• 제목/요약/키워드: Digital Radiography Detector

검색결과 127건 처리시간 0.028초

a-Se을 이용한 디지털 X-선 검출기의 Discharge Erasing Method에 관한 연구 (Study of Discharge Erasing Method of a-Se based Digital X-ray Detector)

  • 이동길;박지군;최장용;강상식;남상희
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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    • pp.395-398
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    • 2002
  • Many research group started study to develope x-ray detector using thin film transistor from 1970. But realization of TFT based x-ray detector development was caused by progress of thin film transistor liquid crystal display(TFTLCD) device technology in 1990. The main current of TFT technology is display device. Research results expend TFT technology field from display device to sensor manufacture technology. These days many research group in the world realize various digital x-ray detector. In this study, We compare discharge erasing method to visible light erasing method in a-Se based digital x-ray detector. Visible light erasing method is known reset process in direct conversion x-ray detector. Digital x-ray detector using visible light erasing method is not adaptive for conventional x-ray device, because of its thickness. And it is not avaliable for real-time imaging for digital fluoroscopy, because of its long reset time. In this study we overcome these limitations and show new idea for real-time imaging method.

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컴퓨터 방사선영상에서 고 관전압 기법을 이용한 안구 입사표면선량 감소에 관한 연구 (A Study on Reducing of Entrance Surface Dose with the Eye in the Computed Radiography by Using High Kilo Voltage Peak Technique)

  • 성열훈;임재동
    • 대한안전경영과학회지
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    • 제13권2호
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    • pp.91-96
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    • 2011
  • The purpose of this study was to minimize of entrance surface dose (ESD) at the eye using high kVp technique in the computed radiography. We used REX-650R (Listem, Korea) general X-ray unit, and external detector with ESD dosimeter of Piranha 657 (RTI Electronics, Sweden). We used head of the whole body phantom. The total 64 images of X-ray anterior-posterior of skull were acquired using the film/screen (F/S) method and the digital of computed radiography method. The three radiology professor of more 10 years of clinical career evaluated a X-rays images in the same space by 5-point scale. The external detector was performed measurement of ESD of three times by same condition on the eye of the head phantom. The good image quality in the F/S method (90 kVp, 2.5 mAs) showed at the minimized ESD of 0.310 ${\pm}$ 0.001 mGy. the good image quality in the computed radiography method (90 kVp, 2.0 mAs) showed at the minimized ESD of 0.180 ${\pm}$ 0.002 mGy (P = 0.002). Finally the radiation dose could reduced about 50% in the computed radiography method more than the F/S method. In addition the eye entrance surface dose using high kVp technique with the computed radiography was reduced 92% more than conventional technique (F/S method).

CR과 DR 영상화질의 정량적 비교분석 (Quantitative Analysis and Comparison of DR and CR image quality)

  • 박혜숙;서장연;정진화;이창래;조효민;김희중
    • 한국방사선학회논문지
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    • 제1권1호
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    • pp.31-37
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    • 2007
  • 본 연구의 목적은 CR(Computed Radiography)과 DR(Digital Radiography)장비의 각 Detector를 통해 획득된 영상의 화질을 비교 분석하기 위한 것이다. CR(AGFA MD 4.0 General plate, JAPAN)과 DR(HOLOGIC nDirect Ray, USA)에 대한 영상평가의 주요인자인 MTF(Modulation transfer function), NPS(Noise power spectrum), Photon fluence, DQE(Detective quantum efficiency)를 정량적인 값으로 도출하여 비교한 결과 CR이 DR보다 우수하게 나타났다. 본 연구의 결과는 CR과 DR장비의 Image quality를 정량적으로 평가할 수 있을 뿐만 아니라 이 장비들을 유지, 보수하는데도 도움이 될 것으로 사료된다.

