• Restorative Dentistry and Endodontics
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• 제37권3호
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• pp.160-164
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• 2012

Objectives: This study was aimed to investigate the methods to reduce operator's radiation dose when taking intraoral radiographs with portable dental X-ray machines. Materials and Methods: Two kinds of portable dental X-ray machines (DX3000, Dexcowin and Rextar, Posdion) were used. Operator's radiation dose was measured with an 1,800 cc ionization chamber (RadCal Corp.) at the hand level of X-ray tubehead and at the operator's chest and waist levels with and without the backscatter shield. The operator's radiation dose at the hand level was measured with and without lead gloves and with long and short cones. Results: The backscatter shield reduced operator's radiation dose at the hand level of X-ray tubehead to 23 - 32%, the lead gloves to 26 - 31%, and long cone to 48 - 52%. And the backscatter shield reduced operator's radiation dose at the operator's chest and waist levels to 0.1 - 37%. Conclusions: When portable dental X-ray systems are used, it is recommended to select X-ray machine attached with a backscatter shield and a long cone and to wear the lead gloves.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2935-2940
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• 2007

To diagnose circulatory diseases in the viewpoint of hemodynamics, we need to get quantitative hemodynamic information of blood flows related with the vascular diseases with high spatial resolution of tens micrometer and high temporal resolution in the order of millisecond. For investigating in-vivo hemodynamic phenomena, a new diagnosing technique combining medical radiography and PIV method was newly proposed and developed. This angiographic PIV technique consists of a medical X-ray tube, an X-ray CCD camera, a shutter module for double pulses of X-ray, and a synchronizer. The feasibility of the angiographic PIV technique was tested and quantitative flow velocity field distribution of a flow inside an opaque conduit was acquired by the developed system. It can be used for measuring flow phenomena of nontransparent fluids inside opaque conduits.

• 대한디지털의료영상학회논문지
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• 제12권1호
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• pp.5-8
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• 2010

Opened a court in February 10, 2006, a rule of safety management of the diagnosis radiation system was promulgated for safety of the radiation worker, patients and patients' family members. The purpose of this rule is to minimize the risk of being exposed to radiation during the process of handling X-ray. For this reason, we manufactured shielding device of mobile X-ray unit collimator for diminution of skin dose. Shielding device is made to a thickness of Pb 0.375mm. For portable chest radiography, we measured skin dose 50cm from center ray to 200cm at intervals of 20cm by Unfors Xi detector. As a result, a rule of safety management of the diagnosis radiation system has been strengthened. But there are exceptions, such as ER, OR, ICU to this rule. So shielding device could contribute to protect unnecessary radiation exposure and improve nation's health.

• 대한방사선기술학회지:방사선기술과학
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• 제1권1호
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• pp.44-54
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• 1978

This study was carried out with statistical materials during the last two years of period from Jan. 1975 to Dec. 1976 which presented at radiologic department of 5 hospitals in Seoul City. The primary purpose of this study was to obtained more detailed informations related to the activities of radiologic technologists in diagnostic X-Ray examinations part and to provide some basic materials for managements in activities of then and manpower managements of their organization and practice. From the results of this study, the following conclusions were obtained [1] During two year from the January of 1975 to the December of 1976, total number of case in X-ray examinations were 464,830 case and 22,029 case in 1975 and 24,461 in 1976. And ratio of icreased in X-Ray examinations by year was 11.09 per cent. [2] Regarding the examined portion of X-Ray examination, a great propotion was chest examination as 56.88 per cent. [3] An average, the required time per case in X-Ray exam. was 9.28 minutes and make used of 1.94 sheets of X-Ray film per case in radiography. [4] An average, ratio of increased in X-Ray film by year was 12.71 per cent and ratio of failed film in it was 2.23 per cent. [5] The frequency rate of film size showed the highest distribution of $8"{\times}10"$(28.17%) and the highest distribution of X-Ray film by month was July(8.93%). [6] An average, the amount of activities per a diagnostic X-Ray equipment was 34.92 case and make used of 67.81 sheets of X-Ray film in a day. [7] The mean number of case in X-Ray examinations by radiologic technologists was 29.29 cases and make used of 56.87 sheets of X-Ray film in a day. Also, the average number of case was reading by radiologists was 32.42 case and 62.97 sheets of X-Ray film in a day.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.683-686
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• 2008

To diagnose vascular diseases from the viewpoint of hemodynamics, detailed quantitative hemodynamic information of related blood flows with a high spatial resolution of tens micrometer and a high temporal resolution in the order of millisecond were required. For investigating the hemodynamic phenomena of vascular circulatory diseases, a new diagnosing technique combining a medical radiography and PIV method was newly developed. This technique consisted of a medical X-ray tube, an X-ray CCD camera, a shutter module for double pulse-type X-ray source, and a synchronizer. Through several preliminary tests, the feasibility of the angiographic PIV technique was verified. For in-vivo measurements to real blood flows, we developed tracer microcapsules which were optimized to this system by encapsulating a contrast material of iodine with a matrix material of PVA (polyvinylpyrrolidone). In near future, the angiographic PIV technique would be useful for diagnosing hemodynamic phenomena of vascular diseases and for their early detection.

