• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.27-30
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• 2002

Photoconductor for direct detection flat-panel imager present a great materials challenge, since their requirements include high X -ray absorption, ionization and charge collection, low leakage current and large area deposition. Selenium is practical material. But it needs high thickness and high voltage in selenium for high ionization rate. We report comparative studies of detector sensitivity. One is an a-Se with $70{\mu}m$ thickness on glass. The other has hybrid layer of depositting ZnS phosphor with $100{\mu}m$ on a-Se. The leakage current of hybrid is similar to it of a-Se, but photocurrent is lager than a-Se. Both of them have high spatial resolution, but hybrid has higher sensitivity than a-Se at comparable bias voltage.

• Journal of Information Display
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• v.1 no.1
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• pp.29-31
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• 2000

A 21.6" a-Si:H TFT array for direct conversion X-ray detector with 2480 by 3072 pixels is successfully developed. To obtain X-ray image of satisfactory quality, a novel structure with a storage electrode on BCB is proposed. The structure reduces the parasitic capacitance of data line, which is one of the main sources of signal noise. Also, the structure shows greater resistance to failure than that of the conventional design.

• Journal of the Korean Society of Radiology
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• v.3 no.1
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• pp.17-21
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• 2009

The Recently, large area matrix-addressed image detectors are investigated for X-ray imaging with medical diagnostic and other applications. In this paper, a new flat panel gas detector for diagnostic X-ray imaging is proposed, and its characteristics are investigated. The research of flat panel gas detector is not exist at all. Because of difficulty to inject gas against to atmospheric pressure. So almost gas detector made by chamber shape. We made flat panel sample by display technique. (ex: PDP, Fed, etc.) The experimental measurements, the transparent electrodes, dielectric layer, and the MgO protection layer were formed in front glass. And, the X-ray phosphor layer and address electrodes are formed in the rare glass. The dark current, the x-ray sensitivity and linearity as a function of electric field were measured to investigate the electrical properties. From the results, the stabilized dark current density and the significant x-ray sensitivity were obtained. And the good linearity as a function of exposure dose was showed in wide diagnostic energy range. These results means that the passive matrix-addressed flat panel gas detector can be used for digital x-ray imaging.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.379-381
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• 2002

A single CdZnTe detector is tested for suitability in a prototype CT/ SPECT system designed to acquire both emission and transmission data. The detector has the size of 1${\times}$l-cm$^2$ with 4${\times}$4 1.5${\times}$l.5mm$^2$ pixellated anodes. Since the detector is smaller than imaged object, we translated it in an arc centered at the x-ray tube to image larger objects. Pulse counting electronics with very short shaping time (50 ns) are used to satisfy high photon rates in x-ray imaging, and response linearity up to 3${\times}$10$\^$5/ counts per second per detector element is achieved. The energy resolution of 122-keV gamma-ray is measured to be 14%. We have characterized the system performance by scanning a radiographic resolution phantom .and the Hoffman brain phantom. The spatial resolution of CT and SPECT are about 1 mm and 7 mm, respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.60-65
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• 2007

The radiologic imaging device was implemented. It can be installed in an ambulance or used when an accident happens. After an equipment which generates X-ray generating unit with a tube in DC 12[V] had been made, a trait experiment using an oscilloscope was made. An experiment was carried out where the generated X-ray was saved as a form of a file using a digital detector. In this experiment, as a result of generating X-ray and detecting it using a digital detector, 1.67[MB]-, jpg- radical rays information could be saved. One distinct advantage of the developed radiologic imaging device is the fact that we can efficiently deal with emergency cases too far from the hospital, difficult to diagnose but treat simultaneously. By using the radiologic imaging device at the urgent scene of an accident or in a moving ambulance, we can provide the patient's X-ray information with the emergency medical specialist who is in the emergent medical center and have the patients prescribed and treated appropriately. As a result the developed emergency medical treatment can be expected.

• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2346-2352
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• 2020

Dual-energy x-ray absorptiometry (DXA) is the noninvasive method to diagnose osteoporosis disease characterized by low bone mass and deterioration of bone tissue. Many global companies and research groups have developed the various DXA detectors using a direct photon-counting detector such as a cadmium zinc telluride (CZT) sensor. However, this approach using CZT sensor has some drawback such as the limitation of scalability by high cost and the loss of efficiency due to the requirement of a thin detector. In this study, a SiPM based DXA system was developed and its performance evaluated experimentally. The DXA detector was composed of a SiPM sensor coupled with a single LYSO scintillation crystal (3 × 3 × 2 ㎣). The prototype DXA detector was mounted on the dedicated front-end circuit consisting of a voltage-sensitive preamplifier, pulse shaping amplifier and constant fraction discriminator (CFD) circuit. The SiPM based DXA detector showed the 34% (at 59 keV) energy resolution with good BMD accuracy. The proposed SiPM based DXA detector showed the performance comparable to the conventional DXA detector based on CZT.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.422-424
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• 2002

The accuracy of DXA(Dual Energy X-ray Absorptiometry) highly depends on the detection and separation capability of dual energy X-ray X-ray photons. In addition both of scan time and patient exposure are affected by detection efficiency. A CZT detector with a good energy resolution and high detection efficiency was evaluated for the application of bone densitometry. Its performance was compared to a photomultiplier tube with a NaI(T1) scintillator in terms of energy resolution, detection efficiency and the accuracy of bone mineral density measurement. The comparison study was performed with CZT detector and PM tube using DXA equipments(OSTEO Plus, OSTEO Prima, ISOL Technology). The energy spectrum was acquired using MCA(Multi-Channel Analyzer). The used X-ray energy ranged from 20keV to 86keV. The MCA result of the CZT detector showed a slightly sharper energy spectrum than that of NaI(T1). Detection efficiency of the CZT detector at 59.5keV was 1.4 times better. Remarkably the final results of bone mineral density measurements demonstrate only less than 1% difference. The CZT detector appears to have many benefits for the application of bone densitometry. Its excellent energy resolution can enhance the counting accuracy of dual energy X-ray spectrum. Furthermore its compactness in physical dimension and no cooling requirement will be additional benefits for a more compact and accurate bone densitometer.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.13-14
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• 2000

21.6" a-Si:H TFT array for direct conversion X-ray detector with 2480 by 3072 pixel is successfully developed. To obtain good X-ray image quality, novel structure, storage on BCB structure, is proposed. The structure reduces the parasitic capacitance of data line, one of the main sources of signal noise. Also, the structure shows higher failure resistance against defects than that of the old design.

• Proceedings of the Materials Research Society of Korea Conference
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• 2006.11a
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• pp.19.1-19.1
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• 2006

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.8
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• pp.60-66
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• 2019

This study aims to develop and manufacture a device for inspecting impurities in a sealed aluminum container using an X-ray technique. Two X-ray oscillators and detectors are used to detect the entire sample. The stage for sample movement was fabricated using two high-voltage generators and X-ray detectors arranged diagonally. In addition, the high-voltage generator is composed of a vacuum tube, a high-voltage generator, and circulating oil for cooling. It includes a control unit for controlling other equipment, a power supply unit, and a video output unit; the most important part of the X-ray is the X-ray generation part. In this study, a flat panel was used along with the aim of developing the detector part. In particular, the development of the scintillator introduced in this study is a primary focus. The developed scintillator can be combined with a lens and can then be assembled with a charge coupled device (CCD) sensor.