In vivo measurement of temperature dependent permittivity of tissues in asmall region

利用小型同轴探头、矢量网络分析仪和射频电源，发展了一种测量小区域组织介电常数随温度变化的新方法。研制的同轴探头不仅可用于介电常数的测量，还可用于测量小范围内的升温。根据在不同温度下测得的复介电常数，计算了介电常数的温度系数。在整个研究过程中，我们取得了以下成果。明确了同轴探头的测量范围。研制了配备四个小型温度传感器的同轴探头，用于小范围介电常数测量和产热。开发了同轴探头下温度分布的测量方法。4.提出了一种估计测量区域平均温度变化的方法。5.估算的温度系数与用其他方法得到的模拟组织模型的复介电常数温度系数具有很好的一致性。综上所述，我们发展了体内测量组织介电常数温度系数的方法。该方法可用于测量各种组织随温度变化的介电常数。通过微波计算机断层扫描和电磁热疗设备的控制，利用关于温度相关性的信息来进行无创温度映射。

A new method for measuring the temperature dependence of tissue permittivity in the small region has been developed by use of the small coaxial probe, vector network analyzer, and RF power source. The developed coaxial probe is used not only for permittivity measurement but also for increasing temperature in the small region of measurement. Temperature coefficients of the permittivity are calculated from complex permittivity measured at different temperatures. Throughout the research, we have obtained the following results.1. Region of the measurement by the coaxial probe has been clarified.2. The coaxial probe equipped with four small temperature sensors has been developed for permittivity measurement and heat generation in the small region of interest.3. The measuring method of the temperature distribution under the coaxial probe has been developed.4.We have proposed a method to estimate the average temperature change in the region of measurement.5.The estimated temperature coefficients show a good agreement with temperature coefficients of complex permittivity of the phantom model of simulated tissues obtained by the other method.In conclusion, we have developed the method for in vivo measurement of temperature coefficient of the tissue permittivity. The method can practically be used for measuring temperature dependent permittivity of various tissues. Information on the temperature dependence is utilized for non-invasive temperature mapping by the microwave computed tomography and control of electromagnetic hyperthermia equipments.