• Imaging Science in Dentistry
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• 제40권4호
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• pp.155-158
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• 2010

Digital radiographic systems allow the implementation of a fully digital picture archiving and communication system (PACS), and provide the greater dynamic range of digital detectors with possible reduction of X-ray exposure to the patient. This article reviewed the basic physical principles of digital radiographic imaging system in dental clinics generally. Digital radiography can be divided into computed radiography (CR) and direct radiography (DR). CR systems acquire digital images using phosphor storage plates (PSP) with a separate image readout process. On the other hand, DR systems convert X-rays into electrical charges by means of a direct readout process. DR systems can be further divided into direct and indirect conversion systems depending on the type of X-ray conversion. While a direct conversion requires a photoconductor that converts X-ray photons into electrical charges directly, in an indirect conversion, lightsensitive sensors such as CCD or a flat-panel detector convert visible light, proportional to the incident X-ray energy by a scintillator, into electrical charges. Indirect conversion sensors using CCD or CMOS without lens-coupling are used in intraoral radiography. CR system using PSP is mainly used in extraoral radiographic system and a linear array CCD or CR sensors, in panoramic system. Currently, the digital radiographic system is an important subject in the dental field. Most studies reported that no significant difference in diagnostic performance was found between the digital and conventional systems. To accept advances in technology and utilize benefits provided by the systems, the continuous feedback between doctors and manufacturers is essential.

• 전자공학회논문지
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• 제50권12호
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• pp.247-253
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• 2013

본 연구의 목적은 Direct DR(Digital Radiography), Indirect DR, I.I(Image Intensifier) DR에서 X선 광자 검출 방식에 따른 선량측정 및 획득된 영상을 정량적이고 객관적인 측정을 통해 DR System을 비교 평가 하는 것이다. Rando phantom을 사용하여 입사표면선량을 측정하였으며, 측정된 입사표면선량 값을 통해 PCXMC 프로그램을 사용하여 유효선량과 방사선 조사로 인한 위험을 평가하였다. 21cm 아크릴 phantom을 사용하여 SNR(Signal to Noise Ratio), NPS(Noise Power Spectrum), CNR(Contrast to Noise Ratio)을 측정하였으며, 측정값은 통계학적 분석기법을 사용하여 유의성을 평가하였다. 입사표면선량, 주요장기선량, 유효선량 모두 direct DR이 가장 낮게 측정되었으며, direct DR 선량을 기준으로 I.I type DR은 약 1.3배, indirect DR은 약 2.4배 높은 선량 비율로 측정되었다. 방사선량에 따른 위험도 역시 동일한 비율로 측정되었다. SNR 측정 결과 direct DR측정값을 기준으로 I.I DR은 약 7.25배, indirect DR이 약 1.48배 낮은 비율로 측정되었다. CNR 측정 결과 direct DR 측정값을 기준으로 I.I DR은 약 1.16배 높고, indirect DR이 약 0.87배 낮은 비율로 측정되었다. 따라서 a-selenium 검출소자를 사용하여 X선 광자를 검출하는 방식인 direct DR은 적은 선량으로 우수한 화질의 영상을 구현함으로써 선량에 민감한 소아나 생식선이 포함된 검사 등에 유용할 것으로 사료된다. 또한 많은 진단 정보를 위한 영상 평가가 요구되는 경우에는 indirect DR이 유용할 것으로 판단된다.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2001년도 추계학술대회(제116회) 및 13회 Workshop 제3회 한ㆍ일 치과보존학회 공동학술대회 초록집
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• pp.592.1-592
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• 2001

Conventional intraoral radiography continues to be the most widely used for the diagnosis of dental caries. But conventional intraoral film has several shortcomings, including processing error, increased radiation dose, etc. Recently, various digital radiographs substitude for conventional radiography to overcome these disadvantages. The digital radiographies are numerous advantages, including elimination of processing errors, lower radiation dose, image quality enhancements such as contrast and density modulation.(omitted)

• 치과방사선
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• 제22권1호
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• pp.117-127
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• 1992

This investigation was performed to test the readability of the video based digital radiography, that can be applied clinically, compared with the periapical radiograph. The experiments were performed with IBM-PC/AT compatible, video camera and ADC (analog-digital converter). And spatial resolution was 512 X 480 with 256 (8 bit) gray levels. The radiographs obtained by using variable steps of exposure time were digitized. and then the digital images were analyzed. The obtained results were as follows: 1. There was no remarkable difference in readability between the radiographs and their digital images. However, under over exposure the digital images were superior to the radiographs in readability and vice versa. 2. As the exposure time was increased, the gray level of the digital image was decreased proportionally. 3. The correlation beween the regions of interest and the aluminum step wedges were relatively close; R=0.9965 (p <0.001).

• 대한방사선기술학회지:방사선기술과학
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• 제33권3호
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• pp.173-178
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• 2010

방사선 일반촬영은 크게 두 가지 유형으로 구분할 수 있는데 디지털 영상 시스템인 CR(Computed Radiography)과 DR(Digital Radiography)이 주로 활용되고 있다. 이 둘의 차이는 선량과 영상의 질 관점에서 정의할 수 있다. 본 연구에는 피부입사선량(Entrance Skin Dose, ESD)의 관점에서 환자에게 투여된 선량을 계산하고 비교하여 CR과 DR 간의 선량 차이를 연구하기 위해 8가지의 표준 영상의학적 검사(Skull AP, Skull LAT, Chest PA, Chest LAT, Abdomen AP, L-spine AP, L-spine LAT, Pelvis AP)가 고려되었다. 영상화질에 대한 평가는 진단방사선학적 영상을 위한 화질 기준에 부합하는지를 보증하기 위해 영상의학과 전문의에 의해 시행되었다. DR의 ESD는 CR의 ESD보다 낮다는 것이 확인되었다. 방사선 촬영을 담당한 방사선사가 동일인 이었고 CR과 DR의 영상 화질이 유사하거나 DR에서 조금 더 우수했기 때문에 본 연구는 고려된 검사 내에서 DR이 CR보다 선량 절감 차원에서 볼 때 더 우수한 기기라는 것을 보여준다.

