• Korean Journal of Digital Imaging in Medicine
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• v.14 no.2
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• pp.63-67
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• 2012

Calcium density in human bones decreases as people are getting older due to the interior or exterior environmental factors. Bone aging forms osteoporosis. And this can bring out various spine fractures which develops a complications. Thus the prediction of seniliy is one of the important factors in spine diseases. Once spine aged, diverse fractures occur such as compression fracture and micro fracture. Side images of the spine by the digital radiography (DR) were prepared, and pixel arbitrary unit with Image J was measured from one spot in the lumbar bone part. By calculating pixel arbitrary unit of the simple contrast, it was obtained that the value of pixel arbitrary unit decreased as seniliy of bones increased. By simply applying Image J to the seniliy of patient's spine, the seniliy of bones predicts the level of danger with only digital radiography(2D) image. consequently we show that Image J value of pixel arbitrary unit index for predicts the level of precaution of osteoporosis patient.

• The Journal of the Korea Contents Association
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• v.17 no.9
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• pp.292-299
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• 2017

Radiation protection aims to prevent a deterministic effect and minimize a stochastic effect. Overestimating a deterministic effect and a stochastic effect can result in an inaccurate assessment of the risks that will occur in the future, and thus accurate evaluation of the absorbed dose of these fundamental amounts is especially important. This study was intended to measure Kerma using PCXMC 2.0 based on Monte Carlo simulations and to assess the exact absorbed dose by comparing doses produced using multipurpose dosimeter and glass dosimeter. It has been decided to conduct experiments for skull, abdomen and pelvis, and Kerma measured PCXMC 2.0 based on Monte Carlo simulations. The absorbed dose was measured using muli purpose dosimeter and glass dosimeter. The results for the experiments conducted in skull, abdomen, pelvis show that the difference in dose appears great in the order of PCXMC 2.0, muli purpose dosimeter, and the glass dosimeter, and muli purpose dosimeter showed a value closer to that of Kerma. As a result, it has been found that the glass dosimeter was the most advantageous in measuring the actual absorbed dose.

• The Journal of the Korea Contents Association
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• v.17 no.9
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• pp.99-106
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• 2017

This study focused on the issue that when a diagnostic detector is found to have a defect, a patient would be exposed to radiation and image quality would be degraded. Though dose analysis, an experiment was conducted to evaluate detector performance as Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR). Absorbed dose, SNR and CNR were measured using a dosimeter and a tissue equivalent phantom. The experiment was conducted to compare whether the dose value shown after being attached to the back side of the phantom matches the dose value attached behind the detector, where in the conditions of skull, chest and abdomen were set at 75 kVp, 25 mAs, 110 kVp, 8 mAs, and 80 kVp, 20 mAs, respectively. As a result, there was a difference in that the dose values attached to the back side of the detector were 0.004 mGy, 0.006 mGy, 0.003 mGy, whereas those of the back side of the phantom were 0.006 mGy, 0.016 mGy, 0.017 mGy. In order to match both values, the condition was increased and SNR and CNR also increased from 88.32, 88.10, 4.09, 1.63, 87.94, 79.97 to 93.87, 93.75, 4.91, 4.03, 92.02, 84.92. Though this study, we found that when a detector is found to have a aging, it shortens the life of equipment and increases the dose of a patient, also the improvement effect of image quality is inadequate.

• The Journal of the Korea Contents Association
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• v.19 no.8
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• pp.276-283
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• 2019

The purpose of this study is to evaluate the usefulness of automatic exposure control (AEC) by analyzing entrance surface dose (ESD) and entropy on using automatic exposure and manual exposure. The experimental method was to measure the dose by placing a semiconductor dosimeter on the Rando Phantom for the Pelvis, Abdomen, Skull, and Chest regions. The DICOM file was simultaneously acquired and then entropy was analyzed by using Matlab. As a result, when using the automatic exposure control, dose of all sites was lower than manual exposure's dose and entropy was high. In addition, paired t-test was performed for each item and p<0.05 was found in each item. In conclusion, the use of automatic exposure control can be a useful method to contribute to the optimization of the exposure dose and the image quality by reducing the amount of unnecessary radiation amount and information loss that can occur in X-ray examination.

• Journal of radiological science and technology
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• v.45 no.5
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• pp.397-405
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• 2022

Computed radiography (CR) systems, which convert an analog signal recorded on a cassette into a digital image, combine the characteristics of analog and digital imaging systems. Compared to digital radiography (DR) systems, CR systems have presented difficulties in evaluating system performance because of their lower detective quantum efficiency, their lower signal-to-noise ratio (SNR), and lower modulation transfer function (MTF). During the step of energy-storing and reading out, a baseline offset occurs in the edge area and makes low-frequency overestimation. The low-frequency offset component in the line spread function (LSF) critically affects the MTF and other image-analysis or qualification processes. In this study, we developed the method of baseline correction using mathematical morphology to determine the LSF and MTF of CR systems accurately. We presented a baseline correction that used a morphological filter to effectively remove the low-frequency offset from the LSF. We also tried an MTF evaluation of the CR system to demonstrate the effectiveness of the baseline correction. The MTF with a 3-pixel structuring element (SE) fluctuated since it overestimated the low-frequency component. This overestimation led the algorithm to over-compensate in the low-frequency region so that high-frequency components appeared relatively strong. The MTFs with between 11- and 15-pixel SEs showed little variation. Compared to spatial or frequency filtering that eliminated baseline effects in the edge spread function, our algorithm performed better at precisely locating the edge position and the averaged LSF was narrower.

