• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.2
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• pp.375-387
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• 1995

The purpose of this study was to quantitatively evaluated experimental tooth root resorption for digital radiography. For this study, experimentally three root sites were used, and radiograms were taken with standardized apparatus. Digital imaging system were consisted of NEC PC-980l(computer), TRINITRON(monitor), SONY XC-711 CCD camera. The display monitor had a resolution of 512X512 pixels. The obtained results were as follows: 1. In the difference of the four X-ray film of the contrast correction, the contrast difference was one gray scale variation at mean value. 2. Viewing of the view box of the periapical radiographs, experimental tooth root resorption of the periapical area of the first premolar, middle of mesial surface of the first molar mesial root, middle of lingual surface of the first molar distal root were recognized by increased diameter. 3. On the analysis by histogram, the periapical area of the first premolar, the middle of mesial surface of the first molar mesial root were each recognized tooth root resorption of the 5,6,7 pixel, 2,4,5 pixel by increased diameter. 4. On the analysis by histogram, the middle of lingual surface of the first molar distal root was each recognized tooth root resorption of the none, 3,6 pixel by increased diameter.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.547-550
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• 2011

We measured that is Gantry, Collimator Star Shot, Light vs. Radiation, HDR QA with Medical LINAC Then, PACS was implemented on the digital images on the monitor that can be confirmed through the QA. Also, for cooperation with OCS system that is using from present source and impose code that need in treatment in each treatment, did so that Order that connect to network, input to CR may appear, did so that can solve support data mistake of Pinacle and PACS that is Planning System and look at Planning premier in PACS.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.271-275
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• 2018

It is possible to do not use the Image Plate for a long time in the clinic. for the acquisition of reliable images the decommissioning process is very important. In this study, we would like to look at complex noises that may occur during Image Plate use depending on the frequency and time of day. first, we got the image from computer radiography. second, We calculate the noise changes using Peak Signal to Noise Ratio(PSNR) and Noise Power Spectrum(NPS). finally, we suggest that remove the noise from the IP for more than 4 hours. and It turned out to be better to remove the noise more than once. this study will be a quantitative reference for Image Plate management and use in the clinical trial.

• Journal of Korea Multimedia Society
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• v.23 no.6
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• pp.729-737
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• 2020

Screening with low-dose spiral computed tomography (LDCT) has been shown to reduce lung cancer mortality by about 20% when compared to standard chest radiography. One of the problems arising from screening programs is that large amounts of CT image data must be interpreted by radiologists. To solve this problem, automated detection of pulmonary nodules is necessary; however, this is a challenging task because of the high number of false positive results. Here we demonstrate detection of pulmonary nodules using six off-the-shelf convolutional neural network (CNN) models after modification of the input/output layers and end-to-end training based on publicly databases for comparative evaluation. We used the well-known CNN models, LeNet-5, VGG-16, GoogLeNet Inception V3, ResNet-152, DensNet-201, and NASNet. Most of the CNN models provided superior results to those of obtained using customized CNN models. It is more desirable to modify the proven off-the-shelf network model than to customize the network model to detect the pulmonary nodules.

• Progress in Medical Physics
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• v.32 no.1
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• pp.1-17
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• 2021

The evolution of X-ray computed tomography (CT) has been based on the discovery of X-rays, the inception of the Radon transform, and the development of X-ray digital data acquisition systems and computer technology. Unlike conventional X-ray imaging (general radiography), CT reconstructs cross-sectional anatomical images of the internal structures according to X-ray attenuation coefficients (approximate tissue density) for almost every region in the body. This article reviews the essential physical principles and technical aspects of the CT scanner, including several notable evolutions in CT technology that resulted in the emergence of helical, multidetector, cone beam, portable, dual-energy, and phase-contrast CT, in integrated imaging modalities, such as positron-emission-tomography-CT and single-photon-emission-computed-tomography-CT, and in clinical applications, including image acquisition parameters, CT angiography, image adjustment, versatile image visualizations, volumetric/surface rendering on a computer workstation, radiation treatment planning, and target localization in radiotherapy. The understanding of CT characteristics will provide more effective and accurate patient care in the fields of diagnostics and radiotherapy, and can lead to the improvement of image quality and the optimization of exposure doses.

• Korean Journal of Applied Biomechanics
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• v.28 no.1
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• pp.55-60
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• 2018

Objective: This study aimed to analyze the effects of computer game exposure on pathological musculoskeletal symptoms in adolescents. Method: This study included 10 male junior high school students who used computers less than 3 times a week for 1 hr per day. The subjects were asked to play computer games for 4 hr. Magnetic resonance imaging of the hand and wrist, from the distal radius and ulnar head to the distal phalanges, and radiography of the cervical vertebrae were performed before and after playing computer games. For each dependent variable, a paired t-test was performed to identify significant changes before and after a 4-hr active computer game (p<.05). Results: The horizontal diameters of the flexor tendons in the index and middle fingers were significantly reduced after playing computer games. The horizontal diameters of the flexor tendons of other fingers did not show any significant differences, but there was a tendency toward a decrease after playing computer games. There was no significant change in the cervical lordosis angle before and after playing computer games. However, the cervical lordosis angle was relatively decreased. Conclusion: The results of this study showed that computer game exposure had direct and indirect effects on morphological changes of flexor tendons. In addition, playing computer games for long periods of time can have a negative effect on normal functioning of the musculoskeletal system, with the possible development of abnormalities. However, computer game exposure in adolescents cannot be decisively identified as a factor causing pathological symptoms, based on the results of this study alone. Thus, longterm longitudinal studies on the overall musculoskeletal system are necessary.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.24 no.2
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• pp.361-368
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• 1994

