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The modeling analysis on porous media hepatic cancer for microwave ablation of an interstitial helix-antenna
(2018-06-23)
Chaichanyut, M.
Microwave ablation is processed, which uses the electro-magnetic transform into heat to destruction or kill cancer cells. This study presents analyses of 2.45GHz Helix-antenna configuration and design for porous hepatic cancer microwave ablation by using 3D-finite-element model. The configurations of Helix-antenna were considered: Tipped tip helix antenna (THA) and Extension tip helix antenna (EHA). 3D finite-element models were utilized to investigate the tissue temperature distribution during and after microwave ablation. The study aims to understand the influences of antenna type on the specific absorption rates (SAR) along the helix-antenna insertion depths and the ablation zone (heating profile and lesion volume) inside the hepatic cancer porous models with 5 cm-in-diameter tumor. All scenarios were the initial power was set at 50 W and simulated under temperature-controlled mode (90°C). Based on the preliminary results, the result illustrates that the THA occur the SAR and heating profile at the lateral around of the antenna, while the SAR and heating trend of EHA occur skew toward of the tip antenna. Both antennas destroy unwanted tissue, but the THA use longer duration than EHA for ablating unwanted tissue. The duration of ablation was 700s, respectively, the coagulation volume of THA and EHA were 95.45 and 104.27 cm3
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The modeling of temperature distributions of an interstitial two-tine antenna for hepatic cancer microwave ablation
(2017-06-22)
Chaichanyut, M.
Hepatic cancer can be treated by microwave ablation, a therapy in which the goal is to increase the tissue temperature in order to induce necrosis. For the application of microwave ablation interstitial antenna have been developed with the objective of delivering and focusing energy deposition on the tissue in an effective manner. In this study, microwave ablation analyses using 2.45 GHz Two-Tine (2T) antenna for hepatic cancer tissue. This research is designed for a 2T-Conductor back-choke (2T-CBC) and 2T-Dielectrics Back-choke antenna (2T-DBC) and modeled using finite element method to obtain their heating patterns, compare them and analyze the effects of the back-choke to treat by microwave ablation. A preliminary study was first carried out with regard to the specific absorption rates (SAR) along the 2T antenna insertion depths and the ablation zone (heating pattern and lesion volume) inside the hepatic cancer models with 5 cm-in-diameter tumor. All scenarios were simulated under temperature-controlled mode (90°C) and the initial power was set at 50 W. Based on the preliminary results, the result shows that the maximum SAR and lesion volume is higher than when using a 2T-DBC antenna for microwave ablation (97.31 cm3). The conductor tine and bake-choke of the antenna has effect to heating pattern and lesion volume.
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FEM modeling for performance evaluation of microwave ablation applicator when using T prong monopole antennas
(2015-01-01)
Chaichanyut, M.
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Tungjitkusolmun, S.
This paper present three-dimensional finite element method (3D FEMs) simulate of temperature distributions in liver cancer tissue. This study focuses on the evaluation of the performance of a T Prong Monopole Antennas. The configurations of monopole antennas were considered: Two-prong Monopole (2PM), Three-Prong Monopole (3PM) and Equilateral Four-Prong Monopole Antenna (4PM). The 3D FEMs solutions were based on Maxwell and bio-heat equations for studying 2.45GHz T Prong monopole antenna design. We apply the microwave power was 20 W; the duration time for ablation in all case was 300s. From our simulation results, all antennas type have occurred the hotspot at the tip of prong of the antenna. Two-prong Monopole antenna can be induced the highest temperature in cancer tissue. Thermal distributions were obtained and compared. The results indicate that the Two-prong Monopole antenna generated maximum temperature within liver cancer tissue and can be maximum ablation cancer tissue (5.94 cm3). The temperature distribution is determined by the direction of bifurcation of the antenna.
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In vitro practical evaluations on heating characteristics of thin microwave antenna in maximum temperature control mode
(2015-01-01)
Chaichanyut, M.
;
Tungjitkusolmun, S.
