CST – Computer Simulation Technology

Simulation of the temperature elevation in children exposed to plane wave electromagnetic fields (10 MHz – 1 GHz) at the ICNIRP reference level

Title:
Simulation of the temperature elevation in children exposed to plane wave electromagnetic fields (10 MHz – 1 GHz) at the ICNIRP reference level
Author(s):
Florian Niedermayr , Norbert Leitgeb, Werner Siegl
Source:
Biomed Tech 2012
Vol./Issue/Date:
Volume: 57, Issue: 3, May 2012
Year:
2012
Page(s):
193 - 200
Keywords:
basic restrictions, bioheat equation, health risk assessment, specifi c energy absorption rate (SAR), thermoregulation
Abstract:
Because of a lack of thermal models, to date, limitation of exposure to an electromagnetic fi eld (EMF) has been based on restricting intracorporal specifi c absorption rates. To allow convenient compliance checks, reference fi eld values have been defi ned. If they are met, compliance with basic restrictions is assumed. This article demonstrates that this assumption is not valid in every case. It has therefore been investigated as to whether the biological goal of limiting tissue heating is still met, in particular with regard to children. The thermal solver applied is based on the bioheat equation, with implemented additional improvements that allow consideration of blood fl ow and metabolic rate as a function of local tissue temperature rise and, in addition, adapt the blood temperature relative to the absorbed power. As a further improvement, heat exchange at the tissue/air boundary has been modeled, with radiation, convection, and sweating considered as well. The mathematical equations describing these additional thermoregulatory mechanisms were taken from the literature and unifi ed in the thermoregulatory model used for this study. For the investigated case of plane wave exposure, the results confi rm the violation of the basic restrictions in fi ve of the six models when exposed to reference EMF levels. However, using thermal modeling, it was possible to demonstrate that heating remained within the biological tolerances. In particular, temperature elevation of the body core temperature remained < 0.014 ° C and the local peak temperature did not exceed 1 ° C.
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