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Author: search.filters.author.Hemtiwakorn, Khaisang

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    Patient-specific aided surgery approach of deviated nasal septum using computational fluid dynamics
    (2015-05-01)
    Hemtiwakorn, Khaisang
    ;
    Mahasitthiwat, Visan
    ;
    Tungjitkusolmun, Supan
    ;
    Hamamoto, Kazuhiko
    ;
    Pintavirooj, Chuchart
    In treating a patient with deviated nasal septum (DNS), a surgeon draws up a surgical plan based on the patient's rhinomanometry outcomes and self-assessment of nose conditions, e.g. the nasal obstruction septoplasty effectiveness (NOSE) score. However, the procedure fails to localize the DNS and determine the nose's aerodynamic effects. This paper proposes a DNS-aided surgery approach using computational fluid dynamics (CFD) and computed tomography (CT) techniques consisting of three main processes: preoperative, presurgical planning, and postoperative processes. The healthy baseline refers to a benchmark consisting of five subjects without DNS and nasal airway obstructions. To assess the possibility of using the CFD-CT-aided surgery approach as a presurgical planning tool in the DNS operation, comparative tests were carried out with DNS patient #1, who received a conventional nasal surgery without the proposed presurgical planning. Although DNS patient #1's surgical outcome was relatively satisfying to the patient, evaluating from the reduction of the NOSE score the conventional surgical method could induce an excessive excision of nasal airway, resulting in water loss in the nasal mucosa and a large reduction in airflow velocity. In addition, the postoperative nasal resistance measured by a rhinomanometer was not acceptable to the surgeon. Virtual surgery using the CFD-CT approach performed after surgery could suggest suitable patient-specific components of nasal operation with predictable results. Subsequently, implementation of the proposed CFD-CT approach in aid of DNS surgery was performed in DNS patient #2. The benefits of the CFD-CT-aided surgery approach were determined based on the pre- and postoperative outcomes (i.e. nasal geometric data and nasal airflow patterns), NOSE scores, and rhinomanometric data of DNS patient #2, which were compared against those of the healthy baseline benchmark. The CFD-CT approach could assist the surgeon to localize the DNS and determine the defective nasal tissues to be removed. The actual postoperative outcomes were clinically acceptable to the surgeon and DNS patient #2. It is evident that the CFD-CT-aided surgery approach is suitable for and applicable to surgery of DNS patients with small variability from the presurgical planning stage.
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    Use of computational fluid dynamics nasal airflow measurement to design septoplasty: A pilot study
    (2013-01-01)
    Mahasittiwat, Visan
    ;
    Hemtiwakorn, Khaisang
    ;
    Pintavirooj, Chuchart
    Deviation in the nasal septum that obstructs airflow is a source of discomfort to patients. Areas of nasal malformation then, need to be identified before performing surgery. In the present study, the authors introduce the computational fluid dynamic (CFD) technique to predict regions of limited airflow based on CT scan reconstruction of the nasal cavity. The present study proposes to use CFD to identify regions of obstructed airflow and design a surgical procedure to correct them. The authors report three cases with obstructed nasal airflow together with CFD measurements before and after the surgery. Results indicate that CFD is useful to verify the areas of airflow abnormality and conform with the results obtained using other methods.
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    Computational Fluid Dynamic (CFD) in Thai patient with Obstructive Sleep Apnea Syndrome (OSAS) - A case report: Comparative study between healthy and OSA subject
    (2012-12-01)
    Sarasaen, Chompunuch
    ;
    Bhongmakapat, Thongchai
    ;
    Hemtiwakorn, Khaisang
    ;
    Laothamatas, Jiraporn
    ;
    Pintavirooj, Chuchart
    In order to investigate flow characteristics in upper airway, this study focuses on applied Computational Fluid Dynamics (CFD) with Obstructive Sleep Apnea Syndrome (OSAS) base on Computed Tomography images. OSAS has been remarked in the several decades because of its disturbance and severity that leading to a serious morbidity and excess mortality in long-term consequences such as heart attack and strokes. Although numerous methods have been advocated for treatment an OSA syndrome, no single procedure employed effectively. To investigate the airflow behavior, three-dimensional airway models during tidal breathing has been performed in a patient with obstructive sleep apnea and one control. Segmentation was carried out from CT data initially. Then, the volumetric surface was performed by reverse engineering process and mesh generation was operated after that. Computational modeling for inspiration was operated by employing k-ω SST turbulence model. For comparison the airflow characteristics, streamline, velocity, pressure, and wall shear stress either of models were illustrated. For patient associated with OSA, Particularly in oropharynx region, velocity significantly increase and negative pressure greater than the control one because of narrower airway. Furthermore, WSS manifestly rises up in stricture area. In brief, The CFD analysis could be employed to evaluate the airflow in OSA patients as an alternative technique for diagnosis and treatment planning. ©2012 IEEE.
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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
    ;
    Phoocharoen, Niwat
    ;
    Tungjitkusolmun, Supan
    ;
    Mahasittiwat, Visan
    ;
    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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    Indirect X-Ray detector panel using multiple cameras
    (2008-12-01)
    Hemtiwakorn, Khaisang
    ;
    Srisuk, Namthip
    ;
    Pintavirooj, Chuchart
    In this paper, the indirect X-ray-detector panel using an array of digital camera with an intensifying screen is designed. To assist the orientation process, the camera calibration was used to derive the information of how the individual camera is oriented. Salt & pepper noise was removed by the median filtering technique. The border of captured image was transformed and registered by using the template matching with cross correlation, and matrix transformation to obtain the registered images. Moreover, the weighted average technique was used to obtain a smooth image mosaic. Finally, Lambert- Beer law was applied to construct the final detector output. Result shows that the mosaic X-ray detector output is as comparable as that of the single X-ray detector. The panel junction smoothness of the detector output is acceptable and the resolution is significantly improved. © 2008 IEEE.