本文選題：磁聲信號(hào) + 特征分析��； 參考：《北京協(xié)和醫(yī)學(xué)院》2017年碩士論文

【摘要】：磁聲成像(Magnetoacoustictomography,MAT)是一項(xiàng)結(jié)合了電磁成像高對(duì)比度與超聲成像高空間分辨率的新型組織電特性功能成像技術(shù)。MAT通過(guò)檢測(cè)組織基于洛倫茲力產(chǎn)生的磁聲信號(hào)重建電導(dǎo)率分布。分析磁聲信號(hào)的特性具有重要意義。本文基于優(yōu)化的MAT系統(tǒng),針對(duì)不同材料不同實(shí)驗(yàn)條件下的磁聲信號(hào)進(jìn)行了時(shí)頻特征分析,主要從激勵(lì)源特性、靜磁場(chǎng)條件、聲換能器特性、樣本特性等方面對(duì)磁聲信號(hào)進(jìn)行了研究。首先,針對(duì)MAT的實(shí)驗(yàn)系統(tǒng)平臺(tái)進(jìn)行了優(yōu)化和測(cè)試,提高了系統(tǒng)的信噪比,確保了實(shí)驗(yàn)的準(zhǔn)確性、可靠性和穩(wěn)定性。其次,通過(guò)對(duì)不同樣本磁聲信號(hào)的特征分析和研究,發(fā)現(xiàn)生物組織和類生物組織在靜磁場(chǎng)為零的條件下,仍有與磁聲理論不符的聲信號(hào)產(chǎn)生,說(shuō)明該類組織信號(hào)中包含大量非磁聲信號(hào)。再次,設(shè)計(jì)實(shí)驗(yàn)對(duì)該非磁聲信號(hào)特性進(jìn)行了系統(tǒng)的分析,實(shí)驗(yàn)得出產(chǎn)生該信號(hào)的非洛倫茲力聲源為矢量源、且與激勵(lì)強(qiáng)度二次正相關(guān),與組織電導(dǎo)率和硬度參數(shù)線性正相關(guān),結(jié)合實(shí)驗(yàn)條件及理論模型,推斷該非磁聲信號(hào)為熱聲信號(hào)�；贛AT與TAT(Thermoacoustictomography,TAT)理論,分別對(duì)不同材料的磁聲信號(hào)及熱聲信號(hào)進(jìn)行了仿真研究及對(duì)比分析,仿真結(jié)果進(jìn)一步驗(yàn)證了實(shí)驗(yàn)結(jié)論。本文通過(guò)分析不同材料不同實(shí)驗(yàn)條件下聲信號(hào)的特性,發(fā)現(xiàn)了不同類材料樣本磁聲信號(hào)的特點(diǎn),探究了在生物組織與類生物組織中占優(yōu)的非洛倫茲力聲源特性,為進(jìn)一步提高M(jìn)AT重建質(zhì)量,優(yōu)化MAT理論及實(shí)驗(yàn)方法提供了新思路。
[Abstract]:Magnetoacoustic tomography (MAA) is a new functional imaging technique combining high contrast of electromagnetic imaging and high spatial resolution of ultrasonic imaging. Mat reconstructs conductivity distribution by detecting the magnetoacoustic signal generated by Lorentz force. It is of great significance to analyze the characteristics of magnetoacoustic signals. Based on the optimized mat system, the time-frequency characteristics of magnetoacoustic signals under different experimental conditions are analyzed. The characteristics of excitation source, static magnetic field and acoustic transducer are analyzed. The magnetoacoustic signals are studied in the aspects of sample characteristics. Firstly, the experiment platform of mat is optimized and tested to improve the signal-to-noise ratio of the system and ensure the accuracy, reliability and stability of the experiment. Secondly, by analyzing and studying the characteristics of magnetoacoustic signals from different samples, it is found that under the condition of zero static magnetic field, there are still acoustic signals which are inconsistent with the magnetoacoustic theory. It shows that this kind of tissue signal contains a large number of non-magnetoacoustic signals. Thirdly, the characteristics of the non-magnetoacoustic signal are systematically analyzed. The non-Lorentz force source is a vector source, which is positively correlated with the excitation intensity, and has a linear positive correlation with the structure conductivity and hardness parameters. According to the experimental conditions and theoretical model, the nonmagnetoacoustic signal is deduced to be thermoacoustic signal. Based on the theory of mat and tat, the magnetoacoustic signals and thermoacoustic signals of different materials are simulated and analyzed respectively. The simulation results further verify the experimental results. By analyzing the characteristics of acoustic signals under different experimental conditions of different materials, the characteristics of magnetoacoustic signals in different material samples are found, and the characteristics of non-Lorentz force sources which are dominant in biological and biomedical tissues are explored. It provides a new idea for improving the quality of mat reconstruction and optimizing the theory and experimental method of mat.
【學(xué)位授予單位】：北京協(xié)和醫(yī)學(xué)院
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：R318;TN911.6

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