• Journal of Radiation Protection and Research
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• 제44권4호
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• pp.128-148
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• 2019

Massive environmental monitoring has been conducted continuously since the Fukushima Daiichi Nuclear Power accident in March of 2011 by different monitoring methods that have different features together with migration studies of radiocesium in diverse environments. These results have clarified the characteristics of radiological environments and their temporal change around the Fukushima site. At three months after the accident, multiple radionuclides including radiostrontium and plutonium were detected in many locations; and it was confirmed that radiocesium was most important from the viewpoint of long-term exposure. Radiation levels around the Fukushima site have decreased greatly over time. The decreasing trend was found to change variously according to local conditions. The air dose rates in environments related to human living have decreased faster than expected from radioactive decay by a factor of 2-3 on average; those in pure forest have decreased more closely to physical decay. The main causes of air dose rate reduction were judged to be radioactive decay, movement of radiocesium in vertical and horizontal directions, and decontamination. Land-use categories and human activities have significantly affected the reduction tendency. Difference in the air dose rate reduction trends can be explained qualitatively according to the knowledge obtained in radiocesium migration studies; whereas, the quantitative explanation for individual sites is an important future challenge. The ecological half-lives of air dose rates have been evaluated by several researchers, and a short-term half-life within 1 year was commonly observed in the studies. An empirical model for predicting air dose rate distribution was developed based on statistical analysis of an extensive car-borne survey dataset, which enabled the prediction with confidence intervals. Different types of contamination maps were integrated to better quantify the spatial data. The obtained data were used for extended studies such as for identifying the main reactor that caused the contamination of arbitrary regions and developing standard procedures for environmental measurement and sampling. Annual external exposure doses for residents who intended to return to their homes were estimated as within a few millisieverts. Different forms of environmental data and knowledge have been provided for wide spectrum of people. Diverse aspects of lessons learned from the Fukushima accident, including practical ones, must be passed on to future generations.

• Imaging Science in Dentistry
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• 제53권1호
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• pp.69-75
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• 2023

Purpose: Maxillofacial trauma predominantly affects young adults between 20 and 40 years of age. Although radioprotection is a legal requirement, the significant potential of dose reduction in computed tomography (CT) is still underused in the clinical routine. The objective of this study was to evaluate whether maxillofacial fractures can be reliably detected and classified using ultra-low-dose CT. Materials and Methods: CT images of 123 clinical cases with maxillofacial fractures were classified by two readers using the AOCOIAC software and compared with the corresponding results from post-treatment images. In group 1, consisting of 97 patients with isolated facial trauma, pre-treatment CT images at different dose levels (volumetric computed tomography dose index: ultra-low dose, 2.6 mGy; low dose, <10 mGy; and regular dose, <20 mGy) were compared with post-treatment cone-beam computed tomography (CBCT). In group 2, consisting of 31 patients with complex midface fractures, pre-treatment shock room CT images were compared with post-treatment CT at different dose levels or CBCT. All images were presented in random order and classified by 2 readers blinded to the clinical results. All cases with an unequal classification were re-evaluated. Results: In both groups, ultra-low-dose CT had no clinically relevant effect on fracture classification. Fourteen cases in group 2 showed minor differences in the classification code, which were no longer obvious after comparing the images directly to each other. Conclusion: Ultra-low-dose CT images allowed the correct diagnosis and classification of maxillofacial fractures. These results might lead to a substantial reconsideration of current reference dose levels.

• 약학회지
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• 제29권3호
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• pp.130-143
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• 1985

Bumetanide, when given intravenously in dogs, induced a potent diuresis with an increased amounts of sodium and potassium excreted in urine due to inhibition of reabsorbing them in renal tubule. Furthermore, clearances of osmolar substance and para-aminohippuric acid were increased, but clearace of free water diminished without any change of creatinine clearance. Bumetanide, administered directly into a renal artery, elicited diuresis only in the infused(experimental) kidney by the same mode of action as in the intravenous cases in renal function of the dog. Renal effects of intravenous bumetanide after pretreatment with the small dose of indomethacin (5.0mg/kg) revealed reduction only in clearance of paraaminohippuric acid. However the much dose of indomethacin (5.0mg/kg+5.0mg/kg/hr) or arachidonic acid showed a significant inhibition in the change rates of all renal function by bumetanide. Morover, pretreatment of probenecid also made a marked reduction in renal effects induced by bumetanide. From the above results, it is thought that bumetanide causes diuretic action due to dual mechanism inhibiting reabsorption of electrolytes in loop of Henle and increasing blood flow in kindney, that are provoked through the mediation of prostaglandins.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(2)
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• pp.583-588
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• 1998

The effectiveness of dose reduction resulting from the application of countermeasures for ingestion pathways after nuclear accidents was investigated together with the derivation of optimized intervention levels for Korean foodstuffs. The radioactivity in foodstuffs was predicted from a dynamic food chain model DYNACON for the date which the deposition occurs. The effectiveness of countermeasures strongly depended on radionuclides, foodstuffs and date of deposition.

