• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.65-85
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• 1999

Objectives: To determine the effect of interpolation functions when processing the digital periapical images. Material and Methods: The digital images were obtained by Digora and CDR system on the dry skull and human subject. 3 oral radiologists evaluated the 3 portions of each processed image using 7 interpolation methods, and ROC curves were obtained by trapezoidal methods. Results: The heighest Az value(0.96) was obtained with cubic spline method and the lowest Az value(0.03) was obtained with facet model method in Digora system. The heighest Az value (0.79) was obtained with gray segment expansion method and the lowest Az value(0.07) was obtained with facet model method in CDR system. There was significant difference of Az value in original image between Digora and CDR system at a=0.05 level. There were significant differences of Az values between Digora and CDR images with cubic spline method, facet model method, linear interpolation method and non-linear interpolation method at α=0.1 level.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.2
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• pp.26-37
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• 2003

Unlike a medical doctor, a dentist performs all the tasks necessary for diagnosis and treatment of a disease all by himself. To increase the diagnostic accuracy, dentists need an efficient working environment providing much more integrated information of clinical data and radiographic image. In this paper, we propose an integrated environment for the dental hospital. It provides paperless and filmless hospital environment by integrating seamlessly three major operations for the dental hospital including patient record generation and management, clinical image acquisition and analysis, and treatment planning and simulation. This system also allows clinicians to provide more predictable dental care for the patients by supporting instant access to all the clinical data and quantitative data analysis.

• Journal of radiological science and technology
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• v.35 no.2
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• pp.109-117
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• 2012

The purpose of this work was to evaluate an amorphous silicon cesium iodide based indirect flat-panel detector (FPD) in terms of their modulation transfer function (MTF), Wiener spectrum (WS, or noise power spectrum, NPS), and detective quantum efficiency (DQE). Measurements were made on flat-panel detector using the International Electrotechnical Commission (IEC) defined RQA3, RQA5, RQA7, and RQA9 radiographic technique. The MTFs of the systems were measured using an edge method. The WS(NPS) of the systems were determined for a range of exposure levels by two-dimensional (2D). Fourier analysis of uniformly exposed radiographs. The DQEs were assessed from the measured MTF, WS(NPS), exposure, and estimated ideal signal-to-noise ratios. Characteristic curve in the RQA3 showed difference in the characteristic curve from RQA5, RQA7, RQA9. MTFs were not differences according to x-ray beam quality. WS(NPS) was reduced with increasing dose, and RQA 3, RQA5, RQA7, RQA9 as the order is reduced. DQE represented the best in the 1mR, RQA 3, RQA5, RQA7, RQA9 decrease in the order. The physical imaging characteristics of FPD may also differ from input beam quality. This study gives an initial motivation that the physical imaging characteristics of FPD is an important issue for the right use of digital radiography system.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.5
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• pp.117-126
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• 2010

In order to obtain more clear x-ray images, an antiscatter grid, which can absorb the scattered rays, is employed. In the high-resolution direct digital radiography, however, the artifacts due to the grid are visible. In this paper, the grid artifacts are reduced by applying simple 1-dimensional low-pass filters in the spatial domain based on the rotated grid. Since the proposed algorithm does not use any detection scheme for the artifact frequencies and discrete Fourier transforms for 2-dimensional filters, it can simply and fast reduce the grid artifacts. The performance using the order 1 average filter is compatible to that of using 2-dimensional filters in the frequency domain.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.1
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• pp.60-69
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• 2016

Purpose: The objective of this study was to compare the accuracy of digital models from 3 dimentional (3D) optical scanner and cone beam computed tomography (CBCT). Materials and Methods: We obtained digital models from 11 pairs of stone casts using a 3D optical scanner and a CBCT, and compared the accuracy of the models. Results: The error range of average positive distance was 0.059 - 0.117 mm and negative distance was 0.066 - 0.146 mm. Statistically (P < 0.05), average positive distance was larger than $70{\mu}m$ and shorter than $100{\mu}m$, and that of negative distance was larger than $100{\mu}m$ and shorter than $120{\mu}m$. Conclusion: We concluded that the accuracy of digital models generated from CBCT is not appropriate to make final prostheses. However, it may be acceptable for provisional restorations and orthodontic diagnoses with respect to the accuracy of the digitalization.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.27 no.2
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• pp.49-61
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• 1997

