Earticle

국내에서는 2012년 천연방사성핵종이 포함된 가공제품의 규제를 위해 생활주변방사선 안전관리법이 시행되었지만, 해당 가공제품 사용에 대한 인체 피폭선량을 평가할 수 있는 기초자료나 피폭선량 평가기술이 미비하다. 따라서 본 연구는 사용자 피폭선량을 정량적으로 평가하기 위한 방법을 제안하고, 방사선의 종류 및 에너지에 따른 피폭선량 특성의확인을 목적으로 한다. 피폭선량 평가를 위해서 몬테칼로 방법을 사용한 Monte Carlo N-Particle Extended (MCNPX)코드를 통해 International Commission on Radiological Protection (ICRP)의 기준팬텀이 전산모사 되었으며, 대표적천연방사성핵종인 우라늄 계열에서 발생되는 알파선, 베타선, 감마선의 최소, 중간, 최대 에너지가 선원항으로 사용되었다. 연간 유효선량은 가공제품 사용시간 및 사용위치를 고려한 피폭시나리오를 기반으로 평가되었다. 짧은 비정의알파선 및 베타선은 대부분의 선량을 피부에 전달한 반면, 감마선은 대부분의 장기에 유사한 선량을 전달하였다. 방사능이 1 Bq·g-1 인 돌침대에 포함된 천연방사성핵종의 함유율이 10%라고 가정하고 한국인 평균 수면시간인 7시간 50분간 돌침대를 사용하였을 때 최대 연간 유효선량은 알파선, 베타선, 감마선에 대해서 각각 0.0222, 0.0836, 0.0101mSv·y-1로 평가되었다.

In Korea, July 2012, the law as called ‘Act on Safety Control of Radioactive Rays Around Living Environment’ wasimplemented to control the consumer product containing Naturally Occurring Radioactive Material (NORM), but, there are noappropriate database and effective dose calculation system. The aim of this study was to develop evaluation technique ofthe exposure dose with the use of the consumer products containing NORM and to understand the characteristics of theexposed dose according to the radiation type and energy. For the evaluate of exposure dose, the ICRP reference phantomwas simulated by the MCNPX code based on Monte Carlo method, and the minimum, medium, maximum energy of alphas,betas, gammas from the representative NORM of Uranium decay series were used as the source term in the simulation. Theannual effective doses were calculated by the exposure scenario of the consumer product usage time and position. Short rangeof the alpha and beta rays are mostly delivered the dose to the skin. On the other hand, the gamma rays mostly deliveredthe similar dose to all of the organs. The results of the annual effective dose with 1 Bq·g-1 radioactive stone-bed and 10%radioactive concentration were employed with the usage time of 7 hours 50 minute per day, the maximum annual effectivedose of alphas, betas, gammas were calculated 0.0222, 0.0836, 0.0101 mSv·y-1, respectively.

This study was designed to assess whether the conventional tangential technique, using a multileaf collimator (MLC), allows a reduced dose to the organs at risk (OAR) in breast radiation therapy. A total of forty right and left 20 for each breast cancer patients that underwent radiation therapy after breast conserving surgery were included in this study. For each patient, the planning target volume (PTV) and OAR (heart, left anterior descending artery (LAD), liver and lung) were defined and dose distribution were produced for conventional tangential beams using 6 MV photons. The treatment plans were made using the following two techniques for all patients. For the first plan (P1), MLC was designed to shield as much of OAR as possible without compromising the coverage of PTV. In the second plan (P2), the treatment plan was created without using MLC. Dose-volume histograms for OARs were calculated for all plans. For left breast cancer, the percentage of maximum dose (Dmax%) and mean dose (Dmean%) of OARs (heart and LAD) were calculated, and for right breast cancer, the percentage of the mean dose (Dmean%) of the liver was calculated. The Dmean% of the lung was calculated in all patients. The mean values of Dmax% of the heart (86.9±19.5% range, 35.1-100.6%) in P1 were significantly lower than in P2 (98.3±3.4% range, 91.7-105.2%) (p=0.001). The mean values of Dmax% of LAD (78.4±22.5% range, 26.5-99.7%) in P1 was significantly lower than in P2 (93.3±8.1% range, 67.9-102.1%) (p<0.001). In P1, the mean values of Dmean% of the liver (4.8±2.0%) were significantly lower than in P2 (6.2±2.5%) (p<0.001). The mean values of Dmean% of the lung were significantly lower in P1 (9.3±2.3%) than in P2 (9.7±2.4%) (p<0.001). P1, by using MLC, allows a significantly reduced dose to OAR compared with P2. We can suggest that it is reasonable to routinely use MLC in the conventional tangential technique for breast radiation therapy considering the primary tumor location.

