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Evaluation of the performance of designed coaxial antennas for hyperthermia using simulation and experimental methods

Ibitoye Ayo Z., Ogese Obande C., Adedokun Margaret B., Habeebu Muhammad Y., Nwoye Ephraim O., Aweda Adebayo M.

Polish Journal of Medical Physics and Engineering

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2021

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Vol. 27, Iss. 1

109--117

EN

Introduction: Antenna geometries and tissue properties affect microwave energy distributions during microwave ablation procedures. There is paucity information on the potential of antenna fabricated from a thick semi-rigid coaxial cable in the field of microwave thermal therapy. This study aimed at comparing the performance of two dual-slot antennas designed from different semi-rigid coaxial cables for the ablation of a liver tumour using numerical simulation and experimental validation methods. Materials and Methods: COMSOL Multiphysics software was used for designing dual-slot antennas and as well as to evaluate microwave energy deposition and heat distribution in the liver tissue. Experimental validations were conducted on the ex-vivo bovine livers to validate the simulation results. Results: Thick antenna developed in this study produced a higher sphericity index, larger ablation diameter and reduced backward heating along the antenna shaft than the existing one. The experimental validation results also indicate significant differences between the two antennas in terms of ablation diameters (p = 0.04), ablation lengths (p = 0.02) and aspect ratios (p = 0.02). Conclusion: Based on the findings in this study, antenna fabricated from a thick coaxial cable has a higher potential of localizing microwave energy in the liver than conventional antennas.

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Wykorzystanie właściwości elektrycznych komórek nowotworowych do monitorowania termoablacji

Szuflitowska B.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2015

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Vol. 21, nr 2

86--90

PL

Badania opisane w pracy dotyczą konduktywności i przenikalności elektrycznej tkanek w aspekcie termoablacji prądem wysokiej częstotliwości. Ablacja elektryczna jest jedną z metod leczenia nieresekcyjnych guzów wątroby. Wzrost konduktywności jest zwykle skorelowany z typem nowotworu i jego stadium. W artykule zaprezentowano symulację zabiegu w zależności od zastosowanego napięcia i wartości konduktywności tkanek nowotworowych.

EN

The influence of the electrical conductivity and dielectric permittivity of biological tissues on the radiofrequency termoablation outcomes is discussed. Increase of conductivity correlates with the tumor type and stage. Radiofrequency thermal ablation is one of the methods used for the treatment of unresectable liver tumors. In this paper, the simulation of the ablation process depending of the applied voltage and the tumor conductivity, is presented.

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Liver Tumour Classification Using Co-Occurrence Matrices on the Contourlet Domain

Kumar S. S., Moni R. S., Rajeesh J.

Machine Graphics and Vision

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2011

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Vol. 20, No. 2

197-214

EN

Liver disease is one of the most common diseases around the world, seriously affecting the health of humans. Computed tomography image based Computer Aided Diagnosis (CAD) could be crucially important in supporting liver cancer diagnosis. An effective approach to realize a CAD system for this purpose is described in this work. The CAD system employs automatic tumour segmentation, texture feature extraction and characterization into malignant and benign tumours. A Region of Inter- est (ROI) cropped from the automatically segmented tumour by confidence connected region growing and alternative fuzzy c means clustering is decomposed using multiresolution and multidirectional con- tourlet transform to obtain contourlet coefficients. Co-occurrence matrices of the contourlet coefficients are determined, and six parameters of texture characteristics, which include Angular Second Moment, Contrast, Correlation, Inverse Difference Moment, Entropy and Variance, are extracted from them. The extracted feature sets are classified into benign and malignant by a Generalized Regression Neural Net- work (GRNN) classifier. The performance of this scheme is evaluated by various performance measures and by the use a of the Receiver Operating Characteristic (ROC) curve. The results are compared with those obtained by a similar system using Wavelet Coefficients co-occurrence Matrix (WCCM) and Gray Level co-occurrence Matrix (GLCM) texture features. The results indicate that the proposed scheme based on the CCCM texture is effective for classifying malignant and begin liver tumours in abdominal CT imaging.