• Development and Reproduction
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• v.24 no.3
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• pp.159-165
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• 2020

Previously, we reported adverse effects of low-dose nonylphenol (NP) exposure on the reproductive parameters of F1 female mice. In the present study we further investigated the pathohistological effect of NP exposure on the reproductive organs in F1 female mice. NP exposures were continuously conducted from parental pre-mating period until the postnatal day (PND) 33 of F1 offspring for vaginal examination. Mice were sacrificed on PND 30 and the reproductive tissue weights were measured. The initial (at PND 21) body weights of the NP-50 group animals were significantly lower than those of control group animals, and the weight deficit were recovered when the terminal (PND 33) body weights were measured. Early vaginal opening was found in NP group animals (p<0.05). Pathohistological studies revealed that NP-treated F1 animals showed prominent increase in the ovarian follicle numbers (p<0.01), and decrease in the diameter of uterine myometrium (p<0.01), and increase in the diameter of luminal epithelium (p<0.05). The present study demonstrated that the subchronic low-dose NP exposure induced early beginning of puberty and pathohistological abnormalities in ovary and uterus of F1 mice. Further studies are needed to achieve a better understanding on the action mechanism of NP in pubertal onset and to find a way to avoid a hazardous situation provoked by NP exposure.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2015.11a
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• pp.294-297
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• 2015

Decommissioning of nuclear facilities should be accomplished by assuring the safety of workers because decommissioning activities of nuclear facilities are under high radioactivity and work difficulty. It is necessary that before decommissioning, the radiation exposure dose of workers has to be evaluated and assessed under the principle of ALARA (as low as reasonably achievable). Furthermore, to improve the proficiency of decommissioning environments, method and system need to be developed. The legacy methods of exposure dose measurement and assessment had the limitations to modify and simulate the exposure dose to workers prior to practical activities because those should be accomplished without changes of working routes under predetermined scenarios. To simulate a lot of decommissioning scenarios, decommissioning environments were designed in virtual reality. To simulate and assess the exposure dose to workers, human model also was designed in virtual environments. These virtual decommissioning environments made it possible to real-time simulate and assess the exposure dose to workers. It can be concluded that this system is able to protect from accidents and enable workers to improve his familiarization about working environments. It is expected that this system can reduce human errors because workers are able to improve the proficiency of hazardous working environments due to virtual training like real decommissioning situations. In the end, the safety during decommissioning of nuclear facilities will be guaranteed under the principle of ALARA.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.1
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• pp.49-53
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• 2011

Dynamic range on the digital detector can be a representation to the ratio of maximum and minimum of pixel value. Wide dynamic range and post processing ability of the digital detector made difficult to recognize visually to high or low dose images. We were evaluated a change of mean pixel value on the original and processed image, when we controlled the kVp, mA, exposure time on the digital detector. On the kVp of a constant condition, we were acquired an original and processed image by changes of mA, exposure time. According to the thickness of the subject under the same conditions, to determine a relation of pixel value and X-ray intensity, we used an aluminum step wedge. When mA and exposure times were changed under the kVp of a constant condition, the X-ray intensity was decreased by the reduction of the mean pixel value. In addition when kVp was increased in a constant condition of mAs, the mean pixel value was increased according to the increment of the X-ray intensity. Therefore, low kVp, high mA and short exposure time were a way to reduce a patient dose.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7407-7411
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• 2014

The incidence of urban female breast cancer has been continuously increasing over the past decade with unknown etiology. One hypothesis for this increase is carcinogen exposure from tobacco. Therefore, the objective of this study was to investigate the risk of urban female breast cancer from tobacco smoke exposure. The matched case control study was conducted among Thai females, aged 17-76 years and living in Bangkok or its surrounding areas. A total of 444 pairs of cases and controls were recruited from the Thai National Cancer Institute. Cases were newly diagnosed and histologically confirmed as breast cancer while controls were selected from healthy women who visited a patient, matched by age ${\pm}5$ years. After obtaining informed consent, tobacco smoke exposure data and information on other potential risk factors were collected by interview. The analysis was performed by conditional logistic regression, and presented with odds ratio (ORs) and 95% confidence intervals(CI). From all subjects, 3.8% of cases and 3.4% of controls were active smokers while 11.0% of cases and 6.1% of controls were passive smokers. The highest to lowest sources of passive tobacco smoke were from spouses (40.8%), the workplace (36.8%) and public areas (26.3%), respectively. After adjusting for other potential risk factors or confounders, females with frequent low-dose passive smoke exposure (${\leq}7$ hours per week) from a spouse or workplace had adjusted odds ratio 3.77 (95%CI=1.11-12.82) and 4.02 (95%CI=1.04-15.50) higher risk of breast cancer compared with non-smokers, respectively. However, this study did not find any association of breast cancer risk in high dose passive tobacco smoke exposure, or a dose response relationship in cumulative passive tobacco smoke exposure per week, or in the active smoker group. In conclusion, passive smoke exposure may be one important risk factor of urban female breast cancer, particularly, from a spouse or workplace. This risk factor highlights the importance of avoiding tobacco smoke exposure as a key measure for breast cancer prevention and control.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.179-184
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• 2013

The biological effects of radiation are dependent on the dose rate and dose of radiation. In this study, effects of dose and dose rate using whole body radiation on plasma cytokines and blood count from male BALB/c mice were evaluated. We examined the blood and cytokine changes in mice exposed to a low (3.49m Gy $h^{-1}$) and high (2.6 Gy $min^{-1}$) dose rate of radiation at a total dose of 0.5 and 2 Gy, respectively. Blood from mice exposed to radiation were evaluated using cytokine assays and complete blood count. Peripheral lymphocytes and neutrophils decreased in a dose dependent manner following high dose rate radiation. The peripheral lymphocytes population remained unchanged following low dose rate radiation; however, the neutrophils population increased after radiation. The sera from these mice exhibited elevated levels of flt3 ligand and granulocyte-colony-stimulating factor (G-CSF), after high/low dose rate radiation. These results suggest that low-dose-rate radiation does not induce blood damage, which was unlike high-dose-rate radiation treatment; low-dose-rate radiation exposure activated the hematopoiesis through the increase of flt3 ligand and G-CSF.

