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44 results on '"Luyen, Hung"'

1. Feasibility Study of Microsecond Pulsed Microwave Ablation using a Minimally Invasive Antenna

Author

Evans, Audrey L., Sawicki, James F., Luyen, Hung, Mohtashami, Yahya, Behdad, Nader, and Hagness, Susan C.

Subjects
Electrical Engineering and Systems Science - Systems and Control, Physics - Medical Physics
Abstract

In this study we established the feasibility of producing localized ablation zones using microsecond pulsed microwave ablation (MWA) as an alternative to conventional continuous wave (CW) MWA. We verified that a thin floating-sleeve dipole ablation probe can withstand pulsed power delivery with peak powers as high as 25 kW, with pulse widths on the order of 1 us. We conducted MWA experiments in egg white using CW and pulsed modes of operation and found that ablation zones achieved via pulsed MWA are comparable in dimension to those created via CW MWA when the average power and procedure duration are equivalent. Finally, we performed pulsed MWA experiments in bovine liver and confirmed that pulsed MWA consistently produces large, localized ablation zones and temperatures that exceed 100{\deg}C. Establishing the feasibility of pulsed MWA opens the opportunity for developing a coupled MWA treatment and imaging system using pulsed MWA and microwave-induced thermoacoustic signals for real-time monitoring of MWA.

Published
2021
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16. Non-coaxial-based microwave ablation antennas for creating symmetric and asymmetric coagulation zones.

Author

Mohtashami, Yahya, Luyen, Hung, Hagness, Susan C., and Behdad, Nader

Subjects
*ABLATION techniques, *MICROWAVES, *ANTENNAS (Electronics), *HEATING, *COAGULATION, *LABORATORY swine, *EGG whites
Abstract

We present an investigation of a new class of microwave ablation (MWA) antennas capable of producing axially symmetric or asymmetric heating patterns. The antenna design is based on a dipole fed by a balanced parallel-wire transmission line. The angle and direction of the deployed dipole arms are used to control the heating pattern. We analyzed the specific absorption rate and temperature profiles using electromagnetic and thermal simulations. Two prototypes were fabricated and tested in ex vivo ablation experiments: one was designed to produce symmetric heating patterns and the other was designed to generate asymmetric heating patterns. Both fabricated prototypes exhibited good impedance matching and produced localized coagulation zones as predicted by the simulations. The prototype operating in porcine muscle created an ∼10 cm3 symmetric ablation zone after 10 min of ablation with a power level of 18 W. The prototype operating in egg white created an ∼4 cm3 asymmetric ablation zone with a directionality ratio of 40% after 5 min of ablation with a power level of 25 W. The proposed MWA antenna design shows promise for minimally invasive treatment of tumors in various clinical scenarios where, depending on the situation, a symmetric or an asymmetric heating pattern may be needed. [ABSTRACT FROM AUTHOR]

Published
2018
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37. The Application of High-Frequency Microwaves in Tissue Ablation for Cancer Treatment

Author

Luyen, Hung Thanh, Behdad, Nader, and Hagness, Susan C.

Subjects
Interstitial Antennas, Microwave Ablation, Hyperthermia
Abstract

The study demonstrates the feasibility of using high-frequency microwaves for tissue ablation by comparing the performance of a 10 GHz microwave ablation system with that of a 1.9 GHz system. Two sets of floating sleeve dipole antennas operating at these frequencies were designed and fabricated for use in ex vivo experiments with bovine livers. Combined electromagnetic and transient thermal simulations were conducted to analyze the performance of these antennas. Subsequently, a total of 16 ablation experiments (eight at 1.9 GHz and eight at 10.0 GHz) were conducted at a power level of 42 W for either 5 or 10 minutes. In all cases, the 1.9 GHz and 10 GHz experiments resulted in comparable ablation zone dimensions. Temperature monitoring probes revealed faster heating rates in the immediate vicinity of the 10.0 GHz antenna compared to the 1.9 GHz antenna, along with a slightly delayed onset of heating farther from the 10 GHz antenna, suggesting that heat conduction plays a greater role at higher microwave frequencies in achieving a comparably sized ablation zone. The results obtained from these experiments agree very well with the combined electromagnetic/thermal simulation results. These simulations and experiments show that using lower frequency microwaves does not offer any significant advantages, in terms of the achievable ablation zones, over using higher frequency microwaves. Indeed, it is demonstrated that high-frequency microwave antennas may be used to create reasonably large ablation zones. Higher frequencies offer the advantage of smaller antenna size, which is expected to lead to less invasive interstitial devices and may possibly lead to the development of more compact multi-element arrays with heating properties not available from single-element antennas.

Published
2014

44. Microwave Ablation at 10.0 GHz Achieves Comparable Ablation Zones to 1.9 GHz in Ex Vivo Bovine Liver.

Author

Luyen, Hung, Gao, Fuqiang, Hagness, Susan C., and Behdad, Nader

Subjects
*ABLATION techniques, *SURGERY, *LASER surgery, *BIOMEDICAL engineering, *DIPOLE array antennas, *DIPOLE antennas
Abstract

We demonstrate the feasibility of using high-frequency microwaves for tissue ablation by comparing the performance of a 10 GHz microwave ablation system with that of a 1.9 GHz system. Two sets of floating sleeve dipole antennas operating at these frequencies were designed and fabricated for use in ex vivo experiments with bovine livers. Combined electromagnetic and transient thermal simulations were conducted to analyze the performance of these antennas. Subsequently, a total of 16 ablation experiments (eight at 1.9 GHz and eight at 10.0 GHz) were conducted at a power level of 42 W for either 5 or 10 min. In all cases, the 1.9 and 10 GHz experiments resulted in comparable ablation zone dimensions. Temperature monitoring probes revealed faster heating rates in the immediate vicinity of the 10.0 GHz antenna compared to the 1.9 GHz antenna, along with a slightly delayed onset of heating farther from the 10 GHz antenna, suggesting that heat conduction plays a greater role at higher microwave frequencies in achieving a comparably sized ablation zone. The results obtained from these experiments agree very well with the combined electromagnetic/thermal simulation results. These simulations and experiments show that using lower frequency microwaves does not offer any significant advantages, in terms of the achievable ablation zones, over using higher frequency microwaves. Indeed, it is demonstrated that high-frequency microwave antennas may be used to create reasonably large ablation zones. Higher frequencies offer the advantage of smaller antenna size, which is expected to lead to less invasive interstitial devices and may possibly lead to the development of more compact multielement arrays with heating properties not available from single-element antennas. [ABSTRACT FROM PUBLISHER]

Published
2014
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