Tungjitkusolmun, Supan

Preferred name

Alternative Name

Tungjitkusolmun, S.

Main Affiliation

School of Engineering

supan.tu@kmitl.ac.th

Now showing 1 - 10 of 23

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Combined medical imaging with CFD analysis for application of diagnostic and treatment planning: The case study of human nasal airflow simulation based on CT imaging
(2009-01-01)
Hemtiwakorn, Khaisang
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Phoocharoen, Niwat
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Tungjitkusolmun, Supan
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Mahasittiwat, Visan
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Sangworasil, Manas
The previous methods of human airflow measurement such as rhinomanometry or acoustic rhinometry could not visualize the airflow and calculated the velocity magnitude in specific region of nasal cavity. Thus, this study proposes the combination of CT and CFD analysis of nasal airflow simulation in normal human breathing. This method can demonstrate the airflow direction, and also calculate the velocity magnitude inside the nasal cavity. The processes of this study are segmentation, meshing, solving, and post-processing. Firstly, Mimic 10.01 software was used to segment the nasal cavity. Secondly, Pro-STAR/amm software was used to generate trimmed mesh of 338, 496 elements. Finally, computational grid model was imported to STAR-CD version 3.26 for numerical computation, and visualize the solution by post-processing. The result shows that velocity magnitude of airflow is greatest in nasal valve area which is the narrowest area of the human nose. Also, the flow commonly pass through the main nasal passage and middle meatus areas of nose. Experimental validation will be reported in the further publication. In conclusion, this study is the important begining of an applied CFD analysis with medical imaging. CT imaging combines with CFD analysis could be useful for rhinologist as a nose function evaluation technique. Moreover, the applications of this method could be utilized in a wide range of research topics, especially development of diagnostic and treatment planning techniques.
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Computational fluid analysis of blood flow characteristics in abdominal aortic aneurysms treated with suprarenal endovascular grafts
(2009-12-01)
Sun, Zhonghua
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Chaichana, Thanapong
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Sangworasil, Manas
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Tungjitkusolmun, Supan
The purpose of this study is to investigate the hemodynamic effects of suprarenal stent grafts on the renal arteries in the treatment of patients with abdominal aortic aneurysm. Suprarenal stent grafts have been increasingly used for treatment of aortic aneurysms with suboptimal aneurysm necks. However, the long-term safety of this procedure is yet to be determined. 2 sample patients undergoing suprarenal stent grafting were included in the study. Four variable configurations of stent wires crossing the renal artery ostium were simulated in aorta models based on CT generated data, at different cardiac cycles. The stent wires thickness was set 0.5 mm which is similar to the actual diameter of a stent wire. Computational fluid dynamic analysis showed slightly decrease of flow velocity to the renal arteries with multiple wires crossing, and no changes of flow velocity to the renal arteries with single wire crossing. Our preliminary results demonstrated the safety of suprarenal stent grafting. Further studies are required to investigate the effect of different wire thickness on subsequent hemodynamic changes to the renal arteries.
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Mechanical compliance of the endocardium
(2002-12-01)
Bin Choy, Young
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Cao, Hong
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Tungjitkusolmun, Supan
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Tsai, Jang Zern
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Haemmerich, Dieter
Radio-frequency (RF) ablation is an accepted treatment for cardiac arrhythmias related to abnormal focal cardiac substrate. The penetration depth of the electrode into the endocardium affects lesion size, a critical determinant of success of RF ablation. We measured the relation between the mechanical compliance and the penetration depth of RF ablation catheter electrode at frequently ablated areas of the endocardium and examined the influence of time after death on mechanical properties of the tissue. We measured force versus time for eight insertion depths of the catheter electrode into full-thickness endocardial samples derived from the mitral valve annulus, the left ventricular free wall and the tricuspid valve annulus. We varied the time after death at 15, 40min, 3, 8, and 18h and repeated our measurements. At 15min after death, the first 0.5mm penetration depth caused the fastest relaxation at 55s. Force decay decreased dramatically at 15min after death as the penetration depth increased from 0.5 to 4mm. We used the force data sampled at 60s after insertion to approximate the elasticity. We observed the relations between the force versus the insertion depth. The force increased by a factor of 5 for the mitral valve annulus and 8 for the left free wall from 15min to 18h. We derived coefficients of a second-order polynomial equation relating the force data to insertion depth with R2>0.99. © 2002 Elsevier Science Ltd. All rights reserved.