• 한국의학물리학회지:의학물리
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• 제32권1호
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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.

• 한국콘텐츠학회논문지
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• 제10권6호
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• pp.329-335
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• 2010

디지털 방사선시스템에서의 의료영상 획득의 방법은 X선을 조사하고, 반도체 디텍터(Detector)를 이용하여 직접 및 간접으로 변환하여 기존 업체마다 여러 가지 알고리즘을 적용하여 적절한 이미지 프로세싱을 거쳐서 임상의 적정한 영상을 획득한다. 방사선과에서 적절한 의료 영상 형성을 위하여 적용하는 이미지 프로세싱 파라미터(Image Processing Parameters)는 Edge, Frequency, Contrast, Latitude, LUT, Noise 등의 영상 증강의 과정은 기술력 및 업체 알고리즘에 따라 다르게 적용되고 있다. 따라서 본 논문에서는 디지털 방사선 환경에서의 최종의 임상 영상을 위한 이미지 증강의 파라미터들의 적정 세팅 값의 기준을 제시하고자 한다. 그리고 각 병원들의 의료 영상을 바탕으로 이미지 프로세싱 파라미터들을 변화하여 각 파라미터들의 세부적인 기준 세팅값을 연구하며, 실제적인 파라미터 변화에 대한 적합한 의료 영상을 디지털방사선시스템의 영상 평가 방법을 도식화하여 결과를 제시하고, 향후 임상에서 적응 및 활용 가능한 객관적인 영상 파라미터에 대한 특성 평가의 응용을 정립하고자 한다. 또한 다양한 표본 병원의 디지털 방사선 환경에서 적정 파라미터 값들을 조사하여 임상에서 영상의 화질에 미치는 영향으로 특성 평가의 객관적인 기준의 변조전달함수(MTF)의 공간해상력을 제시하고 한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.366-369
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• 2002

At present, the study of direct digital X-ray detector and indirect digital X-ray detector proceed actively. But it needs high thickness and high voltage in selenium for high ionization rate. Therefore, we carried out the study of electric characteristics of a-Se with additive ratio of Iodine in drafting study for developing Hybrid X -ray Sensor for complementing direct digital X -ray detector and indirect digital X-ray detector in this paper. On this, there are formed Amorphous selenium multi-layers by sticking phosphor layer$(Gd_{2}O_{2}S(Eu^{2+}))$ using optical adhesives of EFIRON Co. Amorphous selenium multi-layers having dielectric layer(parylene) has characteristics of low dark-current, high X-ray sensitivity. So we can acquired a enhanced signal to noise ratio. We make Amorphous selenium multi-layers with $30{\mu}m$ thickness on glass.

• 한국광학회지
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• 제19권4호
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• pp.249-254
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• 2008

새 구조의 액정 엑스선 감지기를 만들었다. 이것은 액정판을 만들고 유리판을 얇게 식각한 다음, 그 유리판 위에 반사막과 광전도층을 연속하여 입힌 구조이다. 새 구조의 액정엑스선 감지기는 공정의 안정성, 대면적화, 감도 등에서 이미 상품화된 엑스선 감지기와도 충분히 경쟁할 수 있으며, 따라서 성공적으로 상용화 할 수 있음을 확인했다.

• 동력기계공학회지
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• 제15권4호
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• pp.25-30
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• 2011

This study is made to provide with a method for correcting the geometric distortion of the digital radiography image by analytical approach based upon the inverse square law and Beer's law. This study is aimed to find out and improve a mathematic model of nonlinear type. Variations in the alignment of the X-ray source, the object, and imaging plate affect digital radiography images. A model which is expressed in parameter values; e.g, angle, position, absorption coefficient, length, width and pixel account of radiography source, is developed so as to match the sample image. For the best correction of the digital image that is the most similar to the model image, a correction technique based upon tangent is developed; then applied to the digital radiography images of steel tubes. As a result, the image correction is confirmed to be made successfully.