• 대한방사선기술학회지:방사선기술과학
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• 제40권3호
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• pp.363-370
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• 2017

본 연구는 전하결합소자(charged coupled device; CCD), CR (computed radiography), 평판형검출기(flat panel detector; FPD) 등을 사용하는 다양한 디지털 방사선(digital radiography; DR) 시스템의 물리적 영상 특성의 평가를 실시한 것이다. 본 연구에서 적용된 영상 특성은 신호응답특성(system response), 해상력특성(modulation transfer function; MTF), 잡음특성(wiener spectrum; WS), 양자검출효율(detective quantum efficiency; DQE) 등이며 이를 통하여 DR 시스템의 성능을 비교하였다. CCD의 신호응답특성은 입사선량에 비례하여 증가하였으며, CR과 FPD는 입사선량의 증가에 대수적 비례 관계를 보이면서 증가하였다. MTF는 CR과 FPD는 유사한 경향을 나타내었지만 CCD는 떨어지는 값을 나타내었다. WS는 FPD가 가장 낮았고, CR, CCD 순으로 증가하였다. DQE는 FPD, CR, CCD의 순으로 나타났다. DR 시스템은 영상수용체의 종류에 따라 서로 다른 영상 특성이 나타났다. 의료영상 획득 시 DR 시스템을 올바르게 사용하려면 영상의 물리적 특성을 정확히 알고 사용하는 것이 중요하다.

• Korean Journal of Radiology
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• 제22권12호
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• pp.2026-2033
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• 2021

Objective: The aim of this study was to compare the diagnostic performances of digital tomosynthesis (DTS) and conventional radiography in detecting osteonecrosis of the femoral head (ONFH) using computed tomography (CT), as the reference standard and evaluate the diagnostic reproducibility of DTS. Materials and Methods: Forty-five patients (24 male and 21 female; age range, 25-77 years) with clinically suspected ONFH underwent anteroposterior radiography, DTS, and CT. Two musculoskeletal radiologists independently evaluated the presence and type of ONFH. The diagnostic performance of radiography and DTS in detecting the presence of ONFH and determining the types of ONFH were evaluated. The interobserver and intraobserver reliabilities of each imaging modality were analyzed using Cohen's kappa. Results: DTS had higher sensitivity (89.4%-100% vs. 74.5%-76.6%) and specificity (97.3%-100% vs. 78.4%-83.8%) for ONFH detection than radiography. DTS showed higher performance than radiography in identifying the subtypes of ONFH with statistical significance in one reader (type 1, 100% vs. 30.8%, p = 0.004; type II, 97.1% vs. 73.5%, p = 0.008). The interobserver agreement was excellent for DTS and moderate for radiography (kappa of 0.86 vs. 0.57, respectively). The intraobserver agreement for DTS was higher than that of radiography (kappa of 0.96 vs. 0.69, respectively). Conclusion: DTS showed higher diagnostic performance and reproducibility than radiography in detecting ONFH. DTS may be used as a first-line diagnostic modality instead of radiography for patients suspected of having ONFH.

• 대한디지털의료영상학회논문지
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• 제8권1호
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• pp.27-32
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• 2006

The rapid development in digital acquisition technology in radiography has not been accompanied by information regarding optimum radiolographic technique for use with an amorphus silicon flat panel detector. The purpose of our study was to compared imaging characteristics and image quality of an amorphus silicon flat panel detectors for digital chest radiography. All examinations were performed by using an amorphus silicon flat panel detector. Chest radiographs of an chest phantom were obtained with peak kilovoltage values of 60$\sim$150 kVp. Published data ell the effect of x-ray beam energy on imaging characteristics and image qualify when using an amorphus silicon flat panel detector. It is important that radiographers are aware of optimum kVp selection for an amorphus silicon flat panel detector system, particularly for the commonly performed chest examination.

• 대한방사선협회지
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• 제27권2호
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• pp.22-34
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• 2001

DR은 방사선과 뿐만 아니라 병원전체의 생산성 및 업무의 효율성에서 중요한 요소로 자리잡아가고 있다. DR환경은 CR보다 다양한 Parameter를 가지고 있어 양질의 의료서비스 제공이 가능하다. 현재 각 병원의 방사선과는 Film-Screen system에서 Full-PACS를 통한 DR 환경으로 변화하고 있다. Full- PACS를 사용하고 있는 본원에서는 DR환경에서의 일반촬영 System중 CR과 DDR의 최적노출조건과 그에 따른 Image qu

• 대한디지털의료영상학회논문지
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• 제10권1호
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• pp.13-19
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• 2008

Purpose : In sponge quality of the material in digital radiography environment coating because do position blocks two that do not become coating done positioning blocks two that do not become coating done positioning block and sponge quality of the material to testing bench image artifact's difference compare. Method of study : In digital radiography environment positioning block of different two products same sunshine or effect that image and positioning block artifact gents in image analyze. the target used positioning block 2 when examine hand, rib and examination condition did each differently according to used positioning block. reflex compared picture that do image and verify that examine first time. Result : 1. In sponge quality of the material coating in done product artifact appear. Did not appear in product that do not become coating. 2. Can know coating's existence, that artifact according to radish happens. 3. Quality of the material coating's existence, there was difference of slippage according to radish Conclusion : Quality of the material coating phenomenon that done positioning block thus, it may have to be considered that use after estimate degree that get in image.