The object of this paper is to evaluate the fission product inventories and radiological doses in a non- LOCA event, based on the U.S. NRC’s regulatory methodologies recommended by the TID-14844 and the RG 1.195. For choosing a non-LOCA event, one fuel assembly was assumed to be melted by a channel blockage accident. The Hanul nuclear power reactor unit 6 and the CE 16×16 fuel assembly were selected as the computational models. The burnup cross section library for depletion calculations was produced using the TRITON module in the SCALE6.1 computer code system. Based on the recently licensed values for fuel enrichment and burnup, the source term calculation was performed using the ORIGEN-ARP module. The fission product inventories released into the environment were obtained with the assumptions of the TID-14844 and the RG 1.195. With two kinds of source terms, the radiological doses of public in normal environment reflecting realistic circumstances were evaluated by applying the average condition of meteorology, inhalation rate, and shielding factor. The statistical analysis was first carried out using consecutive three year-meteorological data measured at the Hanul site. The annual-averaged atmospheric dispersion factors were evaluated at the shortest representative distance of 1,000 m, where the residents are actually able to live from the reactor core, according to the methodology recommended by the RG 1.111. The Korean characteristic-inhalation rate and shielding factor of a building were considered for a series of dose calculations.

Recently, the use of panoramic radiography has shown a constant increase, and significant research is underway. However, radiation exposure attracts less attention in dental radiography than in other types of radiography. We used an OSLD for measurement of the entrance skin dose in eyeballs and the thyroid region, both of which are not covered by examinations but are included in radiographical regions and are sensitive to radiation, as well as orally in Incheon and reported the results. The entrance skin dose was 0.0282 mSv on average for the oral region, and 0.0259 mSv on average for the eyeball, and 0.0261mSv on average, for thyroid gland. While there is no proper shielding method for the eyeball, a thyroid protector is not used by most hospitals and most hospitals are equipped with an apron and a thyroid protector separately; thus, it is necessary to use an integration of an apron and a thyroid protector and medical device manufacturers need to develop a method for controlling the length of the slit in the slit-type area of radiation occurrence in order to reduce unnecessary exposure.

학교에서 표준화된 원자력 및 방사선 기초교육을 실시하기 위해 학생, 과학교사, 전문가의 입장을 반영한 교육과정을 개발하였다. 초(78.4%), 중(78.6%), 고등학교(93.1%) 모두 높은 빈도로 원자력 및 방사선에 대한 학교교육이 필요하다 고 나타냈다. 교과목 제목은 초등학교의 경우 “방사선과 생활”, 중, 고등학교의 경우 “원자력과 방사선”이다. 학급별로 한 학기, 주당 1시간(초등학교 40분, 중학교 45분, 고등학교 50분 기준) 교육을 요구하였다. 교재는 얇고, 만화와 사진 이 많이 포함된 것을 요구하였다. 교육 시작시기로는 초등학생은 6학년, 중학생은 2학년, 고등학생은 1년 때 배우는 것을 요구하였다. 교육형태는 정규교과가 아니라 창의적 체험학습으로 학교와 과학교사의 필요에 따라서 선택하는 것 을 선호하였다. 학급별로 교육시간, 교재형식, 교육형태, 교육의 필요성에 대해서 모두 같은 요구 경향을 나타냈다. 고안된 교육과정을 모의 실시한 결과 전체적인 적합도는 5점 만점에서 초등학생 3.88±0.60점, 중학생 3.89±0.60점, 고등학생 3.66±0.63점으로 모두 70점(100점 만점 기준) 이상의 수준을 나타냈다. 본 연구는 원자력 및 방사선이해를 바탕으로 가치판단의 능력을 함양하기 위한 학교 교육과정을 최초로 고안했다는 것에 큰 의미를 둔다. 그러나 원자력 및 방사선에 대한 학교 교육이 실현되기 위해서는 후속조치로 교육과정에 적합한 교재개발, 관련 법령 개정, 교안제공 등이 이루어져야 한다.

