• Journal of Biomedical Engineering Research
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• v.12 no.1
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• pp.35-42
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• 1991

In this paper, the information capacity, the intergrate performance measure of digital radiography system has been quantitatively analyzed. The effect of various factors affecting the information capacity of the digital radiography system in multistage detection processes has been considered and analyzed In detail. The results show that the more information capacity can be obtained with the smaller detector cell area, despite of the reduced signal to noise ratio due to the reduced number of X ray photons per detector cell. Considering the limit of human visual acuity, however. the sufficient resolution will be obtained when the detector cell size in $0.2{\times}0.2\textrm{mm}^2$ with 8 bit quantizaion. And also the results indicates that the information capacity may be severely reduced by the mixture of electric noise in final read-out stage.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1301-1304
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• 1987

We have analized electrical error factors generated in the digitizing process of the linear scanning digital radiography system, and obtained improved results using error calibration hardwares. And characteristics of digital radiography system were evaluated by measuring several imaging properties.

• Journal of radiological science and technology
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• v.37 no.3
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• pp.169-175
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• 2014

According to database of medical institutions of health insurance review & assessment service in 2013, 1118 hospitals and clinics have department of radiology in Korea. And there are CT, fluoroscopic and general radiographic equipment in those hospitals. Above all, general radiographic equipment is the most commonly used in the radiology department. And most of the general radiographic equipment are changing the digital radiography system from the film-screen types of the radiography system nowadays. However, most of the digital radiography department are used the film-screen types of the radiography system. Therefore, in this study, we confirmed present conditions of technical items for general radiography used in hospital and research on general radiographic techniques in domestic medical institutions. We analyzed 26 radiography projection method including chest, skull, spine and pelvis which are generally used in the radiography department.

• Journal of the Korea Safety Management & Science
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• v.17 no.4
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• pp.213-221
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• 2015

The aim of this study was to set up the optimal exposure condition according to detector type considering image quality (IQ) with radiation dose in chest digital radiography. We used three detector type such as flat-panel detector (FP) and computed radiography (CR), and charge-coupled device (CCD). Entrance surface dose (ESD) was measured at each exposure condition combined tube voltage with tube current using dosimeter, after attaching on human phantom, it was repeated 3 times. Phantom images were evaluated independently by three chest radiologists after blinding image informations. Standard exposure condition using each institution was 117 kVp-AEC at FP and 117 kVp-8 mAs at CR, and 117 kVp-8 mAs at CCD. Statistical analysis was performed by One way ANOVA (Dunnett T3 test) using SPSS ver. 19.0. In FP, IQ scores were not significant difference between 102 kVp-4 mAs and 117 kVp-AEC (28.4 vs. 31.1, p=1.000), even though ESD was decreased up to 50% ($62.3{\mu}Gy$ vs. $125.1{\mu}Gy$). In CR, ESD was greatly decreased from 117 kVp-8 mAs to 90 kVp-8 mAs without significant difference of IQ score (p=1.000, 24.6 vs. 19.5). In CCD, IQ score of 117 kVp-8 mAs was similar with 109 kVp-8 mAs (29.6 vs. 29.0), with decreasing from $320.8{\mu}Gy$ to $284.7{\mu}Gy$ (about 11%). We conclude that optimal x-ray exposure condition for chest digital radiography is 102 kVp-4 mAs in FP and 90 kVp-8 mAs in CR, and 109 kVp-8 mAs in CCD.

• Journal of Digital Convergence
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• v.16 no.12
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• pp.441-447
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• 2018

This study aims to develop digital techniques that enable repeated practice of dental radiography using augmented reality technology. A three-dimensional object was fabricated by superimposing a photograph of an adult model and a computed tomography image of a manikin phantom. The system was structured using 106 radiographs such that one of these saved radiographs is opened when the user attempts to take a radiograph on a mobile device. This system enabled users to repeatedly practice at the pre-clinical stage without exposure to radiation. We attempt to contribute to enhancing dental hygienists' competency in dental radiography using these techniques. However, a system that enables the user to actually take a radiograph based on face recognition would be more useful in terms of practice, so additional studies are needed on the topic.

