• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.329-335
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• 2010

Digital imaging detectors can use a variety of detection materials to convert X-ray radiation either to light or directly to electron charge. Many detectors such as amorphous silicon flat panels, CCDs, and CMOS photodiode arrays incorporate a scintillator screen to convert x-ray to light. The digital radiography systems based on semiconductor detectors, commonly referred to as flat panel detectors, are gaining popularity in the clinical & hospital. The X-ray detectors are described between a-Silicon based indirect type and a-Selenium based direct type. The DRS of detectors is used to convert the x-ray to electron hole pairs. Image processing is described by specific image features: Latitude compression, Contrast enhancement, Edge enhancement, Look up table, Noise suppression. The image features are tuned independently. The final enhancement result is a combination of all image features. The parameters are altered by using specific image features in the different several hospitals. The image in a radiological report consists of two image evaluation processes: Clinical image parameters and MTF is a descriptor of the spatial resolution of a digital imaging system. We used the edge test phantom and exposure procedure described in the IEC 61267 to obtain an edge spread function from which the MTF is calculated. We can compare image in the processing parameters to change between original and processed image data. The angle of the edge with respect to the axes of detector was varied in order to determine the MTF as a function of direction. Each MTF is integrated within the spatial resolution interval of 1.35-11.70 cycles/mm at the 50% MTF point. Each image enhancement parameters consists of edge, frequency, contrast, LUT, noise, sensitometry curve, threshold level, windows. The digital device is also shown to have good uniformity of MTF and image parameters across its modality. The measurements reported here represent a comprehensive evaluation of digital radiography system designed for use in the DRS. The results indicate that the parameter enables very good image quality in the digital radiography. Of course, the quality of image from a parameter is determined by other digital devices in addition to the proper clinical image.

• Journal of the Korean Society of Radiology
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• v.16 no.4
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• pp.395-403
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• 2022

Flat-panel detector (FPD) used in digital radiographic imaging systems was used to perform a quantitative power spectrum evaluation as a result of the thickness change of polymethyl methacrylate (PMMA), a tissue equivalent. As the PMMA thickness increases with the resolution-chart phantom image, the effect of the scattering line increases, indicating that the modulation characteristics decrease, and the image is bright. The results show that the noise of the image increases, and noise-power spectral images are obtained by Fourier transform to confirm by spatial frequency. Thus, it can be verified that the PMMA thickness and noise are proportional through the result of evaluating the change of resolution characteristics and representing the 2D noise-power spectrum as one-dimensional values by evaluating the change of scattering line with MTF as the PMMA thickness increases in the image.

• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.139-148
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• 2020

The purpose of this study is to propose a method to optimize the performance of Digital Radiography (DR) by analyzing the effect of exposure time change on the stability of radiation output and image quality. The experimental method was used to change the exposure time to 50 msec, 100 msec, 200 msec, and 400 msec so that the Percentage Average Error (PAE), Time-to-Radiation Dose Curve, Signal to Noise Ratio (SNR), Contrast to Noise Ratio (CNR) and theses analysis were performed to evaluate the normal operation of parameters, radiation output and image quality. As a result, all the parameters used in the experiment showed the Percentage Average Error in the normal range, and the shorter the exposure time, the stability of radiation output and image quality decrease. In conclusion, it was found that the performance of Digital Radiography can be optimized when stable radiation output and image quality are applied by applying 100 msec ~ 200 msec exposure time.

• Journal of radiological science and technology
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• v.40 no.1
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• pp.71-78
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• 2017

Scattered radiation is inherent phenomenon of x-ray, which occurs to the subject (or patient). Therefore it cannot be avoidable but also interacts as serious noise factor because the only meaningful information on x-ray radiography is primary x-ray photons. The purpose of this study was to quantify scattered radiation for various shooting parameters and to verify the effect of anti-scatter grid. We employed beam stopper method to characterize scatter to primary ratio. To evaluate effect on the projection images calculated contrast to noise ratio of given shooting parameters. From the experiments, we identified the scattered radiation increases in thicker patient and smaller air gap. Moreover, scattered radiation degraded contrast to noise ratio of the projection images. We find out that the anti-scatter grid rejected scattered radiation effectively, however there were not fewer than 100% of scatter to primary ratio in some shooting parameters. The results demonstrate that the scattered radiation was serious problem of medical x-ray system, we confirmed that the scattered radiation was not considerable factor of dig ital radiog raphy.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.375-381
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• 2015