I developed a curriculum reflecting the perspectives of students, science teachers, and professionals in order to carry out standardized, fundamental nuclear power and radiation education in schools. Among elementary, middle, and high schools, 78.4%, 78.6%, and 93.1% respectively exhibited (with high frequency) a need for nuclear power and radiation education. The proposed elementary and middle/high school course titles are “Radiation and Life” and “Nuclear Power and Radiation” respectively. The courses are offered at every grade level and span one semester each year. The duration of each weekly class varies; at the elementary, middle, and high school levels classes meet for 40, 45, and 50 minutes respectively. Thin textbooks containing an abundance of cartoons and photos were requested. The starting points for education were fixed at the sixth grade, second year of middle school, and the first year of high school. It was stipulated that the education be separate from the regular curriculum, and encompass a creative and experimental field study based on the principal and science teachers’ needs. Similar trends were observable according to grade levels regarding class hours, textbook format, form of education, and educational necessity. A simulation of the devised curriculum revealed an overall goodness of fit totaling 3.88±0.60, 3.89±0.60, and 3.66±0.63 out of five for elementary, middle school, and high school students respectively, which are scores equivalent to 70 and above (out of 100). The significance of this study is that it is the first to propose a curriculum designed to cultivate value judgment based on understanding nuclear power and radiation. However, the realization of nuclear power and radiation education requires that follow-up measures be taken regarding textbook development, amendments to related laws, and the providing of teaching plans.

중성자 검출분야에서 3He는 높은 중성자 검출효율 때문에 아주 많이 사용되고 있다. 하지만 2009년 초반부터 발생하 고 있는 전세계적인 3He의 품귀현상으로 인하여 가격이 급등하고 수급이 어려워졌기 때문에 대체 중성자 검출물질에 대한 필요성이 높아졌다. 그러므로 중성자 검출물질로 사용될 수는 있지만 3He에 비해 반응효율이 낮아 중성자 검출용 으로 주로 사용되지 않던 물질들을 사용하여 검출기를 제작하는 연구가 다시 활발하게 진행되고 있다. BF3, 6Li, 10B, Gd2O2S 등과 같은 3He 대체 물질들 중 하나인 10B은 손쉬운 감마선 구별, 무독성, 낮은 가격 등과 같은 여러 장점으로 인하여 여러 연구그룹에서 연구되고 있다. 10B 박막을 이용한 중성자 검출은 중성자와 반응하여 발생되는 2차 방사선 을 측정하여 간접적으로 중성자를 측정하는 검출기법이다. 반응을 통해 생성된 알파입자의 비정은 고체 내에서 아주 짧기 때문에 10B 층은 박막 형태로 얇게 제작해야 한다. 그러므로 중성자와 박막의 반응을 통해 발생되는 알파입자의 검출효율을 증가시키기 위해서는 10B 박막의 두께를 얇게 제작하는 것이 중요하다. 하지만 박막의 두께를 얇게 제작하 는 것은 중성자와 반응하여 생성되는 알파입자의 수집효율을 증가시키는 장점이 있지만 또한 중성자와 반응할 단면적 을 감소시키는 단점이 있다. 본 논문에서는 리튬이온전지에 사용되는 초박막 극판 제조 기술을 이용하여 중성자 검출 을 위한 대략 60 μm 두께의 얇은 10B 박막을 제작하였다. 그리고 전도성, 분포, 점착력, 유연성와 같은 간단한 물리적 실험을 통해 제작된 10B 박막의 물성을 확인하였다. 또한, 제작된 10B 박막을 사용하여 중성자 모니터링을 위한 비례계 수기 제작하고 이를 이용하여 한국원자력연구원의 중성자 조사시설의 중성자 파고 스펙트럼을 측정하였다. 또한, 중성 자 검출효율을 증가시킬 수 있는 방법 중 하나인 다층 박막을 이용한 중성자 측정 방법을 이용하여 박막 층수에 따른 중성자 검출효율의 변화를 몬테칼로 전산모사 기법을 이용하여 계산하였고 실험을 통해 박막층의 증가에 따른 신호변 화를 측정하였다.

