Duyan Geng

The Acquisition Hardware System with Direct Digital Synthesis and Filtered Back-Projection Imaging in Electrical Impedance Tomography

Electrical impedance tomography is a new imaging modality that produces images by computing electrical conductivity within the body. This paper presents a basic acquisition hardware system of electrical impedance tomography with direct digital synthesis (DDS), which is used for studying the human head electrical property. The filtered back-projection algorithm is used for image reconstruction

Electromagnetic Field Simulation of 3D Realistic Head Model During Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) is a powerful, non-invasive tool for investigating functions in the brain. The target inside the head is stimulated with eddy currents induced in the tissues by the time-varying magnetic field. TMS has been used in several applications in medical and clinical research which include brain mapping, treatment of mood disorder and schizophrenia, treatment of epilepsy, treatment of chronic pain and so on. The stimulation effect can be affected by stimulation site and intensity which are changed with the shape and parameters of the coil. In this paper, the electromagnetic field induced in the head by two kinds of coils which are usually used in study and treatments during TMS has been analyzed. This three-dimensional simulation is useful for eddy currents evaluation and spatial localization of stimulation.

Implementation of Generalized Back Projection Algorithm in 3D EIT Model

Electrical impedance tomography (EIT) is an imaging modality of determining imaging the interior conductivity distribution within an object. In the paper, generalized back projection algorithm (GBPA) is proposed for EIT image reconstruction. The algorithm is based on node back projection algorithm (NBPA), and extends projection range to arbitrary part of the object. To evaluate the proposed method, GBPA is first applied to image reconstruction using a simulated cylinder model. Compared with conventional back projection algorithm (BPA) and NBPA, the images reconstructed by GBPA are more accurate in terms of several metrics used in the paper. In addition, we present image reconstruction results using a 128-channel EIT system to demonstrate the performance of GBPA in real experiments.Electrical Impedance Tomography (EIT) is an attractive method for clinical detection. A new method called Generalized Back Projection Algorithm (GBPA) is proposed in this paper, which developed from Node Back Projection Algorithm (NBPA). This algorithm extends projection range to aggregate of arbitrary node in the subject. Compared with each other it is indicated the images reconstructed by GBPA contained more information and better characterization following several defined evaluation parameters than those of conventional Back Projection Algorithm (BPA) and NBPA.

Optimal design of energy transmission system for implantable device base on WiTricity

WiTricity is a new technology which energy can be transmitted via resonant coupling in the non-radiation near-field. In this paper, optimal design of energy transmission system for implantable devices base on WiTricity is performanced, the influence of system structure parameter on energy transmission efficiency based on WiTricity is investigated.

Effects of Electromagnetic Field of UHV Transmission Lines Exposure on Testis Tissue in Mice

The main goal of this study was to evaluate the possible effects of electromagnetic field (EMF) of transmission lines exposure on testis tissue of mice. Forty adult BALB/c mice were divided into two groups. One group (twenty mice) has been done by daily exposures of 24 hours, and the other sham-exposed group (twenty mice) served as the control. After seven weeks of exposure, two groups of the mice were sacrificed. The testis tissue was assessed by serum biochemical assay, histopathological examination and flow cytometric analysis (FCM). EMF exposure did not significantly affect the distribution of DNA ploidy (1n, 2n and 4n cells), but significantly decreased the S phase fraction and the Proliferation Index of testis germ cells.

A Fast Image Reconstruction Algorithm of Electrical Capacitance Tomography Based on Engle Criterion

To improve the speed and quality of the reconstruction image for Electrical Capacitance Tomography (ECT), a fast image reconstruction algorithm based on Engle criterion is proposed. ECT image reconstruction is an ill-posed problem, and Tikhonov regularization is employed to get the stable solution. Engle criterion is used to choice regularization parameter. A further research about three-order method for fast choosing regularization parameter is proposed. Simulation results show that the proposed method has fast convergence rate and the reconstruction image quality is improved markedly.

Preliminary studies of putative bioeffects of experimental ultra high voltage transmission environment on mice

In order to evaluate the effects of electromagnetic fields (EMF) of ultra high voltage (UHV) transmission lines exposure on important life organs and tissues of BALB/c mice, an exposed environment was constructed in laboratory. Fifty male adult BALB/c mice were divided into two groups. One group has been done by daily exposures of 24 hours, and the other sham-exposed group served as the control. After six weeks of exposure, all the mice were sacrificed. The important life organs of BALB/c mice in vivo were screened with serum biochemical assay, morphological observation at histological and ultrastructural levels as well as flow cytometric analysis (FCM). There were no significant differences in important organs and tissues except testis germ cells and bone marrow between exposed groups and control groups.

Three dimensional detection and imaging for human lung based on node back-projection algorithm with a 64 electrodes EIT system

Electrical impedance tomography (EIT) is a medical imaging technique in which an image of the conductivity or permittivity of part of the body is inferred from surface electrical measurements. In the paper an approach of a fast, real-time, three dimensional human lungs detection and imaging based on node back-projection algorithm with a 64 electrodes EIT system is introduced. The results shows that the system has the capability of reflection on impedance change of the thorax by the images reconstructed during ones breathing.

Development of Electromagnetic Environment of Three Phase Power Lines for Bio-Effects Evaluation

In order to evaluate the possible effects of electromagnetic irradiation of power lines on white mice, an electromagnetic environment was constructed in laboratory setting. Charge simulation method (CSM) and Biot-Savart law have respectively been adopted to compute the three-dimensional electric field and magnetic field of the environment. Both methods are programmed using the MATLAB software. Simulation and measurement indicate that the intensity of electric field can reach up to 10kil-volt per meter (kV/m) at ground level, and the magnetic flux density can reach as high as 100microtesla (μT). It is demonstrated that the electromagnetic environment can be utilized in studying white mice simultaneous exposure to extremely low frequency electric field and magnetic field emitted from power lines.

Regularization Parameter Optimum Based on Quasi-Optimum Criterion for Image Reconstruction of Electrical Capacitance Tomography

Electrical Capacitance Tomography (ECT) image reconstruction is an ill-posed problem, and Tikhonov regularization is widely employed to get the stable solution. Correctly selecting regularization parameter is crucial for image reconstruction, which affects both quality and speed of image reconstruction. In this paper, a method of selecting optimum parameter based on quasi-optimum criterion is proposed. Simulation results show that the reconstruction image quality is improved markedly by using the proposed method.