• Journal of the Korean Society of Radiology
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• v.5 no.3
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• pp.155-159
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• 2011

The purposed of this study were measured the radiation exposure of patients and workers by generators, and the protection state for radiation facilities. The subject of the study by X-ray generators in university hospitals of capital area, we measured the maximum irradiation condition of 80 kVp, 200 mA, 0.1 second in the control entrance, control room window, entrance of radiography, adjacent site. The leakage dose per week was which the control entrance was 0.11 mR/week, control room window was 0.15 mR/week, entrance of radiography was 0.12 mR/week and adjacent site was 0.06 mR/week with X-ray unit the mean And the leakage mean dose was 0.11 mR/week. Diagnostic X-ray tubes must ensure that the leakage radiation in the maximum leakage dose in week emitted by the tube outside the useful beam does not exceed certain levels provided by standards.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2797-2801
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• 2023

CdZnTeSe (CZTS) has attracted attention for applications in X- and gamma-ray detectors owing to its improved properties compared to those of CdZnTe (CZT). In this study, we grew and processed single crystals of CZT and CZTS using the Bridgeman method to confirm the feasibility of using a dosimeter for high-energy X-rays in radiotherapy. We evaluated their linearity and precision using the coefficient of determination (R²) and relative standard deviation (RSD). CZTS showed sufficient RSD values lower than 1.5% of the standard for X-ray dosimetry, whereas CZT's RSD values increased dramatically under some conditions. CZTS exhibited an R² value of 0.9968 at 500 V/cm, whereas CZT has an R² value of 0.9373 under the same conditions. The X-ray response of CZTS maintains its pulse shape at various dose rates, and its properties are improved by adding selenium to the CdTe matrix to lower the defect density and sub-grain boundaries. Thus, we validated that CZTS shows a better response than CZT to high-energy X-rays used for radiotherapy. Further, the applicability of an onboard imager, a high-energy X-ray (>6 MV) image, is presented. The proposed methodology and results can guide future advances in X-ray dose detection.

• Journal of Radiation Protection and Research
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• v.23 no.3
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• pp.159-174
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• 1998

Personal dosimetry system is required to measure the personal dose equivalent accurately in a wide range of radiation fields, but the dose evaluation algorithms have been developed with the X-ray fields described in MOST Ordinance (equivalent to the ANSI N13.11) from which the actual fields to be monitored may be significantly different. To evaluate the dose more accurately when workers are exposed to the non-ANSI N13.11 radiation fields, two algorithms for monochromatic radiations (one algorithm was used for various ratios of TL dosimeter and the other for matrix approximation) were developed with the experimental data of the energy responses of the $CaSO_4:Dy$ TL materials irradiated by monochromatic X-ray fields recently established in KAERI, and compared with the another algorithm developed on the basis of the ANSI N13.11 continuous spectrum X-ray fields. Then it follows the discussions for some results of the algorithm testing including mixed fields irradiations and angular response conducted in IAEA/RCA intercomparison as well as ANSI and ISO continuous spectrum X-ray and monochromatic radiation fields. The developed algorithms were successfully performed the test not only in the continuous spectrum X-ray fields given by MOST Ordinance but also in the several non-MOST Ordinance radiation fields which could be encountered in the practical working environments.

• Food Science and Industry
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• v.53 no.3
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• pp.264-276
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• 2020

Ionizing radiation is one of the efficient non-thermal pasteurization methods. The US Food and Drug Administration (FDA) allows the use of ionizing radiation to a dose up to 10 kGy for controlling foodborne pathogens and extending the self-life of foods. Recently X-rays, generated on absorption of high energy electrons in an appropriate metal target, have been used commercially for sterilization purposes. X-rays have the advantages of higher penetration power than E-beams and absence of harmful radioactive sources, such as Cobalt-60 or Cesium-137 associated with gamma-rays. That is why it has continued to receive attention as an attractive alternative to gamma-ray or E-beam irradiation. In this article, the potential of X-ray irradiation for controlling foodborne pathogens in various food products and necessary pre-requisite knowledge for the introduction of X-ray irradiation to the Korean food industry will be provided.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.535-540
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• 2015

Collimator has important functions with control primary X-ray that decrease radiation exposure dose for patients and reduce scatter ray and make better quality of image. But there are no regulations for X-ray mammography device of collimator, so widely used device adopt rectangularly controlled collimator. Though digital X-ray mammography device expand supply recently, rectangularly controlled collimator of film/screen mode still used. After searching for real condition of beam field with digital mammography, we made a multi-leaf collimator which is able to adjust the beam field in accordance with size and shape of breast, and we measuring up the transitions of image quality, average glandular dose(AGD) and, Dose area product(DAP). There are no significant differences between rectangularly controlled collimator and multi-leaf collimator, and DAP value decreased by 50.72%. As conclusion, there needs to expand the use of multi-leaf collimator for optimum adoption of beam field in digital mammography, and also need to develop an automatic regulation of beam field for reduce of exposure dose to patients.

