Variability in EMF permittivity values: implications for SAR calculations

Hurt, W. D.; Ziriax, John M.; Mason, Patrick A.

doi:10.1109/10.827308

Cited by 49 publications

(38 citation statements)

References 9 publications

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“…Recently, Hurt et al [2000] reported on the permittivity values of biological tissues published elsewhere in literature that deviate substantially from the data published by Gabriel. The ratios that re¯ect the unchanged differences among published data were calculated.…”

Section: Introductionmentioning

confidence: 71%

Predicted SAR in sprague‐dawley rat as a function of permittivity values*†

Gajšek

Ziriax

Hurt

et al. 2001

Bioelectromagnetics

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Specific absorption rate (SAR) value is dependent on permittivity value. However, variability in the published permittivity values for human and animal tissue and the development of sophisticated 3-dimensional digital anatomical models to predict SAR values has resulted in the need to understand how model parameters (permittivity value) affect the predicted whole body and localized SAR values. In this paper, we establish the partial derivative of whole body SARs and localized SAR values (defined as SAR for individual organs with respect to a change in the permittivity values of all tissue types, as well as for those tissues with the most variable permittivity values. Variations in the published permittivity values may substantially influence whole body and localized SAR values, but only under special conditions. Orientation of the exposed object to the incident electromagnetic wave is one of the most crucial factors. Published 2001 Wiley-Liss, Inc.

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Section: Introductionmentioning

confidence: 71%

Predicted SAR in sprague‐dawley rat as a function of permittivity values*†

Gajšek

Ziriax

Hurt

et al. 2001

Bioelectromagnetics

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“…The choice of complex permittivity values is not a definitive one because of the uncertainty that exists in the literature on the dielectric properties of normal breast tissue at microwave frequencies [17]. Three dielectric spectroscopy studies [18]- [20] suggest that normal breast tissue is a low-dielectric-constant, low-loss material and that the within-patient variability in dielectric properties is less than 10% around the nominal values.…”

Section: B Em Modelmentioning

confidence: 99%

A computational study of ultra-wideband versus narrowband microwave hyperthermia for breast cancer treatment

Converse

Bond

Veen

et al. 2006

IEEE Trans. Microwave Theory Techn.

170

123

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Abstract-We present a computational study comparing the performance of narrowband (NB) microwave hyperthermia for breast cancer treatment with a recently proposed ultra-wideband (UWB) approach. Space-time beamforming is used to preprocess input signals from both UWB and NB sources. The train of UWB pulses or the NB sinusoidal signals are then transmitted simultaneously from multiple antennas into the breast. Performance is evaluated using finite-difference time-domain electromagnetic (EM) and thermal simulations with realistic numerical breast phantoms derived from magnetic resonance images (MRIs) of the breast. We use three methods of mapping MRI data to complex permittivity data to account for uncertainty in the embodiment of the dielectric properties transitions in heterogeneous breast tissue. EM power-density deposition profiles and temperature profiles are compared for the UWB and NB cases in the three different breast phantoms. Dominant mechanisms that influence the efficacy of focusing UWB and NB signals in the breast are identified. The results of this study suggest that, while NB focusing performs reasonably well when the excitation frequency is optimized, UWB focusing consistently performs better, offering the potential for tighter focusing and greater reduction of hot spots, particularly in breast tissue, which exhibits distinct dielectric-properties boundaries within the tissue heterogeneity.Index Terms-Breast cancer, electromagnetic (EM) hyperthermia, finite-difference time-domain (FDTD) method, microwave imaging, space-time beamforming, ultra-wideband (UWB) radar.

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“…The dielectric properties are defined in terms of relative permittivity and conductivity , and their numerical values for the simulations are described in Table 2. The absorption is well-known to depend more on conductivity than on relative permittivity; namely, as conductivity increases, the AL also increases [12,13].…”

Section: Resultsmentioning

confidence: 99%

Analysis of Absorption Loss by a Human Body in On-to-Off Body Communication at 2.45 GHz

Jeon¹,

Lee²,

Choi³

et al. 2015

Journal of electromagnetic engineering and science

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This paper investigates the effect of absorption loss by a human body to the received signal strength with respect to on-body transmitting antenna positions in on-to-off wireless body area networks. This investigation is based on measurement results obtained from experiments performed on human bodies (male and female) using planar inverted-F antennas in an anechoic chamber. The total absorption loss by the human body is also presented through the SEMCAD-X simulations. Our investigation showed that the received signal strength becomes lower when the transmitting antenna is mounted at a specific position where more absorption loss is experienced. The statistical analyses of on-to-off body channel characteristics based on the measurement results are presented. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ⓒ

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Variability in EMF permittivity values: implications for SAR calculations

Cited by 49 publications

References 9 publications

Predicted SAR in sprague‐dawley rat as a function of permittivity values*†

Predicted SAR in sprague‐dawley rat as a function of permittivity values*†

A computational study of ultra-wideband versus narrowband microwave hyperthermia for breast cancer treatment

Analysis of Absorption Loss by a Human Body in On-to-Off Body Communication at 2.45 GHz

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