• 대한방사선기술학회지:방사선기술과학
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• 제41권5호
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• pp.437-444
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• 2018

Whole-Body counters have been used to evaluate the internal contamination of gamma emitting radionuclides. Among the whole-body counters used in domestic nuclear facilities, Fastscan made by CANBERRA contains 2 NaI(Tl) detectors and is generally used to monitor the primary internal exposure. It has the advantage of achieving MDA even with short time measurements. Accuscan is a bed type, and has good energy resolution because it is composed of HPGe detector. Since the Accuscan with better energy resolution than Fastscan has better able to identify radionuclides, it is used to monitor secondary internal exposure. Some nuclear facilities have only Fastscan. We analyzed statistically whether Fastscan is enough to ensure accuracy and precision comparing with Accuscan. To do this, we prepared a CRM created by the Korea Research Institute of Standards and Science. We also obtained the data of 6 Fastscans and 5 Accuscans in domestic nuclear facilities. As a result of the study, although Fastscan compared with Accuscan is not as accurate as the Accuscan, the precision is statistically same. However, accuracy of Fastscan is in compliance with international standards except low energy range. In terms of accuracy and precision except radionuclides emitting low energy, it is possible to measure radioactivity inside workers even in nuclear facilities where only Fastscan is used.

• 한국환경과학회지
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• 제14권4호
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• pp.435-444
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• 2005

A survey was conducted to 890 radiological technologists working at 44 general hospitals of 16 cities and provinces across the county to determine their stress level according to regions divided into the capital city, metropolitan areas and small- and medium-sized cities. For this purpose, such factors as their working environment, role playing, job conflict and job burden were compared and analyzed according to the regions. The findings may be summed up as follows: 1. In terms of working environment, radiological technologists in the capital city were found to have the least stress(23.46), followed by those in metropolitan areas(24.53) and small- and medium-sized cities(24.85). There was a significant difference according to the regions as for the item 'worry about influence of radioactive contamination(genetic, decisive and plausible)(P<0.001). 2. As for role playing, radiological technologists in small-and medium-sized cities appeared to receive the highest stress(l8.25) followed by metropolitan areas(l7. 71) and the capital city(l6.69). There was a statistically significant difference(P<0.001) according to the regions 3. Regarding job conflict, those who work in small- and medium-sized cities turned out to get the highest stress(15.66) compared to those in metropolitan areas(15.35) and the capital city(l4.44). In terms of job autonomy, there was no significant result from the survey in spite of the difference between metropolitan areas(14.87), small- and medium-sized cities(l4.79) and the capital city(l4.66). 4. Little difference was detected according to the regions as far as the job burden(excessive or too little) was concerned. But their was a significant regional difference in tenns of patient-related factors with the capital city(11.50), small- and medium-sized cities(l0.75), and metropolitan areas(1.63)(P<0.001).

• Journal of Radiation Protection and Research
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• 제32권1호
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• pp.1-8
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• 2007

도시지역의 방사능 오염으로 거주민의 피폭영향을 평가할 수 있는 모델 METRO-K를 개발하였다. 모델의 특성으로 1) 실험 또는 경험자료를 사용하기 때문에 수학식이 간단하여 이해가 쉬울 뿐 아니라 계산에 필요한 변수의 수가 적으며 2) 도시환경을 구성하는 5가지 기본표면 만을 사용하여 복잡하고 다양한 주변 환경을 쉽게 구성할 수 있으며 3) 각기 다른 오염 표면으로 인한 선량을 평가함으로써 표면마다 적합한 제염대책을 수립하는데 용이하다. 피폭자의 특정 위치에서 각기 다른 오염표면으로부터 받게 되는 선량은 감마에너지와 오염 표면별 공기커마 값을 데이터 라이브러리로 만들어 평가에 이용하였다. 유럽 도시지 역의 4가지 대표적 거주형태 에 대한 공기커마 값을 사용하여 우리나라 도시지역의 7가지 대표적 주거형태에 적합하도록 공기커마 값을 조합하여 적용하였다. 장기간 방사성물질의 누설을 고려하여 하루 단위의 핵종별 공기중 농도, 강우량, 핵종의 화학적 형태 구성분율이 입력되면 침적 후 시간에 따른 각기 다른 표면에서의 공기중 흡수선량률과 피폭자의 거주 위치에 따른 인체 선량률이 평가된다. 아파트 밀집지역에 대한 가상 오염 시나리오의 적용결과 피폭자의 거주위치 뿐 아니라 피폭자가 거주하는 주변 환경에 따라 인체 선량률은 확연한 차이를 나타냈다.

