Optimization of dual slot antenna using floating metallic sleeve for microwave ablation

Ibitoye, A. Z.; Nwoye, E. O.; Aweda, Moses Adebayo; Oremosu, A.A.; AnnunobI, c. c.; Akanmu, Olanrewaju

doi:10.1016/j.medengphy.2015.01.015

Cited by 28 publications

(34 citation statements)

References 17 publications

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“…Previous studies have suggested that changes in dielectric properties can produce elongation of the electric field along the antenna, leading to elongation of the ablation zone itself . Other studies have attempted to create more spherical ablations through antenna design optimization . The present study demonstrated that for all powers and energy types, the primary direction of tissue contraction was orthogonal to this antenna design, with mean principal angles of −8.1º to 5.4º, dependent on the ablation powers and energy types (Fig.…”

Section: Discussionsupporting

confidence: 53%

“…[34][35][36][37][38] Other studies have attempted to create more spherical ablations through antenna design optimization. [39][40][41] The present study demonstrated that for all powers and energy types, the primary direction of tissue contraction was orthogonal to this antenna design, with mean principal angles of À8.1°to 5.4°, dependent on the ablation powers and energy types (Fig. 11).…”

Section: Discussionmentioning

confidence: 58%

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Evaluation of tissue deformation during radiofrequency and microwave ablation procedures: Influence of output energy delivery

Liu

Brace

2019

Medical Physics

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Purpose The purpose of this study was to quantitatively analyze tissue deformation during radiofrequency (RF) and microwave ablation for varying output energy levels. Methods A total of 46 fiducial markers which were classified into outer, middle, and inner lines were positioned into a single plane around an RF or microwave ablation applicator in each ex vivo bovine liver sample (8 cm × 6 cm × 4 cm, n = 18). Radiofrequency (500 kHz; ~35 W average) or microwave (2.4 GHz; 50–100 W output, ~35–70 W delivered) ablation was performed for 10 min (n = 4–6 each setting). CT images were acquired over the entire liver volume every 15 s. Principle strain magnitude and direction were determined from fiducial marker displacement. Normal and shear strain were then calculated such that negative strain denoted contraction and positive strain denoted expansion. Temporal variations, the final magnitudes, and angles of the strain were compared across energy delivery settings, using one‐way ANOVA with post hoc Tukey's tests. Results On average, tissue strain rates peak at around 1 min and decayed exponentially over time. No evidence of tissue expansion was observed. The tissue strains from RF and 50 W, 75 W, and 100 W microwave ablation at 10 min were −8.5%, −38.9%, −54.4%, and −65.7%, respectively, from the inner region and −3.6%, −23.7%, −41.8%, and −44.3%, respectively, from the outer region. Negative strain magnitude was positively correlated to energy delivery in the inner region (Spearman’s ρ = −0.99). Microwaves at higher powers (75–100 W) induced significantly more strain than at lower power (50 W) or after RF ablation (P < 0.01). Principal strain angles ranged from 0.8° to −8.1°, indicating that tissue deformed more in the direction transverse to the applicator than along the direction of the applicator. Conclusions The influence of output energy on tissue deformation during RF and microwave ablation was analyzed. Microwave ablation created significantly greater contraction than RF ablation with similar energy delivery. During microwave ablation, more contraction was noted at higher power levels and in proximity to the antenna. Contraction primarily transverse to the antenna produces ablation zones that are more elongated than the original tissue volume.

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Section: Discussionsupporting

confidence: 53%

Section: Discussionmentioning

confidence: 58%

Evaluation of tissue deformation during radiofrequency and microwave ablation procedures: Influence of output energy delivery

Liu

Brace

2019

Medical Physics

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“…Chiang et al [28] compared dual slot and monopole antennas; their results showed that the dual slot antenna produced more spherical ablation than the monopole antenna. Inclusion of a floating sleeve on the dual slot antenna has been reported to constrain microwave energy at the distal end of the antenna and produced ablation of high sphericity index than the dual slot without a sleeve [21]. The findings of this study indicate that the dual slot antenna with sleeve will be suitable for most clinical applications.…”

Section: Discussionmentioning

confidence: 74%

“…Ablation was carried out in large bovine tissues with initial temperatures recorded by a highly sensitive 4-Channel Datalogging thermometer (SPER Scientific, Scottsdale, AZ). The use of 40 W as input power was based on the previous studies reported in the literature [16,21].…”

Section: Methodsmentioning

confidence: 99%

“…A schematic diagram of the antennas used in the study is depicted in Figure 1. The coaxial monopole antenna (Figure 1(a)) was created with a 14 mm radiating segment as in Labonte et al [20] while the dual slot antenna with floating metallic sleeve (Figure 1(b)) was designed and fabricated to match the dimensions of the optimal geometry proposed by Ibitoye et al [21]. Both antennas were based on a 50 X R405/U semi-rigid coaxial cable from Pasternack Enterprise Inc. (Los Angeles, CA).…”

Section: Modelling and Simulation Of Antennasmentioning

confidence: 99%

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