Gao Xiang, Tian Zhen, Cheng Yanyan, Geng Binghao, Chen Shilin, Nan Qun
College of Life Science and Bioengineering, Beijing University of Technology , Beijing , China.
Jiangsu Caneer Hospital , Jiangsu , China.
Electromagn Biol Med. 2019;38(4):249-261. doi: 10.1080/15368378.2019.1669635. Epub 2019 Sep 26.
Microwave ablation is used to treat lung tumors by releasing microwave magnetic field to produce high temperature of more than 60 ℃ in the tumor tissues, thus causing tissue coagulation, dehydration and necrosis to achieve the purpose of treatment. However, the lack of appropriate power and time parameters for microwave ablation in clinical treatment of lung tumors leads to poor ablation or excessive ablation. In this paper, a two-dimensional simulation model of microwave antenna and ideal lung was established to realize the simulation of microwave ablation process. Meanwhile, microwave ablation experiments were carried out in ex-vivo porcine lung under different power and time. The temperature distribution was obtained by thermocouples and compared with the simulation calculation. Set 60℃ as boundary of the ablation area and the ablation time was 360 s. The length of the ablation area parallel to the antenna direction is longitudinal, and the length perpendicular to the antenna direction is transverse. From the simulation results, with the increase of ablation power (20 W to 60 W), the transverse diameter of ablation area increased from 32.5 mm to 55.6 mm, and the longitudinal diameter increased from 47.8 mm to 69.1 mm. From the results of ex-vivo experiments, with the increase of ablation power (30 W to 50 W), the transverse diameter of ablation area increased from 29.5 mm to 48.9 mm, the longitudinal diameter increased from 41.1 mm to 66.3 mm, and the maximum slot temperature increased from 75.6 ℃ to 106.7 ℃. The results of numerical simulation are slightly larger than those of ex-vivo experiments under the same parameters. When the average diameter of lung tumors is less than 40 mm, 30 W and 40 W ablation power can be selected. The ablation time is limited to 360 s. 50 W ablation power can be used to ablate the lesion quickly in a shorter time to achieve the same purpose. Although there are differences between ex-vivo and in vivo, the validity of the lung model and the influence of ablation parameters in the simulation are verified in this paper. The ablation area under different parameters was obtained, which served as a reference data for clinical practice. A basic study was made to consider the complex lung model and the changes of parameters with temperature in the future.
微波消融通过释放微波磁场使肿瘤组织产生60℃以上的高温来治疗肺部肿瘤，从而导致组织凝固、脱水和坏死以达到治疗目的。然而，在肺部肿瘤临床治疗中，微波消融缺乏合适的功率和时间参数，导致消融效果不佳或过度消融。本文建立了微波天线与理想肺部的二维仿真模型，以实现微波消融过程的模拟。同时，在离体猪肺上进行了不同功率和时间的微波消融实验。通过热电偶获得温度分布，并与模拟计算结果进行比较。设定60℃为消融区域边界，消融时间为360 s。消融区域平行于天线方向的长度为纵向，垂直于天线方向的长度为横向。从模拟结果来看，随着消融功率（20 W至60 W）的增加，消融区域的横向直径从32.5 mm增加到55.6 mm，纵向直径从47.8 mm增加到69.1 mm。从离体实验结果来看，随着消融功率（30 W至50 W）的增加，消融区域的横向直径从29.5 mm增加到48.9 mm，纵向直径从41.1 mm增加到66.3 mm，最高槽温度从75.6℃增加到106.7℃。在相同参数下，数值模拟结果略大于离体实验结果。当肺部肿瘤平均直径小于40 mm时，可选择30 W和40 W的消融功率。消融时间限制在360 s。50 W消融功率可用于在较短时间内快速消融病灶以达到相同目的。虽然离体和体内存在差异，但本文验证了肺部模型的有效性以及模拟中消融参数的影响。获得了不同参数下的消融区域，为临床实践提供了参考数据。未来将开展基础研究以考虑复杂的肺部模型以及参数随温度的变化。