• 대한방사선기술학회지:방사선기술과학
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• 제40권1호
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• pp.7-12
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• 2017

본 연구는 일개대학병원의 디지털 이동방사선검사 장비를 대상으로 이동방사선검사 시 검출기와 장비의 세균학적 오염도를 조사하여 이동방사선검사 장비로 인한 병원감염을 예방하고자 실시하였다. 중환자실 감염관리 환자는 검출기위에 비닐을 씌우고 검사를 실시한 후 비닐 위에서 검체를 채취한 결과 CNS, VRE가 검출되었고 비닐을 제거한 검출기에서는 균이 발견되지 않았다. 일반병실 환자를 연속해서 검사한 결과, 1번 환자에서는 균이 발견되지 않았고, 2번과 3번 환자에서는 CNS, 4번 환자는 CNS, Enterococcus faecalis, 5번 환자는 CNS, Enterococcus casseliflavus, 6번 환자에서는 CNS, Enterococcus casseliflavus, Klebsiella pneumoniae가 검출되었다. 조사야 조절 손잡이에서는 CNS, Enterococcus faecium이 검출되었다. X-선 발생스위치, 검출기 손잡이에서는 CNS가 검출되었다. 검사 후 방사선사의 진료 장갑에서는 CNS, Enterococcus gallinarum, Klebsiella pneumoniae가 검출되었다. 따라서 1회 검사 후 검출기를 소독하고 재검사 하는 방법과 검출기에 1회용 비닐을 씌워 검사한 후 제거하는 방법을 권장하며, 진료장갑은 1회 검사 후 반드시 새로운 장갑으로 교체해야 한다. 또한, 검사 중 많이 조작하는 조사야 조절 손잡이의 철저한 소독과 근무자의 감염교육을 통해 이동방사선검사로 인한 병원감염을 예방하여야 한다.

• Journal of Radiation Protection and Research
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• 제47권4호
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• pp.204-213
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• 2022

Background: The accident at the Fukushima Daiichi nuclear power plant increased the level of anxiety related to the radioactive contamination of various foods sourced in Japan. Particularly, after the accident, the detection of artificial radionuclides in locally produced foods raised food safety concerns. In this study, the radioactivity concentrations and annual ingestions of ⁴⁰K and ¹³⁷Cs in food products commonly and frequently consumed by the general public were investigated, and the annual effective dose of each was evaluated. Materials and Methods: The 2016-2018 data from the Radiation Safety Management Report released by the Korea Nuclear Safety Technology Center was referenced for the evaluation of the amounts of ⁴⁰K and ¹³⁷Cs contained in food. Using the food-ingestion survey mentioned above as a reference, we selected 62 foods to include in our radioactivity concentration and dose assessment. We also developed a questionnaire and evaluated the responses from the subjects who answered the questionnaire. Results and Discussion: The radioactivity concentration of ¹³⁷Cs was found to be close to or below the level of minimum detectable activity. Additionally, the annual ingestion of 62 foods was 294.77 kg/yr, the effective doses from ⁴⁰K and ¹³⁷Cs were 136.4 and 0.163 μSv/yr, respectively. Conclusion: Thus, the findings confirmed that the effective dose from ⁴⁰K and ¹³⁷Cs in food tends to be lower than the effective dose limit of 1 mSv/yr suggested by the International Commission on Radiological Protection (ICRP) Publication 60. The questionnaire developed in this study is expected to be useful for estimating the annual effective dose status of Korean adults who consume foods containing ⁴⁰K and ¹³⁷Cs.

• 방사성폐기물학회지
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• 제6권2호
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• pp.111-117
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• 2008

배관 내부의 방사성 오염도를 측정하기 위한 ZnS(Ag)/플라스틱섬광체 조합의 알파/베타선 동시측정용 phoswich 검출기를 개발하였다. 알파/베타선 동시측정용 phoswich 검출기의 오염위치에 따른 검출 성능을 PSD (Pulse shape discrimination) 방법을 이용하여 평가하였다. 또한, 검출기를 방사성 오염물질로부터 보호하기 위한 오염방지용 필름에 대한 방사선 감쇄 정도를 실험적으로 평가하였다. PSD 방법으로 알파/베타선 분리 정도를 측정한 결과 충분히 알파와 베타선이 분리되었으며 오염방지용 필름의 적용 가능성을 확인하였다.

• Journal of Radiation Protection and Research
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• 제46권4호
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• pp.178-183
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• 2021

Background: This study was carried out to provide environmental transfer parameter values to estimate activity concentrations of these radionuclides in agricultural crops when direct contamination occurred. Materials and Methods: Mass interception fractions (F_Bs) and weathering half-lives (T_ws) of ¹³¹I and radiocesium were calculated using openly available monitoring data obtained after the Fukushima Daiichi Nuclear Power Plant accident. F_B is the ratio between the initial radioactivity concentration of a radionuclide retained by the edible part of the plant (Bq·kg^-1 fresh weight [FW]) and the amount of deposited radionuclide in that area (Bq·m^-2). T_w values can be calculated using activity concentrations of crops decreased with time after the initial contamination. Results and Discussion: Calculated F_B and T_w values for ¹³¹I and radiocesium were mostly obtained for leafy vegetables. The analytical results showed that there was no difference of F_Bs between ¹³¹I and radiocesium by t-test; geometric mean values for leafy vegetables cultivated under outdoor conditions were 0.058 and 0.12 m²·kg^-1 FW, respectively. Geometric mean T_w value of ¹³¹I in leafy vegetables grown under outdoor conditions was 8.6 days, and that of radiocesium was 6.6 days; there was no significant difference between T_w values of these radionuclides by Wilcoxon rank sum test. Conclusion: There was no difference between ¹³¹I and radiocesium for F_Bs and T_ws. By using these factors, we would be able to carry out a rough estimation of the activity concentrations of ¹³¹I and radiocesium in the edible part of leafy crops when a nuclear accident occurred.

