与人体接触波导探头微波反射特性的 FDTD 分析

采用ＦＤＴＤ法分析开口矩形波导探头直接与人体表层接触时的微波反射特性及皮下肿瘤的存在对其反射特性的影响。人体组织采用简化的双层模型，由外皮肤层和半无限大脂肪层组成，脂肪层中的肿瘤则近似看成球状物。鉴于肿瘤组织和正常组织介电特性的差异性，皮下组织介电特性的变化可以通过测量反射系数反映出来。分析了肿瘤大小和深浅对探头反射系数灵敏度的影响。数值结果表明，反射系数对肿瘤的存在是非常敏感的，据其可以确定肿瘤存在的位置。该方法可应用于皮下肿瘤尤其是乳腺癌的普查和早期诊断。

FDTD ANALYSIS OF THE MICROWAVE REFLECTION CHARACTERISTICS OF A BODY_CONTACTING WAVEGUIDE PROBE

Microwave reflection characteristics of an open_ended rectangular waveguide probe in direct contact with a bilayered biological tissue is analyzed by the FDTD method.Two_layer tissue model consisting of an outer thin skin layer over a semi_infinite fat layer is adopted.A spherical tumor with the difference permittivity from the surrounding normal fat tissue is assumed to exist inside the fat tissue.It is well known that the difference of the permittivity between the tumor and the normal fat tissue can be detected through microwave reflection measurement.Microwave reflection characteristics of the probe determined for tumors of various sizes and depths are also discussed.Numerical results show that the position of the tumor can be determined by measuring the reflection of the probe.This technique can be applied to general examination and early diagnosis of the subcutaneous tumor especially of the breast cancer.