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DR Responses to X-Ray: in Terms of Absorbed Energy

  • Kim, Do-Il;Lee, Hyoung-Koo;Kim, Sung-Hyeon;Ho, Dong-Su;Suh, Tae-Suk;Choe, Bo-Young
    • 한국의학물리학회:학술대회논문집
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    • 한국의학물리학회 2002년도 Proceedings
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    • pp.389-392
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    • 2002
  • Digital radiography (DR) is being developed for numerous applications in medical imaging. For understanding DR image, it is necessary to comprehend DR responses to X-ray in terms of absorbed energy. This study reports on the relationship of absorbed energy in the scintillator vs. pixel value of detector. Pixel value and exposure were measured from 50 kVp to 120 kVp until the detector was saturated. For representing radiation produced at the X-ray tube, we used program Srs-78 and compared experimental exposure with calculated exposure. Absorbed energy was acquired using spectrum and we got the relation between the two values.

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A Polycrystalline CdZnTe Film and Its X-ray Response Characteristics for Digital Radiography

  • Kim, Jae-Hyung;Park, Chang-Hee;Kang, Sang-Sik;Nam, Sang-Hee
    • Transactions on Electrical and Electronic Materials
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    • 제4권5호
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    • pp.15-18
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    • 2003
  • The Cd$\_$1-x/Zn$\_$x/Te film was produced by thermal evaporation for the flat-panel X-ray detector. The crystal structure and the surface morphology of poly crystalline Cd$\_$1-x/Zn$\_$x/Te film were examined using XRD and SEM, respectively. The leakage current and X-ray sensitivity of the fabricated films were measured to analyze the X-ray response characteristic of Zn in a polycrystalline CdZnTe thin film. The leakage current and the output charge density of Cd$\_$0.7/Zn$\_$0.3/Te thin film were measured to 0.3 1nA/$\textrm{cm}^2$ and 260 pC/$\textrm{cm}^2$ at an applied voltage of 2.5 V/$\mu\textrm{m}$, respectively. Experimental results showed that the increase of Zn doping rates in Cd$\_$1-x/Zn$\_$x/Te detectors reduced the leakage current and improved the X-ray sensitivity significantly. The leakage current was drastically diminished by the formation of thin parylene layer in the Cd$\_$0.7/Zn$\_$0.3/Te detector.

X-ray 반응 특성 개선을 위한 Hybrid형 디지털 방사선 검출기의 구조 설계 (Structural Design of Digital Radiography Detector using Hybrid Method for the Improvement of Response Property by X-ray)

  • 김교태;한무재;김진선;허예지;오경민;박지군;남상희
    • 한국방사선학회논문지
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    • 제9권6호
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    • pp.363-367
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    • 2015
  • 디지털 방사선촬영 기술은 영상 정보를 획득하는 원리에 따라 광도전체를 이용하는 직접 방식과 형광체를 이용하는 간접 방식으로 구분되지만, 모두 다양한 장단점을 내포하고 있다. 이에 본 연구에서는 X-ray 민감도를 개선하고자 형광체 및 광도전체를 병용한 Hybrid형 검출기의 구조에 대한 기초 연구를 수행하였다. 실험 결과, 조사 시간을 30 ms로 고정하고 관전압을 변화할 경우 전체적으로 직접 방식의 구조에서 우수한 민감도가 나타났으나, 조사 시간이 50 ms 이상에서는 Hybrid 구조의 경우가 더 우수한 것으로 나타났다. 이는 임상에서 다양한 검사를 수행할 경우에 일반적으로 50 ms 이상의 조사시간을 이용한다는 점에서 충분한 연구적 가치를 가질 것으로 사료된다.

