RESUMO
Numerical simulation of electromagnetic, thermal, and mechanical responses of the human body to different stimuli in magnetic resonance imaging safety, antenna research, electromagnetic tomography, and electromagnetic stimulation is currently limited by the availability of anatomically adequate and numerically efficient cross-platform computational models or "virtual humans." The objective of this study is to provide a comprehensive review of modern human models and body region models available in the field and their important features.
Assuntos
Fenômenos Eletromagnéticos , Modelos Anatômicos , Simulação por Computador , Desenho Assistido por Computador , Análise de Elementos Finitos , Humanos , SoftwareRESUMO
Simulation of the electromagnetic response of the human body relies heavily upon efficient computational models or phantoms. The first objective of this paper is to present an improved platform-independent full-body electromagnetic computational model (computational phantom), the Visible Human Project® (VHP)-Female v. 3.1 and to describe its distinct features and enhancements compared to VHP-Female v. 2.0. The second objective is to report phantom simulation for electric stimulation studies using the commercial FEM electromagnetic solver ANSYS MAXWELL.
Assuntos
Simulação por Computador , Corpo Humano , Imagens de Fantasmas , Fenômenos Eletromagnéticos , Feminino , Humanos , Modelos Anatômicos , Projetos Ser Humano VisívelRESUMO
Simulation of the electromagnetic response of the human body relies upon efficient computational models. The objective of this paper is to describe a new platform-independent and computationally-efficient full-body electromagnetic model, the Visible Human Project® (VHP)-Female v.3.0 and to outline its distinct features. We also report model performance results using two leading commercial electromagnetic antenna simulation packages: ANSYS HFSS and CST MICROWAVE STUDIO®.
Assuntos
Fenômenos Eletromagnéticos , Modelos Biológicos , Projetos Ser Humano Visível , Simulação por Computador , Feminino , Corpo Humano , Humanos , Micro-Ondas , Pessoa de Meia-Idade , Modelos Anatômicos , National Library of Medicine (U.S.) , Couro Cabeludo/fisiologia , Estados UnidosRESUMO
GOALS: Transcranial magnetic stimulation (TMS) is increasingly used as a diagnostic and therapeutic tool for numerous neuropsychiatric disorders. The use of TMS might cause whole-body exposure to undesired induced currents in patients and TMS operators. The aim of this study is to test and justify a simple analytical model known previously, which may be helpful as an upper estimate of eddy current density at a particular distant observation point for any body composition and any coil setup. METHODS: We compare the analytical solution with comprehensive adaptive mesh refinement-based FEM simulations of a detailed full-body human model, two coil types, five coil positions, about 100 000 observation points, and two distinct pulse rise times; thus, providing a representative number of different datasets for comparison, while also using other numerical data. RESULTS: Our simulations reveal that, after a certain modification, the analytical model provides an upper estimate for the eddy current density at any location within the body. In particular, it overestimates the peak eddy currents at distant locations from a TMS coil by a factor of 10 on average. CONCLUSION: The simple analytical model tested in this study may be valuable as a rapid method to safely estimate levels of TMS currents at different locations within a human body. SIGNIFICANCE: At present, safe limits of general exposure to TMS electric and magnetic fields are an open subject, including fetal exposure for pregnant women.
Assuntos
Campos Magnéticos , Modelos Biológicos , Doses de Radiação , Exposição à Radiação/análise , Estimulação Magnética Transcraniana/métodos , Contagem Corporal Total/métodos , Encéfalo/fisiologia , Encéfalo/efeitos da radiação , Simulação por Computador , Humanos , Reprodutibilidade dos Testes , Espalhamento de Radiação , Sensibilidade e EspecificidadeRESUMO
Simulation of the electromagnetic response of the human body relies heavily upon efficient computational models or phantoms. The first objective of this paper is to present a new platform-independent full-body electromagnetic computational model (computational phantom), the Visible Human Project(®) (VHP)-Female v. 2.0 and to describe its distinct features. The second objective is to report phantom simulation performance metrics using the commercial FEM electromagnetic solver ANSYS HFSS.
Assuntos
Simulação por Computador , Imagens de Fantasmas , Osso e Ossos/química , Fenômenos Eletromagnéticos , Feminino , Corpo Humano , Humanos , Processamento de Imagem Assistida por Computador , Reprodutibilidade dos TestesRESUMO
While studies have shown that the application of transcranial direct current stimulation (tDCS) has been beneficial in the stimulation of cortical activity and treatment of neurological disorders in humans, open questions remain regarding the placement of electrodes for optimal targeting of currents for a given functional area. Given the difficulty of obtaining in vivo measurements of current density, modeling of conventional and alternative electrode montages via the finite element method has been utilized to provide insight into tDCS montage performance. It has been shown that extracephalic montages might create larger total current densities in deeper brain regions, specifically in white matter as compared to an equivalent cephalic montage. Extracephalic montages might also create larger average vertical current densities in the primary motor cortex and in the somatosensory cortex.At the same time, the horizontal current density either remains approximately the same or decreases. The metrics used in this paper include either the total local current density through the entire brain volume or the average vertical current density as well as the average horizontal current density for every individual lobe/cortex.