Douglas Deas Yero - Academia.edu (original) (raw)
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Papers by Douglas Deas Yero
A study of the electromagnetic environment was carried out in 2 electrotherapy departments of Pal... more A study of the electromagnetic environment was carried out in 2 electrotherapy departments of Palma Soriano in Santiago de Cuba, in order to obtain the distribution pattern for different operability ways and exploitation of the medical-therapeutic equipment. For the electromagnetic characterization of the evaluated environments a measurement protocol was elaborated starting from the analysis of international standards and an isotropic measure was used that showed the results through contour maps. The electro-medical device Magnetomed, model 7200 was the one that contributed the most, although the maximum value of the obtained magnetic induction (19.7 µT) was below the established exhibition limit and above the exhibition limit suggested by the Bioiniciativa Work Group. It is recommended to limit the permanency of people around, while it is in operation.
RESUMEN A comparative numerical study of three probe types with the same radial dimensions, three... more RESUMEN A comparative numerical study of three probe types with the same radial dimensions, three probe models, and five reference materials is presented for six biological tissues: liver, muscle, kidney, heart, blood and fat. The Probe-Model-Reference (PMR) combinations that lead to the most accurate results of the permittivity at frequencies from 300 MHz to 3 GHz are investigated for a coaxial probe without flange, a coaxial probe with flange, and a coaxial probe open into a propagation circular wave guide. The probe models considered are capacitive model, antenna model, and virtual line model. The reference materials are distilled water, 0.02 M NaCl(aq) solution, ethanol, methanol and 0.5 M NaCl(aq) solution. The results corroborates that when measuring the RF permittivity of biological materials using an open-ended coaxial line the proper selection of the probe type, probe model and reference material is crucial if good accuracy of measurements is expected. The presented methodo...
A study of the electromagnetic field generated by different electrodes of capacitive type, used b... more A study of the electromagnetic field generated by different electrodes of capacitive type, used by the physiotherapy device for short wave diathermy (YB4-66), was carried out considering their interaction with the surrounding environment. The measurements of the electric field for different treatment configurations were carried out and a meter with electric isotropic field probe was used. By means of a professional software of simulation, a two-dimensional parametric electromagnetic model with axial symmetry was designed, to obtain detailedly in each configuration of the evaluated electrodes the interaction of the electromagnetic field with the biological tissue and the external environment. A good correspondence was found between the obtained results in an experimental way and the simulations, which allowed to identify the exposure levels and to make decisions to achieve a more effective treatment and with the shortest possible damage for the human beings.
IEEE Transactions on Biomedical Engineering, 2018
The released energy during radio frequency thermal ablation (RFTA) therapy changes the dielectric... more The released energy during radio frequency thermal ablation (RFTA) therapy changes the dielectric properties of biological tissues. Understanding changes of dielectric properties of biological tissues during heating is fundamental to suitably model the medical procedure. The aim of this work is to obtain the thermal dependences of conductivity and permittivity of ex-vivo porcine liver tissue at six frequencies from 5 to 500 kHz, during heating from 37 °C to 100 °C at three heating rates of approximately 0.1, 3 and 10 °C/min. Methods: Two experimental setups using different heating sources and a four-needle electrode connected to an Impedance Analyzer were developed to evaluate the thermal dependencies. Results: The results at a body temperature of 37 °C show a good agreement with the data reported in the literature. The conductivity initially shows an increase followed by a decrease, whereas the permittivity increases before a subsequent sharp decrease. Above 60 °C different trends are observed for the three heating rates studied. Conclusion: The electric conductivity and permittivity show a similar behavior at all evaluated frequencies and heating rates. The observed abrupt change of the slope near 45 °C at slow heating rate may be used to identify the region of reversible changes in the tissue. Significance: These results confirm the connection between tissue dielectric properties, working frequency and exposure time with thermal damage during heating.
Ciencia En Su Pc, 2006
El desarrollo tecnológico actual conduce a que la industria del reciclaje se convierta en importa... more El desarrollo tecnológico actual conduce a que la industria del reciclaje se convierta en importantes suministradoras de materias primas para la fabricación de los más disímiles artículos de consumo diario o de equipos de larga duración. Al mismo tiempo permite proteger el medio ambiente, ahorrar los recursos minerales y la energía. Los países desarrollados son los abanderados de esta industria, la misma también se conoce como la "Industria del Futuro" ya que cada día miles de toneladas (millones) de elementos y desechos de chatarra metálica se incorporan al proceso de reciclaje. Este trabajo tiene el objetivo de contribuir a dar a conocer el estado actual de ésta temática en el mundo y en nuestro país. Hoy en día se hace más necesario desarrollar una sociedad en la que los sistemas Científico-Tecnológicos sirvan al hombre, quien requiere que la tecnología sea centrada en lo humano, atendiendo a fines sociales más que técnicos a los.
The outcome of radio frequency thermal ablation (RFTA) is significantly affected by the tissue el... more The outcome of radio frequency thermal ablation (RFTA) is significantly affected by the tissue electrical conductivity; thus, understanding the changes of this property during heating is fundamental to suitably model the medical procedure. In this work a reasonable procedure is proposed for selecting the appropriate experimental data of the temperature dependence of electrical conductivity for the simulation taking into account the heating rate at which the data was acquired and the power that will be delivered to the electrodes in the RFTA situation of interest, based on the computing of the time average of the heating rate in a representative point of the ablation zone. The numerical results confirmed that the use of lower frequencies (20 kHz) than currently used during RFTA (450 kHz) may result in preferential heating of the tumor and consequently in less damage on healthy tissue. Also, the effect on the computed thermal lesion size of three different models of the temperature de...
