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Theoretical Investigation into the Feasibility to Deposit RF Energy Centrally in the Head-and-Neck Region

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Author: Paulides, M.M. · Vossen, S.H.J.A. · Zwamborn, A.P.M. · Rhoon, G.C. van
Type:article
Date:2005
Institution: TNO Defensie en Veiligheid
Source:International Journal of Radiation Oncolgy . Biology . Physics, 2, 63, 634-642
Identifier: 220805
doi: doi:10.1016/j.ijrobp.2005.04.048
Keywords: Biology · Antenna array · Head-and-neck tumors · Hyperthermia · Power absorption · SAR calculations · Irradiation · Feasibility study · Mathematical analysis · Model · Radiation absorption · Radiofrequency radiation · Theoretical study · Humans · Radio Waves

Abstract

Purpose: To investigate the ability to deposit radiofrequency energy centrally in the neck as a function of antenna positions, number of antennas, and operating frequency. Methods and Materials: Power absorption (PA) distributions in a realistic model of the head-and-neck anatomy are calculated in which the head model is irradiated by an array of dipole antennas. The relative PA distributions corresponding to different setups are visualized and analyzed using the ratio of the average PA (aPA) in the target and neck region. Results: Both the PA distributions and aPA ratios indicate an optimal focusing ability of the setups (i.e., the ability to direct energy efficiently into the target region), between 400 and 600 MHz. In this frequency band, the focusing ability depends only moderately on the size of the neck. Finally, it is found that the focusing ability at 433 MHz is increased significantly by increasing the number of antenna elements. Conclusions: The optimal frequency is found to be highly dependent on the size of the target volume; thus, a single optimum is hard to define. However, future clinical research will focus on 433 MHz based on the optimal range of frequencies, as found in this study. © 2005 Elsevier Inc.