Publicação
Electrical Impedance Tomography Acquisition System
| Resumo: | Electrical Impedance Tomography (EIT) is a non-invasive medical imaging tech nique that, from voltage and current measurements taken at the body’s frontier, allows the determination of the electrical conductivity from different tissues in side the body. Since each tissue presents distinct electrical conductivity values, it is possible to form a medical image. In this method, some factors should be considered, for example, the number of electrodes supported and the excitation pattern used. An increase in the number of electrodes allows for an increase in spatial resolution. Another characteristic is the implication different measurement frequencies have in the produced medical image. In this dissertation, a low-cost prototype with a capacity for 32 electrodes to ac quire these signals was developed. This new prototype allows measurements starting at 1 kHz up to 100 kHz, with a fixed current amplitude of 500 µA. To acquire the response, a Programmable Gain Amplifier (PGA) was used, with gains of 1, 10, 100 and 1000 V/V, followed by a 12-bit Analog-to-Digital Con verter (ADC) at a sampling rate up to 1 MSPS. To validate the system a few medical images were produced and presented in this dissertation, namely of a human arm, a phantom used for Microwave Medical Imaging and, finally, a water tank with different objects placed inside. |
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| Autores principais: | Silva, Fábio Miguel Ricardo da |
| Assunto: | Electrical Impedance Tomography Conductivity Tissue Digital Signal Processing Tomografia de Impedância Elétrica Condutividade Tecido Processamento Digital de Sinal |
| Ano: | 2022 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Instituto Politécnico de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório Científico do Instituto Politécnico de Lisboa |
| Resumo: | Electrical Impedance Tomography (EIT) is a non-invasive medical imaging tech nique that, from voltage and current measurements taken at the body’s frontier, allows the determination of the electrical conductivity from different tissues in side the body. Since each tissue presents distinct electrical conductivity values, it is possible to form a medical image. In this method, some factors should be considered, for example, the number of electrodes supported and the excitation pattern used. An increase in the number of electrodes allows for an increase in spatial resolution. Another characteristic is the implication different measurement frequencies have in the produced medical image. In this dissertation, a low-cost prototype with a capacity for 32 electrodes to ac quire these signals was developed. This new prototype allows measurements starting at 1 kHz up to 100 kHz, with a fixed current amplitude of 500 µA. To acquire the response, a Programmable Gain Amplifier (PGA) was used, with gains of 1, 10, 100 and 1000 V/V, followed by a 12-bit Analog-to-Digital Con verter (ADC) at a sampling rate up to 1 MSPS. To validate the system a few medical images were produced and presented in this dissertation, namely of a human arm, a phantom used for Microwave Medical Imaging and, finally, a water tank with different objects placed inside. |
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