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Transcranial magnetic stimulation safety from operator exposure perspective
Grant Rutherford1, Brian Lithgow2,3, Zahra Moussavi2,3
1Graduate Program in Biomedical Engineering, University of Manitoba, Winnipeg, MB, R3T 5V6, Canada. gruther4@gmail.com.
Medical & Biological Engineering & Computing
|December 14, 2019
Summary
Operator exposure to electromagnetic fields (EMF) from transcranial magnetic stimulation (TMS) coils was simulated. Safety guidelines were exceeded at specific distances, but occupational exposure during TMS treatment may be reasonable due to a focus on acute effects.
Area of Science:
- Biomedical Engineering
- Medical Physics
- Occupational Health
Background:
- Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique.
- Operator safety during TMS procedures requires understanding electromagnetic field (EMF) exposure.
- Existing research lacks detailed analysis of operator EMF exposure from commercial TMS coils.
Purpose of the Study:
- To simulate and quantify operator EMF exposure from a commercial TMS coil.
- To compare simulated exposure levels with international occupational EMF exposure guidelines.
- To assess the potential risks associated with operator exposure during TMS treatment.
Main Methods:
- A simulated model of a commercial figure-8 TMS coil was developed.
- Geometrical models of the operator's head, torso, and hand were incorporated.
- Induced EMF strengths were calculated at various positions relative to the coil.
- Simulated exposure levels were compared against established international guidelines.
Main Results:
- International EMF exposure guidelines (0.8 V/m rms) were exceeded at 24.6 cm for the torso and 20.3 cm for the head, perpendicular to the coil plane.
- In the coil's plane, operators can approach closer without exceeding guidelines.
- Hand exposure along the coil edge reached 9.9 V/m (average) and 88.5 V/m (peak).
Conclusions:
- Operator EMF exposure from TMS coils can exceed safety guidelines at certain distances.
- Guidelines primarily address acute effects, with no suggested chronic effects.
- Occupational exposure during TMS treatment delivery is considered potentially reasonable.