Radiographic planning is needed for implant placement in order to determine implant length, jaw bone volume, anatomical stucture and so on. Radiographic examination includes conventional radiography, conventional tomography and CT scan. The most accurate mesurement can be obtained from CT scan. For the cross-sectional view of mandible, CT scan reconstruction is generally needed. But the cross-sectional view of mandible can be reformed by personal computer. This study was performed to examine the clinical usefulness of reformed image using personal computer in comparison with CT scan reconstructed image. CT axial slices of 4 mandibles of 4 volunteers were used. Digital imaging system was composed of Macintosh Ⅱ ci computer, high resolution Sony XC-77 CCD camera, Quick Capture frame grabber board and 'NIH Image' program. Seven reconstructed cross-sectional images within CT machine(CT group) were obtained. And seven reformed cross-sectional images(PC group) after digitization of CT axial slices into the personal computer were obtained. PC group was compared with CT group in the objective and subjective aspects. The results were as follow: 1. Measurement of mandibular height & width in both group showed insignificant difference(P>0.05). 2. Subjective assessment of the mandibular canal in both group showed insignificant difference(P>0.05). 3. Image reformation using personal computer could provide panoramic view, which could not be obtained in CT scan reconstruction.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.462-463
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• 2012

팍스시스템은 의료 영상을 디지탈화한 시스템이다. PACS데이터는 초창기 CR(Computed Radiography)의 경우 10MB내외의 데이터를 발생하였으나 의료장비의 발전으로 인해 DB(Digital Radiography)는 20MB이상의 데이터를 발생하였다. 또 CT(Computed Tomography)의 경우 0.5MB데이터를 100Slice내외의 데이터를 발생하였으나, 현재는 Cardiac/PET 등의 CT는 Multi Frame을 지원하며 300~5000Slice이상의 데이터를 발생하게 됨에 따라 네트워크에 상당한 트래픽이 발생하여 병원 진료 환경에 심각한 영향을 초래한다. 또한, 스마트 폰, 태블릿 pc등의 발전으로 인해 많은 사용자들은 실시간 또는 멀티미디어와 같은 데이터 표현 방식으로 팍스 데이터를 보길 원할 것이며, 팍스 시스템 또한 그러한 요구조건을 만족시키기 위해 발전하고 있다. 병원에서 사용하는 네트워크는 인터넷 서비스의 모토인 best effort방법을 일반적으로 사용한다. 이러한 데이터 전송방식은 진료에 직접적인 영향을 미치는 팍스 데이터의 전송에 영향을 미칠 수 있다. 특히 네트워크의 트래픽이 제한적인 환경에서 높은 대역폭을 요구하는 멀티미디어 팍스 데이터를 다수의 사용자들이 전송받기 원하면 지연시간으로 인해 원활한 진료진행을 방해 받을 수 있다. 이러한 문제를 해결하기 위해 네트워크 개발자들은 QoS라는 개념을 도입하였고, 여러 계층에서 QoS를 보장하기 위한 연구가 진행되였다. 일반적으로, 네트워크에서 QoS를 지원하기 위한 여러가지 형태의 연구들을 조사하고, 분산 시스템을 제어하기 위한 DDS 미들웨어에 대한 연구를 기반으로 병원 네트워크에서 적용 방안을 설계하고 시뮬레이션을 통해 검증함으로써 새로운 형태의 병원 네트워크를 제안하고자 한다.

• Journal of the Korean Society of Radiology
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• v.8 no.7
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• pp.377-382
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• 2014

Because of using computer system in the field of medical radiology, many artifacts which can not be seen in film/screen system are being created, especially ghosting artifacts. This artifacts could be yielded by taking advantage of a flat panel Thin-Film Transistor array detector. Ghosting artifacts can be rarely seen in clinical practice when an image that has a high-contrast object within a region of high exposure is quickly followed by another image that puts the high-contrast ghosting image in an area of lower radiation exposure. In this experiment, the ghosting artifacts were minimized for approximately 3 minutes with the unaided eye and almost disappeared for 6 minutes quantitatively between exposures. Moreover, the artifacts were influenced by more tube voltage than current and those depended not upon the number of readout cycles, but upon time.

• Imaging Science in Dentistry
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• v.45 no.3
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• pp.175-180
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• 2015

Purpose: This study was performed to evaluate the reliability of the identification of anatomical landmarks in panoramic and lateral cephalometric radiographs on a standard medical grade picture archiving communication system (PACS) monitor and a tablet computer (iPad 5). Materials and Methods: A total of 1000 radiographs, including 500 panoramic and 500 lateral cephalometric radiographs, were retrieved from the de-identified dataset of the archive of the Section of Oral and Maxillofacial Radiology of the University Of Connecticut School Of Dental Medicine. Major radiographic anatomical landmarks were independently reviewed by two examiners on both displays. The examiners initially reviewed ten panoramic and ten lateral cephalometric radiographs using each imaging system, in order to verify interoperator agreement in landmark identification. The images were scored on a four-point scale reflecting the diagnostic image quality and exposure level of the images. Results: Statistical analysis showed no significant difference between the two displays regarding the visibility and clarity of the landmarks in either the panoramic or cephalometric radiographs. Conclusion: Tablet computers can reliably show anatomical landmarks in panoramic and lateral cephalometric radiographs.