• 대한방사선기술학회지:방사선기술과학
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• 제43권5호
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• pp.337-341
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• 2020

Although the screening with a mammography has been shown to be economical, simple and effective in detecting breast cancer, it is accompanied by the risk from radiation. Therefore, this study analyzed the glandular dose and organ dose according to the target-filter combination and the presence and absence of implants using Monte Carlo simulation. The results indicate that at a tube voltage of 30 kV and a tube current of 50 mAs, the dose increased in the order of Mo/Mo. Mo/Rh, Rh/Rh and W/Rh in proportion to the atomic number of the target-filter. In addition, in phantom without implant a reduction in dose was seen when compared to the phantom with implant. The organ dose was highest in the lens except for the breast on the examination side regardless of the presence or absence of the implant. These results may contribute to use basic data for the diagnostic reference level of breast plastic surgery patients.

• 대한방사선기술학회지:방사선기술과학
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• 제41권6호
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• pp.573-580
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• 2018

The Nuclear Safety Commission amended the Nuclear Safety Act by strengthening the safety management system for the frequent workers to the level of radiation workers. And students entering radiation management zones for testing and practical purposes are subject to frequent workers. It is inevitable that this will incur additional costs. In this paper, the validity of the amendment to the Nuclear Safety Act was to be assessed in terms of radiation protection. Study subjects are from 2014 to 2016, among university students in Seong-nam Korea and comparisons for analyses were made taking into account variables that are differences in annual, practical types, on-class and clinical practice students exposure dose. The analysis showed that exposures between on-class and clinical practice received were less than the annual dose limit of 1 mSv for the public. Then, some alternatives that excluding from frequent workers during on-class practice or mitigating the frequent workers' safety regulation for only on-class frequent workers can be considered. Optimization is how rational is the reduction in exposure dose to the costs required. Therefore, the results are hardly considered for optimization. If the data accumulated, it could be considered that the revision of the act could be evaluated and improved.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권1호
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• pp.7-12
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• 2006

Telomerase activation is detected in most cancerous cells; hence, telomerase is a highly selective target for cancer therapy, which plays an important role in the apoptotic process. We have previously reported that the ginseng saponin metabolite, Compound K (20-O-D-glucopyranosyl-20(S)-protopanaxadiol, IH901), inhibits cell proliferation by inducing apoptosis and cell cycle arrest at the $G_1$ phase. The present study investigated the regulation of telomerase activity in Compound K treated U937 cells. Compound K treatment caused a reduction in telomerase activity and down-regulated the human telomerase reverse transcriptase (hTERT) gene, resulting in the decreased expressions of its protein, and of the c-Myc and Spl proteins (transcription factors of hTERT). These results indicate that the anticancer activity of Compound K could be mediated by inhibition of the telomerase activity.

• 한국인공지능학회지
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• 제9권2호
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• pp.1-5
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• 2021

Although CT has an advantage in describing the three-dimensional anatomical structure of the human body, it also has a disadvantage in that high doses are exposed to the patient. Recently, a deep learning-based image reconstruction method has been used to reduce patient dose. The purpose of this study is to analyze the dose reduction and image quality improvement of deep learning-based reconstruction (DLR) on the adult's chest CT examination. Adult lung phantom was used for image acquisition and analysis. Lung phantom was scanned at ultra-low-dose (ULD), low-dose (LD), and standard dose (SD) modes, and images were reconstructed using FBP (Filtered back projection), IR (Iterative reconstruction), DLR (Deep learning reconstruction) algorithms. Image quality variations with respect to varying imaging doses were evaluated using noise and SNR. At ULD mode, the noise of the DLR image was reduced by 62.42% compared to the FBP image, and at SD mode, the SNR of the DLR image was increased by 159.60% compared to the SNR of the FBP image. Based on this study, it is anticipated that the DLR will not only substantially reduce the chest CT dose but also drastic improvement of the image quality.

• Advances in Traditional Medicine
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• 제10권1호
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• pp.1-6
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• 2010

The efficacy of the radioprotective effect of Callophyllis japonica ethyl acetate (CJEA) extract was studied by comparing it to that of amifostine, a well-known radioprotective agent, and by evaluating the dose reduction factor, an indicator of radioprotective efficacy. Pretreatment with CJEA extract (100 mg/kg body weight) prior to receiving 12 Gy irradiation significantly improved the survival of jejunal crypts at 3.5 day post-irradiation, but attenuated the level of malondialdehyde compared to vehicle alone (P < 0.01). A similar gastroprotective effect was also obtained in the amifostine-treated irradiated group (P < 0.01). The efficacy of the radioprotective effect was further confirmed by the dose reduction factor, 1.41. Collectively, these results suggest that CJEA extract is a useful radioprotectant whose efficacy is similar to that of amifostine and whose radioprotective mechanism is in part the reduction of lipid peroxidation caused by gamma irradiation.

