A Head Model for the Calculation of SAR and Temperature Rise Induced by Cellular Phones

Rodrigues, A.O.; Malta, L.R.P.; Viana, J.J.; Rodrigues, Luiz Oswaldo Carneiro; Ramírez, J.A.

doi:10.1109/tmag.2008.915837

Cited by 12 publications

(7 citation statements)

References 8 publications

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“…Most of the energy was absorbed in the CSF layer compared to the deep seated tumor located centrally within the head. This observation is consistent with those used to assess SAR values deposited in the head due to the exposure to microwave frequencies emanating from cellular phones [ 34 ] and MRI equipment [ 35 ]. SAR patterns computed in the realistic 3D head model using any of the two antenna configurations showed a distorted SAR distribution and hot spots in the ventricles as well as in the brain tumor compared to those observed in the simple head models.…”

Section: Discussionsupporting

confidence: 88%

FDTD analysis of a noninvasive hyperthermia system for brain tumors

Yacoob

Hassan

2012

BioMedical Engineering OnLine

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BackgroundHyperthermia is considered one of the new therapeutic modalities for cancer treatment and is based on the difference in thermal sensitivity between healthy tissues and tumors. During hyperthermia treatment, the temperature of the tumor is raised to 40–45°C for a definite period resulting in the destruction of cancer cells. This paper investigates design, modeling and simulation of a new non-invasive hyperthermia applicator system capable of effectively heating deep seated as well as superficial brain tumors using inexpensive, simple, and easy to fabricate components without harming surrounding healthy brain tissues.MethodsThe proposed hyperthermia applicator system is composed of an air filled partial half ellipsoidal chamber, a patch antenna, and a head model with an embedded tumor at an arbitrary location. The irradiating antenna is placed at one of the foci of the hyperthermia chamber while the center of the brain tumor is placed at the other focus. The finite difference time domain (FDTD) method is used to compute both the SAR patterns and the temperature distribution in three different head models due to two different patch antennas at a frequency of 915 MHz.ResultsThe obtained results suggest that by using the proposed noninvasive hyperthermia system it is feasible to achieve sufficient and focused energy deposition and temperature rise to therapeutic values in deep seated as well as superficial brain tumors without harming surrounding healthy tissue.ConclusionsThe proposed noninvasive hyperthermia system proved suitable for raising the temperature in tumors embedded in the brain to therapeutic values by carefully selecting the systems components. The operator of the system only needs to place the center of the brain tumor at a pre-specified location and excite the antenna at a single frequency of 915 MHz. Our study may provide a basis for a clinical applicator prototype capable of heating brain tumors.

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Section: Discussionsupporting

confidence: 88%

FDTD analysis of a noninvasive hyperthermia system for brain tumors

Yacoob

Hassan

2012

BioMedical Engineering OnLine

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“…) propagates through the human body, the electromagnetic energy is absorbed by the tissues. The energy absorbed is denoted in terms of SAR as [31]:…”

Section: Mathematical Models 21 Pennes' Bioheat Transfer Equation (Bte)mentioning

confidence: 99%

Thermal changes in Human Abdomen Exposed to Microwaves: A Model Study

Kaur

Khan

2019

AEM

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The electromagnetic energy associated with microwave radiation interacts with the biological tissues and consequently, may produce thermo-physiological effects in living beings. Traditionally, Pennes’ bioheat equation (BTE) is employed to analyze the heat transfer in biological medium. Being based on Fourier Law, Pennes’ BTE assumes infinite speed of propagation of heat transfer. However, heat propagates with finite speed within biological tissues, and thermal wave model of bioheat transfer (TWBHT) demonstrates this non-Fourier behavior of heat transfer in biological medium. In present study, we employed Pennes’ BTE and TWMBT to numerically analyze temperature variations in human abdomen model exposed to plane microwaves at 2450 MHz. The numerical scheme comprises coupling of solution of Maxwell's equation of wave propagation within tissue to Pennes’ BTE and TWMBT. Temperatures predicted by both the bioheat models are compared and effect of relaxation time on temperature variations is investigated. Additionally, electric field distribution and specific absorption rate (SAR) distribution is also studied. Transient temperatures predicted by TWMBT are lower than that by traditional Pennes’ BTE, while temperatures are identical in steady state. The results provide comprehensive understanding of temperature changes in irradiated human body, if microwave exposure duration is short.

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“…In order to precisely model the configuration of eyes which comprise ultra-thin millimetre-scale membrane structures, a resolution of 0.2 mm is proposed. Table 1 [24][25][26][27][28][29][30][31]35] presents the dielectric properties at 0.915 GHz and densities assigned to different biological materials for the following calculation. ε r and σ represent the relative dielectric constant and conductivity, respectively.…”

Section: Head Modelmentioning

confidence: 99%

Evaluation of Microwave Microdosimetry for Human Eyes With Glasses Exposed to Wireless Eyewear Devices at Phone Call State

Lan¹,

Hong²,

Liang³

et al. 2018

PIER M

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Abstract-This paper evaluates the effect of glasses on the Specific Absorption Rate (SAR) and the absorbed power in the human head exposed to microwave from wireless eyewear device at phone call state. Due to the sensitivity of eyes to microwave, this paper mainly concentrates on the SAR and the absorbed power in ocular tissues. The calculated results indicate that wearing glasses can obviously increase the maximal SAR and the absorbed power in ocular tissues. Glasses has almost doubled the maximal SAR in ocular tissues. The absorbed power with glasses is about 3.1-4.5 times as big as that without glasses. Furthermore, we find that the maximal SAR and absorbed power are sensitive to the width of glass leg and the thickness of spectacle lens, while variation trends with the varying glasses size are quite different. Hypermyopia patient might suffer from higher risk of getting the oculopathy due to the larger SAR caused by the thicker spectacle lens. In conclusion, wearing glasses may pose higher health risk on eyes of wireless eyewear device user. This paper would provide valuable reference data for the future evaluation of microwave biological effect on eyes.

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A Head Model for the Calculation of SAR and Temperature Rise Induced by Cellular Phones

Cited by 12 publications

References 8 publications

FDTD analysis of a noninvasive hyperthermia system for brain tumors

FDTD analysis of a noninvasive hyperthermia system for brain tumors

Thermal changes in Human Abdomen Exposed to Microwaves: A Model Study

Evaluation of Microwave Microdosimetry for Human Eyes With Glasses Exposed to Wireless Eyewear Devices at Phone Call State

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