Design of Site‐Specific Microwave Phased Array Hyperthermia Applicators Using 434 MHz Reduced Cavity‐Backed Patch Antenna

Abstract

Cancers of the neck, breast, and lower extremities are common malignancies diagnosed in India with a higher incidence of advanced-stage disease. Phased array (PA) applicators reported for hyperthermia treatment (HT) of the breast have small focal region and high cross-coupling, and those reported for lower extremities provide regional heating and limited steering. In this study, we present the numerical design of site-specific PA applicators for HT of large solid tumors in the neck, breast, and lower extremities using a miniaturized 434 MHz cavity-backed water-loaded patch antenna. The fabricated antenna has 38 × 36 mm 2 aperture, more than 90% power coupling, 25 MHz bandwidth, and good agreement between simulated and measured specific absorption rate (SAR) in phantom. The site-specific applicators demonstrated less power reflection (<−17.9 dB) and crosscoupling (<−26.8 dB) for 5 mm interring spacing. SAR indicators for 64 cc tumor at varying locations in simplified layered three-dimensional (3D) tissue models of the neck, breast, and leg showed average power absorption ratio (aPA ratio) ≥ 3.16, target to hotspot quotient (THQ) ≥ 0.57, 25% iso-SAR coverage (TC 25) ≥ 81%, and 50% iso-SAR coverage (TC 50) ≥51.8%. Simulation results of site-specific applicators for 3D inhomogeneous patient models showed aPA ratio ≥ 5.98, THQ ≥ 0.9, TC 50 ≥ 86%, and 100% TC 25 for all sites. It is concluded that the 434 MHz miniaturized cavity-backed patch antenna can be used to develop high-density PA applicators with 12-24 antennas for HT of large solid tumors (≥4 cm) in the neck, breast, and lower extremities with 3D steering ability and less cross-coupling (

Microwave intracavitary applicator using 434 MHz conformal patch antennas for hyperthermia treatment of gynaecological cancers

“…Unlike wire antennas, patch antennas are aperture type antennas that are compact, low profile, that possess directional radiation pattern and high gain. Thus, patch antennas are widely used for passive [38] and active medical microwave imaging [39] and external means of tissue heating for HT [40][41][42][43][44]. However, there are no intracavitary applicators reported in the literature employing patch antennas.…”

Design and Simulations of 2D Planar Antenna for Dielectric Characterization of Biological Samples

“…The patch antennas are extensively used for implantable medical devices for various applications, such as microwave hyperthermia treatment, cancer tumor detection, tissue characterization, and imaging [1][2][3][4][5]. A patch antenna can be used as a dielectric-based biosensor which resonates depending upon the dielectric and other physical properties of the biological tissues.…”