Application of portable digital radiography for dental investigations of ancient Egyptian mummies during archaeological excavations: Evaluation and discussion of the advantages and limitations of different approaches and projections

  • Seiler, Roger;Eppenberger, Patrick;Ruhli, Frank
    • Imaging Science in Dentistry
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    • 제48권3호
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    • pp.167-176
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    • 2018
  • Purpose: In the age of X-ray computed tomography (CT) and digital volume tomography (DVT), with their outstanding post-processing capabilities, indications for planar radiography for the study of the dentition of ancient Egyptian mummies may easily be overlooked. In this article, the advantages and limitations of different approaches and projections are discussed for planar oral and maxillofacial radiography using portable digital X-ray equipment during archaeological excavations. Furthermore, recommendations are provided regarding projections and sample positioning in this context. Materials and Methods: A total of 55 specimens, including 19 skeletonized mandibles, 14 skeletonized skulls, 18 separate mummified heads, and 4 partially preserved mummies were imaged using portable digital X-ray equipment in the course of archaeological excavations led by the University of Basel in the Valley of the Kings between 2009 and 2012. Images were evaluated by 2 authors with regard to the visibility of diagnostically relevant dental structures using a 4-point grading system(Likert scale). Results: Overall, the visibility of diagnostically relevant dental structures was rated highest by both authors on X-ray images acquired using a dental detector. The tube-shift technique in the lateral projections of mandibular dentition achieved the second-best rating, and lateral projections achieved the third-best rating. Conclusion: Conventional planar digital X-ray imaging, due to its ubiquity, remains an excellent method-and often the only practicable one-for examining the skulls and teeth of ancient Egyptian mummies under field conditions. Radiographic images of excellent diagnostic quality can be obtained, if an appropriate methodology regarding the selected projections and sample placement is followed.

$CaWO_4/a-Se$ 구조의 X선 변환센서에서 a-Se의 Arsenic 첨가량에 따른 반응 특성 (The Response Characteristics of as Addition Ratio of Arsenic in $CaWO_4/a-Se$ based X-ray Conversion Sensor)

  • 강상식;석대우;조성호;김재형;남상희
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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    • pp.416-419
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    • 2002
  • There are being two prominent studying for Digital Radiography. Direct and Indirect method of Digital Radiography are announced for producing high quality digital image. The one is using amorphous selenium as photoconductor and the other is using phosphor layer as a light conversion. But each two systems have strength and weakness such as high voltage and blurring effect. In this study, we investigated the electrical characteristic of $multi-layer\left(CaWO_{4}+a-Se \right)$ as a photoconductor according to the changing arsenic composition ratio. This is a basic research for developing of Hybrid digital radiography which is a new type X-ray detector. The arsenic composition ratio of a-Se compound is classified into 7 different kinds which have 0.1%, 0.3%, 0.5%, 1%, 1.5%, 5%, 10% and were made test sample throught thermo-evaporation. The phosphor layer of $CaWO_4$ was overlapped on a-Se using EFIRON optical adhesives. We measured the dark and photo current about the test sample and compared the electrical characteristic of the net charge and signal-to-noise ratio. Among other things, test sample of compound material of 0.3% arsenic showed good characteristic of $2.45nA/cm^2$ dark current and $357.19pC/cm^2/mR$ net charge at $3V/{\mu}m$.

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진공증착된 $Cd_{1-x}Zn_{x}Te$ 검출기의 X선 반응 특성 비교 (The Comparison of X-ray Response Characteristics of Vacuum Evaporated $Cd_{1-x}Zn_{x}Te$ Detector)

  • 강상식;최장용;이동길;차병열;김재형;남상희
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
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    • pp.39-42
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    • 2002
  • There is a renewed interest in the application of photoconductors especially Cd(Zn)Te to x-ray imaging. In this paper, We investigate effects on x-ray detection characteristic of Zn dopped CdTe detector. Cd(Zn)Te film was fabricated by vacuum thermal evaporation method and then investigate physical analysis using EPMA and XRD. We investigated the leakage current and X-ray photosensitivity as applied voltage about fabricated Cd(Zn)Te film. Experimental results showed that the increase of Zn dopped concentration in $Cd_{1-x}Zn_{x}Te$ detector reduced a leakage current and improved a signal to noise ratio significantly.

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