• 한국융합학회논문지
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• 제11권8호
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• pp.71-76
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• 2020

본 연구는 병원 내 일반 공용화장실과 핵의학 전용화장실내의 방사성 표면오염도를 측정하였다. 측정방법은 Berthold(LB 124, Germany)을 이용하여 화장실 입구, 대변기 안, 대변기 주위바닥, 소변기 안, 소변기 주위바닥에서 측정하였다. 화장실 사용실태 결과 3곳의 병원 중 1곳의 병원에서 방사성동위원소를 투여 받은 환자가 대기하는 전용장소가 없었다. 방사성동위원소 전용 화장실을 측정한 결과 방사성옥소 치료병실에서 모든 측정 장소가 가장 높게 측정되었고, 공용화장실을 측정한 결과는 B병원을 제외한 모든 병원의 측정 장소에서 백그라운드 수준의 오염도를 나타냈다. 하지만 B병원의 1층 공용화장실 소변기 안, 소변기 주위바닥에서 8.073 Bq/㎠, 6.426 Bq/㎠으로 측정되었다. 따라서 환자들에게 방사선피폭의 위험성을 설명하고, 환자가 대기할 수 있는 장소를 마련할 것을 권고 한다. 그리고 방사성동위원소를 투여 받은 환자는 불필요한 이동과 일반 공용화장실을 사용하지 못하도록 하는 방안이 모색되어야 할 것이다.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.274-281
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• 2016

Background: Whole-body counters are widely used to evaluate internal contamination of the internal presence of gamma-emitting radionuclides. In internal dosimetry, it is a basic requirement that quality control procedures be applied to verify the reliability of the measured results. The implementation of intercomparison programs plays an important role in quality control, and the accuracy of the calibration and the reliability of the results should be verified through intercomparison. In this study, we evaluated the reliability of 2 whole-body counting systems using 2 calibration methods. Materials and Methods: In this study, 2 whole-body counters were calibrated using a reference male bottle manikin absorption (BOMAB) phantom and a Radiation Management Corporation (RMC-II) phantom. The reliability of the whole-body counting systems was evaluated by performing an intercomparison with International Atomic Energy Agencyto assess counting efficiency according to the type of the phantom. Results and Discussion: In the analysis of counting efficiency using the BOMAB phantom, the performance criteria of the counters were satisfied. The relative bias of activity for all radionuclides was -0.16 to 0.01 in the Fastscan and -0.01 to 0.03 in the Accuscan. However, when counting efficiency was analyzed using the RMC- II phantom, the relative bias of $^{241}Am$ activity was -0.49 in the Fastscan and 0.55 in the Accuscan, indicating that its performance criteria was not satisfactory. Conclusion: The intercomparison process demonstrated the reliability of whole-body counting systems calibrated with a BOMAB phantom. However, when the RMC-II phantom was used, the accuracy of measurements decreased for low-energy nuclides. Therefore, it appears that the RMC-II phantom should only be used for efficiency calibration for high-energy nuclides. Moreover, a novel phantom capable of matching the efficiency of the BOMAB phantom in low-energy nuclides should be developed.

• Journal of Radiation Protection and Research
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• 제41권4호
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• pp.333-338
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• 2016

Background: In case of radiation emergencies, internal exposure monitoring for the members of public will be required to confirm internal contamination of each individual. In-vivo monitoring technique using portable gamma spectrometer can be easily applied for internal exposure monitoring in the vicinity of the on-site area. Materials and Methods: In this study, minimum detectable doses (MDDs) for $^{134}Cs$, $^{137}Cs$, and $^{131}I$ were calculated adjusting minimum detectable activities (MDAs) from 50 to 1,000 Bq to find out the optimal in-vivo counting condition. DCAL software was used to derive retention fraction of Cs and I isotopes in the whole body and thyroid, respectively. A minimum detect-able level was determined to set committed effective dose of 0.1 mSv for emergency response. Results and Discussion: We found that MDDs at each MDA increased along with the elapsed time. 1,000 Bq for $^{134}Cs$ and $^{137}Cs$, and 100 Bq for $^{131}I$ were suggested as optimal MDAs to provide in-vivo monitoring service in case of radiation emergencies. Conclusion: In-vivo monitoring program for emergency response should be designed to achieve the optimal MDA suggested from the present work. We expect that a reduction of counting time compared with routine monitoring program can achieve the high throughput system in case of radiation emergencies.