• 방사선산업학회지
• /
• 제17권2호
• /
• pp.151-160
• /
• 2023

The International Atomic Energy Agency (IAEA) proposes 11 industries that handle Naturally Occurring Radioactive Material (NORM) that are considered to need management. A water treatment facility is one of the above industries that takes in groundwater and produces drinking water through a water treatment process. Groundwater can accumulate natural radionuclides such as uranium and thorium in raw water by contacting rocks or soil containing natural radionuclides. Therefore, there is a possibility that workers in water treatment facilities will be exposed due to the accumulation of natural radionuclides in the water treatment process. The goal of this study is to evaluate the external radiation dose according to the working type of workers in water treatment facilities. In order to achieve the above goal, the study was conducted by dividing it into 1) analysis of the exposure environment, 2) measurement of the external radiation dose rate 3) evaluation of the external radiation dose. In the stage of analyzing the exposure environment, major processes that are expected to occur significantly were derived. In the measurement stage of the external radiation dose rate, a map of the external radiation dose rate was prepared by measuring the spatial radiation dose rate in major processes. Through this, detailed measurement points were selected considering the movement of workers. In the external radiation dose evaluation stage, the external radiation dose was evaluated based on the previously derived external radiation dose rate and working time. As a result of measuring the external radiation dose rate at the detailed points of water treatment facilities A to C, it was 1.90×10^-1 to 3.75×10⁰ μSv h^-1, and the external radiation dose was analyzed as 3.27×10^-3 to 9.85×10^-2 mSv y^-1. The maximum external radiation dose appeared during the disinfection and cleaning of activated carbon at facility B, and it is judged that natural radionuclides were concentrated in activated carbon. It was found that the external radiation dose of workers in the water treatment facility was less than 1mSv y^-1, which is about 10% of the dose limit for the public. As a result of this study, it was found that the radiological effect of external radiation dose of domestic water treatment facility workers was insignificant. The results are expected to contribute as background data to present optimized safety management measures for domestic NORM industries in the future.

• Journal of Radiation Protection and Research
• /
• 제37권4호
• /
• pp.231-236
• /
• 2012

This study derived measures to reduce exposure doses by identifying factors which affect the external radiation dose rate of patients treated with radiopharmaceuticals for PET-CT tests. The external radiation dose rates were measured on three parts of head, thorax and abdomen at a distance of 50cm from the surface of 60 PET-CT patients. It showed there are changes in factors affecting the external radiation dose rate over time after the administration of F-18 FDG. The external radiation dose rate was lower in the patients with more water intake than those with less water intake before the injection of radiopharmaceuticals at all three points: right after the injection of radiopharmaceuticals (average 4.17 mins), after the pre-PEET-CT urination step (average 77.47 mins), and right after the PET-CT test (average 114.15 mins). The study also found there is a need to increase the amount of water intake before the injection of radiopharmaceuticals in order to maintain a low external radiation dose rate in patients. This strategy is only possible under the assumption that the quality of the video has not changed after conducting this study on the relations between the image and quality. This study also found a need to use radiopharmaceuticals with the minimum amount needed for each patient because F-FDG doses affects the external radiation dose rate at the point right after the injection of radiopharmaceuticals. Urination frequency was the most significant factor to affect the external radiation dose rates at the point right after the PET-CT test and the point after the pre-PET-CT urination step. There is a need to realize the strategy to increase the urination frequency of patients to maintain the external radiation dose rate low (average 77.47 mins) before and after the injection of radiopharmaceuticals. In addition, at this point, there is a need to take advantage of personal strategies because the external radiation dose rate is lower if the fasting time is shorter, the contrast medium is used, and the amount of water intake is increased after the administration of radiopharmaceuticals. Finally this study found the need to be able to generalize these findings through an in-depth research on the factors affecting the external radiation dose rate, which includes radiopharmaceutical dose, urination frequency, the amount of water intake, fasting time and the use of contrast medium.

