Identification of factors influencing the Whole Body Absorption Rate using statistical analysis

To protect people from Electromagnetic Fields (EMF), ICNIRP has defined limits. The fundamental ones are the Basic Restrictions (BRs) [1]. The BRs determine the maximum values (averaged over the whole body and averaged over 10 grams of tissues) of Specific Absorption Rate (SAR). Since BRs can be complex to assess ICNIRP has also defined derived value: the reference levels (RLs). These RLs were established to guaranty the compliance to the BRs. Several studies with human model voxels (a.k.a. phantoms) show that even below the RLs, the WBSAR (Whole Body average SAR) may exceed the BRs due to the variability of human morphology [2]. In this paper we will identify the morphological factors influencing the WBSAR in the case of a frontal plane wave exposure at the frequency of 2100MHz in isolated conditions and vertical polar. The method is based on the construction of a model that makes it possible to estimate the statistical distribution of the WBSAR for a given human population

Identification des facteurs morphologiques impactant le Débit d'Absorption Spécifique du Corps Entier

Les systèmes fondés sur des technologies liées aux champs électromagnétiques (EM) sont de plus en plus répandus. La question des effets possibles sur la santé dus à ces technologies sont devenues une préoccupation publique. Afin de limiter l'exposition des personnes aux ondes EM, des niveaux de protection appelés restrictions de bases, ont été définis par l'ICNIRP [1]. Ces niveaux fixent des valeurs de Débit d'Absorption Spécifique (Specific Absorption Rate : SAR) à ne pas dépasser. Des niveaux de références ont été dérivés des restrictions de base de façon conservative. Plusieurs études menées avec des modèles numériques d'humains [2,3] (fantômes) montrent que, pour certaines configurations, le WBSAR (Whole Body averged Specific Absorption Rate) est très proche des restrictions de base. D'autres études ont souligné la variabilité du WBSAR due à la variabilité de la morphologie humaine [2]. L'objectif de ce papier est d'identifier les facteurs morphologiques (internes et externes) qui ont un impact sur le WBSAR pour des fantômes exposés à une onde plane à une fréquence fixée à 2100MHz et une densité de puissance de 1W/m²

Bayesian experiment planning applied to numerical dosimetry

To protect people from electromagnetic field, Basic Restrictions (BR) are defined [1]. These BR fix a limit to be not exceeded. The metric associated with these BR is the Specific Absorption Rate (SAR). Reference Levels (RL) are also defined since the BR are difficult to check in situ. These RL set the maximum allowed electromagnetic field. The compliance to RL guaranties the compliance to BR. To evaluate the SAR in the human body, some anatomical models (phantoms) and numerical methods are used (e.g. Finite Difference in Time Domain). Based on this, studies show that for some configurations the Whole Body SAR (WBSAR) is close to BR. Other studies stressed the variability of the WBSAR due to the variability of human morphology [2]. Despite the computing resources development, the number of the phantoms is very limited. This limited number of phantoms does not allow using usual method such as Monte Carlo to assess the maximal threshold of the WBSAR for a given population. Hence the construction of a model of the WBSAR as a function of morphology is required. Nevertheless, the WBSAR is impacted by the external morphology (height and weight) and the internal morphology (proportion of fat, proportion of muscles...). But there is no statistical data concerning the internal ones. In this paper, the external morphology is focused and the internal morphology is released by considering homogeneous phantoms. A Bayesian sequential experiment planning is proposed. This method consists in refining the region of interest of the WBSAR statistical distribution for a given population. This region of interest is the threshold of the WBSAR at 95% (WBSAR95). This study is conducted in the case of a plane wave vertically polarized and frontally oriented on phantoms. The incident power is equal to 1W/m². The frequency is fixed at 2.1GHz