Realistic Human Body Models Research Articles

A103 CFD解析用Virtual Manikinの開発とグリッドライブラリ構築

Currently indoor environment studies focus on phenomena around the hunun body at the microclimate level, and therefore the need for more realistic and detailed human body models has been pointed out. Numerical models representing closely the actual shape of the human body have already been proposed for seated female models (or androgynous models based on female body shapes), and are available for indoor environment analysis applications. However, other human body shapes have not been modeled. In addition, since existing models use coarse meshes, sufficient detailed data on various parts of the human body has not been gathered. This study aims to develop virtual manikins that represent human body scales for adult males and females as well as child (almost seven-year-olds). This report provides an overview of the development of models for seven-year-olds child.

Finite‐difference time‐domain‐based studies of MRI pulsed field gradient‐induced eddy currents inside the human body

AbstractIn modern magnetic resonance imaging (MRI), patients are exposed to strong, rapidly switching magnetic gradient fields that, in extreme cases, may be able to elicit nerve stimulation. This paper presents theoretical investigations into the spatial distribution of induced current inside human tissues caused by pulsed z‐gradient fields. A variety of gradient waveforms have been studied. The simulations are based on a new, high‐definition, finite‐difference time‐domain method and a realistic inhomogeneous 10‐mm resolution human body model with appropriate tissue parameters. It was found that the eddy current densities are affected not only by the pulse sequences but by many parameters such as the position of the body inside the gradient set, the local biological material properties and the geometry of the body. The discussion contains a comparison of these results with previous results found in the literature. This study and the new methods presented herein will help to further investigate the biological effects caused by the switched gradient fields in a MRI scan. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 26–36, 2002.

Influence of human model resolution on computed currents induced in organs by 60‐Hz magnetic fields

The effects of human body model resolution on computed electric fields induced by 60 Hz uniform magnetic fields are investigated. A recently-developed scalar potential finite difference code for low-frequency electromagnetic computations is used to model induction in two anatomically realistic human body models. The first model consists of 204290 cubic voxels with 7.2-mm edges, while the second comprises 1639146 cubic voxels with 3.6-mm edges. Calculations on the lower-resolution model using, for example, the finite difference time domain or impedance methods, push the capabilities of workstations. The scalar method, in contrast, can handle the higher-resolution model using comparable resources. The results are given in terms of average and maximum electric field intensities and current density magnitudes in selected tissues and organs. Although the lower-resolution model provides generally acceptable results, there are important differences that make the added computational burden of the higher-resolution calculations worthwhile. In particular, the higher-resolution modelling generally predicts peak electric fields intensities and current density magnitudes that are slightly higher than those computed using the lower-resolution modelling. The differences can be quite large for small organs such as glands.