• 한국방사선학회논문지
• /
• 제11권5호
• /
• pp.321-328
• /
• 2017

D-Shuttle (Chiyoda Technol Corporation, Tokyo, Japan) 선량계를 이용하여 개인피폭관리 및 자연방사선량의 모니터링을 위한 기초자료를 제공하는데 연구의 목적이 있다. D-Shuttle을 이용하여 선량을 산출하였다. 선량보고서에서 400 일 노출되었을 때에 1.346 mSv 이었고, 연간선량 (annual dose per year)은 1.228 mSv/year, 평균시간선량 (average dose per hour)은 $0.014{\mu}Sv/hr$ 이었다. 국내의 개인 외부피폭선량 (1.295 mSv/year =Korea average natural individual external dose), 국내의 연간부가선량 (additional dose per year)은 -0.0663 mSv/year 이다. D-Shuttle은 방사선모니터링을 위한 개인선량계로 방사선의 검출성능 우수한 기능, 실시간 방사선 피폭관리, 방사선 작업의 경보 기능, 효율적이고 사용이 편리한 개인 방사선선량의 피폭관리로 ALARA에 매우 유용한 선량계로 사용할 수 있다. 방사선작업종사자와 지역주민의 방사선모니터링 측정기기로 병원, 산업, 의료현장, 원전사고 지역과 비파괴 분야의 위험한 지역에서 방사선모니터링으로 활용될 수 있다.

• Journal of Radiation Protection and Research
• /
• 제38권3호
• /
• pp.157-165
• /
• 2013

To determine the factors affecting the external radiation dose rates of patients undergoing PET-MRI examinations and to assess the trends of these differences, we measured the changes in the dose rates of $^{18}F$-FDG during a set period of time for each body region. Consistent with theoretical predictions, the dose rate decreased over time in patients undergoing PET-MRI examinations. Furthermore, immediately after the $^{18}F$-FDG injection, the dose rate in the chest region was the highest, followed by the abdominal region, the head region, and the foot region. The dose rate decreased drastically as time passed, by 2.47-fold, from $339.23{\pm}74.70mSv\;h^{-1}$ ($6.73{\pm}5.79$ min) at the time point immediately after the $^{18}F$-FDG injection to $102.71{\pm}26.17mSv\;h^{-1}$ ($136.11{\pm}25.64$ min) after the examination. In the foot region, there were no significant changes over time, from $32.05{\pm}20.23mSv\;h^{-1}$ ($6.73{\pm}5.79$ min) at the time point immediately after the $^{18}F$-FDG injection, to $23.89{\pm}9.14mSv\;h^{-1}$ ($136.11{\pm}25.64$ min) after the examination. The dose rate is dependent on the individual characteristics of the patient, and differed depending on the body region and time point. However, the dose rates were higher in patients who had a lower body weight, shorter stature, fewer urinations, lower fluid intake, and history of diabetes mellitus. To decrease radiation exposure, it is difficult or impossible to change factors inherent to the patient, such as sex, age, height, body weight, obesity, and history of diabetes mellitus. However, factors which can be changed, such as the $^{18}F$-FDG dose, fasting time, fluid intake, number of urinations, and contrast agent dose can be controlled to minimize the external radiation exposure of the patient.

• Nuclear Medicine and Molecular Imaging
• /
• 제43권4호
• /
• pp.259-279
• /
• 2009

Radioiodine ablation therapy has been considered to be a standard treatment for patient with differentiated thyroid cancer after total thyroidectomy. Patients may need to be hospitalized to reduce radiation exposure of other people and relatives from radioactive patients receiving radioiodine therapy. Medical staffs, nursing staffs and technologists sometimes hesitate to contact patients in radioiodine therapy ward. The purpose of this paper is to introduce radiation dosimetry, estimate radiation dose from patients and emphasize the safety of radiation exposure from patients treated with high dose radioiodine in therapy ward. The major component of radiation dose from patient is external exposure. However external radiation dose from these patients treated with typical therapeutic dose of 4 to 8 GBq have a very low risk of cancer induction compared with other various risks occurring in daily life. The typical annual radiation dose without shielding received by patient is estimated to be 5 to 10 mSv, which is comparable with 100 to 200 times effective dose received by chest PA examination. Therefore, when we should keep in mind the general principle of radiation protection, the risks of radiation exposure from patients are low and the medical personnel are considered to be safe from radiation exposure.

