Abstract
This research proposes a triple-antenna scheme of three coaxial half slot antennas (CHSA) for minimally invasive hepatic microwave ablation (MWA). In the MWA treatment, the antennas were positioned around the cancer tissue in equilateral triangle formation, with the half-slot side of the antennas directed at the triangle center to concentrate the microwave energy. Finite element (FE) simulations and in vitro experiments with swine liver were carried out to determine the temperatures and coagulation zone under different distances between the three antennas: 10, 20, and 30 mm. Besides, a regression-based deep learning algorithm was utilized to predict temperatures at the midpoint of the triple-CHSA arrangement without inserting a temperature sensor into the targeted tissue. The algorithm relied on temperatures at a site adjacent to the targeted cancer tissue to predict the midpoint temperatures. The triple-CHSA scheme could achieve a large coagulation zone with temperatures of 60 °C or higher. The FE simulation results showed that the largest coagulation volumes achieved were 18.425, 29.312, and 63.507 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> for the between-antenna distances of 10, 20, and 30 mm, respectively. The largest coagulation volumes of in vitro experiments were 18.437, 29.317, and 63.504 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> for the corresponding between-antenna distances. The prediction accuracy of the deep learning algorithm were 99.98 % for mean square error, 98.75 % for mean absolute error, and 99.22 % for mean absolute percentage error. The novelty of the research lies in the use of CHSA surrounding the cancer tissue in equilateral triangle formation for hepatic MWA, as opposed to the conventional hepatic MWA procedure which requires inserting antennas into the targeted tissue. Another research novelty is the use of regression-based deep learning algorithm to predict the temperature of liver tissue at the midpoint of the triple-CHSA arrangement.
Highlights
Consumption of undercooked meat and excessive alcohol use contribute to the prevalence of hepatic cancer in several Southeast Asian countries, and the situation has worsened with the passing years despite efforts to increase awareness
The results showed that the triple-antenna scheme could achieve larger destruction zone, in comparison with the single-antenna microwave ablation (MWA) scheme
DEEP LEARNING ALGORITHM AND TEMPERATURE PREDICTION PERFORMANCE The optimized weight (W) and bias (B) of the regressionbased deep learning algorithm to predict the temperature of liver tissue at the midpoint of the triple-coaxial half slot antennas (CHSA) arrangement, given the between-antenna distance of 10 mm, as an example, are as follows: Note: In the execution of the deep learning algorithm, the bias coefficients (B1 – B4) were combined with the weighted features using array broadcasting (8)
Summary
Consumption of undercooked meat and excessive alcohol use contribute to the prevalence of hepatic cancer in several Southeast Asian countries, and the situation has worsened with the passing years despite efforts to increase awareness. The multi-antenna schemes for MWA treatment could achieve specific destruction patterns and large areas of cancer tissue destruction. A dual-slot coaxial single-antenna scheme was developed to treat cancer tissue using microwave [15]. In [16], a multi-slot coaxial MW single-antenna scheme was proposed to ablate liver tumors. The coagulation symmetry renders the first-generation single-antenna MWA schemes unsuitable for ablation in zones adjacent to critical areas. The results showed that phase shift between antennas from 90◦, 180◦ to 270◦ affected the coagulation volume, and the triple-antenna scheme could achieve asymmetrical destruction patterns. The results showed that the triple-antenna scheme could achieve larger destruction zone, in comparison with the single-antenna MWA scheme. The results showed that the double-slot triple-antenna schemes achieved larger ablation zones than the single-antenna scheme. On temperatures at the site adjacent to the targeted cancer tissue
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