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Changes in the dielectric properties of ex vivo bovine liver during microwave thermal ablation at 2.45 GHz

TitoloChanges in the dielectric properties of ex vivo bovine liver during microwave thermal ablation at 2.45 GHz
Tipo di pubblicazioneArticolo su Rivista peer-reviewed
Anno di Pubblicazione2012
AutoriLopresto, Vanni, Pinto Rosanna, Lovisolo G.A., and Cavagnaro M.
RivistaPhysics in Medicine and Biology
Volume57
Paginazione2309-2327
ISSN00319155
Parole chiaveAblation, Ablation Techniques, ablation therapy, animal, Animals, Antennas, article, Bovine liver, Cattle, cytology, Electric conductivity, Electric Impedance, Ex-vivo, Heat, Hot Temperature, impedance, instrumentation, Liver, Mammals, Measured data, methodology, Microwave ablation, microwave radiation, Microwaves, Numerical studies, Permittivity, Radar antennas, Radiation effects, Radiation exposure, Radiation properties, Relative permittivity, Specific absorption, Target tissues, Thermal ablation, Thermal lesion, Tissue, treatment planning, Water baths
Abstract

In microwave thermal ablation (MTA) therapy, the dielectric properties of the target tissue play an important role in determining the radiation properties of the microwave ablation antenna. In this work, the ex vivo dielectric properties of bovine liver were experimentally characterized as a function of the temperature during MTA at the frequency of 2.45 GHz. The obtained data were compared with measurements performed at the end of the MTA treatment, and considering the heating achieved with a temperature-controlled water bath. Finally, measured data were used to perform a numerical study evaluating the effects of changes in tissue's dielectric properties during the MTA treatment on the radiation properties of a microwave interstitial ablation antenna, as well as on the obtained thermal lesion. Results evidenced a significant decrease of both relative permittivity (about 38%) and electric conductivity (about 33%) in the tissue during treatment as the temperature increased to over 60 °C, with a dramatic drop when the temperature approached 100 °C. Moreover, the numerical study evidenced that changes in tissue's dielectric properties during the MTA treatment affect the distribution of the power absorbed by the tissue (specific absorption rateSAR, W kg 1) surrounding the microwave interstitial ablation antenna, leading to a peak SAR up to 20% lower, as well as to a thermal lesion up to 8% longer. This work may represent a preliminary step towards the future development of a procedure for MTA treatment planning. © 2012 Institute of Physics and Engineering in Medicine.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-84859319822&doi=10.1088%2f0031-9155%2f57%2f8%2f2309&partnerID=40&md5=a711eb620f8c4ba704b41057ed345970
DOI10.1088/0031-9155/57/8/2309
Citation KeyLopresto20122309