Digital Radiography is a big part of diagnostic radiology. Because uncorrected digital radiography image supported false effect of Patient's health care. We must be manage the correct digital radiography image. Thus, the artifact images can have effect to make a wrong diagnosis. We report types of occurrence by analyzing the artifacts that occurs in digital radiography system. We had collected the artifacts occurred in digital radiography system of general hospital from 2007 to 2014. The collected data had analyzed and then had categorize as the occurred causes. The artifacts could be categorized by hardware artifacts, software artifacts, operating errors, system artifacts, and others. Hardware artifact from a Ghost artifact that is caused by lag effect occurred most frequently. The others cases are the artifacts caused by RF noise and foreign body in equipments. Software artifacts are many different types of reasons. The uncorrected processing artifacts and the image processing error artifacts occurred most frequently. Exposure data recognize (EDR) error artifacts, the processing error of commissural line, and etc., the software artifacts were caused by various reasons. Operating artifacts were caused when the user didn't have the full understanding of the digital medical image system. System artifacts had appeared the error due to DICOM header information and the compression algorithm. The obvious artifacts should be re-examined, and it could result in increasing the exposure dose of the patient. The unclear artifact leads to a wrong diagnosis and added examination. The ability to correctly determine artifact are required. We have to reduce the artifact occurrences by understanding its characteristic and providing sustainable education as well as the maintenance of the equipments.

• Korean Journal of Digital Imaging in Medicine
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• v.7 no.1
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• pp.23-31
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• 2005

원격진료 홈네트워크 아파트 진료용 키오스크 모바일주치의 등으로 대표되는 U-헬스케어에 있어서 기초가 되는 것은 의료정보를 디지털화해서 전자적 자료의 형태로 저장 보관하고 이를 송 수신할 수 있는 기술이라고 할 수 있다. 우리나라의 경우, U-Korea 전략의 하나로 보건복지부가 주축이 되어 2005년 10월 현재 국가보건의료정보화계획(ISP)을 수립하기 위한 작업을 추진중에 있다. 여기서, 예컨대 임상병리검사소견이나 방사선촬영소견 등의 의료정보가 전자적 장치에 의해 디지털화 할 경우 디지털 의료정보가 되는 것이며, 이 가운데 특히 방사선촬영소견 등 방사선분야의 모든 촬영기록이 PACS시스템을 통해 기재되거나 저장 전송될 경우 이를 디지털 의료영상정보라고 할 수 있다. 그런데 오늘날 정보통신기술의 발달로 말미암아 디지털 의료영상정보를 포함한 디지털의료정보는 대량적으로 수집 저장되고 유통 내지 공동활용이 보편화되어 감에 따라 그 의료정보의 보호에 관한 문제가 중요한 이슈로 대두되고 있다. 결론적으로 말하자면, 이러한 디지털 의료영상정보가 전자의무기록(EMR) 형태로 저장 보관되는 경우 이는 전자의무기록에 관한 법률규정이 적용되어 법률적 보호를 받게 되며, 그 보호의 강도는 종래 오프라인 상의 의료정보 보호보다 한층 강화된 규정을 두고 있다. 이와 같은 흐름에 있어서 최근 정부가 국가보건의료정보화계획 수립과 함께 제정작업을 추진하고 있는 가칭 의료정보화촉진 및 개인정보보호에 관한 법률(안)은 시사점이 크다고 보기 때문에 소개하고자 한다.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2795-2797
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• 2003

