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Investigation of Microwave Ablation Process in Sweet Potatoes as Substitute Liver

The microwave ablation technique to destroy cancer tissues in liver is practiced clinically and is the subject of ongoing research, e.g., ablation monitoring. For studies, liver tissue from cattle or pigs is often used as a substitute material. In this work, sweet potato is presented as an alternati...

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Autores principales: Khan, Muhammad Saad, Hawlitzki, Michael, Taheri, Shadan Mofrad, Rose, Georg, Schweizer, Bernd, Brensing, Andreas
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8200201/
https://www.ncbi.nlm.nih.gov/pubmed/34200011
http://dx.doi.org/10.3390/s21113894
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author Khan, Muhammad Saad
Hawlitzki, Michael
Taheri, Shadan Mofrad
Rose, Georg
Schweizer, Bernd
Brensing, Andreas
author_facet Khan, Muhammad Saad
Hawlitzki, Michael
Taheri, Shadan Mofrad
Rose, Georg
Schweizer, Bernd
Brensing, Andreas
author_sort Khan, Muhammad Saad
collection PubMed
description The microwave ablation technique to destroy cancer tissues in liver is practiced clinically and is the subject of ongoing research, e.g., ablation monitoring. For studies, liver tissue from cattle or pigs is often used as a substitute material. In this work, sweet potato is presented as an alternative material for microwave ablation experiments in liver due to similar material properties. Sweet potatoes as a substitute for liver have the advantages of better handling, easy procurement and stable material properties over time for microwave ablation experiments. The dielectric constant and electrical conductivity of sweet potato are characterized for temperature variation with the help of high-temperature dielectric probe. Furthermore, a test setup is presented for microwave ablation experiments in which a bowtie slot antenna matched to sweet potato is placed on its surface to directly receive the microwave power from a self-developed microwave applicator inserted into a sweet potato 4 cm below the surface antenna. A high-power source was used to excite the microwave powers up to 80 W and a spectrum analyzer was used to measure the signal received by the surface antenna. The experiments were performed in an anechoic chamber for safety reasons. Power at 50 W and 80 W was stimulated for a maximum of 600 s at the 2.45 GHz ISM band in different sweet potato experiments. A correlation is found between the power received by the surface antenna and rise of temperature inside sweet potato; relative received power drops from 1 at 76 [Formula: see text] C to 0.6 at 88 [Formula: see text] C (max. temperature) represents a 40% relative change in a 50 W microwave ablation experiment. The received power envelope at the surface antenna is between 10 mW and 32 mW during 50 W microwave ablation. Other important results for 10 min, 80 W microwave ablation include: a maximum ablation zone short axis diameter of 4.5 cm and a maximum ablation temperature reached at 99 [Formula: see text] C, 3 mm away from the applicator’s slot. The results are compared with the state of the art in microwave ablation in animal liver. The dielectric constant and electrical conductivity evolution of sweet potato with rising temperature is comparable to animal liver in 50–60 [Formula: see text] C range. The reflection loss of self-developed applicator in sweet potato is below 15 dB which is equal to reflection loss in liver experiments for 600 s. The temperature rise for the first 90 s in sweet potato is 76 [Formula: see text] C as compared to 73 [Formula: see text] C in liver with 50 W microwave ablation. Similarly, with 80–75 W microwave ablation, for the first 60 s, the temperature is 98 [Formula: see text] C in sweet potato as compared to 100 [Formula: see text] C in liver. The ablation zone short-axis diameter after 600 s is 3.3 cm for 50 W microwave ablation in sweet potato as compared to 3.5 cm for 30 W microwave ablation in liver. The reasons for difference in microwave ablation results in sweet potato and animal liver are discussed. This is the first study to directly receive a signal from microwave applicator during a microwave ablation process with the help of a surface antenna. The work can be extended to multiple array antennas for microwave ablation monitoring.
