高频率微波信号对微波消融效果影响的仿真研究

生物体的介电常数能反映其对微波频率的响应程度,相同微波频率下,不同生物组织的介电常数存在差异,在不同频率的微波消融过程中,微波对消融对象的材料选择性也存在差异性。参照乳腺癌结构建立肿瘤、脂肪相接的生物模型,对比研究高频率微波(6、12、18 GHz)和传统微波(915、2 450 MHz)的消融特性,讨论高频率微波信号在微波消融领域应用的可行性。模拟结果显示,当消融时间达到600 s时,微波频率为12 GHz对正常组织损伤最少,相比正常组织误杀范围最大的2 450 MHz小61.6%;当肿瘤区域达到100%消融时,微波频率为6 GHz对正常组织损伤最少,相比正常组织误杀范围最大的2 450 MHz小71.4%;当肿瘤边缘温度达到52℃时,微波频率为18 GHz时肿瘤边缘两侧温差最大,6 mm区域内最大温差达111.2℃,相同区域内2 450 MHz温差仅为40.1℃。模拟结果表明,高频率微波对介电常数较高的肿瘤组织材料选择性较强,相对于传统的915和2 450 MHz的微波消融,高频率微波具有对周围正常组织的损伤低、消融范围集中的优点。

The Simulation of High Frequency Microwave Ablation Effect

The permittivity of biological tissue can show the reaction on difference microwave frequency. Different tissue shows different permittivity under the same microwave frequency radiation, and the same tissue has different permittivity under different microwave frequency radiation. A numerical model reference to breast cancer was built to study the ablation difference between high frequency microwave (6 GHz, 12 GHz, 18 GHz) ablation and traditional microwave (915 MHz, 2 450 MHz) ablation and the clinical feasibility of high frequency microwave ablation was discussed. Simulation results showed that the 12 GHz microwave ablation caused the least damage to the normal tissue, which was 61.6% less than that caused by 2 450 MHz microwave ablation. The latter caused the most damage to the normal tissue when melting time was 600 s. The 6 GHz microwave ablation caused the least damage area in the normal tissue, which was 71.4% less than that caused by the 2 450 MHz microwave ablation. The latter caused the most damage to the normal tissue when the tumor tissue was damaged completely. When the temperature of tumor edge reached 52℃, the maximum difference of temperature was 111.2℃ in the 18 GHz microwave ablation, however, the difference of temperature was only 40.1℃ in the 2 450 MHz microwave ablation. Simulation results suggest that high frequency microwave ablation has advantages of material selection, less damage to the normal tissue, and more concentrated ablation area.