• The Journal of the Korea Contents Association
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• v.10 no.7
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• pp.253-258
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• 2010

The image intensifier tube that is clinically used gets changed depending on its terms of use. As the brightness gets deteriorated and the performance gets decrease, the X-ray output needs to be increased to maintain the identical diagnosis outcome. As a consequence, the patients are exposed to the increased radiation. Since not many accurate studies have been made, this study measured the conversion factor and resolution depending on the use of the devices that were currently used in Korea. When comparison was made with a device with less than 1 year-use, the conversion factor of a device with 6 year-use got decreased up to 25% while its resolution was reduced from 3.4 lp/mm to 2.5 lp/mm. Such outcome highlights the necessary measures to be supplemented as the increased terms of use implied also the increased radiation exposure among the patients as well as difficulty to conduct an accurate exam.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.1
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• pp.117-122
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• 2004

Exessive UV radiation causes a lot of problems in our skin. In order to find out the alternative UV absorber that can safely be used in cosmetics, we have screened various natural extracts in terms of their UV absorbing effect. Some natural extracts, which possess antioxidative activities, have also been found to retard the oxidation process in our experiment. Natural compound such as 7-hydroxycymopol, baicalein, etc. could be transformed into adjuvant UV absorber by chemical modification. In cosmetics, its chemical stability against UV radiation, exposure to oxygen and other factors could be improved by using the silicone or W/S type emulsion. The values of MED (minimal erythema dose) were improved to 0.10 ${\pm}$ 0.02∼0.11 ${\pm}$ 0.02 by adding this natural extract into the cosmetic formulations. In conclusion, the results of the present study show that natural extracts could be used as an adjuvant UV absorber, if they are stabilized.

• Journal of Radiation Protection and Research
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• v.41 no.4
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• pp.368-372
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• 2016

Background: Methodologies for a series of radiological consequence assessments show a distinctive difference according to the design principles of the original nuclear suppliers and their technical standards to be imposed. This is due to the uncertainties of the accidental source term, radionuclide behavior in the environment, and subsequent radiological dose. Both types of PWR and PHWR are operated in Korea. However, technical standards for evaluating atmospheric dispersion have been enacted based on the U.S. NRC's positions regardless of the reactor types. For this reason, it might cause a controversy between the licensor and licensee of a nuclear power plant. Materials and Methods: It was modelled under the framework of the NRC Regulatory Guide 1.145 for light-water reactors, reflecting the features of heavy-water reactors as specified in the Canadian National Standard and the modelling features in MACCS2, such as atmospheric diffusion coefficient, ground deposition, surface roughness, radioactive plume depletion, and exposure from ground deposition. Results and Discussion: An integrated accident consequence assessment code, ACCESS (Accident Consequence Assessment Code for Evaluating Site Suitability), was developed by taking into account the unique regulatory positions for reactor types under the framework of the current Korean technical standards. Field tracer experiments and hand calculations have been carried out for validation and verification of the models. Conclusion: The modelling approaches of ACCESS and its features are introduced, and its applicative results for a hypothetical accidental scenario are comprehensively discussed. In an applicative study, the predicted results by the light-water reactor assessment model were higher than those by other models in terms of total doses.

• Journal of Radiation Protection and Research
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• v.28 no.1
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• pp.43-50
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• 2003

This study describes a practical method for interpretation of bioassay results of inhaled uranium to assess the committed effective doses both for chronic and acute intake situations. Organs in the body were represented by a series of mathematical compartments for analysis of the behavior of uranium in the body according to the gastrointestinal track model, respiratory track model and biokinetic model recommended by the ICRP. An analytical solutions of the system of balance equations among the compartments were obtained using the Birchall's algorithm, and the urinary excretion function and the lung retention function of uranium were obtained. An initial or total intakes by intake modes were calculated by applying excretion and retention functions to the urinary uranium concentration and the lung burden measured with a lung counter. The dose coefficients given in ICRP 78 are used to estimate the committed effective doses from the calculated intakes.