• Journal of radiological science and technology
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• v.16 no.2
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• pp.27-38
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• 1993

To investigate relationships between image guality and exposure dose, Chest X-ray films were evaluated for the following points:how much scattered radiation can affect reduction in image quality and can be permissible diagnostically? For this purpose using a test charts and Burger's phantoms. The visual evaluation of their X-ray films and the measurements of scattered radiation were carried out. The dose of scattered radiation ranging from 20 to 25% was found to be for nothing in any diagnostic obstacle. In this range, surface doses were low of 17, 21, and $25{\mu}Gy$ for The thickness of the chest of 15, 20 and 25 cm respectively. Comparison of these high voltage X-ray films with low voltage ones showed a surface dose rate of 1:11.7. Therefore, X-ray quality, photosensitive materials(film and screen) and grid should be selected very carefully for the purpose of reduction in exposure dose.

• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.187-193
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• 2015

Deleterious effects of high dose radiation exposure with high-dose-rate are unarguable, but they are still controversial in low-dose-rate. The regulator of G-protein signaling (RGS) is a negative regulator of G protein-coupled receptor (GPCR) signaling. In addition, it is reported that irradiation stress led to GPCR-mediated mitogen-activated protein kinase (MAPK) and phosphotidylinositol 3-kinase (PI3-k) signaling. The RGS mRNA expression profiles by whole body radiation with low-dose-rate has not yet been explored. In the present study, we, therefore, examined which RGS was modulated by the whole body radiation with low-dose-rate ($3.49mGy{\cdot}h^{-1}$). Among 16 RGS expression tested, RGS6, RGS13 and RGS16 mRNA were down-regulated by low-dose-rate irradiation. This is the first report that whole body radiation with low-dose-rate can modulate the different RGS expression levels. These results are expected to reveal the potential target and/or the biomarker proteins associated with male testis toxicity induced by low-dose-rate irradiation, which might contribute to understanding the mechanism beyond the testis toxicity.

• Journal of the Korean Society of Radiology
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• v.12 no.7
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• pp.827-832
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• 2018

Research on effective dose analysis of actual conditions of use based on large data is scarce. In this study, the exposure conditions of Chest X-Ray examinations used by 324 medical institutions in Korea were calculated and evaluated using computer simulations. As a result of the experiment, the effective dose in the low energy parameter bands was 0.024 mSv, followed by spleen, adrenal glands, and lung. The effective dose in the high-energy exposure parameter band was 0.123 mSv, followed by height, spleen and adrenal glands. The effective dose was 0.017 mSv when the optimal conditions considered the quality and exposure proposed in Park's study were used. The results of the study will be a reference for chest X-rays and will help reduce patient exposure.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.45-50
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• 2011

Purpose: It appears the different value when the injection dose is calculating for patients on each PET/CT systems. It directly affects the technologists' radiation exposed dose. We studied the effect of the variable injection doses from several PET/CT systems to exposure dose for technologists. Materials and Methods: Six technologists have worked for 5 months through unit rotations with 3 PET/CT systems {Scanner 1 (S1): 0.15 mCi/kg, Scanner 2 (S2): 0.17 mCi/kg, Scanner 3 (S3): 0.12 mCi/kg}. Eighteen to 19 patients have had examinations per a day on each PET/CT systems. Examination parameters were adjusted to the same. TLDs were used for checking the exposure dose of technologists. Results: Each technologists' the monthly average exposure dose was as follows; S1: 0.76 mSv, S2: 0.93 mSv, S3: 0.47 mSv. The maximum exposure dose was 1.12 mSv, and minimum was 0.42 mSv. The results showed significance in the correlation between the PET/CT system and the exposure dose (p<0.005). Conclusion: When the amount of injection dose was small, the exposure dose was decreased not only the patients but also the technologists. The exposure dose was decreased by the individual proficiency of technologists. However, the low injection dose can highly reduce the exposure dose for technologist so that there will be needed to following studies.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.145-154
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• 2003

By optimizing the radiation protection the collective dose and individual dose could be reduced during YGN #4 $5^{th}$ outage in 2001. The collective doses for the two high radiation jobs decreased to 85% and 65% of expected doses. The proportion of workers with low dose (below 1mSv) exposure increased 4% while the proportion of workers with over 3mSv and 5mSv exposure are decreased to 2%, 1% respectively. But none is exposed over 8mSv for the annual dose. To aid decision of utilizing the robot, cost- benefit analysis was performed and reasonable point was proposed to use the robot. For the first time job, repeated ALARA meeting and mock up training were implemented to set up working procedure by identifying the trouble. To easily set up standard procedure, mockup process was videotaped and reviewed during ALARA meeting. Monitoring is a good approach to chase radiological working condition such as working time, dose rate. behavior of workers, especially for high radiation work. Those data were estimated and adjusted from the stage of work planning to mock up. At the stage of actual work the monitoring data were compared to the estimation and recorded to database. This database will not only be used as a powerful tool for dose optimization at the following outage but also as a guideline to dose constraint set up for optimization for each specific situation.