Chiang Jason, Song Lingnan, Abtin Fereidoun, Rahmat-Samii Yahya
Department of Radiology, Ronald Reagan UCLA Medical Center.
Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA 90095 USA.
IEEE J Electromagn RF Microw Med Biol. 2021 Dec;5(4):295-304. doi: 10.1109/jerm.2021.3066103. Epub 2021 Mar 17.
The goal of this study was to optimize a lung-tuned monopole antenna to deliver microwave energy at 2.45 GHz into a novel ventilator-controlled lung model. An analytic and parametric approach was utilized to create an optimized monopole antenna that was impedance-matched to aerated lung tissue. This lung-tuned antenna was then fabricated using a copper 0.085" semi-rigid copper coaxial cable. For validation, the lung-tuned antenna was inserted centrally into lobes of a porcine lung that was fully inflated to physiologically appropriate volumes. Microwave ablations were then created at 50 and 100 W for 1 minute and 5 minutes. Reflected power, cross sectional ablation sizes and spherical shape of the lung-tuned antenna were compared against a liver-tuned antenna in the ventilator-controlled lung tissue. The study showed that the lung-tuned antennas delivered energy significantly more efficiently, with less reflected power, compared to the conventionally-used liver-tuned antennas at 50 W at 1 minute (11.8±3.0 vs 16.3±3.1 W; p value=0.03) and 5 minutes (16.2±2.8 vs 19.4±2.9 W; p value=0.04), although this was only true using 100 W at the 1 minute time point (29.0±3.5 vs 38.0±5.3 W; p value=0.02). While overall ablation zone sizes were comparable between the two types of antenna, the lung-tuned antenna did create a significantly more spherical ablation zone compared to the liver-tuned antenna at the 1 minute, 50 W setting (aspect ratio: 0.43±0.07 vs 0.38±0.04; p value=0.04). In both antenna groups, there was a significant rise in the ablation zone aspect ratio between 1 and 5 minutes, indicating that higher power and time settings can increase the spherical shape of ablation zones when using tuned antennas. Adapting this combined analytic and parametric approach to antenna design can be implemented in adaptive tissue-tuning for real-time microwave ablation optimization in lung tissue.
本研究的目的是优化一种肺部调谐单极天线，以便将2.45 GHz的微波能量传输到一种新型呼吸机控制的肺部模型中。采用解析和参数化方法来创建一个与充气肺组织阻抗匹配的优化单极天线。然后使用一根0.085英寸的半刚性铜质同轴电缆制作这种肺部调谐天线。为进行验证，将肺部调谐天线插入到一个充分膨胀至生理合适体积的猪肺叶中央。随后分别以50瓦和100瓦的功率进行1分钟和5分钟的微波消融。在呼吸机控制的肺组织中，将肺部调谐天线的反射功率、横截面消融尺寸和球形形状与肝脏调谐天线进行比较。研究表明，与传统使用的肝脏调谐天线相比，肺部调谐天线在50瓦功率下1分钟（11.8±3.0对16.3±3.1瓦；p值 = 0.03）和5分钟（16.2±2.8对19.4±2.9瓦；p值 = 0.04）时能更高效地传输能量，反射功率更低，不过仅在1分钟时间点使用100瓦功率时才是如此（29.0±3.5对38.0±5.3瓦；p值 = 0.02）。虽然两种类型天线的总体消融区大小相当，但在1分钟、50瓦功率设置下，肺部调谐天线产生的消融区相比肝脏调谐天线明显更接近球形（纵横比：0.43±0.07对0.38±0.04；p值 = 0.04）。在两个天线组中，1至5分钟之间消融区纵横比均显著增加，这表明使用调谐天线时，更高的功率和时间设置可增加消融区的球形程度。将这种解析与参数化相结合的天线设计方法应用于自适应组织调谐，可实现肺部组织实时微波消融的优化。