• Journal of radiological science and technology
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• v.42 no.3
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• pp.223-229
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• 2019

In order to reduce the radiation exposure dose of the patient and to obtain accurate diagnosis results, the quality control of the diagnostic radiation generator must be conducted periodically In particular, bone density test equipment could be influenced by many factors, and it is far more important because inaccurate measurement would eventually affect the result value. However, the cross-correction phantom of DXA equipment is poorly penetrated due to lack of awareness of the industry and the high cost. Therefore, this study developed a BMD phantom using a 3D printer and Korean BMD phantom with low cost by cross analyzing Korean BMD value from The Korean National Health and Nutrition Examination Survey and evaluated it. The L1, L2, and L3 BMD values of phantoms produced with the 3D printer were measured to be $0.887{\pm}0.006g/cm^2$, $0.927{\pm}0.006g/cm^2$, and $0.960{\pm}0.005g/cm^2$, at 215 mm height and $0.882{\pm}0.011g/cm^2$, $0.914{\pm}0.005g/cm^2$, $0.933{\pm}0.008g/cm^2$ at 155 mm height displaying statistically significant relevance. The result suggests that a proper quality control and cross calibration of DXA device be possible and expected to be an essential data for various medical phantom manufacture development using 3D printer.

• Journal of the Korean Society of Radiology
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• v.10 no.6
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• pp.435-442
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• 2016

This study was an investigation of the anode heel effect caused by changing the angle of the x-ray tube. We established the following conditions for experimental measurements: 70 kV, 30 mAs, focus-detector distance of 100cm, and a collimator setting of $35{\times}43cm^2$. The measurement points were set up at the center of the collimator and extended to each side in intervals of 3.5cm, with points A1, A2, A3, A4, A5, A6 on the anode side and points C1, C2, C3, C4, C5, C6 on the cathode side. We measured the entrance surface dose from point A6 to point C6 with each point perpendicular to an x-ray tube. And we did the same when measuring different angles of the x-ray tube from 15 to 30 degrees for every point on the anode and cathode sides. Using perpendicular x-ray tube, we found that the entrance surface dose of the A5 point was three times higher than that of the C5 point. Thus, we conclude that if the anode side is placed near highly radiosensitive organs, then there will be less radiation exposure when using a perpendicular x-ray tube. When imaging using x-ray tube angles, an angle to the cathode side can reduce the gap of the entrance surface dose on both the anode and cathode sides. When imaging areas where there are differences in thickness between the upper and lower sides, the angle to the cathode side that is closer to the thicker area can reduce the gap of the entrance surface dose and capture a higher quality image.

• Imaging Science in Dentistry
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• v.34 no.2
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• pp.99-106
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• 2004

Purpose: To investigate the effects of irradiation on the phenotypic expression of the MC3T3-El osteoblastic cell line, especially on the osteonectin and bone sialoprotein. Materials and Methods: Cells were irradiated with a single dose of 0.5, 1, 4 and 8 Gy at a dose rate of 5.38 Gy/min using Cs-I37 irradiator. After specimens were harvested, total RNA was extracted on the 3rd, 7th, 14th, 21st day after irradiation. The total RNA was reverse-transcribed and the resulting cDNAs were subjected to amplification by PCR with a pair of primers. Results: The irradiated cells showed a dose-dependent increase in osteonectin mRNA expression when compared with the unirradiated control group. The irradiated cells showed no difference in bone sialoprotein mRNA expression when compared with the unirradiated control group. In accordance with the duration of culture period after irradiation, the level of osteonectin mRNA expression showed no difference, but it increased a little at the 21st day in the 4 and 8 Gy exposure groups. In the case of bone sialoprotein, however, the level of mRNA expression increased significantly at the 3rd and 7th day after irradiation, but it showed no difference at the 14th and 21st day when compared with the control group. Conclusion: These results showed that each single dose of 0.5, 1, 4 and 8 Gy influenced the mRNA expression of osteonectin and bone sialoprotein at the calcification stage of osteoblastic cells, suggesting that single dose of irradiation affected the osteoblastic bone formation at the cell level.

