Projects per year
International exposure standard/guidelines establish limits for external electromagnetic field strengths. At low frequencies, these maximum allowable exposure levels are derived from the limits defined for internal electric field strengths which have been set to avoid adverse health effects. In the IEEE International Committee on Electromagnetic Safety standard, the relationship between internal and external fields was obtained through homogeneous elliptical models without considering the dielectric properties of tissues. However, the International Commission on Non-Ionizing Radiation Protection guidelines were established using computational dosimetry on realistic anatomical models. In this case, variability in the electrical conductivity of the tissues represents a major source of uncertainty when deriving allowable external field strengths. Here we characterized this uncertainty by studying the effect of different tissue conductivity values on the variability of the peak electric field strengths induced in the brain of twenty-five individuals exposed to uniform magnetic fields at 50 Hz. Results showed that the maximum electric field strengths computed with new estimations of brain tissue conductivities were significantly lower than those obtained with commonly used values in low-frequency dosimetry. The lower strengths were due to the new brain conductivity values being considerably higher than those usually adopted in dosimetry modeling studies. A sensitivity analysis also revealed that variations in the electrical conductivities of the grey and white matter had a major effect on the peak electric field strengths in the brain. Our findings are intended to lessen dosimetric uncertainty in the evaluation of the electric field strengths due to electrical properties of the biological tissues.
|Number of pages||13|
|Publication status||Published - 9 Dec 2020|
|MoE publication type||A1 Journal article-refereed|
- Anatomical head models
- Electromagnetic field exposure
- Induced electric field
- Low frequency
- Tissue conductivity
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Transkraniaalinen magneettinen sormenjälkitunnistus — työkalu aivostimulaation kvantifiointiin
Laakso, I., Kataja, J., Matilainen, N., Soldati, M., Kangasmaa, O. & Mikkonen, M.
01/09/2019 → 31/08/2023
Project: Academy of Finland: Other research funding
Aalto Neuroimaging Infrastructure
Veikko Jousmäki (Manager)School of Science
Characterization of open issues in low-frequency computational dosimetry
1 item of Media coverage
Press/Media: Media appearance