• 대한방사선기술학회지:방사선기술과학
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• 제37권1호
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• pp.21-28
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• 2014

배양된 췌장베타세포와 신경세포를 10% FBS (fetal bovine serum), 11.1 mM glucose의 normal 조건과 1% FBS, 30 mM glucose의 hyperglycemia 조건으로 배양하고, 저 LET X-선을 0.5 Gy/hr의 선량률로 총 선량이 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 Gy가 되도록 저 LET 방사선을 조사한 후 MTT assay로 생존율을 측정하고 비교하였다. 분화된 췌장베타세포에 방사선을 조사하지 않았을 때는 normal 조건에 비해 hyperglycemia 조건의 생존율이 경미한 감소를 보였다. 그러나 X선의 총 선량이 점차 누적됨에 따라 normal 조건에서 생존율이 조금씩 감소하는 것에 비해 hyperglycemia 조건에서는 급격히 감소하여 시너지 효과를 나타냈다. 미분화된 신경세포에서는 방사선을 조사하지 않은 때도 normal 조건에 비해 hyperglycemia 조건의 생존율이 뚜렷하게 감소하였다. X선의 총 선량이 점차 누적됨에 따라 normal 과 hyperglycemia 조건 모두에서 비교적 급격한 세포사멸이 나타났지만 그 생존율의 감소비율이 거의 평행하게 진행되어 시너지 효과를 보이지 않았다.

• 대한방사선기술학회지:방사선기술과학
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• 제46권6호
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• pp.475-484
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• 2023

This study aimed to compare filters for reducing speckle noise in ultrasound images using clinical liver images. We acquired the clinical liver ultrasound images, and noisy images were obtained by adding 0.01, 0.05, 0.10, and 0.50 intensity levels of speckle noise to the liver images. The Wiener filter, median modified Wiener filter, gamma filter, and Lee filter were designed for the noisy images by setting window sizes at 3×3, 5×5, and 7×7. The coefficient of variation (COV) and contrast to noise ratio (CNR) were calculated to evaluate noise reduction and various filters. Moreover, the filter with the highest image quality was selected and quantitatively compared to a noisy image. As a result, COV and CNR showed the noise improved result when the Lee filter was applied. Furthermore, the Lee filter image with a window size of 7×7 was noted to possess approximately a minimum of 1.28 to a maximum of 3.38 times better COV and a minimum of 2.18 to a maximum of 5.50 times better CNR than the noisy image. In conclusion, we confirmed that the Lee filter was effective in reducing speckle noise and proved that an appropriate window size needs to be set considering blurring.

• 산업공학
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• 제15권4호
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• pp.439-443
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• 2002

In this paper, we study to evaluate the relative time required to perform the CT scanning in the PACS versus a film-based system and helical versus non-helical studies. Time studies were performed in 175 consecutive CT scanning. Images from 85 examinations were electronically transferred to a PACS, and 90 were printed to film. The time required to obtain and electronically transfer the images or print the images to film and make the current and previous studies available to the radiologists for interpretation was recorded. The time required for a radiological technologist to complete a CT test was reduced by 43% with the PACS compared with the film-based system and nonhelical was reduced 10~20% with helical studies. This reduction was due to the elimination of a transfer and printing, such as the printing at window or level settings. The use of PACS can result in the elimination of time tasks for the radiological technologist, resulting in marked reduction in examination time. This reduction can result in decreased cost and increased productivity in PACS operation.

• 대한방사선기술학회지:방사선기술과학
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• 제15권1호
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• pp.89-97
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• 1992

X-ray quality is identified numerically by half value layer(H.V.L) and the HVL is affected by the kVp and the amount of filtration in the useful beam. X-ray quality evaluated by H.L.D is influenced by kVp and filtration. Author had several experiments with phantom in diameter of 8 cm normal adult chest, for reduction of radiation dose of the patients in diagnostic radiology and got some results. 1. H.V.L is increased the thicker the filter and the higher the kVp. 2. If the kVp is increased from 60 to 120, the skin dose can be reduced as 34%(Skin dose of 60 kVp with 4 mmAl filter : 100%). 3. If the 4 mmAl filter with 60 kVp is added to x-ray tube, skin dose can be reduced as 23% than no filter. 4. Therefore high kVp and filtration can increase output to input dose ratio and 120 kVp and 4 mmAl filter were most effective for reduction of patient dose in chest radiography.

• 대한디지털의료영상학회논문지
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• 제5권1호
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• pp.78-84
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• 2002

To evaluate the relative time required to perform a CT(computed tomography) examination in a filmless versus a film-based system and helical versus nonhelical studies. Time and Motion studies were performed in 175 consecutive CT examinations. Images from 85 examinations were electronically transferred to a PACS, and 90 were printed to film. The time required to obtain and electronically transfer the images or print the images to film and make the current and previous studies available to the radiologists for interpretation was recorded. The time required for a radiological technologist to complete a CT examination was reduced by 43% with the PACS compared with the film-based system and nonhelical was reduced 10-20% with helical studies. This reduction was due to the elimination of a transfer and printing, such as the printing at window or level settings. The use of PACS can result in the elimination of time tasks for the radiological technologist, resulting in marked reduction in examination time. This reduction can result in decreased cost and increased productivity in PACS operation.