A study of the electromagnetic environment was carried out in 2 electrotherapy departments of Pal... more A study of the electromagnetic environment was carried out in 2 electrotherapy departments of Palma Soriano in Santiago de Cuba, in order to obtain the distribution pattern for different operability ways and exploitation of the medical-therapeutic equipment. For the electromagnetic characterization of the evaluated environments a measurement protocol was elaborated starting from the analysis of international standards and an isotropic measure was used that showed the results through contour maps. The electro-medical device Magnetomed, model 7200 was the one that contributed the most, although the maximum value of the obtained magnetic induction (19.7 µT) was below the established exhibition limit and above the exhibition limit suggested by the Bioiniciativa Work Group. It is recommended to limit the permanency of people around, while it is in operation.
RESUMEN A comparative numerical study of three probe types with the same radial dimensions, three... more RESUMEN A comparative numerical study of three probe types with the same radial dimensions, three probe models, and five reference materials is presented for six biological tissues: liver, muscle, kidney, heart, blood and fat. The Probe-Model-Reference (PMR) combinations that lead to the most accurate results of the permittivity at frequencies from 300 MHz to 3 GHz are investigated for a coaxial probe without flange, a coaxial probe with flange, and a coaxial probe open into a propagation circular wave guide. The probe models considered are capacitive model, antenna model, and virtual line model. The reference materials are distilled water, 0.02 M NaCl(aq) solution, ethanol, methanol and 0.5 M NaCl(aq) solution. The results corroborates that when measuring the RF permittivity of biological materials using an open-ended coaxial line the proper selection of the probe type, probe model and reference material is crucial if good accuracy of measurements is expected. The presented methodo...
A study of the electromagnetic field generated by different electrodes of capacitive type, used b... more A study of the electromagnetic field generated by different electrodes of capacitive type, used by the physiotherapy device for short wave diathermy (YB4-66), was carried out considering their interaction with the surrounding environment. The measurements of the electric field for different treatment configurations were carried out and a meter with electric isotropic field probe was used. By means of a professional software of simulation, a two-dimensional parametric electromagnetic model with axial symmetry was designed, to obtain detailedly in each configuration of the evaluated electrodes the interaction of the electromagnetic field with the biological tissue and the external environment. A good correspondence was found between the obtained results in an experimental way and the simulations, which allowed to identify the exposure levels and to make decisions to achieve a more effective treatment and with the shortest possible damage for the human beings.
IEEE Transactions on Biomedical Engineering, 2018
The released energy during radio frequency thermal ablation (RFTA) therapy changes the dielectric... more The released energy during radio frequency thermal ablation (RFTA) therapy changes the dielectric properties of biological tissues. Understanding changes of dielectric properties of biological tissues during heating is fundamental to suitably model the medical procedure. The aim of this work is to obtain the thermal dependences of conductivity and permittivity of ex-vivo porcine liver tissue at six frequencies from 5 to 500 kHz, during heating from 37 °C to 100 °C at three heating rates of approximately 0.1, 3 and 10 °C/min. Methods: Two experimental setups using different heating sources and a four-needle electrode connected to an Impedance Analyzer were developed to evaluate the thermal dependencies. Results: The results at a body temperature of 37 °C show a good agreement with the data reported in the literature. The conductivity initially shows an increase followed by a decrease, whereas the permittivity increases before a subsequent sharp decrease. Above 60 °C different trends are observed for the three heating rates studied. Conclusion: The electric conductivity and permittivity show a similar behavior at all evaluated frequencies and heating rates. The observed abrupt change of the slope near 45 °C at slow heating rate may be used to identify the region of reversible changes in the tissue. Significance: These results confirm the connection between tissue dielectric properties, working frequency and exposure time with thermal damage during heating.
Ciencia En Su Pc, 2006
El desarrollo tecnológico actual conduce a que la industria del reciclaje se convierta en importa... more El desarrollo tecnológico actual conduce a que la industria del reciclaje se convierta en importantes suministradoras de materias primas para la fabricación de los más disímiles artículos de consumo diario o de equipos de larga duración. Al mismo tiempo permite proteger el medio ambiente, ahorrar los recursos minerales y la energía. Los países desarrollados son los abanderados de esta industria, la misma también se conoce como la "Industria del Futuro" ya que cada día miles de toneladas (millones) de elementos y desechos de chatarra metálica se incorporan al proceso de reciclaje. Este trabajo tiene el objetivo de contribuir a dar a conocer el estado actual de ésta temática en el mundo y en nuestro país. Hoy en día se hace más necesario desarrollar una sociedad en la que los sistemas Científico-Tecnológicos sirvan al hombre, quien requiere que la tecnología sea centrada en lo humano, atendiendo a fines sociales más que técnicos a los.
The outcome of radio frequency thermal ablation (RFTA) is significantly affected by the tissue el... more The outcome of radio frequency thermal ablation (RFTA) is significantly affected by the tissue electrical conductivity; thus, understanding the changes of this property during heating is fundamental to suitably model the medical procedure. In this work a reasonable procedure is proposed for selecting the appropriate experimental data of the temperature dependence of electrical conductivity for the simulation taking into account the heating rate at which the data was acquired and the power that will be delivered to the electrodes in the RFTA situation of interest, based on the computing of the time average of the heating rate in a representative point of the ablation zone. The numerical results confirmed that the use of lower frequencies (20 kHz) than currently used during RFTA (450 kHz) may result in preferential heating of the tumor and consequently in less damage on healthy tissue. Also, the effect on the computed thermal lesion size of three different models of the temperature de...