• Journal of Radiation Protection and Research
• /
• 제45권2호
• /
• pp.81-87
• /
• 2020

Background: Kori unit #1 is permanently shut down after a 40-year lifetime. The Nuclear Safety and Security Commission recommends establishing initial decommissioning plans for all nuclear and radwaste treatment facilities. Therefore, the Korea Atomic Energy Research Institute (KAERI) must establish an initial and final decommissioning plan for radwaste-treatment facilities. Radiation safety assessment, which constitutes one chapter of the decommissioning plan, is important for establishing a decommissioning schedule, a strategy, and cost. It is also a critical issue for the government and public to understand. Materials and Methods: This study provides a method for assessing external radiation dose to workers during decommissioning. An external dose is calculated following each exposure scenario, decommissioning strategy, and working schedule. In this study, exposure dose is evaluated using the deterministic method. Physical characterization of the facility is obtained by both direct measurement and analysis of the drawings, and radiological characterization is analyzed using the annual report of KAERI, which measures the ambient dose every month. Results and Discussion: External doses are calculated at each stage of a decommissioning strategy and found to increase with each successive stage. The maximum external dose was evaluated to be 397.06 man-mSv when working in liquid-waste storage. To satisfy the regulations, working period and manpower must be managed. In this study, average and cumulative exposure doses were calculated for three cases, and the average exposure dose was found to be about 17 mSv/yr in all the cases. Conclusion: For the three cases presented, the average exposure dose is well below the annual maximum effective dose restriction imposed by the international and domestic regulations. Working period and manpower greatly affect the cost and entire decommissioning plan; hence, the chosen option must take account of these factors with due consideration of worker safety.

• Nuclear Engineering and Technology
• /
• 제54권5호
• /
• pp.1781-1788
• /
• 2022

The containment building Kori Unit 1 may require sequential steps for full decommissioning. This study assumes that the containment building is to be used as an auxiliary building that handles nuclear power systems and materials during decommissioning before conversion into a greenfield. Through the derivation of guidelines and dose evaluation, it was confirmed whether the radiation workers were satisfied with the ALARA decision. The specific modeling of the external radiation exposure was performed based on the facility investigation procedures. The external radiation specific derived concentration guideline levels (DCGLs) for radiation workers in containment building were obtained using the RESRAD-BUILD code and were applied to the VISIPLAN 3D ALARA Planning Tool code to calculate the working dose and check worker safety. The derivation of site-specific and realistic DCGLs and dose evaluation via 3D modeling can contribute to the scenario development for the decommission and remediation of containment building.

• 대한방사선방어학회:학술대회논문집
• /
• 대한방사선방어학회 2009년도 춘계 학술발표
• /
• pp.272-273
• /
• 2009

• Journal of Radiation Protection and Research
• /
• 제45권2호
• /
• pp.53-68
• /
• 2020

