• Journal of The Korean Radiological Technologist Association
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• v.25 no.1
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• pp.157.2-158
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• 1999

• Journal of The Korean Radiological Technologist Association
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• v.27 no.2
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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

• Journal of Veterinary Clinics
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• v.29 no.1
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• pp.18-22
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• 2012

This study was performed to evaluate the sensitivity of conventional film-screen radiography (CFSR) and direct digital radiography (DDR) for detection of various amounts of free peritoneal fluid. Ten adult male healthy beagles were used in this study. Radiographic examinations were performed in the right lateral and ventrodorsal positions. Fluid was injected in increments of 2.0 ml/kg of body weight up to 20.0 ml/kg of body weight. The images of CFSR and DDR were evaluated by two veterinary radiologists for evidence of abdominal fluid without knowledge of injected fluid volume. Data were evaluated by using the receiver operation curve (ROC) analysis and the area under the curve (AUC). There was no significant difference in detection of peritoneal fluid between DDR and CFSR in the ROC analysis. The accuracy of CFSR (0.805) was relatively higher than that of DDR (0.733), based on the ROC analysis and AUC. AUC of CFSR was higher in most injection doses. These results suggest that CFSR is more accurate than DDR for the detecting peritoneal fluid. Therefore, for situation in which digital radiographs are equivocal or small amount of fluid is suspected, other imaging modalities, such as ultrasonography would be helpful for determining the presence of fluids.

• Journal of radiological science and technology
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• v.36 no.4
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• pp.273-280
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• 2013

This study was proven for the T-spine breathing technique in lateral projection, using computer radiography (CR), charge coupled device (CCD), indirect digital radiography (IDR) and direct digital radiography (DDR). All images were evaluated and compared with CNR and SNR measured with the mean pixels and the standard deviation as setting ROI of spinous process, pedicle, vertebral body, intervertebral foramen and intervertebral disk using Image J. In experiment results of 4 type detectors, T-spine breathing technique was indicated as excellent in ROI of spinous process, pedicle, vertebral body, intervertebral foramen and intervertebral disk. As T-spine breathing technique indicated excellent images compared to the existing T-spine lateral radiography, this method would be useful for elderly patients who have difficulty in deep exhalation. This study was indicated the application possibility of T-spine breathing technique by presenting contrast to noise ratio (CNR) and signal to noise ratio (SNR) with quantitative value in 4 type detectors.

• Imaging Science in Dentistry
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• v.43 no.2
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• pp.77-84
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• 2013

Purpose: This study aimed to provide comparative measurements of the effective dose from direct and indirect digital panoramic units according to phantoms and exposure parameters. Materials and Methods: Dose measurements were carried out using a head phantom representing an average man (175 cm tall, 73.5 kg male) and a limbless whole body phantom representing an average woman (155 cm tall, 50 kg female). Lithium fluoride thermoluminescent dosimeter (TLD) chips were used for the dosimeter. Two direct and 2 indirect digital panoramic units were evaluated in this study. Effective doses were derived using 2007 International Commission on Radiological Protection (ICRP) recommendations. Results: The effective doses of the 4 digital panoramic units ranged between $8.9{\mu}Sv$ and $37.8{\mu}Sv$. By using the head phantom, the effective doses from the direct digital panoramic units ($37.8{\mu}Sv$, $27.6{\mu}Sv$) were higher than those from the indirect units ($8.9{\mu}Sv$, $15.9{\mu}Sv$). The same panoramic unit showed the difference in effective doses according to the gender of the phantom, numbers and locations of TLDs, and kVp. Conclusion: To reasonably assess the radiation risk from various dental radiographic units, the effective doses should be obtained with the same numbers and locations of TLDs, and with standard hospital exposure. After that, it is necessary to survey the effective doses from various dental radiographic units according to the gender with the corresponding phantom.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.3
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• pp.30-41
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• 2011

In order to obtain more clear x-ray images, an antiscatter grid, which can absorb the scattered rays, is employed. In the high-resolution direct digital radiography, however, the artifacts due to the grid are visible. In this paper, within the methods of obtaining x-ray digital images by employing the rotated grids for the facility of grid artifact reduction, the previous work, where the frequencies of the artifact components on the boundary, is further analyzed and extended, and a min-max optimization for a given grid density is proposed. For practical grid densities, appropriate grid angles are provided and a grid artifact reduction algorithm is proposed for the appropriate grid angles. The proposed algorithm is tested for real x-ray digital images with a comparison, and can remove the grid artifacts while maintaining the resolution of the original image.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.392-395
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• 2003

For the purpose of digital x-ray imaging, many materials such as $PbI_2$, $HgI_2$, TlBr, CdTe and CdZnTe have been under development for servaral years as direct converter layer. $Hgl_2$ film detector have recently been shown as one of the most promising semiconductor materials to be used as direct converters in x-ray digital radiography. This paper, the $HgI_2$ films are deposited on conductive-coated glass by screen printing, in which $HgI_2$ powder is embedded in a binder and solvent, and the slurry is used to coat the conductive-coated glass. We investigated electrical characteristic of the fabricated $HgI_2$ films. The x-ray response to radiological x-ray generator of 70Kvp using the current integration mode will be reported for screen printing films. These results indicate that $HgI_2$ detectors have high potential as new digital x-ray imaging devices for radiography.

• Imaging Science in Dentistry
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• v.37 no.1
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• pp.9-14
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• 2007

Purpose : To determine the more valuable information to detect the mandibular canal and the mental foramen in panoramic radiographs of a selected Korean population for the implant. Materials and Methods : This study analysed 288 panoramic radiographic images of patients taken at the Dental hospital of Chosun University retrospectively. Indirect digital panoramic X-ray machine (ProlineXC, PLANMECA, Finland) with processing by using Directview $CR950^@$ (Kodak, U.S.A.) and Direct digital panoramic X-ray machine (Promax, PLANMECA, Finland) were used for all exposures. All images were converted into Dicom format. Results : The common position of the mental foramen was in line with the longitudinal axis of the second premolar (68.1%). The mental foramen was symmetrical in 81.8% of cases. The mandibular canal was not identified at anterior portion and discontinued with the mental foramen in 27.8% of all cases, in 42.4% identified with lower border line continued with the mental foramen, in 14.6% with both upper and lower border lines, and in 15.3% unilaterally identified with lower border line. Conclusion : Clinicians can estimate the upper border line of the mandibular canal from the confirmation of the mental foramen and the lower border line of the mandibular canal symmetrically on the panoramic radiography taken in adjusted midsaggital plane of patient's head.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.384-387
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• 2003

In this paper, the evaluation of image quality was performed for digital radiography which is developing in using amorphous selenium as a photoconductor material for the purpose of offering basic research data and measurement technique about Medical Imaging Quality. So Modulation Transfer Function as a main factor of imaging quality evaluation was investigated by slit method. For measurement of MTF, Nuclear associates. 07-624 Slit camera image was obtained to study the variation of MTF corresponding to changing spatial frequency. And Presampling MTF was estimated by slit camera image with $10\;{\mu}m$ width at Digital Radiography. In this study, the obtained data demonstrates that the clinical value of a direct conversion type digital radiation detector using the amorphous selenium, which is being developed by domestic technology.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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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 $3V/{\mu}m$.