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注入電流式磁聲耦合成像實驗研究

發(fā)布時間:2018-03-30 16:39

  本文選題:注入式 切入點:磁聲耦合 出處:《北京協(xié)和醫(yī)學(xué)院》2012年碩士論文


【摘要】:長期以來,生物組織電特性研究引起了多個領(lǐng)域?qū)<业膹V泛關(guān)注。研究顯示,不僅生物組織電特性差異大,且組織和器官的電特性隨其功能狀態(tài)而改變,故組織電特性成像可反映人體生理、病理狀態(tài)及其變化。利用無損技術(shù)檢測生物組織的電特性對臨床診斷,尤其是癌癥的早期診斷具有重要意義。 注入式磁聲耦合成像是對組織電特性無損檢測的一種方法,其原理為將被測生物組織置于穩(wěn)恒磁場中,并對其施加脈沖電場,組織內(nèi)的離子在正交的磁場和電場作用下將受到洛倫茲力作用,力致振動發(fā)射聲波,在組織周圍放置聲傳感器檢測聲響應(yīng)信號即可了解組織內(nèi)部的電特性信息。 本文旨在對注入式磁聲耦合成像進(jìn)行簡單模型仿真和實驗研究。在仿真研究中分別建立了圓形環(huán)、同心圓環(huán)、有孔圓片模型,借助有限元分析軟件仿真模型中施加于其上的電流密度分布,并計算求得聲振動源分布及空間聲場分布。 實驗研究中,本文首先對不同激勵脈沖作用下產(chǎn)生的磁聲信號進(jìn)行研究,選定正弦脈沖信號為實驗研究的激勵信號。當(dāng)探頭在某一位置沿不同角度采集磁聲信號時,信號強度存在差異,探頭旋轉(zhuǎn)一定角度后信號較為微弱。對不同形狀模型下產(chǎn)生的聲信號進(jìn)行檢測和分析,證明了磁聲耦合效應(yīng)用于組織電特性成像的可行性。選用電特性與生物組織接近的凝膠作為實驗對象,產(chǎn)生的聲信號較為微弱但可反映出樣本邊界信息。聲信號采集實驗中信號頻段為1MHz量級,能有效避免外界低頻噪聲干擾,信號的信噪比較高。在成像實驗研究中,通過旋轉(zhuǎn)探頭和沿圓周運動掃描樣本采集數(shù)據(jù),用直接反投影方法重建圖像可以反映出樣本的基本形狀。 本文通過不同實驗?zāi)P蛯Υ怕曬詈铣上襁M(jìn)行聲信號檢測及初步成像研究,取得較好實驗結(jié)果,對磁聲耦合成像的深入研究也具有重要意義。
[Abstract]:For a long time, the study of electrical properties of biological tissue has attracted wide attention of many experts.Nondestructive detection of electrical properties of biological tissues is of great significance for clinical diagnosis, especially for early diagnosis of cancer.Injection magnetoacoustic coupling imaging is a method for nondestructive detection of the electrical properties of tissues. The principle is to place the tested biological tissue in a steady magnetic field and to apply a pulsed electric field to it.The ions in the tissue will be subjected to Lorentz force under the action of orthogonal magnetic field and electric field. The acoustic response signals can be detected by placing sound sensors around the tissue to understand the electrical characteristics of the tissue.In this paper, the simple model simulation and experimental study of injection magnetoacoustic coupling imaging are carried out.In the simulation research, the circular ring, the concentric ring and the perforated disk model are established respectively. The distribution of the current density applied to the circular ring, the concentric ring and the perforated circular ring is obtained by means of the finite element analysis software, and the distribution of the acoustic vibration source and the spatial sound field are obtained by means of the finite element analysis software.In the experimental research, the magnetoacoustic signals produced by different excitation pulses are studied firstly, and the sinusoidal pulse signals are selected as the excitation signals in the experiment.When the probe collects the magnetoacoustic signal at different angles at a certain position, the signal intensity is different, and the signal is weak after the probe rotates at a certain angle.The acoustic signals generated by different shape models are detected and analyzed, which proves the feasibility of magnetoacoustic coupling effect in the imaging of tissue electrical characteristics.The gel which is close to the biological tissue is chosen as the experimental object. The acoustic signal produced is weak but it can reflect the sample boundary information.In the acoustic signal acquisition experiment, the signal frequency band is of the order of 1MHz, which can effectively avoid the external low-frequency noise interference, and the signal-to-noise ratio of the signal is high.In this paper, the sound signal detection and preliminary imaging of magnetoacoustic coupling imaging are studied by different experimental models, and good experimental results are obtained, which is also of great significance to the further study of magnetoacoustic coupling imaging.
【學(xué)位授予單位】:北京協(xié)和醫(yī)學(xué)院
【學(xué)位級別】:碩士
【學(xué)位授予年份】:2012
【分類號】:R310

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