Background: International organizations such as the World Health Organization (WHO) and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) reported public exposure doses due to radionuclides released in the Fukushima nuclear accident a few years after the event. However, the reported doses were generally overestimated due to conservative assumptions such as a longer stay in deliberate areas designated for evacuation than the actual stay. After these reports had been published, more realistic dose values were reported by Japanese scientists. Materials and Methods: The present paper reviews those reports, including the most recently published articles; and summarizes estimated effective doses (external and internal) and issues related to their estimation. Results and Discussion: External dose estimation can be categorized as taking two approaches-estimation from ambient dose rate and peoples' behavior patterns-and measurements using personal dosimeters. The former approach was useful for estimating external doses in an early stage after the accident. The first 4-month doses were less than 2 mSv for most (94%) study subjects. Later on, individual doses came to be monitored by personal dosimeter measurements. On the basis of these measurements, the estimated median annual external dose was reported to be < 1 mSv in 2011 for 22 municipalities of Fukushima Prefecture. Internal dose estimation also can be categorized as taking two approaches: estimation from whole-body counting and estimation from monitoring of environmental samples such as radioactivity concentrations in food and drinking water. According to results by the former approach, committed effective dose due to ¹³⁴Cs and ¹³⁷Cs could be less than 0.1 mSv for most residents including those from evacuated areas. Conclusion: Realistic doses estimated by Japanese scientists indicated that the doses reported by WHO and UNSCEAR were generally overestimated. Average values for the first-year effective doses for residents in two affected areas (Namie Town and Iitate Village) were not likely to reach 10 mSv, the lower end of the doses estimated by WHO.

• Radiation Oncology Journal
• /
• 제14권3호
• /
• pp.201-209
• /
• 1996

목적 : FIGO 병기 Ib 자궁경부편평상피암 환자에서 고선량율 강내치료를 이용한 방사선치료후 환해율, 5년 국소제어을, 5년 생존율 및 예후인자, 방사선 합병증을 분석하여 고선량율 강내치료의 효용성을 평가하고자 하였다. 그리고 심각한 후기 합병증 없이 만족스런 국소 제어율을 얻기 위한 외부방사선선량과 강내치료선량의 최적 선량배합을 알아보고자 하였다. 대상 및 방법 : 1979. 5 - 1990. 12월 까지 연세암센타 치료방사선과에서 자궁경부 편평상피암 FlGO 병기 Ib로 진단된후 근치적 목적하에 외부 및 강내치료를 받은 162명의 환자들을 대상으로 치료 결과를 후향적 분석하였다. 외부 방사선 치료는 LINAC 10MV X-ray를 이용해 180-200cGy/fr씩 4000-4600cGy14.5-5주를 전골반 부위에 시행하였근데, 일부환자에서 2000-4000 cGy에서 중앙차폐(midline block)를 시행하였다. 코발트 선원을 이용한 원격 조정 아프터 로딩 고선량율 강내치료를 A점에 1회당 300cGy씩 주 3회, 총 10-13회 (3000-3900 cGy)실시하여 A 점에 들어간 총방사선 조사량은 6420 - 9500cGy 으로 평균 8394 cGy 였다. 결과 : 방사선 치료후 완전 관해율은 $99.4\%$ 였다. 5년 전체생존율은 $91.1\%$이고, 5년 무병생존율은 $90.9\%$였다. 추적 관찰 기간동안 치료 실패 양상을 관찰해 보면 국소 실패만 보인 경우는 7명이었고 원격전이만 보인경우가 6명이었으며, 국소 및 원격전이가 모두 발생한 경우가 1예 있어서 국소제어 실괘율은 $4.9\%$(8/163), 원격전이율은 $4.3\%$(7/164)였다. 후기 합병증은 38명 ($23.5\%$)에서 발생하였초, 그 중 30병 직장 합병증으로 $18.5\%$ 후기 합병증 발생율을 보였고, 방광 합병증은 8명에서 발생하여 $4.9\%$ 후기 합병증 발생율을 보였다. 직장 합병증이 생긴 환자관에서 직장에 소사된 방사선량은 평균 7887 cGy 이었고, 합병증이 발생하지 않은 환자군의 평균조사량은 7488 cGy이었다. 결론 : 근치적 목적으로 외부 방사선 치료 및 고선량률 강내 치료는 FIGO병기 Ib 자궁경 부편평상피암을 치료하는데 매우 효과석이라 생각하였고, 외부방사선치료중 중앙차폐를 시행하여 A점 선량이 75Gy를 넘지 않게 방사선치료 설계를 하면 심각 합병증없이 좋은 치료성적을 얻을 수 있겠다.