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SAR / Device Absorption

A method for safety testing of radiofrequency/microwave-emitting devices using MRI.

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Alon L, Cho GY, Yang X, Sodickson DK, Deniz CM. · 2014

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Researchers found that MR temperature mapping can assess RF/microwave safety with high resolution and fidelity.

Plain English Summary

Summary written for general audiences

Researchers investigated MR temperature mapping and 10-g average specific absorption rate (SAR) computation for safety evaluation of RF-emitting devices. They tested an MRI-compatible dipole antenna and a non-MRI-compatible mobile phone, measuring temperature changes in phantoms and comparing results with physical probe measurements and electromagnetic field simulations. The researchers concluded that MR temperature mapping alongside physical property measurements can assess RF/microwave safety with high resolution and fidelity.

Why This Matters

For the dipole antenna, simulations found a maximum temperature change of 1.83°C and a maximum 10-g average SAR of 12.4 W/kg, while experiments found 1.73°C and 11.9 W/kg, respectively. The difference between MR and probe thermometry was less than 0.15°C. For a cell phone radiating at maximum output for 15 min, the maximum temperature change was 1.7°C and the maximum 10-g average SAR was 0.54 W/kg. MR temperature measurements alongside physical property measurements were used to reconstruct 10-g average SAR.

Exposure Details

SAR
0.54, 11.9, 12.4 W/kg
Exposure Duration
15 min

Exposure Context

This study used 0.54, 11.9, 12.4 W/kg for SAR (device absorption):

Building Biology guidelines are practitioner-based limits from real-world assessments. BioInitiative Report recommendations are based on peer-reviewed science. Check Your Exposure to compare your own measurements.

Where This Falls on the Concern Scale

Study Exposure Level in ContextStudy Exposure Level in ContextThis study: 0.54, 11.9, 12.4 W/kgExtreme Concern - 0.1 W/kgFCC Limit - 1.6 W/kgEffects observed in the Extreme Concern range (Building Biology)FCC limit is 3 times higher than this level

Study Details

We investigated the application of MR temperature mapping and 10-g average specific absorption rate (SAR) computation for safety evaluation of RF-emitting devices.

Quantification of the RF power deposition was shown for an MRI-compatible dipole antenna and a non-M...

The maximum temperature change for a dipole antenna and the maximum 10-g average SAR were 1.83°C and...

Information acquired using MR temperature mapping and thermal property measurements can assess RF/microwave safety with high resolution and fidelity.

Cite This Study
Alon L, Cho GY, Yang X, Sodickson DK, Deniz CM. (2014). A method for safety testing of radiofrequency/microwave-emitting devices using MRI. Magn Reson Med. 2014 Nov 25. doi: 10.1002/mrm.25521.
Show BibTeX
@article{l_2014_a_method_for_safety_807,
  author = {Alon L and Cho GY and Yang X and Sodickson DK and Deniz CM.},
  title = {A method for safety testing of radiofrequency/microwave-emitting devices using MRI.},
  year = {2014},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/25424724/},
}
PubMed: 25424724

Cited By (20 papers)

Quick Questions About This Study

The study tested an MRI-compatible dipole antenna and a non-MRI-compatible mobile phone.
The difference between MR and probe thermometry was less than 0.15°C.
For a cell phone radiating at maximum output for 15 min, the maximum temperature change was 1.7°C and the maximum 10-g average SAR was 0.54 W/kg.
The researchers found that MR temperature mapping and thermal property measurements can assess RF/microwave safety with high resolution and fidelity.