面向生物磁感应成像的线圈阵列优化与测量方法研究

发布时间：2018-04-24 10:38

本文选题：生物磁感应成像 + 耦合模型　；参考：《南京理工大学》2017年硕士论文

【摘要】：磁感应断层成像技术作为一种新兴的非接触式生物组织成像技术,是当今生物医学工程无损检测的热点之一。针对生物磁感应成像中强背景下有效信号的提取难题,开展面向生物磁感应成像线圈阵列优化和测量方法的研究,以提高测量信号的信噪比。根据电磁感应耦合理论,基于生物EMT检测系统线圈传感器和被测生物组织的电路模型分别对其阻抗特性进行了仿真计算与分析,采用等效电路法建立了生物电磁感应层析成像的谐振能量耦合模型。基于Matlab的数值分析,得出了线圈品质因数、耦合系数、传感器安装个数及位置等参数对耦合模型的影响,确定了激励线圈品质因数为影响传感器及测量系统输出的关键调控因素。针对检测线圈与激励线圈之间的干扰问题,提出了空间阵列四通道生物EMT检测模型,并对该检测模型的特性进行了仿真分析与研究;根据现有的激励传感器参数,基于虚拟正交响应面法对激励传感器的参数进行了仿真优化;基于相关分析方法实验研究了检测线圈传感器的选取与匹配;针对高频成像系统容易受到外界的噪声干扰,引入屏蔽技术,对屏蔽层的关键参数进行了仿真与实验研究,并完成了传感器阵列载体结构的设计及材料选型。设计了生物EMT检测电路,确定了鉴相方法。仿真分析了高频特征下FFT等鉴相算法的鉴相精度与采样率及信噪比之间的关系;分析了检测线圈空场试验下所叠加的噪声特性,采用小波去噪与中值滤波的混合去噪方法可以有效抑制高斯及脉冲干扰。实验研究了低电导率盐溶液空间位置变化、电导率变化及异物干扰对检测系统输出信号的影响,实验结果表明,基于正交差分的空间阵列EMT系统在减小了线圈间的耦合作用下,提高了成像系统的灵敏度,且系统检测线性区间的下限值提高至0.25S/m,在0.60～1.40S/m范围内线性化程度较高;针对旋转测量周期长的问题,进行了旋转测量方法的优化,在均匀被测物下利用多通道线圈数据融合测量可以有效减少检测数据的冗余输出。
[Abstract]:As a new non-contact tissue imaging technique, magnetic induction tomography (MRT) is one of the hot spots in biomedical engineering nondestructive testing (NDT). In order to improve the signal-to-noise ratio (SNR) of biomagnetic induction imaging, the optimization of coil array and the measurement method are studied in order to improve the signal to noise ratio (SNR) of the measured signal. Based on the electromagnetic induction coupling theory, the impedance characteristics of the system are simulated and analyzed based on the circuit model of the coil sensor and the biological tissue of the biological EMT detection system. The resonant energy coupling model of biological electromagnetic induction tomography is established by using equivalent circuit method. Based on the numerical analysis of Matlab, the influence of the parameters such as coil quality factor, coupling coefficient, sensor installation number and position on the coupling model is obtained. The quality factor of the exciting coil is determined as the key control factor affecting the output of the sensor and the measuring system. Aiming at the interference between the detection coil and the excitation coil, a four-channel biological EMT detection model of space array is proposed, and the characteristics of the detection model are simulated and analyzed. Based on the virtual orthogonal response surface method, the parameters of the excitation sensor are simulated and optimized. Based on the correlation analysis method, the selection and matching of the detection coil sensor are studied experimentally. The key parameters of the shield layer are simulated and experimentally studied by introducing the shielding technology, and the design of the sensor array carrier structure and the selection of the material are completed. The biological EMT detection circuit is designed and the phase detection method is determined. The relationship between phase detection accuracy and sampling rate and signal-to-noise ratio (SNR) of FFT equal-phase detection algorithm under high frequency characteristic is analyzed, and the superposition noise characteristic of detection coil in empty field test is analyzed. The mixed method of wavelet denoising and median filtering can effectively suppress Gao Si and pulse interference. The effects of the change of the spatial position of the low conductivity salt solution, the change of the conductivity and the foreign body interference on the output signal of the detection system are studied experimentally. The experimental results show that the spatial array EMT system based on orthogonal difference can reduce the coupling between the coils. The sensitivity of the imaging system is improved, and the lower limit of the detection linear range of the system is raised to 0.25 S / m, and the degree of linearization is higher in the 0.60~1.40S/m range. The rotation measurement method is optimized to solve the problem of long rotation measurement period. The redundant output of detection data can be effectively reduced by using multi-channel coils data fusion measurement under uniform measurement.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R318;TP391.41

【相似文献】