A high-performance, multi-frequency micro-controlled Electrical Impedance Mammography (EIM) excitation and phantom validation system

The research concentrates on the design, development and calibration of a high performance Electrical Impedance Mammography (EIM) system for early detection of breast cancer at the macro and micro scale (at an early stage applicable for different breast sizes and shapes). The enhancement of the Electrical Impedance Tomography (EIT) system focuses on developing electrical and electronic instrumentations and improving the current source topologies to make them operate at multiple frequencies for the purpose of measuring permittivity and conductivity of different breast tissues. The calibration, assessment systems have employed current calibration in the EIT to evaluate the impedance distribution. This facilitates the acquisition of accurate impedance images to enable images of the internal structure of the breast to be constructed. A constraint on EIT systems is that the current injection system suffers from the effects of stray capacitance having a major impact on the hardware subsystem as the EIT is an ill-posed inverse problem which depends on the noise level in EIT measured data and regularization parameter in the reconstruction algorithm. This research aims are to prevent this problem by using a capacitance cancellation method based on a General Impedance Converter (GIC) implemented by operation of a second generation of current conveyor called OCCII-GIC and calibration methods to facilitate operation in the high frequency range. An EIT system based on a planar 85-electrode channel and using a Microcontroller unit (MCU) for addressing control between 85 electrodes and implementing calibration methods has been constructed. In EIT systems, assessment, validation of the performance and calibration of systematic errors in the electrical field generated inside of the interrogated volume is important. Evaluation of the EIT system will be assessed using a realistic electronic phantom (E-phantom). This enables the evaluation of the different conductivity values of the tissue, which has been created and evaluated based on the RSC circuit model for the different electrical conductivities and electrical impedivities in breast tissue

Using planar electrical impedance tomography as a structural health monitoring method to detect and evaluate the damage to CFRP composite

Electrical Impedance Tomography (EIT) is an emerging imaging modality that produces either a 2D or 3D impedance image (conductivity or impedivity) of the subject under test. In this study we tested and demonstrated a new application of applying an EIT system to detect delamination and evaluate the damage location, size, strain and severity for Structure Health Monitoring (SHM) of composites (i.e. Carbonfibre-reinforced polymer (CFRP) composites)

An Electronic Mesh phantom for planar structure EIS systems

There are two phantom types to assess EIT or EIS systems: physical and electronic phantoms. The physical phantom that is used for EIT or EIS systems typically is composed of a conductive saline solution or gel medium with objects embedded in this medium. The medium and object have different impedances, which permit the system to detect changes of impedance and image them. Physical phantoms have common problems of: short life, inflexibility, instability and uncontrollable physical characteristics. The E-phantom is used to assess the system characteristics of the EIT or EIS systems such as: current or voltage delivered, internal stray impedance and the effects of the impedance of the medium on the measurements. These results can then be used to optimise the electronic circuitry and components relevant to the impedance measurements to improve the performance of the system. Thus, the advantages of an E-phantom compared with a physical phantom are: improved quality, reproducibility, predictability and stability of signals. The Sussex EIS system is based on a planar 85-electrodes structure located at the bottom of the tank. Figure 1 shows planar 85-electrodes and 2D and 3D meshes of the system

Promoting Entrepreneurial Behavior among Agricultural Students: A Two-Step Approach to Structural Equation Modeling

I ncreasing rate of unemployment among the graduates of Iranian higher agricultural education system has been developed into one of the major socio-economic problems of the nation. Entrepreneurship is one of the most important factors contributing to economic and social development, that is, it is a main driver for employment creation. As such, many policy initiatives in Iran attempt to pull agricultural students toward an entrepreneurial career choice. In this regard, considering the importance of entrepreneurship, and applying Ajzen’s (1991) theory of planned behavior, the present study was conducted to investigate the factors affecting entrepreneurial behavior of agricultural students in Razi University. The population of this study consisted of all senior agricultural students of Razi University in Iran (N=300), 169 of whom were selected as the sample using the proportional stratified sampling method. Data were analyzed by SPSS and AMOS version23 software in two phases of descriptive and inferential statistics. Results of structural equation modeling revealed that personal attitude toward entrepreneurship, perceived behavioral control, and subjective norm were the main predictors of entrepreneurial intention (R 2=0.46) and behavior (R 2=0.45) among agricultural students. The findings of this study can have practical implications concerning the promotion of entrepreneurial intention and behavior among agricultural students for higher agricultural education managers, planners, and educators

