A formula for human average whole-body SARwb under diffuse fields exposure in the GHz region

Area of Science:

• Electromagnetics and Dosimetry
• Computational Biology and Bioelectrics

Background:

• Assessing human exposure to radiofrequency (RF) electromagnetic fields is crucial for health and safety.
• Existing methods for calculating whole-body Specific Absorption Rate (SAR(wb)) can be complex and computationally intensive.
• Realistic propagation conditions, including diffuse scattered illumination and Line-of-Sight (LOS) components, require accurate dosimetry models.

Purpose of the Study:

• To develop a simple, accurate formula for estimating human average whole-body SAR (SAR(wb)) in the GHz frequency range (1.45 GHz to 5.8 GHz).
• To validate the proposed formula against numerical simulations using realistic human body models under various exposure conditions.
• To assess the formula's applicability for rapid dosimetry in personal monitoring and epidemiological studies.

Main Methods:

• Development of a simplified formula based on simulations of ellipsoidal human body models.
• Inclusion of diffuse scattered and Line-of-Sight (LOS) electromagnetic field exposure scenarios.
• Validation using 3D heterogeneous human phantoms (Virtual Family) compared against Finite-Difference Time-Domain (FDTD) simulations at 3 GHz.

Main Results:

• The formula provides estimations for SAR(wb) with average relative errors ranging from 12% to 28% for LOS exposure and varying errors for diffuse illumination across different age groups and sexes.
• The formula's accuracy generally improves with increasing human mass, performing particularly well for adult models.
• The proposed formula demonstrates good agreement with FDTD results, especially under diffuse illumination conditions.

Conclusions:

• The developed formula offers a practical tool for rapidly and accurately assessing human whole-body SAR(wb) from diffuse RF fields in the GHz region.
• The formula's simplicity and reliance on basic inputs (exposure and mass) make it valuable for the dosimetry community.
• The study highlights the formula's potential utility in personal dosimetry for epidemiological research, enabling better exposure assessment.