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spelling pubmed-82002012021-06-14 Investigation of Microwave Ablation Process in Sweet Potatoes as Substitute Liver Khan, Muhammad Saad Hawlitzki, Michael Taheri, Shadan Mofrad Rose, Georg Schweizer, Bernd Brensing, Andreas Sensors (Basel) Article The microwave ablation technique to destroy cancer tissues in liver is practiced clinically and is the subject of ongoing research, e.g., ablation monitoring. For studies, liver tissue from cattle or pigs is often used as a substitute material. In this work, sweet potato is presented as an alternative material for microwave ablation experiments in liver due to similar material properties. Sweet potatoes as a substitute for liver have the advantages of better handling, easy procurement and stable material properties over time for microwave ablation experiments. The dielectric constant and electrical conductivity of sweet potato are characterized for temperature variation with the help of high-temperature dielectric probe. Furthermore, a test setup is presented for microwave ablation experiments in which a bowtie slot antenna matched to sweet potato is placed on its surface to directly receive the microwave power from a self-developed microwave applicator inserted into a sweet potato 4 cm below the surface antenna. A high-power source was used to excite the microwave powers up to 80 W and a spectrum analyzer was used to measure the signal received by the surface antenna. The experiments were performed in an anechoic chamber for safety reasons. Power at 50 W and 80 W was stimulated for a maximum of 600 s at the 2.45 GHz ISM band in different sweet potato experiments. A correlation is found between the power received by the surface antenna and rise of temperature inside sweet potato; relative received power drops from 1 at 76 [Formula: see text] C to 0.6 at 88 [Formula: see text] C (max. temperature) represents a 40% relative change in a 50 W microwave ablation experiment. The received power envelope at the surface antenna is between 10 mW and 32 mW during 50 W microwave ablation. Other important results for 10 min, 80 W microwave ablation include: a maximum ablation zone short axis diameter of 4.5 cm and a maximum ablation temperature reached at 99 [Formula: see text] C, 3 mm away from the applicator’s slot. The results are compared with the state of the art in microwave ablation in animal liver. The dielectric constant and electrical conductivity evolution of sweet potato with rising temperature is comparable to animal liver in 50–60 [Formula: see text] C range. The reflection loss of self-developed applicator in sweet potato is below 15 dB which is equal to reflection loss in liver experiments for 600 s. The temperature rise for the first 90 s in sweet potato is 76 [Formula: see text] C as compared to 73 [Formula: see text] C in liver with 50 W microwave ablation. Similarly, with 80–75 W microwave ablation, for the first 60 s, the temperature is 98 [Formula: see text] C in sweet potato as compared to 100 [Formula: see text] C in liver. The ablation zone short-axis diameter after 600 s is 3.3 cm for 50 W microwave ablation in sweet potato as compared to 3.5 cm for 30 W microwave ablation in liver. The reasons for difference in microwave ablation results in sweet potato and animal liver are discussed. This is the first study to directly receive a signal from microwave applicator during a microwave ablation process with the help of a surface antenna. The work can be extended to multiple array antennas for microwave ablation monitoring. MDPI 2021-06-04 /pmc/articles/PMC8200201/ /pubmed/34200011 http://dx.doi.org/10.3390/s21113894 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Khan, Muhammad Saad
Hawlitzki, Michael
Taheri, Shadan Mofrad
Rose, Georg
Schweizer, Bernd
Brensing, Andreas
Investigation of Microwave Ablation Process in Sweet Potatoes as Substitute Liver
title Investigation of Microwave Ablation Process in Sweet Potatoes as Substitute Liver
title_full Investigation of Microwave Ablation Process in Sweet Potatoes as Substitute Liver
title_fullStr Investigation of Microwave Ablation Process in Sweet Potatoes as Substitute Liver
title_full_unstemmed Investigation of Microwave Ablation Process in Sweet Potatoes as Substitute Liver
title_short Investigation of Microwave Ablation Process in Sweet Potatoes as Substitute Liver
title_sort investigation of microwave ablation process in sweet potatoes as substitute liver
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8200201/
https://www.ncbi.nlm.nih.gov/pubmed/34200011
http://dx.doi.org/10.3390/s21113894
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