• The KIPS Transactions:PartB
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• v.11B no.3
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• pp.275-280
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• 2004

In this paper, we propose automatic subtraction radiography algorithms to overcome conventional subtraction radiography's defects by applying image processing technique. In order to reach these goals, this paper suggests the image alignment method that is necessary for getting subtraction image and ROI(Region Of Interest) focused on a selection method using the structure characteristics in target images. Therefore, we use these methods because they give accurary, consistency and objective information or data to results. According to the results, easily and visually we can identify fine difference int the affected parts wether they have problems or not.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.12
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• pp.120-127
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• 2016

In order to acquire digital x-ray images, developing radiography detectors have been recently conducted based on the DR (digital radiography) technology. The noise property of the radiography detector can be observed from measuring the NNPS (normalized noise power spectrum) using uniform exposure images. Here, the image difference of two images is used to remove the fixed pattern noise in measuring the detector NNPS. In this paper, two average images are first calculated using several images and then their difference is used to calculate an NNPS value. Here, the obtained NNPS value is usually lower than the true detector NNPS due to the average. Hence, a compensation constant, which is a function of the number of used images, is also proposed to compensate the NNPS value to obtain the true detector NNPS. Furthermore, another measurement method, in which the ratio of the average images is used, is proposed. Through NNPS measuring experiments using real x-ray images, it is observed that the proposed method can provide further accurate NNPS measurements.

• Journal of Digital Convergence
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• v.12 no.11
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• pp.407-414
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• 2014

The aim of the present study was to carry out quantitative analysis of spatial resolution for the influence of the focus size and digital image post-processing on the Computed Radiography (CR). The modulation transfer functions of an edge measuring method (MTF) was used for the evaluation of the spatial resolution. The focus size of X-ray tube was used the small focus (0.6 mm) and the large focus (1.2 mm). We evaluated the 50% and 10% of MTF for the enhancement of edge and contrast by using multi-scale image contrast amplification (MUSICA) in digital image post-processing. As a results, the edge enhancement than the contrast enhancement were significantly higher the spatial resolution of MTF 50% in all focus. Also the spatial resolution of the obtained images in a large focus were improved by digital image processing. In conclusion, the results of this study should serve as a basic data for obtain the high resolution clinical images, such as skeletal and chest images on the CR.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.3
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• pp.30-41
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• 2011

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, within the methods of obtaining x-ray digital images by employing the rotated grids for the facility of grid artifact reduction, the previous work, where the frequencies of the artifact components on the boundary, is further analyzed and extended, and a min-max optimization for a given grid density is proposed. For practical grid densities, appropriate grid angles are provided and a grid artifact reduction algorithm is proposed for the appropriate grid angles. The proposed algorithm is tested for real x-ray digital images with a comparison, and can remove the grid artifacts while maintaining the resolution of the original image.

• Imaging Science in Dentistry
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• v.33 no.2
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• pp.91-95
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• 2003

Purpose : To compare the diagnostic accuracy of proximal caries detection between Kodak Insight film and the Biomedisys CDX2000HQ digital (CCD) sensor. Materials and Methods: 156 proximal surfaces of extracted teeth, 78 of which had chemical artificial caries, were used in this study. Four observers interpreted the radiographs using a five-point confidence rating scale to record their diagnoses. The results were analyzed by receiver operating characteristic curves, ANOVA and Kappa values. Result: Analysis using receiver operating characteristic curves revealed the areas under each curve which indicated a diagnostic accuracy of 0.951 in Insight and 0.952 in CDX2000HQ digital sensor. ANOVA revealed no significant differences between the two images with respect to caries detection. Kappa values indicated that the mean intra-observer agreement was 0.85 and inter-observer agreement 0.71 in conventional radiography. In digital radiography, the mean intra-observer agreement was 0.84 and inter-observer agreement 0.72. Conclusion: The results suggest that no significant difference exists between the two modalities for artificial caries detection and that CDX2000HQ was as good as Insight film for this purpose.