对探针式同轴探头在骨肿瘤微波热疗中电磁场分布的数值模拟分析

目的研究探针式热疗探头在骨肿瘤微波热疗中产生电磁场分布的模拟数值结果。方法取分层柱状结构骨肿瘤模型，将同轴电缆剥掉外导体后构成探针式探头。采用有限元数值分析方法，对不同插入深度及不同尺寸的同轴探头在组织中产生的电磁场进行数值模拟计算。结果当探头外导体的截断面处于组织内部时，辐射能量能较好地集中于被辐射组织中；当探头接近被辐射组织顶端但又不穿透时，可使顶端辐射增强。结论热疗时探头不同的插入深度及规格，可使被辐射组织的电磁场发生相应变化，故在临床微波热疗操作中，应根据肿瘤大小、部位等特性合理选择探头尺寸进行治疗。

Analysis of the simulated electromagnetic field distribution of the insert applicator used in microwave hyperthermia for treating bone tumors

Objective To simulate and investigate th e electromagnetic field distribution of the insert applicator used in microwave hy perthermia for treating bone tumors. Methods Bone t umor model with layered cylindrical shape was made. The applicator was made from a coaxial cable that peeled off the out copper at the end, which were inserted into the cylindrical bone with different depths. The three dimensions finite ele ment method (FEM) was used to calculate the various parameters of the simulated electromagnetic field. Results The electromagnetic energy could be well transmitted into the tissues when the section of the out co pper cutting was embedded in the tissues. The electromagnetic energy to the tiss ue was enhanced when the tip of the applicator got close to but not penetrated t he tissue. Conclusion The intensity of irradiation t o the target tissue was determined by the dimension and depth of insertion of th e applicator. This is very important for the selection of the type and insertion depth of the applicator when using microwave hyperthermia for treating bone tum or in clinical practice.