• Journal of the Korean Society of Radiology
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• v.7 no.6
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• pp.389-395
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• 2013

This study intended to investigate the optimum conditions for lumbar test that has the highest level of irradiation conditions among general test sites. To to this, the most widely used irradiation conditions in terms of statistics were set as standards; test groups applied with DMF were selected; tests groups suitable for clinical trials were selected by using suggested patient dose. Blind tests were conducted by 10 specialists and radiologists. The results suggested that under the optimum conditions, the radiation dose reduction of 2.09 mGy, 4.42 mGy and 3.65 mGy can be achieved in forward-backward test, lateral test and 4-direction test, respectively. There is a need of further studies on the optimization of irradiation conditions in accordance with the conditions of patients.

• Journal of Trauma and Injury
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• v.35 no.1
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• pp.12-18
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• 2022

Purpose: Pedicle screw fixation provides 3-column stabilization, multidimensional control, and a higher rate of interbody fusion. Although computed tomography (CT) is recommended for the postoperative assessment of pedicle screw fixation, its use is limited due to the radiation exposure dose. The purpose of this preliminary retrospective study was to assess the clinical usefulness of low-dose mobile cone-beam CT (CBCT) for the postoperative evaluation of pedicle screw fixation. Methods: The author retrospectively reviewed postoperative mobile CBCT images of 15 patients who underwent posterior pedicle screw fixation for spinal disease from November 2019 to April 2020. Pedicle screw placement was assessed for breaches of the bony structures. The breaches were graded based on the Heary classification. Results: The patients included 11 men and four women, and their mean age was 66±12 years. Of the 122 pedicle screws, 34 (27.9%) were inserted in the thoracic segment (from T7 to T12), 82 (67.2%) in the lumbar segment (from L1 to L5), and six (4.9%) in the first sacral segment. Although there were metal-related artifacts, the image of the screw position (according to Heary classification) after surgery could be assessed using mobile CBCT at all levels (T7-S1). Conclusions: Mobile CBCT was accurate in determining the location and integrity of the pedicle screw and identifying the surrounding bony structures. In the postoperative setting, mobile CBCT can be used as a primary modality for assessing the accuracy of pedicle screw fixation and detecting postoperative complications.

• Progress in Medical Physics
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• v.24 no.2
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• pp.119-126
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• 2013

Due to the introduction of CR and DR, it has been neglected the use of the X-ray beam collimator and field size. This study examines nationwide survey of the proper use of collimator and field size by area in a specific field of plain radiography and the current status. Authors emphasized the need for the field size criteria, and propose a standard reference field size in each specific radiologic examination. Total 333 medical institutions (included in Seoul, Gyeonggi-do, Jeolla, Chungcheong, Gangwon-do, Busan area), were investigated in relation to the status of the X-ray beam collimation field size, type specific inspection areas, medical facilities, and image analyses by type to figure out whether they use the adjustment of image field to the specific examination. To assess the awareness and the impact of radiation exposure to the collimation adjustable, 168 radiographers who was working in 10 general hospitals, 10 hospitals, and 10 clinics, were surveyed how they haver adjusted the actual field size. We examine that 61.3% of medical institutions used the "Proper collimation" and only 49.9% of them employed proper one in lumbar spine densely crowded by major organs. 69% among general hospitals, and 65% among hospitals using DR system were using proper collimation. Radiographers recognized that proper adjustment of collimation could reduce the harmful radiation dose on patients. In the survey, 97.6% of respondents were aware of this fact, but only 83.3% of respondents did the adjustment of the size of the collimation field. The using of proper collimation field was low in the nationwide survey, so the effort to reduce the radiation dose on the patients is urgently needed. A unified standard for the field accompanied by thorough education should be needed.