Microwave thermal therapy is one of the modalities for cancer treatment. There are several schemes of microwave heating. The authors have been studying thin Coaxial Quarter Conductor Antennas (CQCA) for intracavitary microwave heating aiming at the treatment of hepatic cancer. Experimental protocol was composed by a radiation microwave power system and a thermometry system. We apply the microwave power during experiments was 10W, 20W, 30W, 40W, 50W, 60W, 70W and 80W which we set the maximum temperature control at 90°C for all case Experiment, Thermal sensors were placed next to the antenna at 1mm, a large number of experiments on porcine liver are carried out, the temperature distribution within the porcine liver are measured, for cases of different injected microwave power. Experiment for finding a possibility of the treatment. In this study, in order to consider practical situations of the treatment, heating characteristics of the antenna inserted into sample tissue. Moreover, the relation between coagulation size of the tissue, the radiation power from the antenna and the volume of lesion which the hepatic cancer was successful hepatic ablation. From these investigations, some useful results for practical treatments were found.
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Microwave ablation system design to study the effects of coaxial antenna on in-vitro animal tissue
(2014-01-01)
Chaichanyut, M.
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Lertprasert, P.
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Tungjitkusolmun, S.
This paper presents a novel low cost microwave ablation system design to study the effects of coaxial antenna on In Vitro animal tissues. The system utilizes a high-voltage power supply so that the magnetron can generate a microwave field continuously, and its output power can be adjusted from 10 - 80 W at frequency of 2.45GHz. We control output microwave power level by using control the magnetron power supply, which it is an important part of a microwave heating system. Power control of the magnetron’s power supply is desired for microwave heating to enhance performance and to provide system flexibility. The high frequency switching technique in the power supply control is costly and complicated. In another way, pulsing the output power of the magnetron can be simply realized with TRIAC, but in that case the magnetron does not operate continuously. The proposed circuit is a simple one with TRIAC. The power control is achieved by controlling the triggering events at appropriate phase angle of the household 220V. Experimental protocol was composed by a radiation system and a thermometry system. Coaxial antenna works at 2.45 GHz, power apply during experiments was 10W×8min; 20W×4min; 40W×2min and 80W×1min. Thermal sensors were placed next to the antenna at 1mm., a large number of experiments on porcine liver are carried out, the temperature distribution within the liver are measured and illustrated, for cases of different injected microwave power and ablation time. In addition, the ablation areas in cases of different input microwave powers are measured also. All these results indicate the potential validity of this system on medical treatment of liver cancer of human body.
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The modeling techniques for analyses of electromagnetic distributions and reflection coefficients for microwave ablation
(2014-01-01)
Chaichanyut, M.
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Lertprasert, P.
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Tungjitkusolmun, S.
many advantages of microwave ablation over the other ablative therapies in the field of liver tumor ablation have driven researchers to develop innovative interstitial microwave antennas to effectively treat deep seated, nonresectable hepatic tumors. A new coaxial antenna for microwave ablation therapies has been proposed in this research paper. Three dimensional Finite Element Method (FEM) has been used to design the results of the proposed antenna. Objective metrics for assessing the characteristics of helix antennas for microwave ablation by analyzing the electromagnetic field distributions and reflection coefficients for efficiency of antenna has been specified and verified for the proposed antenna, at frequency of 2.45GHz. Our simulation results, Relative permittivity at 2.45 GHz during thermal ablation. Accumulated ablation times noted on each figure to identify temporal variations. Values tended to drop quickly in all cases when temperatures reached 100 °C and continued to drop as temperature was maintained and the tissue became more dehydrated. Changes were irreversible as tissue returned to baseline temperatures. We designs the antenna matching obtained at 2.45 GHz. During thermal ablation, the reflection coefficients it can be noted that the antenna resonance shifts toward higher frequencies and the electric field distribution at the near field region changing follow the temperature variations in tumor tissue.
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Experimental studies on power control microwave ablation in vitro animal tissues with microwave percutaneous coagulator
(2013-12-01)
Chaichanyut, M.
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Lertprasert, P.
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Tungjitkusolmun, S.
