生物介质中水冷式双缝微波偶极子的比吸收率分布特征研究

SAR DISTRIBUTION CHARACTERS FOR A WATER-COOLED TWO-SLOT MICROWAVE DIPOLE RADIATOR IN A BIOLOGICAL MEDIUM

微波辐射器在生物介质中近场辐射特性对腔道肿瘤热疗有重要实用意义 .根据电磁场理论模型和迭加原理 ,采用高斯积分法和辛普森积分法相结合 ,计算了水冷式双缝隙微波偶极子辐射器在生物介质中的比吸收率 (SAR)分布 ;分析了比吸收率分布随两缝隙间距变化的特征关系 .结果表明 ,适当选择缝间距离 (如等于 1/ 4～ 1/ 2波长 ) ,双缝辐射器不仅在径向 ,尤其在轴向可比单缝具有更为平坦的 SAR分布 ,从而可获得更大的有效治疗空间 .计算结果与相应的等效肌肉体模实验及热疗临床经验相符 。

It is very important to know the near field properties of a radiating dipole antenna for intracavitory microwave hyperthermia.In this paper,an insulated,water-cooled two-slot dipole radiator in a biological tissue,is analyzed with a theoretical electro-magnetic model by using the additivity principle.The SAR (specific absorption rate) distributions are calculated in view of the effect of the water flowing inside the applicator,and compared with each other in different slot-slot distances.It is shown that,the SAR distribution will be uniformally improved on the extension of the therapy depth by suitably selecting the distance of the slot-slot as to λ/4～λ/2(λ:wave length).Therefore,the heat power can be increased,and the coresponding effective therapeutic volume will be larger than that of the water-cooled one-slot dipole.The numerical calculation results are in comformity with the results of the equivalent muscle phantom experiment and the clinical engineering.