Monte-Carlo based Numerical Dosimetry in Reverberation Chamber Exposure Systems Employed for In-Vivo Rodent Bioassays

Authors: De Santis V, Di Fracesco A, Foster KR, Bit-Babik G, Faraone A

Year: 2023

Category: Radiobiology

Journal: IEEE Access

Institution: IEEE Access

DOI: 10.1109/ACCESS.2023.3251889

URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10057396&isnumber=6514899

Abstract

Overview

This study employs a Monte-Carlo based computational approach to statistically characterize the variability of whole-body specific absorption rate (wbSAR) in rodents exposed to radio-frequency (RF) energy in reverberation chambers. The investigation was particularly reflective of protocols used by the US National Toxicology Program (NTP) in cancer bioassays.

Methodology

Analysis involved generating numerous 3D electromagnetic field realizations within a simulated reverberation chamber, large enough to represent an ideal environment. This produced detailed wbSAR distributions for an ensemble of 96 homogeneously modeled rodents under varied conditions including mass, posture, position, and orientation.

Two exposure scenarios were studied: a 'momentary exposure' with fixed rat positions and a 'day-long exposure' with variable conditions.
Over 500 to 2500 field realizations were analyzed, respectively.

Findings

The instant and time-averaged wbSARs of these rodents followed log-normal distributions. Significant variability in wbSAR was attributed primarily to the inherent variability within reverberation chambers (70-80%) and to a lesser extent on variables like weight and posture positions (20-30%).

It was noted that averaging exposure over several field realizations could significantly reduce the range of wbSARs, pointing to differences in thermal and non-thermal effects relevance in exposure metrics.

Conclusion

The study highlights the crucial implications of such research in adjusting and setting target wbSARs in rodent bioassays for identifying potential dose-effect trends without inducing undue thermal stress.

Health Risk Implication

This research underscores the importance of detailed exposure assessment in understanding the health risks associated with electromagnetic fields, particularly the fluctuations in exposure patterns which could influence the biological outcomes of the exposed non-human subjects and potentially humans as well.

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