The purpose of this study was to compare E-speed film, CDR, and modified CDR images by means of observing some artificial defects of alveolar bone wall in the sound human dried mandibles. High diagnostic accuracy was shown in 1 wall and 4 wall defects by all 5 observers (2 Radiologists, 2 Periodontists, 1 General practitioner), but the diagnosis in 2 wall and 3 wall defects was inaccurate. Modified CDR images had the more diagnostic accuracy than E-speed film and CDR images, but there was no statistical difference among them. Finally, radiologist used modified CDR images more than others and used equalization effect more than the change in contrast and/or brightness.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.73-85
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• 1998

The purpose of this study was to aid in the use of the digital images by edge-detect interpolation for direct digital periapical images using edge-detect interpolation. This study was performed by image processing of 20 digital periapical images; pixel replication, linear non-interpolation, linear interpolation. and edge-sensitive interpolation. The obtained results were as follows : 1. Pixel replication showed blocking artifact and serious image distortion. 2. Linear interpolation showed smoothing effect on the edge. 3. Edge-sensitive interpolation overcame the smoothing effect on the edge and showed better image.

• Journal of radiological science and technology
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• v.25 no.2
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• pp.57-64
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• 2002

The recent development of embodiment technology of the medical images makes most medical institutions introduce PACS(Picture Archiving and Communication System) in haste. However lots of PACS solutions, currently developed and distributed, haven't been able to serve the convenience of users and to satisfy user's demand because of economic limitations and administrator-oriented considerations in the process of development. So we have developed MIH(Medical Image History), by which we can search and refer to the patient's medical images and information with few restrictions of time and space for diagnosis and treatment. This program will contribute to the improvement in the medical environment and meet the clients' need. We'll make more effort to develop the application which insures the better quality of medical images. MIH manages the patient's image files and medical records like film chart in connection with time. This trial will contribute to the reduction of the economical loss caused by unnecessary references and improve the quality in the medical services. The demand on the development or the program which refers to the medical +ata quickly and keeps them stable will be continued by the medical institute. This will satisfy the client's demand and improve the service to the patients in that tile program will be modified from the standpoint of the users. MIH is trying to keep user-oriented policy and to apply the benefit of the analog system to the digital environment. It is necessary to lead the public to the better understanding that the systematic management and referring of the medical images is as important as the quality of the images.

• Journal of the Korean Society of Radiology
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• v.9 no.3
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• pp.175-181
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• 2015

In this paper, we studied additional filter and Ion chamber combinations to reduce patient dose without decreasing image quality in digital chest x-ray projection. The experiment set 125 kVp, 320 mA, AEC mode. Ion chamber sensors was divided by 4 cases of combinations, then, we measured patient dose and calculated organ dose using PCXMC. Also, physical image assessment using MTF was performed. As a results, The surface entrance dose and organ dose were the lowest when selecting both left and right Ion chamber sensors under the same conditions of additional filter. In image quality assessment, The spatial frequency scored 2.494 lp/mm which was highest when selecting both right and left Ion-chambers and 0.1 mmCu filter. And to conclude, to select both right and left Ion chamber sensors and 0.1 mmCu filter will help for acquiring good quality image as well as reducing patient dose.

• Korean Journal of Digital Imaging in Medicine
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• v.14 no.2
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• pp.15-22
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• 2012

The purpose of this study was to measure the absorbed dose and calculate the effective dose for cone beam computed tomography (CBCT) and panorama units and to estimate usefulness of x-ray protective. Rando phantom and glass dosimeters were used for dosimetry. The absorbed doses were measured at 15 organs and 14 remainder from correspond to ICRP 2007 recommendations. The absorbed dose was highest in salivary glands as measured CBCT 2.420mGy, panorama 0.307mGy. Absorbed dose in another organs were high in order of thyroid, brain, skin, esophagus. The effective dose was CBCT 0.100mSv, panorama 0.011mSv and effective dose of panorama was higher than that of CBCT by 10 times. In case of wearing x-ray protective, reducing effective dose of CBCT by 0.066mSv (66%) and panorama by 0.008mSv (72%). Effective dose were reduced by radiological shielding but it needs further optimization studies, where dosimetric data are analyzed in combination with image quality with keep the patients' exposure as low as possible.