• Korean Journal of Digital Imaging in Medicine
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• v.4 no.1
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• pp.58-61
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• 1998

현재 국내에서는 Virtual CT endoscopy가 초기단계에 있으므로 앞으로 많은 임상 경험과 data의 축적을 쌓는 것이 중요하다고 보여진다. Virtual CT endoscopy는 조직학적 검사를 위한 병변부위의 조직검사가 불가능한 단점을 갖고 있으나 내시경 검사와 거의 비슷한 소견을 얻을 수 있어 앞으로 병변의 진단 뿐 아니라 병변의 치료 후 추적 검사로도 유용하게 이용되리라 사료된다.

• Journal of Biomedical Engineering Research
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• v.26 no.1
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• pp.23-30
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• 2005

3D virtual endoscopy has been used as an alternative non-invasive procedure for visualization of hollow organs. However, due to computational complexity, this is a time-consuming procedure. In this paper, we propose a fast volume rendering algorithm based on perspective ray casting for virtual endoscopy. As a pre-processing step, the algorithm divides a volume into hierarchical blocks and classifies them into opaque or transparent blocks. Then, in the first step, we perform ray casting only for sub-sampled pixels on the image plane, and determine their pixel values and depth information. In the next step, by reducing the sub-sampling factor by half, we repeat ray casting for newly added pixels, and their pixel values and depth information are determined. Here, the previously obtained depth information is utilized to reduce the processing time. This step is recursively performed until a full-size rendering image is acquired. Experiments conducted on a PC show that the proposed algorithm can reduce the rendering time by 70- 80% for bronchus and colon endoscopy, compared with the brute-force ray casting scheme. Using the proposed algorithm, interactive volume rendering becomes more realizable in a PC environment without any specific hardware.

• Clinical Endoscopy
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• v.51 no.6
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• pp.534-540
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• 2018

From dye-assisted conventional chromoendoscopy to novel virtual chromoendoscopy, image-enhanced endoscopy (IEE) is continuously evolving to meet clinical needs and improve the quality of colonoscopy. Dye-assisted chromoendoscopy using indigo carmine or crystal violet, although slightly old-fashioned, is still useful to emphasize the pit patterns of the colonic mucosa and predict the histological structures of relevant lesions. Equipment-based virtual chromoendoscopy has the advantage of being relatively easy to use. There are several types of virtual chromoendoscopy that vary depending on the manufacturer and operating principle. IEE plays distinctive roles with respect to histologic characterization of colorectal polyps and prediction of the invasion depth of colorectal cancers. In addition, the newest models of IEE have the potential to increase adenoma and polyp detection rates in screening colonoscopy.

• Korean Journal of Bronchoesophagology
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• v.17 no.2
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• pp.108-111
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• 2011

Epiglottic cysts cause stridor mimicking asthma and hinder intubation in surgery. A huge cyst can obstruct the airway, making laryngeal examinations impossible. Before surgery, complete visualization of the larynx is necessary for the successful excision of a cyst. If laryngeal examination fails, computed tomography (CT) scanning can provide detailed information. Virtual endoscopy based on CT data reconstruction can yield a detailed three-dimensional image of the larynx. Here, we report two cases of epiglottic cysts along with virtual endoscopic findings and surgical photographs.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.8
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• pp.463-471
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• 2002

In order to implement virtual endoscopy, high-speed rendering algorithm that generates accurate perspective projection images and efficient collision detection method are essential. In this paper we propose an efficient virtual endoscopy system based on volume rendering technique. It is possible to skip over empty (transparent) space using the distance value produced in preprocessing time, and it does not deteriorate image quality since it is an extension of ray-casting. It also accelerates rendering speed with minimal loss of image quality by adjusting sampling interval along a ray according to direction of the ray. Using the distance information, we can simplify the collision detection of volumetric objects.

• Archives of Plastic Surgery
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• v.47 no.2
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• pp.178-181
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• 2020

In this report, we present a case in which good results were achieved by treatment using a free jejunal patch graft with virtual endoscopy (VE) assistance in a patient whose swallowing had failed to improve for 40 years after he mistakenly swallowed sulfuric acid, despite pectoralis major myocutaneous flap grafting and frequent balloon dilatation surgery. During the last 20 years, virtual computed tomography imaging has improved remarkably and continues to be used to address new challenges. For reconstructive surgeons, the greatest advantage of VE is that it is a noninvasive modality capable of visualizing areas inaccessible to a flexible endoscope. Using VE findings, we were able to visualize the 3-dimensional shape beyond the stenosis. VE can also help predict the area of the defect after contracture release.

• Journal of the Korean Society of Radiology
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• v.1 no.2
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• pp.23-30
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• 2007

This paper presents a method of generating 3-dimensional images by preprocessing 2-dimensional abdominal images obtained using CT (computed tomography) and MRI (magnetic resonance imaging) through segmentation, threshold technique, etc. and apply the method to virtual endoscopy. Three-dimensional images were visualized using indirect volume rendering, which can render at high speed using a general-purpose graphic accelerator used in personal computers. The algorithm used in the rendering is Marching Cubes, which has only a small volume of calculation. In addition, we suggested a method of producing 3-dimensional images in VRML (virtual reality modeling language) running on the Web browser without a workstation or an exclusive program. The number of nodes, the number of triangles and the size of a 3-dimensional image file from CT were 85,367, 174,150 and 10,124, respectively, and those from MRI were 34,029, 67,824 and 3,804, respectively.

• Journal of The Korean Radiological Technologist Association
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• v.25 no.1
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• pp.121.2-122
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• 1999

• Journal of KIISE:Software and Applications
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• v.30 no.9
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• pp.821-828
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• 2003

The virtual angioscopy was implemented using MR angiography image of carotid artery Inside of the carotid artery is one of the body region not accessible by real optical endoscopy but can be visualized with virtual endoscopy. In order to determine the navigation path, we segmented the common carotid artery and internal carotid artery from the MR angiography image. We used the coordinates as a navigation path for virtual camera that were calculated from medial axis transformation. We used the perspective projection and marching cube algorithm to render the surface from volumetric MRA image data. A stroke occurs when brain cells die because of decreased blood flow to the brain. The carotid artery is the primary blood vessel that supplies the blood flow to the brain. Therefore, the carotid artery stenosis is the primary reason of stroke. The virtual angioscopy is highly recommended as a diagnosis tool with which the specific Place of stenosis can be identified and the degree of stenosis can be measured qualitatively. Also, the virtual angioscopy can be used as an education and training tool for endoscopist and radiologist.

• Journal of Biomedical Engineering Research
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• v.24 no.2
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• pp.69-75
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• 2003

Virtual colonoscopy is one of the Powerful tool for non-invasive colon examination and many in-vitro and in-vivo studies have shown its accuracy in Polyp or adenoma detection. But most of virtual colonoscopy requires high quality workstation and software and its cost is high to setup whole system. We developed PC-based 3D model creation and navigation program which has diverse functions. It can be easily installed to PC and connected to network system. The performance. when used as a virtual colonoscopy. is evaluated by calculating sensitivity of detection for the simulated polyp which is artificially made inside the Pig's colon and checked its clinical feasibility, Its total sensitivity is 76%. Grouping according to Polyps diameter, the sensitivity for detection of polyps 10 ㎜ or larger was 100%(40 of 40); 5.0-9.9 ㎜, 90.0(90 of 100): and smaller then 5 ㎜. 36.7%(22 of 60).