Abstract

Overview

This study investigates the effect of absorption metrics and averaging schemes on the correlation between RF/microwave energy and temperature elevations in human subjects exposed to plane waves.

Methods

• An anatomically realistic voxel-based model of the human body was used.
• Correlations between electromagnetic fields and temperature increases were assessed across several frequencies.
• Both Specific Absorption Rate (SAR) and Volume Absorption Rate (VAR) metrics were analyzed.

Findings

The strongest correlation with temperature increase was found for exposure durations between 1 and 2 minutes using both SAR and VAR metrics, across most frequencies ranging from 700 to 2700 MHz. Optimal configurations were identified as 1-g mass or 1-cm3 volume for these conditions. However, as frequency increases above 900 MHz, VAR showed better correlations at slightly longer exposure times and larger volumes. At steady-state (30 minutes), the best correlation with SAR was observed at 9 g mass and with VAR at volumes of 15 cm3 to 20 cm3 depending on the frequency.

Conclusion

Overall, SAR proved to be a more reliable measure for shorter exposures, whereas VAR provided better correlations for longer exposures and higher frequencies. This study emphasizes the importance of carefully selecting exposure metrics in setting guidelines to limit human exposure to electromagnetic fields and for applications in biomedical imaging, sensing, and hyperthermia treatments.