高磁导率高电导率介质影响H1型线圈颅内感应电场分布的仿真研究

Simulation study on influence of high permeability and high conductivity medium on intracranial induced electric field distribution induced by H1-coil

目的:探究在高磁导率、高电导率介质影响下,H1型线圈在真实头部电导率分布模型中产生的感应电场分布发生的变化。方法:建立包含头皮组织和边缘系统的真实头部电导率分析模型、H1型线圈模型,并分别在H1型线圈前额回路部分和底座部分建立高导磁块和高导电块模型。运用有限元方法进行H1型线圈颅内感应电场分布仿真分析。结果:增加高导磁块模型后,头皮和边缘系统处的感应电场强度峰值分别增加了30.28%和22.73%,头皮处的聚焦体积减小了40.39%,表现出更好的刺激强度和聚焦性。增加高导电块模型后,头皮和边缘系统的感应电场强度峰值均降低,但在头皮处聚焦体积缩小了71.73%,聚焦性明显增加。增加高导磁块、高导电块后,评价参数q(边缘系统电场强度峰值和聚焦体积的乘积与头皮电场强度峰值和聚焦体积的乘积之比)均得到提升,H1型线圈表现出更好的深度特性。结论:增加高导磁块、高导电块可在一定程度上调控H1型线圈的聚焦特性和深度特性,为H1型线圈固定条件下的颅内电场调控提供帮助。

Objective To investigate the variation of the induced electric field distribution generated by the H1-coil in the real head conductivity distribution model under the influence of high permeability and high conductivity medium.Methods A real head model that included scalp tissue and limbic systems,an H1-coil model,a high permeability model over the forehead portion of H1-coil and a high conductivity model based on the loop portion of H1-coil were established.Finite element method was used to simulate the intracranial induced electric field distribution of the H1-coil.Results When the high permeability model was added,the peaks of the induced electric field of the scalp and the limbic system increased by 30.28%and 22.73%respectively while the focus volume at the scalp decreased by 40.39%,which meant high stimulation intensity and focusing characteristics.When the high conductivity model was added,the peaks of the induced electric field of the scalp and limbic systems were reduced while the focus volume at the scalp was lowered by 71.73%,which meant the focusing characteristics significantly increased.When the magnetic and conductive model were added,the value of the evaluation parameter q was enhanced and the H1-coil showed better depth characteristics.Conclusion The focusing characteristics and depth characteristics of the H1-coil can be adjusted to some extent by increasing the high permeability and high conductivity model,so that the regulation can be facilitated for the intracranial electric field under the condition that the H1-coil is fixed.