• Proceedings of the Korea Contents Association Conference
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• 2014.11a
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• pp.207-208
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• 2014

본 연구는 Film System의 경우 카세트를 사용하여 환자검사부위와 tube 중심선속, 카세트의 중심이 맞았지만 디텍터의 경우 $17^{{\prime}{\prime}}{\times}17^{{\prime}{\prime}}$ 고정형으로써 디텍터의 중심과 tube의 중심선속, 환자의 검사부위가 맞지 않은체로 검사가 이루어지는 경우가 있어, 디지털 방사선장비에서 중심선속에 따른 화질의 변화를 파악하여 Tube의 중심선속과 환자와의 중심선속 일치에 따른 중요성을 제시하고자 한다.

• Proceedings of the Korea Contents Association Conference
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• 2014.11a
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• pp.195-196
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• 2014

현재 디지털방사선 환경으로 변화하고 있는 추세에 과거 필름-스크린 방식에서 사용되던 흉부 후 전 방향 검사 시 초점 영상 수신부 간의 거리가 디지털방식의 장비에도 여전히 적용되고 있다. 이에 본 연구에서는 3개의 DR장비에서 각 영상수용체의 제조특성을 고려하였을 때 실제 심장 및 심흉비의 확대정도에 대해 알아보고, 임상에서 DR 장비를 이용한 Chest PA 검사 시 심장 및 심흉비의 확대도에 대한 정보를 제공하고자 한다.

• Imaging Science in Dentistry
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• v.42 no.4
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• pp.237-242
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• 2012

Purpose: The objectives of this study were to survey the radiographic exposure parameters, to measure the patient doses for intraoral dental radiography nationwide, and thus to establish the diagnostic reference levels (DRLs) in intraoral dental X-ray examination in Korea. Materials and Methods: One hundred two intraoral dental radiographic machines from all regions of South Korea were selected for this study. Radiographic exposure parameters, size of hospital, type of image receptor system, installation duration of machine, and type of dental X-ray machine were documented. Patient entrance doses (PED) and dose-area products (DAP) were measured three times at the end of the exit cone of the X-ray unit with a DAP meter (DIAMENTOR M4-KDK, PTW, Freiburg, Germany) for adult mandibular molar intraoral dental radiography, and corrections were made for room temperature and pressure. Measured PED and DAP were averaged and compared according to the size of hospital, type of image receptor system, installation duration, and type of dental X-ray machine. Results: The mean exposure parameters were 62.6 kVp, 7.9 mA, and 0.5 second for adult mandibular molar intraoral dental radiography. The mean patient dose was 2.11 mGy (PED) and 59.4 $mGycm^2$ (DAP) and the third quartile one 3.07 mGy (PED) and 87.4 $mGycm^2$ (DAP). Doses at university dental hospitals were lower than those at dental clinics (p<0.05). Doses of digital radiography (DR) type were lower than those of film-based type (p<0.05). Conclusion: We recommend 3.1 mGy (PED), 87.4 $mGycm^2$ (DAP) as the DRLs in adult mandibular molar intraoral dental radiography in Korea.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.295-296
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• 1998

With xeroradiography appearance, DR (Digital Radiography) system have been studying for X-ray detection using photoreceptor. Also detection method for receptor charge change have been developing variably. We use photoreceptor material of a-Se(Amorphous Selenium) with high DQE, high SNR(Signal to Noise Ratio) and high transformation efficiency of X-ray signals into electrical signals. After a-Se receptor is uniformly charged by using Arc discharge, X-ray is exposed. Then a-Se receptor produce subtle charge variation and MOSFET detect charge variations. The detected signal pass A/D converter and signal processing by PC. As results, the initial voltage is 8V. It has wide dynamic range needed digital radiography system. In this study, we obtained data with changing kVp(tube potential voltage) and fixed 8mAs(tube current by exposure time) in X-ray system. However MOSFET detector for X-ray signal is not tested X-ray mAs variations. But if MOSFET detector is tested X-ray mAs variation and exactly calibrated multichannel is made and noise-reduction is done, suitable DR system readout method will be done.

• Journal of the Korea Convergence Society
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• v.10 no.10
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• pp.15-21
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• 2019

X-rays with shorter wavelengths than ultraviolet light have very good penetration power. It is convergence in industrial and medical fields has been used a lot. n particular, in the industrial field, various researches have been conducted on the detection of foregin body inside metal that can occur in the production process of products such as metal using x-ray, a non-destructive inspection device. Detectors are becoming increasingly popular for the popularization of DR (Digital Radiography) photography methods that digitally acquire X-ray video images. However, there are cases where foreign body detection is impossible depending on the sensor noise and sensitivity inside the detector. When producing a metal product, since the defective rate of the produced product may increase due to contamination of the foreign body, accurate detection is necessary. In this paper, we provide a correction model for X-ray images acquired in order to improve the efficiency of defect detection such as foreign body inside metal. When applied to defect detection in the production process of metal products through the proposed model, it is expected that the detection of product defects can be processed accurately and quickly.