Microwave coagulation therapy (MCT) has been used mainly for the treatment of small-size tumors. The operating frequency is 2450 MHz for the present MCT. In this paper, we analyzed the heating characteristics (temperature distributions patterns, lesion on size and etc.) of an applicator composed of thin microwave antenna. The configurations of thin microwave monopole antennas were considered: Coaxial Quarter Conductor Antennas (CQCA). Experimental protocol was composed by a radiation system and a thermometry system. We apply the microwave power during experiments was 10W, 20W, 40W and 80W which microwave power all case will vary the duration time for ablation were 60s 120s 240s and 480s respectively; Thermal sensors were placed next to the antenna at 1mm, a large number of experiments on porcine liver are carried out, the temperature distribution within the liver are measured and illustrated, for cases of different injected microwave power and ablation time. From our experimental results, if we considered the region where temperature exceeds 50°C, the threshold for successful hepatic ablation. The CQCA has lesion size was larger, with a lesion width of approximately 20 mm. In addition, the ablation areas in cases of different input microwave powers are measured also. All these results indicate the potential validity of this system on medical treatment of liver cancer of human body. © 2013 IEEE.
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Microwave ablation with cap-choke antenna: Result in computer simulation
(2010-07-30)
Chaichanyut, M.
This paper reports a novel three-dimensional finite element analysis of coaxial antenna for hepatic microwave ablation. We analyses the temperature distribution pattern and lesion size on hepatic cancer of cap-choke antenna at frequency of 2.45GHz. We set duration time for microwave ablation in the range 60s, 100s, 200s and 300s. We set the potential difference between the inner and an outer conductor was 50V. From our simulation results, if we considered the region where temperature exceeds 50°C, the threshold for successful hepatic ablation. The temperature distributions that all time had similar characteristics but, there are differently at the lesion size. When we set the ablation time was 300s the lesion size was larger, with a lesion width of approximately 26 mm, compared to 12 mm for set the ablation time was 60s. If we considered the lesion volumes at the ablation time was 300s this case can be induced the highest temperature in cancer tissue and maximum ablation cancer tissue (10.22cm3). In addition, we also set the boundary conditions on temperature control mode which maximum temperature control within hepatic cancer at 96°C, duration time at 300s. From the simulation results, the volume of lesion size was 4.25 cm3, lesion width and depth approximately 18mm, 27mm. respectively.
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Linear equation method for Hematocrit monitoring by optical transmittance
(2007-01-01)
Phonphruksa, Phimon
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Chaichanyut, M.
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Potejanasaja, I.
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Naktawan, A.
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Tungjitkusolmun, S.
The objective of the present study is to investigate an optical transmittance system for prediction of hematocrit level by linear equation from the wavelength in the range of 426 nm to 950 nm. We constructed a simplified system with a light detecting finger clip probe to determine the transmittance spectra. We compared the results from our simplified measurement system with the hematocrit levels measured with the centrifuge using blood sample drawn from patients. From the analysis, we discovered that wavelengths between 525 nm to 610 nm, and between 700 to 950 nm are potential optimal choices for use to predict the hematocrit value. Then, four LEDs (525 nm, 585 nm, 875, and 950 nm) were used as the source which shone light through a finger, while the photodiode was placed at the opposite side of the finger for light transmission detection. We calibrated our system with the 117 sample hematocrit levels measured clinically by the centrifuge to obtain the linear equation model. We compared the results of our linear equation model for predicting the hematocrit levels with measured hematocrit levels from the centrifuge. From our analysis, the error obtained from the linear equation was less than 25% in more than 90% of the 117 collected data from patients.
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Comparison temperature distribution between microwave and radio-frequency ablation probe in hepatic cancer
(2007-01-01)
Chaichanyut, M.
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Tungjitkusolmun, S.
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Potejanasaja, I.
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Lertprasert, P.
This paper presents three-dimensional finite element analyses of hepatic cancer ablation. The analyses performed in this paper are composed of two systems. In the first system, the simulation was microwave ablation by using open-tip monopole antenna. We analyses microwave ablation at frequency of 2.45GHz. Additional simulations of radiofrequency ablation by using monopolar probe. All simulations, we studied and compared the characteristics of the electric field and temperature distributions between monopole antenna and monopolar probe. From the simulation results, the electric field distribution of open-tip monopole was a wide electric field distribution while the electric field distribution of monopolar has a narrower. The temperature distribution has distributed same with electric field distribution. The temperature distribution of open-tip monopole was larger when compared with monopolar probe.

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