Coil design considerations for deep-brain transcranial magnetic stimulation (dTMS).
← Research streamFigures of merit were proposed to compare dTMS coil designs, and two configurations (circular crown coil and C-core coil) were analyzed. Both coils were reported to have less attenuation of electric field strength at depth than conventional TMS coils; simulat…
Study snapshot
Abstract
Deep-brain transcranial magnetic stimulation (dTMS) could provide new, non-invasive therapeutic options for various psychiatric and neurological disorders. Figures of merit (FoMs) are proposed to evaluate and compare dTMS coil designs. These FoMs characterize the depth of electric field penetration, scalp stimulation, focality, and energy. Two coil configurations potentially suitable for dTMS are analyzed: circular crown coil and C-core coil. These coils have significantly less attenuation of the electric field strength in depth, compared to conventional TMS coils. In the limiting case as the coil dimensions become large relative to the head, the electric field decay in depth becomes linear, which indicates that, at best, the electric field attenuation is directly proportional to the depth of the target. The charge density and heating induced in the brain are at safe levels, but the risk of unintended neuromodulation and seizures with dTMS has to be evaluated further. Preliminary simulation results suggest that the crown coil has the best overall performance for dTMS. Finally, synchronous firing of all TMS coil elements appears more effective at stimulating deep neurons than is sequential firing.
AI evidence extraction
Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.
Main findings
Figures of merit were proposed to compare dTMS coil designs, and two configurations (circular crown coil and C-core coil) were analyzed. Both coils were reported to have less attenuation of electric field strength at depth than conventional TMS coils; simulations suggested the crown coil had the best overall performance. Charge density and heating in the brain were described as being at safe levels, while risks of unintended neuromodulation and seizures were noted as requiring further evaluation.
Outcomes measured
- Depth of electric field penetration
- Scalp stimulation
- Focality
- Energy requirements
- Electric field attenuation with depth
- Charge density induced in brain
- Heating induced in brain
- Risk of unintended neuromodulation
- Risk of seizures
- Effectiveness of synchronous vs sequential firing of coil elements
Limitations
- Results described as preliminary simulation results
- Risk of unintended neuromodulation and seizures stated as needing further evaluation
- No human/clinical outcomes reported in the abstract
View raw extracted JSON
{
"study_type": "engineering",
"exposure": {
"band": null,
"source": "transcranial magnetic stimulation (dTMS) coil designs",
"frequency_mhz": null,
"sar_wkg": null,
"duration": null
},
"population": null,
"sample_size": null,
"outcomes": [
"Depth of electric field penetration",
"Scalp stimulation",
"Focality",
"Energy requirements",
"Electric field attenuation with depth",
"Charge density induced in brain",
"Heating induced in brain",
"Risk of unintended neuromodulation",
"Risk of seizures",
"Effectiveness of synchronous vs sequential firing of coil elements"
],
"main_findings": "Figures of merit were proposed to compare dTMS coil designs, and two configurations (circular crown coil and C-core coil) were analyzed. Both coils were reported to have less attenuation of electric field strength at depth than conventional TMS coils; simulations suggested the crown coil had the best overall performance. Charge density and heating in the brain were described as being at safe levels, while risks of unintended neuromodulation and seizures were noted as requiring further evaluation.",
"effect_direction": "mixed",
"limitations": [
"Results described as preliminary simulation results",
"Risk of unintended neuromodulation and seizures stated as needing further evaluation",
"No human/clinical outcomes reported in the abstract"
],
"evidence_strength": "low",
"confidence": 0.74,
"peer_reviewed_likely": "yes",
"keywords": [
"deep-brain transcranial magnetic stimulation",
"dTMS",
"coil design",
"crown coil",
"C-core coil",
"electric field penetration",
"focality",
"scalp stimulation",
"energy",
"heating",
"charge density",
"seizures",
"neuromodulation",
"simulation"
],
"suggested_hubs": [
{
"slug": "occupational-exposure",
"weight": 0.1,
"reason": "Engineering-focused EMF exposure from medical device context; no specific occupational setting described."
}
]
}AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.
Identifiers and source
DOI: 10.1109/iembs.2008.4650502
PubMed: 19164005