Conditioning electrical impedance mammography system

A multi-frequency Electrical Impedance Mammography (EIM) system has been developed to evaluate the conductivity and permittivity spectrums of breast tissues, which aims to improve early detection of breast cancer as a non-invasive, relatively low cost and label-free screening (or pre-screening) method. Multi-frequency EIM systems typically employ current excitations and measure differential potentials from the subject under test. Both the output impedance and system performance (SNR and accuracy) depend on the total output resistance, stray and output capacitances, capacitance at the electrode level, crosstalk at the chip and PCB levels. This makes the system design highly complex due to the impact of the unwanted capacitive effects, which substantially reduce the output impedance of stable current sources and bandwidth of the data that can be acquired. To overcome these difficulties, we present new methods to design a high performance, wide bandwidth EIM system using novel second generation current conveyor operational amplifiers based on a gyrator (OCCII-GIC) combination with different current excitation systems to cancel unwanted capacitive effects from the whole system. We reconstructed tomography images using a planar E-phantom consisting of an RSC circuit model, which represents the resistance of extra-cellular (R), intra-cellular (S) and membrane capacitance (C) of the breast tissues to validate the performance of the system. The experimental results demonstrated that an EIM system with the new design achieved a high output impedance of 10MΩ at 1MHz to at least 3MΩ at 3MHz frequency, with an average SNR and modelling accuracy of over 80dB and 99%, respectively

Promoting Entrepreneurial Behavior among Agricultural Students: A Two-Step Approach to Structural Equation Modeling

Increasing rate of unemployment among the graduates of Iranian higher agricultural education system has been developed into one of the major socio-economic problems of the nation. Entrepreneurship is one of the most important factors contributing to economic and social development, that is, it is a main driver for employment creation. As such, many policy initiatives in Iran attempt to pull agricultural students toward an entrepreneurial career choice. In this regard, considering the importance of entrepreneurship, and applying Ajzen’s (1991) theory of planned behavior, the present study was conducted to investigate the factors affecting entrepreneurial behavior of agricultural students in Razi University. The population of this study consisted of all senior agricultural students of Razi University in Iran (N=300), 169 of whom were selected as the sample using the proportional stratified sampling method. Data were analyzed by SPSS and AMOS version23 software in two phases of descriptive and inferential statistics. Results of structural equation modeling revealed that personal attitude toward entrepreneurship, perceived behavioral control, and subjective norm were the main predictors of entrepreneurial intention (R 2 =0.46) and behavior (R 2 =0.45) among agricultural students. The findings of this study can have practical implications concerning the promotion of entrepreneurial intention and behavior among agricultural students for higher agricultural education managers, planners, and educators

Converting EIT voxel based imaging and pixel based ultrasound imaging to standardised DICOM

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A flexible and configurable hardware for the combined EIM and Ultrasound device

One of the current methods in breast cancer detection is Sonography, also known as Ultrasound imaging. Sonography is effective for imaging soft tissues of the body and returns a high resolution image. Its operation is highly subjective depending on the operator and the images do vary with positioning. At the University of Sussex we have successfully built an automated and repeatable Ultrasound scanner and combined and reconstructed the data in 3D. Ultrasound imaging does have its limitations when it comes to cancer detection and diagnosis. The Sussex EIM (Electrical Impedance Mammography) device is a novel imaging system developed at the University of Sussex for the detection of breast lesions in-vivo using quadrature detection of impedance. Combining the high resolution images of Ultrasound with the parametric data of EIT would give a more precise diagnosis. This paper describes how we have achieved a totally configurable system where we have combined our current EIT technology for breast cancer detection to the 3D Ultrasound scanner we have built. This was done with a quick turn-around in development time using off-the-shelf hardware and a 3U PXI Chassis. The system is based around a National Instruments PXI (PCI eXtensions for Instrumentation) chassis which is a modular electronic instrumentation platform

An electrical mesh phantom for the planar structure EIT systems

Evaluation of planar EIT systems used in clinical studies can be based on a realistic electronic phantom (E-phantom). This paper describes a mesh phantom based on an 85 electrode planar mesh structure. The design presents a dynamic mesh phantom to assess the performance of the planar topology to simulate in vivo conditions. The phantom is especially designed for the Sussex EIT system to validate system measurements

Multi-frequency response mesh phantom for validation of EIT system performance

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