기존의 X-ray System을 보면 방사선 소스와 방사선을 가시광선으로 변환시키는 형광판, 그리고 이 발광된 빛을 증폭시키는 작용을 하는 영상 증배관과 필름으로 구성된다. 이에 따른 시스템의 부피와 한 장의 필름이 나오기까지의 과정 등이 매우 번거롭다. 이 시스템을 저비용의 디지털 X-ray 시스템으로 대체함에 있어서 형광판과 디지털 CCD카메라를 이용하여 저가이면서 시스템 자체는 간소화시킨 X-ray시스템을 개발하고자한다. X-ray이미지는 형광판의 밀도와 카메라의 분해능에 따라 그 해상도가 결정이 되지만, 이번연구에서는 8bit의 분해능에 $1300{\times}1030$의 해상도를 갖는 Monochrome Digital 카메라를 사용하고, 기존 시스템에 사용되던 간접촬영용 형광판을 사용하였다. 기존시스템의 영상증배관을 배제시켜 후처리에 중점을 두어 시스템은 간소화하고, 저비용을 실현시켰다.

• Journal of the Korean Society of Radiology
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• v.2 no.2
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• pp.5-10
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• 2008

Most of the diagnostic medical radiography are rapidly replaced by digital imaging systems recently. Although with the current transition of analog to digital most of the exposure conditions and parameters are still on the basis of film-screen analog system. Moreover the evaluation of acquired digital radiographic image is not fulfilled normally because of the difficulties in handling the digital raw data. The user friendly windows program for the evaluations of digital radiographic image was developed on the MatLab platform. The program has functions for the calculation of the contrast profile, NPS(noise power spectrum), MTF(modulation transfer function), and NEQ(noise equivalent quanta).

• Journal of radiological science and technology
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• v.31 no.2
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• pp.177-182
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• 2008

Digital imaging for general rediography has many advantages over the film/screen systems, including a wider dynamic range and the ability to manipulate the images produced. The wider range means that acceptable images may by acquired at a range of dose levels, and therefore repeat exposures can be reduced. Digital imaging can result in the over use of radiation, however, because there is a tendency can be reduced. Digital imaging can result in the over use of radiation, however, because there is a tendency for images to be acquired at too high a dose. We investigated the actual exposure dose conditions on general radiography and a questionnaire survey was conducted with radiotechnologiest at medical institutions using digital radiology system. As a results, the dose of exposure was not controlled with patient's figure and dose optimization but was controlled by worker's convenience and image quality. Radio-technologiests often set up the exposure dose regardless of patient figure and body part to be examined. Many organizations, such as the International Commission on Radiological Protection, recommend to keep the dose as low as possible. In addition, they strongly recommend to keep the optimal but minimal dosage by proper training programs and constant quality control, including frequent patient dose evaluations and education.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.177-178
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• 2015

디지털방사선영상시스템의 영상 품질을 비교하기 위해 영상의 정량적인 분해능을 나타내는 변조전달함수(MTF), 노이즈 특성을 나타내는 잡음력 스펙트럼(NPS)을 이용하여 영상 품질평가를 하였다. IEC61267 선질을 사용하여 IEC62220-1에서 제시하는 기하학적인 조건과 실제 임상에서 사용되어지는 기하학적인 조건을 사용하여 그리드 및 부가필터, 임상선량을 이용하여 edge 팬텀을 사용하여 MTF, NPS값을 측정하였다. 그리드사용 유 무, 부가필터사용 유 무, kV, 임상선량(mAs), 영상검출기까지의 거리에 따른 MTF 결과는 임상조건 100cm, 180cm과 IEC62220-1 기하학적인 조건 150cm에서 MTF 공간주파수 측정값은 비슷하게 나타났으며, 오히려 임상조건 100cm에서 공간주파수가 높게 나타나는 경우도 있었다. NPS 결과는 선량(mAs)이 증가함에 따라 감소함을 나타내었다. IEC61267 선질을 이용한 영상품질평가에서는 IEC62220-1기하학적인 조건을 이용한 품질평가보다 임상조건 기하학적인 조건을 사용한 영상의 품질이 좋았다. 본 논문의 영상특성 평가 연구 결과들을 바탕으로 향후 IEC 표준의 영상평가에서 제시하는 평가방법보다는 임상 조건을 적용한 영상특성 평가방법을 적용한다면 실제 임상의 디지털방사선영상시스템의 영상품질을 적절하게 유지할 수 있을 것으로 사료된다.