Effect of coil size on transcranial magnetic stimulation (TMS) focality
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Date
2019-05-02
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Citation of Original Publication
Hedyeh Bagherzadeh and Fow-sen Choa "Effect of coil size on transcranial magnetic stimulation (TMS) focality", Proc. SPIE 11020, Smart Biomedical and Physiological Sensor Technology XV, 110200Z (2 May 2019); doi: 10.1117/12.2524503
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© (2019) Society of Photo-Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
© (2019) Society of Photo-Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
Abstract
In recent years, there is an increasing interest in noninvasive treatments for neurological disorders like Alzheimer and
Depression. Transcranial magnetic stimulation (TMS) is one of the most effective methods used for this purpose. The
performance of TMS highly depends on the coils used for the generation of magnetic field and induced electric field
particularly their designs affecting depth and focality tradeoff characteristics. Among a variety of proposed and used
TMS coil designs, circular coils are commonly used both in research and medical and clinical applications. In current
study, we focus on changing the outer and inner sizes (diameter) and winding turns of ring coils and try to reach deeper
brain regions without significant field strength decay. The induced electric field and the decay rate of the generated field
with depth were studied with finite element method calculations. The results of the performed simulations indicate that
larger diameter coils have a larger equivalent field emission aperture and produce larger footprint of induced electric
field initially. However, their emission solid angles are smaller and, as a result, the field divergence or the decay rates of
the generated field with depth are smaller as well, which give them a good potential to perform better for deep brain
stimulation compared with that of smaller coil.