• 약학회지
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• 제23권1호
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• pp.31-39
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• 1979

Bethanidine was administered into the lateral ventricle of the rabbit brain for the investigation of the effect on the renal function in doses ranging from 0.1 to 1.0mg/kg. In a dose of 0.1 mg/kg, bethanidine did not exhibit significant changes on the renal function of the rabbit, on the other hand, in the doses of 0.3 and 1.0mg/kg bethanidine elicited the reduction of renal plasma flow and glomerular filtration rate with a marked antidiuresis, at the same time bethanidine produced the decrement of urinary sodium and potassium excretion. After intravenous pretreatment of phentolamine, intraventricular bethanidine in a dose of 0.3mg/kg did not produced the antidiuresis and the decrement of urinary sodium and potassium excretion, wherease renal plasma flow and glomerular filtration rate reduced as before of phentolamine pretreatment although the durations of their reduction were shortened. These observations suggest that bethanidine induces the antidiuresis through the centrally mediated mechanism which interposed other factors in addition to sympathetic stimulation affected by phentolamine, alpha adrenergic blocking agent.

• 한국방사선학회논문지
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• 제12권6호
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• pp.763-768
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• 2018

방사선치료 기법의 발전으로 치료가 더욱 정밀해졌음에도 불구하고 치료 부위 외에도 방사선에 의해 피폭되는 것은 피할 수 없다. 이에 본 연구에서는 유방암의 방사선치료 시 치료 반대편 유방의 bolus 두께에 따른 흡수선량을 평가하고 선량 저감 효과에 대해 분석하고자 하였다. 실험 및 방법으로 Rando phantom을 대상으로 VMAT 치료방법을 이용하여 실험을 진행하였다. 치료 반대편 유방에 A, B, C, D, E의 5개 지점을 선정하여 bolus를 사용하지 않았을 때와 5, 10, 15, 20 mm의 bolus를 사용하였을 때의 선량을 유리선량계를 사용해 평가하였다. 그 결과, 치료지점과 가장 가까운 지점에서 높은 흡수선량이 측정되었으며 치료지점과 가장 먼 B 지점에서는 가장 낮게 측정되었다. 평균 흡수선량은 bolus를 사용하지 않았을 때 8.61 cGy 그리고 두께에 따라 8.10, 7.94, 8.06, 8.10 cGy로 나타났다. 연구 결과 선량 저감 효과를 확인할 수 있었으며, 본 연구를 바탕으로 적절한 bolus 두께를 설정하여 정상조직의 선량 저감화를 위해 노력해야 할 것이다.

• Restorative Dentistry and Endodontics
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• 제37권3호
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• pp.160-164
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• 2012

Objectives: This study was aimed to investigate the methods to reduce operator's radiation dose when taking intraoral radiographs with portable dental X-ray machines. Materials and Methods: Two kinds of portable dental X-ray machines (DX3000, Dexcowin and Rextar, Posdion) were used. Operator's radiation dose was measured with an 1,800 cc ionization chamber (RadCal Corp.) at the hand level of X-ray tubehead and at the operator's chest and waist levels with and without the backscatter shield. The operator's radiation dose at the hand level was measured with and without lead gloves and with long and short cones. Results: The backscatter shield reduced operator's radiation dose at the hand level of X-ray tubehead to 23 - 32%, the lead gloves to 26 - 31%, and long cone to 48 - 52%. And the backscatter shield reduced operator's radiation dose at the operator's chest and waist levels to 0.1 - 37%. Conclusions: When portable dental X-ray systems are used, it is recommended to select X-ray machine attached with a backscatter shield and a long cone and to wear the lead gloves.

• 한국물환경학회지
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• 제20권4호
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• pp.376-381
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• 2004

The use of electron beam irradiation was investigated to disinfect total coliforms in the secondary sewage treatment effluent. Unchlorinated secondary effluent was irradiated at different dose of 0.2~1.0 kGy by 1 MeV, ELV-4 Model electron beam accelerator. It is interesting to note that a 100 % reduction in total coliforms and total colonies were achieved until a dose of approximately 0.8 kGy. Even at low dose of 0.2 kGy, the total coliforms and total colonies were successfully inactivated to the level of satisfying the new effluent discharge guideline. Besides disinfection of total coliforms, approximately a 50% removal in biochemical oxygen demand was pronounced at a dose of 0.2 kGy. More than 20 % removal in suspended solids and turbidity was also observed at a dose of 1.0 kGy. The application of electron beam irradiation appeared to be one of options to reuse sewage treatment effluent as agricultural or industrial water.

• Nuclear Engineering and Technology
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• 제50권5호
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• pp.806-813
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• 2018

$^{222}Rn$ exists in nature in the form of a rare radioactive gas. In terms of environmental radiation, issues regarding $^{222}Rn$ have persisted because of its radiological hazardousness. Ulju County is one of the regions of Ulsan metropolitan city, with a population of 227,699. Ulju County has the highest density of industrial complexes in Korea. In this study, $^{222}Rn$ radioactivity concentration was measured and analyzed in 57 schools in Ulju County using 114 passive LR-115 type detectors to secure radiological safety and confirm basic information for reduction of resident exposure to $^{222}Rn$. The effective dose of $^{222}Rn$ was assessed to find the actual risk of the concentration surveyed in schools to human beings. The dose depended on four factors: subjects, $^{222}Rn$ concentration, dose coefficient, and time. The individuals subjected to dose estimation were classified into three types: students, teachers, and office workers. The subjects had different dwelling locations and times. The findings demonstrate that the radiological hazard to students and workers at schools in Ulju County owing to $^{222}Rn$ is negligible in terms of $^{222}Rn$ activity recommendation level.

• 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.