A Floating Sleeve Antenna Yields Localized Hepatic Microwave Ablation

Yang, Deshan; Bertram, John M; Converse, M.C.; O’Rourke, Ann P.; Webster, John G.; Hagness, Susan C.; Will, James A.; Mahvi, David M.

doi:10.1109/tbme.2005.869794

Cited by 150 publications

(121 citation statements)

References 20 publications

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“…[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] However, previous studies have considered a fixed antenna geometry based on a 10 mm short-circuited stub and 1 mm slot width. Little focus has been given to the balance between reflection coefficient and antenna heating pattern.…”

Section: Discussionmentioning

confidence: 99%

“…[10][11][12][13][14][15][16] Coaxial sleeve chokes, which may be floating or attached to the outer conductor of the coaxial cable, can help confine the heating pattern to the distal aspect of the antenna, thereby reducing backwards heating along the antenna shaft. [17][18][19] These choked designs are not without drawbacks, as they increase the antenna diameter and potentially increase power reflections from the antenna. Increased antenna diameter may lead to greater incidence of complications when applied percutaneously in some organs.…”

Section: Introductionmentioning

confidence: 99%

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Dual‐slot antennas for microwave tissue heating: Parametric design analysis and experimental validation

Brace

2011

Medical Physics

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Purpose: Design and validate an efficient dual-slot coaxial microwave ablation antenna that produces an approximately spherical heating pattern to match the shape of most abdominal and pulmonary tumor targets. Methods: A dual-slot antenna geometry was utilized for this study. Permutations of the antenna geometry using proximal and distal slot widths from 1 to 10 mm separated by 1-20 mm were analyzed using finite-element electromagnetic simulations. From this series, the most optimal antenna geometry was selected using a two-term sigmoidal objective function to minimize antenna reflection coefficient and maximize the diameter-to-length aspect ratio of heat generation. Sensitivities to variations in tissue properties and insertion depth were also evaluated in numerical models. The most optimal dual-slot geometry of the parametric analysis was then fabricated from semirigid coaxial cable. Antenna reflection coefficients at various insertion depths were recorded in ex vivo bovine livers and compared to numerical results. Ablation zones were then created by applying 50 W for 2-10 min in simulations and ex vivo livers. Mean zone diameter, length, aspect ratio, and reflection coefficients before and after heating were then compared to a conventional monopole antenna using ANOVA with post-hoc t-tests. Statistical significance was indicated for P < 0.05. Results: Antenna performance was highly sensitive to dual-slot geometry. The best-performing designs utilized a proximal slot width of 1 mm, distal slot width of 4 mm 6 1 mm and separation of 8 mm 6 1 mm. These designs were characterized by an active choking mechanism that focused heating to the distal tip of the antenna. A dual-band resonance was observed in the most optimal design, with a minimum reflection coefficient of À20.9 dB at 2.45 and 1.25 GHz. Total operating bandwidth was greater than 1 GHz, but the desired heating pattern was achieved only near 2.45 GHz. As a result, antenna performance was robust to changes in insertion depth and variations in relative permittivity of the surrounding tissue medium. In both simulations and ex vivo liver, the dual-slot antenna created ablations greater in diameter than a coaxial monopole (35 mm 6 2 mm versus 31 mm 6 2 mm; P < 0.05), while also shorter in length (49 mm 6 2 mm versus 60 mm 6 6 mm; P < 0.001) after 10 min. Similar results were obtained after 2 and 5 min as well. Conclusions: Dual-slot antennas can produce more spherical ablation zones while retaining low reflection coefficients. These benefits are obtained without adding to the antenna diameter. Further evaluation for clinical microwave ablation appears warranted.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dual‐slot antennas for microwave tissue heating: Parametric design analysis and experimental validation

Brace

2011

Medical Physics

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“…Trade-offs in design involve probe diameter versus maximum application of power and ablation power versus ablation time. Early coaxial antennas developed for MWA yielded ablation zones resembling a 'tear drop', as opposed to the desired spherical shape [9]. More recent MWA probes were designed to minimize probe size, maximize ablation zone size, minimize detrimental heating of the feedline and yield more spherical lesions, by minimizing impedance mismatch [10][11][12].…”

Section: Microwave Ablationmentioning

confidence: 99%

High Temperature Hyperthermia in Breast Cancer Treatment

Rubio¹,

Salas²

2013

Hyperthermia

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“…Other notable proposed MW antenna designs include: cap-choke catheter antenna proposed by Lin et al [15] for MW treatment with localized heating of tissue surrounding the distal end of the catheter, the floating sleeve antenna proposed by Yang et al [16] where the inclusion of the floating sleeve could prevent the flow of electromagnetic energy along the coaxial applicator.…”

Section: Introductionmentioning

confidence: 99%

“…Simulations of three-dimensional (3-D) coupled thermal-electric FE analysis were previously introduced for RF ablation [17]− [22]. However all previous FE analysis for MW hepatic ablation have been performed in two dimensions (approximating the geometry of the FE model to be asymmetric) [2], [23]− [30]. Lui et al [31] studied thermal characteristics of MW Ablation in the vicinity of arterial bifurcation using 3-D thermal FE model.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Slot Sizes on Non-Asymmetry Slot Antennafor Microwave Coagulation Therapy

Wongtrairat¹,

Phasukkit²,

Tungjitkusolmun³

et al. 2011

IJBBB

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Abstract-This paper presents analyses of non-asymmetry antenna configuration for microwave ablation at 2450 MHz using three-dimensional finite element analyses. Treatment of hepatic cancer often requires removal or destruction. Using coaxial-slot antenna is opened slot at one-side of antenna. We study the characteristics of various slot size and various power for non-asymmetry structure antenna to observe temperature distributions and SAR. The results illustrate that the coaxial-slot non-asymmetry structure antenna can be used in microwave ablation for destruction of the cancer cell in the area closed to the very fragile tissue or blood vessel.Index Terms-Microwave(MW) ablation, finite-element(FE) analysis, non-asymmetry structure antenna.

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A Floating Sleeve Antenna Yields Localized Hepatic Microwave Ablation

Cited by 150 publications

References 20 publications

Dual‐slot antennas for microwave tissue heating: Parametric design analysis and experimental validation

Dual‐slot antennas for microwave tissue heating: Parametric design analysis and experimental validation

High Temperature Hyperthermia in Breast Cancer Treatment

The Effect of Slot Sizes on Non-Asymmetry Slot Antennafor Microwave Coagulation Therapy

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