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Classification of magnetic resonance images using support vector machines
(2001-12-01)
Sookpotharom, Supot
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Tungjitkusolmun, Supan
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Airphaiboon, Surapan
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Sangworasil, Manas
The classification of medical images obtained from magnetic resonance imaging (MRI) is an important step in the visualization of soft issue in the human body. MRI is a multidimensional technique as it provides information about three tissue dependent parameters. This paper presents the potential of Support Vector Machines (SVMs) technique for the supervised classification of MRI images. The SVMs approach was originally developed for binary classification problems. In this paper SVM architectures for multi-class classification are used, in particular we consider binary trees of SVMs to solve the multiclass of MR brain images. The experiments using the SVMs technique presented in this paper performed the quality and correctly position of the internal organ.
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Error analysis of tissue resistivity measurement
(2002-04-30)
Tsai, Jang Zern
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Will, James A.
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Stelle, Scott Hubbard Van
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Cao, Hong
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Tungjitkusolmun, Supan
We identified the error sources in a system for measuring tissue resistivity at eight frequencies from 1 Hz to 1 MHz using the four-terminal method. We expressed the measured resistivity with an analytical formula containing all error terms. We conducted practical error measurements with in-vivo and bench-top experiments. We averaged errors at all frequencies for all measurements. The standard deviations of error of the quantization error of the 8-bit digital oscilloscope with voltage averaging, the nonideality of the circuit, the in-vivo motion artifact and electrical interference combined to yield an error of ±1.19%. The dimension error in measuring the syringe tube for measuring the reference saline resistivity added ±1.32% error. The estimation of the working probe constant by interpolating a set of probe constants measured in reference saline solutions added ±0.48% error. The difference in the current magnitudes used during the probe calibration and that during the tissue resistivity measurement caused ±0.14% error. Variation of the electrode spacing, alignment, and electrode surface property due to the insertion of electrodes into the tissue caused ±0.61% error. We combined the above errors to yield an overall standard deviation error of the measured tissue resistivity of ±1.96%.
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Length effect of metal-tip monopole antenna to temperature distributions for microwave ablation
(2007-01-01)
Chaichanyut, M.
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Lertprasert, P.
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Phonphruksa, P.
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Tungjitkusolmun, S.
This paper present three-dimensional finite element analyses of hepatic cancer. We studied the characteristics of metal-tip monopole (MTM) antennas for microwave ablation by analyzing the length effect of metal at the antenna tip. We analyses microwave ablation at frequency of 2.45GHz.The length of metallic tip (ht) are varied so as to observe the effect on the temperature distribution. Simulations the length of metallic tip are 1mm, 2mm and 4 mm. From the simulation results, we considered the hepatic cancer region where temperature exceeds 50 °C. The lengths of metallic tip are 1 mm, 2 mm and 4mm had similar temperature distribution profiles and the maximum temperature occurred around the tips of the antennas. In case the length of metallic tip is 4mm, the temperature distribution was widest and induced the highest temperature in cancer tissue. In addition, the temperature distribution was narrowly shaped along the length in regions the shaft body of the antenna. For case the length of metallic tip is 2 mm, the temperature had minimum in cancer tissue and can be minimum ablation cancer tissue (17.34cm3). For case the length of metallic tip is 1 mm, this case can be maximum ablation cancer tissue (18.67cm3).
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Three-dimensional finite-element analyses for radio-frequency hepatic tumor ablation
(2002-01-05)
Tungjitkusolmun, Supan
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Staelin, S. Tyler
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Haemmerich, Dieter
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Tsai, Jang Zern
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Cao, Hong
Radio-frequency (RF) hepatic ablation, offers an alternative method for the treatment of hepatic malignancies. We employed finite-element method (FEM) analysis to determine tissue temperature distribution during RF hepatic ablation. We constructed three-dimensional (3-D) thermal-electrical FEM models consisting of a four-tine RF probe, hepatic tissue, and a large blood vessel (10-mm diameter) located at different locations. We simulated our FEM analyses under temperature-controlled (90 °C) 8-min ablation. We also present a preliminary result from a simplified two-dimensional (2-D) FEM model that includes a bifurcated blood vessel. Lesion shapes created by the four-tine RF probe were mushroom-like, and were limited by the blood vessel. When the distance of the blood vessel was 5 mm from the nearest distal electrode 1) in the 3-D model, the maximum tissue temperature (hot spot) appeared next to electrods A. The location of the hot spot was adjacent to another electrode 2) on the opposite side when the blood vessel was 1 mm from electrode A. The temperature distribution in the 2-D model was highly nonuniform due to the presence of the bifurcated blood vessel. Underdosed areas might be present next to the blood vessel from which the tumor can regenerate.