• Design & Manufacturing
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• v.15 no.1
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• pp.26-31
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• 2021

As the aging ages, the disease also increases, and the development of AI technology and X-ray equipment used to treat patients' diseases is also progressing a lot. X-ray tube converts only 1% of electron energy into X-ray and 99% into thermal energy. Therefore, when the cooling time of the anode and the X-ray tube are frequently used in large hospitals, the amount of X-ray emission increases due to temperature rise, the image quality deteriorates due to the difference in X-ray dose, and the lifespan of the overheated X-ray tube may be shortened. Therefore, in this study, temperature rise and cooling time of 60kW, 75kW, and 90kW of X-ray tube anode input power were studied. In the X-ray Tube One shot 0.1s, the section where the temperature rises fastest is 0.03s from 0s, and it is judged that the temperature has risen by more than 50%. The section in which the temperature drop changes most rapidly at 20 seconds of cooling time for the X-ray tube is 0.1 seconds to 0.2 seconds, and it is judged that a high temperature drop of about 65% or more has occurred. After 20 seconds of cooling time from 0 seconds to 0.1 seconds of the X-ray tube, the temperature is expected to rise by more than 3.7% from the beginning. In particular, since 90kW can be damaged by thermal shock at high temperatures, it is necessary to increase the surface area of the anode or to require an efficient cooling system.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.897-902
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• 2023

The purpose of this paper is to analyze the characteristics of Silicon Photomultiplier (SiPM) for the realization of high-sensitivity radiation detection in portable detectors. Portable X-ray detectors offer the advantage of quickly accessing the patient's location and obtaining real-time images, allowing physicians to perform rapid diagnoses. However, this mobility comes with challenges in achieving accurate radiation detection. In existing detectors, SiPM is used for a simple purpose of detecting X-ray triggers. To verify the feasibility of high-sensitivity X-ray detection through SiPM, seven types of SiPM sensors were compared and selected, and their characteristics were analyzed. The SiPM used in the final test demonstrated the ability to distinguish signals at the ultra-low radiation level of 10 nGy, and it was observed that the slope of the signal rise curve varies with the X-ray tube voltage. Utilizing the characteristics of SiPM, which exhibits changes in signal level and duration with X-ray dose, it appears possible to achieve high-sensitivity measurements for X-ray detection.

• Journal of the Korean Society of Radiology
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• v.13 no.6
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• pp.831-840
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• 2019

The X-ray detector by liquid crystal with front light was proposed and verified by a X-ray image. The proposed detector utilizes the visible light instead of the electric signal by transistor. Therefore, it shows low noise and can be fabricated at low cost. The liquid crystal detector uses the orientation change of the liquid crystal molecule by conductivity change of the photoconductive layer. We can get the X-ray image from the transmitted light through the liquid crystal. The X-ray dose was calibrated from the measured transmittance of the visible light after comparison to the reference transmittance curve of the liquid crystal. The amorphous Se was used for photo con ducting layer and parylene was used for the liquid crystal alignment instead of the conventional alignment layer which needs high-temperature process over 200℃. The proposed X-ray detector can decrease the X-ray dose by high sensitivity which was verified by simulation. After the fabrication of the X-ray detector, the X-ray image was obtained as a function of the bias voltage to the liquid crystal. 10 lines/mm resolution was obtained from the line pattern and we will apply it to the 17inch diagonal liquid crystal X-ray detector with 3π retardation.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.639-639
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• 2013

In this research we report the significant contribution of the as-spun multi-walled carbon nanotube (MWCNT) on the x-ray images formation using a low tube voltage x-ray source. The MWCNT, which was used for the fabrication of the spun CNT, was grown using a microwave plasma-enhanced chemical vapor deposition machine. Electrical-optics simulation software was utilized to determine the electron field emission trajectory of the triode-structure-as-spun CNT-based x-ray source. It was shown that a significant amount of converging electrons hit the target anode producing a clear x-ray image. These x-ray images where produced at a small amount of anode current of 0.67 mA at a tube voltage of 5 kV with the gate voltage of 0 V. Also, comparisons of the radiographs at various exposure times of the sample where analyzed with and without an x-ray dose filter. Results showed that spatially-resolved images were formed using the as-spun CNT at a low tube voltage with a $54-{\mu}m$ Al x-ray filter. This study can be used for low-voltage medical applications.

• Journal of radiological science and technology
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• v.21 no.2
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• pp.5-10
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• 1998

In the mammography, X-ray beam quality is one of the most important factors. Using X-ray mammography unit model GE/CGR Senography 600T Senix H.F, Authors studied four subjects. 1. The aluminum attenuation rate in 30 kVp when used with or without compression plate. 2. HVLs at 5 different area of the X-ray field of $26{\sim}32kVp$. 3. HVLs to know the influence of corrected measurement or parallel measurement. 4. Film density with microdensitometer along and cross to the long axis of X-ray tube, in terms of the Heel effect in the X-ray field. The following results were obtained. 1. Beam quality of anode area was harder than cathode area. 2. The dose reduction rate of compression plate was approximately $65.5%{\sim}88.1%$ and the beam quality with compression plate was hardened up to 4kVp accordingly. 3. If the X-ray beam enters the attenuation plate obliquely, HVL was $2.6{\sim}2.9%$ harder than perpendicular to it. 4. Because of heel effect, the film density of cathode area is higher than anode area to film density of 0.5.