理論激勵(lì)信號(hào)比較復(fù)雜，導(dǎo)致其在仿真經(jīng)濟(jì)成本和時(shí)間耗費(fèi)過高。基于此，本文提出一種使用矩形波或三角波的簡(jiǎn)單波取代復(fù)雜的激勵(lì)信號(hào)的方法。方法首先使用簡(jiǎn)單波（矩形波和三角波）取代原有的X-wave的激勵(lì)信號(hào)，采用L2的優(yōu)化算法選擇哪一種簡(jiǎn)單波最接近原有的激勵(lì)信號(hào)，再通過計(jì)算空間脈沖響應(yīng)實(shí)現(xiàn)聲場(chǎng)的仿真。結(jié)果聲場(chǎng)仿真結(jié)果顯示，該方法能最大限度減少激勵(lì)信號(hào)的差異，減少X-wave仿真運(yùn)算時(shí)間，并為降低X-wave的硬件成本提供空間。結(jié)論該方法可以在較高精度的前提下顯著降低X-wave的仿真成本，為X-wave的應(yīng)用提供一種新思路。

Objective X-wave is a particular case of limited diffracting waves which has great application potential for field focus depth enlargement in acoustic imaging systems. In practice, the generation of real-time X-wave fields needs complex technologies and expensive hardware which involve precise and specific voltage time distributions for the excitation of each distinct array element. We proposed an approach for simplifying the generation process by approximating the X-wave excitations with rectangular or triangle pulses. Methods Simple driving pulses (rectangular and triangular) are cheap and easy to realize. The differences between theoretical X-wave signals and each driving pulse are minimized by L2 curve criterion separately. The pulse with the minimal optimization result is chosen as the approximation driving pulses. Results Simulation test shows that the new method can achieve more precise results than the original method and is closer to the theoretical X-wave result. The tradeoff is obtained between the cost of implementation of classical zero-order X-wave and the precision of approximation. Conclusions The new approach proposes a low-cost limited-diffraction wave generation and a new idea for the application of X-wave.

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