Time-Multiplexed Beamforming for Noninvasive Microwave Hyperthermia Treatment

Abstract

A noninvasive microwave beamforming strategy is proposed for selective localized heating of biological tissue. The proposed technique is based on time multiplexing of multiple beamformers. We investigate the effectiveness of the time-multiplexed beamforming in the context of brain hyperthermia treatment by using a high-fidelity numerical head phantom of an adult female from the Virtual Family (IT'IS Foundation) as our testbed. An operating frequency of 1 GHz is considered to balance the improved treatment resolution afforded by higher frequencies against the increased penetration through the brain afforded by lower frequencies. The exact head geometry and dielectric properties of biological tissues in the head are assumed to be available for the creation of patient-specific propagation models used in beamformer design. Electromagnetic and thermal simulations based on the finite-difference time-domain method are used to evaluate the hyperthermia performance of time-multiplexed beamforming and conventional beamforming strategies. The proposed time-multiplexing technique is shown to reduce the unintended heating of healthy tissue without affecting the treatment temperature or volume. The efficacy of the method is demonstrated for target locations in three different regions of the brain. This approach has the potential to improve microwave-induced localized heating for cancer treatment via hyperthermia or heat-activated chemotherapeutic drug release.

Constrained power focusing of vector fields: an innovative globally optimal strategy

“…Similar comments apply to the approach proposed in [7][8][9], where the problem is faced as the maximization of the ratio of two quadratic forms. In particular, while the adaptive reweighting procedure described in [9] allows to control the side lobe power deposition, it cannot ensure the global optimality of the solution.…”

Generalized characterization of microwave power absorption for processing of circular shaped materials

“…The scenario becomes even more crucial for microwave therapy, where successful ablation of the target zone without damaging the surrounding tissues requires accurate knowledge of the detailed power absorption patterns. Accordingly, a series of target oriented research works has been conducted over the years, to identify the microwave heating dynamics within circular domains related to food processing (Basak, 2005, 2006, Basak, 2007a,b, Basak, 2011Ayappa, 2001, 2002;Gunasekaran and Yang, 2007;Knoerzer et al, 2008;Liu et al, 2013;Franca, 2000, 2002;Pandit and Prasad, 2003;Pitchai et al, 2012;Rakesh et al, 2010;Sakai et al, 2003Sakai et al, , 2004Samanta and Basak, 2009;Souraki et al, 2009;Zhou et al, 1995;Zhu et al, 2007), material processing (Chen et al, 2001(Chen et al, , 2011Kowalski and Pawlowski, 2011;Meier et al, 2009;Navarrete et al, 2012;Perry et al, 2002;Sangdao et al, 2006;Wang et al, 2009;Wu et al, 2004;Yasaka et al, 2006;Zhao et al, 2009), medical therapy (Brace et al, 2007;Li et al, 2012;Park et al, 2012;Stang et al, 2012;Tanaka et al, 1993;Yacoob and Hassan, 2012;Zastrow et al, 2011), etc. In spite of extensive research, a generalized material invariant analysis of the microwave power absorption characteristics within circular samples as a function of sample dimensions and material properties is yet to appear in the literature....…”

Enhancement of intra-body propagation and communication under the Brillouin precursor perspective

“…In addition, the dispersive nature of the tissue itself indicates that there could be precursor formations [12 -17] as ultra wideband (UWB) or low-frequency electromagnetic (EM) waves propagate through it. The precursor formation in the transmitted or propagating signal, however, can produce undesired features, the main of which is the pulse broadening undergone by the signal through the dispersive media, turning the frequency dispersion into an extremely important impairment in receiver systems [14], or for the reliability of the communications through these kind of media, such as the intra-body case in order to obtain a higher signal-to-noise ratio and/or greater penetration depths [1][2][3][4][5].…”