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In vivo electrical conductivity of hepatic tumours
(2003-01-01)
Haemmerich, Dieter
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Staelin, S. T.
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Tsai, J. Z.
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Tungjitkusolmun, S.
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Mahvi, D. M.
Knowledge of electrical tissue conductivity is necessary to determine deposition of electromagnetic energy and can further be used to diagnostically differentiate between normal and neoplastic tissue. We measured 17 rats with a total of 24 tumours of the K12/TRb rat colon cancer cell line. In each animal we measured in vivo hepatic tumour and normal tissue conductivity at seven frequencies from 10 Hz to 1 MHz, at different tumour stages between 6 and 12 weeks after induction. Conductivity of normal liver tissue was 1.26 ± 0.15 mS cm-1 at 10 Hz, and 4.61 ± 0.42 mS cm-1 at 1 MHz. Conductivity of tumour was 2.69 ± 0.91 mS cm-1 at 10 Hz, and 5.23 ± 0.82 mS cm-1 at 1 MHz. Conductivity was significantly different between normal and tumour tissue (p < 0.05). We determined the percentage of necrosis and fibrosis at the measurement site. We fitted the conductivity data to the Cole-Cole model. For the tumour data we determined Spearman's correlation coefficients between the Cole-Cole parameters and age, necrosis, fibrosis and tumour volume and found significant correlation between necrosis and the Cole-Cole parameters (p < 0.05). We conclude that necrosis within the tumour and the associated membrane breakdown is likely responsible for the observed change in conductivity.
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Modeling bipolar phase-shifted multielectrode catheter ablation
(2002-01-05)
Tungjitkusolmun, Supan
;
Haemmerich, Dieter
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Cao, Hong
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Tsai, Jang Zern
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Choy, Young Bin
Atrial fibrillation (AFIB) is a common clinical problem affecting approximately 0.5-1% of the United States population. Radio-frequency (RF) multielectrode catheter (MEC) ablation has successes in curing AFIB. We utilized finite-element method analysis to determine the myocardial temperature distribution after 30 s, 80 °C temperature-controlled unipolar ablation using three 7F 12.5-mm electrodes with 2-mm interelectrode spacing MEC. Numerical results demonstrated that cold spots occurred at the edges of the middle electrode and hot spots at the side electrodes. We introduced the bipolar phase-shifted technique for RF energy delivery of MEC ablation. We determined the optimal phase-shift (φ) between the two sinusoidal voltage sources of a simplified two-dimensional finite-element model. At the optimal φ, we can achieve a temperature distribution that minimizes the difference between temperatures at electrode edges. We also studied the effects of myocardial electric conductivity (σ), thermal conductivity (κ), and the electrode spacing on the optimal φ. When we varied σ and κ from 50% to 150%, optimal φ ranged from 29.5° to 23.5°, and in the vicinity of 26.5°, respectively. The optimal φ for 3-mm spacing MEC was 30.5°. We show the design of a simplified bipolar phase-shifted MEC ablation system.
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Finite element analyses for a study of hepatic cancer tissue destruction using monopolar and bipolar radio-frequency ablation
(2005-11-28)
Tungjitkusolmun, S.
;
Boontaram, A.
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Lertprasert, P.
;
Krairiksh, M.
This paper presents three-dimensional finite element analyses of radio-frequency hepatic tumor ablation. The analyses performed in this paper are composed of two systems. In the first system, the simulation was of monopolar ablation (one needle), while the second system was the simulation of bipolar ablation (two needles). We performed a preliminary study of thermal and electrical distributions of both systems. Additional simulations of bipolar ablation were performed to investigate the effect of spacing distance between two needle electrodes (2 cm, 3 cm, 4 cm, and 5 cm). The ablation duration used in all cases was 10 min, and the controlled maximum temperature was set to 90°C. From the results, the electric field in monopolar ablation appeared to be distributed uniformly between the electrode and the ground surface, but the electric field in bipolar ablation was focused in the regions between the two electrodes. For bipolar ablation, when the distances between the electrodes were 2 cm and 3 cm, the lesion created was contiguous and covered the areas surrounding both electrodes. However, when the distances between the electrodes were 4 cm and 5 cm, the lesions created were not contiguous and shaped similar to performing two monopolar ablation operations.

Tungjitkusolmun, Supan

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