Voxel-based Human Models Research Articles

Temperature elevation of a human brain induced by a mobile phone electromagnetic radiation

This paper analyzes the specific absorption rate and the temperature elevation of the brain within an adult?s man head exposed to electromagnetic radiation. The source of electromagnetic radiation is a contemporary mobile phone operating at 900 MHz. Simulations were performed on an anatomically accurate AustinMan 2.6 voxel-based human model with a resolution of 1 ? 1 ? 1 mm3. The thermal analysis focuses on temperature distribution on the brain surface in fixed time steps during one hour of continuous mobile phone use.

Calculation of Internal Electric Fields Induced by Power Frequency Magnetic Fields During Live-Line Working Using Human Models With Realistic Postures

Worker exposure to high-intensity magnetic fields encountered during bare-handed live-line working on a conductor of an overhead transmission line is a major safety concern. In this article, internal ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> ) electric fields in a live-line worker induced by power frequency magnetic fields were numerically calculated considering realistic exposure conditions, i.e., different working postures on a conductor bundle of an overhead transmission line. The scalar potential finite difference (SPFD) method was adopted to voxel-based human models with realistic postures to calculate internal electric fields inside the models. The results showed that the internal electric fields were far below the basic restriction for occupational exposure stipulated in the International Commission on Nonionizing Radiation Protection guidelines even when the maximum magnetic field exceeded the reference level in the guidelines.

A GPU Computational Code for Eddy-Current Problems in Voxel-Based Anatomy

A hybrid finite element–boundary element method, developed to solve eddy-current problems in the frequency domain, is applied to the electromagnetic analysis of voxel-based human models. A specific procedure employs a massively parallelized algorithm implemented on a multiple Graphic Processing Units (GPU) code to speed up the solution of large systems whose matrix exceeds the RAM capability. The database structure used for the electromagnetic problem is also suitable for a successive thermal analysis to evaluate the distribution of the temperature elevation due to the energy deposited by the waves in the tissues. Finally, some examples of application are presented.

Massively Parallelized Boundary Element Simulation of Voxel-Based Human Models Exposed to MRI Fields

Boundary element and hybrid boundary element-finite element approaches are applied to the computation of induced electric field and specific absorption rate in voxel-based human models undergoing magnetic resonance imaging. Due to the very large size of the algebraic system, the procedure uses an iterative GMRES solver recalculating the element matrix at each iteration. A suitable processing of the Green integrals and a massively parallelized algorithm, based on the use of graphical processing units, leads to a strong reduction of the computational time.

Application of postured human model for SAR measurements

Abstract. In the last two decades, the increasing number of electronic devices used in day-to-day life led to a growing interest in the study of the electromagnetic field interaction with biological tissues. The design of medical devices and wireless communication devices such as mobile phones benefits a lot from the bio-electromagnetic simulations in which digital human models are used. The digital human models currently available have an upright position which limits the research activities in realistic scenarios, where postured human bodies must be considered. For this reason, a software application called "BodyFlex for CST STUDIO SUITE" was developed. In its current version, this application can deform the voxel-based human model named HUGO (Dipp GmbH, 2010) to allow the generation of common postures that people use in normal life, ensuring the continuity of tissues and conserving the mass to an acceptable level. This paper describes the enhancement of the "BodyFlex" application, which is related to the movements of the forearm and the wrist of a digital human model. One of the electromagnetic applications in which the forearm and the wrist movement of a voxel based human model has a significant meaning is the measurement of the specific absorption rate (SAR) when a model is exposed to a radio frequency electromagnetic field produced by a mobile phone. Current SAR measurements of the exposure from mobile phones are performed with the SAM (Specific Anthropomorphic Mannequin) phantom which is filled with a dispersive but homogeneous material. We are interested what happens with the SAR values if a realistic inhomogeneous human model is used. To this aim, two human models, a homogeneous and an inhomogeneous one, in two simulation scenarios are used, in order to examine and observe the differences in the results for the SAR values.

Generation of postured voxel-based human models for the study of step voltage excited by lightning current

Abstract. With the development of medical technique and computational electromagnetics, high resolution anatomic human models have already been widely developed and used in computation of electromagnetic fields induced in human body. Although these so called voxel-based human models are powerful tools for research on electromagnetic safety, their unchangeable standing posture makes it impossible to simulate a realistic scenario in which people have a lot of different postures. This paper describes a poser program package which was developed as an improved version of the free-from deformation technique to overcome this problem. It can set rotation angles of different human joints and then deform the original human model to make it have different postures. The original whole-body human model can be deformed smoothly, continuity of internal tissues and organs is maintained and the mass of different tissues and organs can be conserved in a reasonable level. As a typical application of the postured human models, this paper also studies the effect of the step voltage due to a lightning strike on the human body. Two voxel-based human body models with standing and walking posture were developed and integrated into simulation models to compute the current density distribution in the human body shocked by the step voltage. In order to speed up the transient simulation, the reduced c technique was used, leading to a speedup factor of around 20. The error introduced by the reduced c technique is discussed and simulation results are presented in detail.

Postured voxel-based human models for electromagnetic dosimetry

High-resolution anatomically realistic whole-body voxel models have recently been developed for electromagnetic dosimetry. However, the posture of most models is similar to the standing one, which strongly limits electromagnetic dosimetry when simulating a realistic exposure scenario. In this paper, we present the development of postured models based on anatomically realistic voxel models with standing posture. Voxel models of the Japanese adult male and female were used as the original upright standing models. The Japanese models were composed of 2 mm cubic voxels, each of which was segmented into 51 different tissue types. We developed several different types of posture models using a novel posture transformation method. These posture models were smoothly transformed, while the continuity of the internal tissues and organs was maintained. In this paper, we also present our calculations of the whole-body averaged specific absorption rates (SARs) of sitting male and female models exposed to electromagnetic plane waves at very high (VHF) and ultra high frequency (UHF) bands.

High-resolution human anatomy models for advanced electromagnetic field computations

High-resolution anatomy models are used in the computation of induced electromagnetic fields, SAR, and temperature profiles in the human body. In particular, the HUGO model with a voxel resolution of up to 1/spl times/1/spl times/1 mm allows accurate modeling of more than 30 distinct human organs and tissues. The numerical calculations use the finite integration technique, which proves appropriate for the voxel-based human models. Simulation results for the induced electromagnetic fields in the human head due to the high-frequency radiation of a cellular phone are given. In a second application the electromagnetic field pattern and temperature distribution in the human body in regional hyperthermia therapy are calculated.