In the field of neutron detections, 3He gas, the so-called “the gold standard,” is the most widely used material for neutron detections because of its high efficiency in neutron capturing. However, from variable causes since early 2009, 3He is being depleted, which has maintained an upward pressure on its cost. For this reason, the demands for 3He replacements are rising sharply. Research into neutron converting materials, which has not been used well due to a neutron detection efficiency lower than the efficiency of 3He, although it can be chosen for use in a neutron detector, has been highlighted again. 10B, which is one of the 3He replacements, such as BF3, 6Li, 10B, Gd2O2S, is being researched by various detector development groups owing to a number of advantages such as easy gamma-ray discrimination, non- toxicity, low cost, etc. One of the possible techniques for the detection is an indirect neutron detection method measuring secondary radiation generated by interactions between neutrons and 10B. Because of the mean free path of alpha particle from interactions that are very short in a solid material, the thickness of 10B should be thin. Therefore, to increase the neutron detection efficiency, it is important to make a 10B thin film. In this study, we fabricated a 10B thin film that is about 60 um in thickness for neutron detection using well-known technology for the manufacturing of a thin electrode for use in lithium ion batteries. In addition, by performing simple physical tests on the conductivity, dispersion, adhesion, and flexibility, we confirmed that the physical characteristics of the fabricated 10B thin film are good. Using the fabricated 10B thin film, we made a proportional counter for neutron monitoring and measured the neutron pulse height spectrum at a neutron facility at KAERI. Furthermore, we calculated using the Monte Carlo simulation the change of neutron detection efficiency according to the number of thin film layers. In conclusion, we suggest a fabrication method of a 10B thin film using the technology used in making a thin electrode of lithium ion batteries and made the 10B thin film for neutron detection using suggested method.

진폐요양기관에 대한 실태조사를 실시하여 진폐요양환자에게 사용되는 흉부 CT촬영 선량이 국내외 진단 참고 준위 내에서 사용되는지 알아보았다.진폐요양기관은 27개 중에서 운용자 콘솔 컴퓨터에서 환자 피폭선량(dose length product, mGy*cm, 이하 DLP) 확인이 가능한 2-Detector 이상 설치된 17개 기관을 대상으로 하였다. 연구대상기관을 직접 연구자가 방문하여 위치잡이촬영, 조영제 사용전,후촬영 및 총 DLP 값을 각각 확인하였다. 또한, 장치의 기본 항목, 위치잡이촬영 조건, 본촬영(scanning) 조건 및 영상 획득 조건을 확인하였다. 흉부 CT촬영에서 확인된 총 DLP 값, 조영제주입전촬영 DLP 값의 상향서열 3/4 순위에 해당하는 DLP 값을 구하였다. SPSS ver. 19.0을 사용하여 전체 영상과 폐야영상 간에 조영제주입전촬영 DLP 값의 비교는 비모수 검정(Wilcoxon signed rank test)을 실시하였다. 전체영상보다 폐야영상을 얻을 때 20.2%의 유의한 DLP 값 감소를 보였다(707.2 vs. 555.9, p<0.001). 흉부 CT촬영에 서 확인된 총 DLP 값의 상향서열 3/4 순위(third quartile)의 DLP 값은 1036.1 mGy·cm였다. 흉부 CT촬영의 조영제 주입전촬영에서 확인된 DLP 값의 상향서열 3/4 순위의 DLP 값은 504.1 mGy·cm였다. 진폐요양환자의 흉부 CT촬영 에 사용하는 선량은 국내외 진단 참고 준위와 큰 차이를 보이지 않았다.

We report here on the results of evaluating the radiation doses using chest computed tomography (CT) for patients with pneumoconiosis complication. For the first time, we visited the 17 MIPs to evaluate the dose-length product (DLP, mGy·cm), CT unit, and protocols of scanning and image reconstruction those is routinely used for treating patients with pneumoconiosis who have complication. All statistical analysis was performed using the Statistical Program for Social Sciences (SPSS ver. 19.0, Chicago, IL, USA). Mean of total DLP was 727.7 mGy·cm, ranging from 272.0 to 1228.7 mGy·cm. DLP from obtaining parenchymal lung images was significantly reduced than that from obtaining total lung images (555.9 vs. 707.2, p<0.001). Third quartile of total and pre-scanning DLP was 1036.1 and 504.1 mGy·cm, respectively. Chest CT radiation doses for patients with pneumoconiosis complication are similar with korean diagnostic reference level as well as international guidelines.

중재방사선을 이용한 의료적 시술이나 진단은 꾸준히 증가하고 있다. 특히 환자에 근접하여 이루어지는 중재방사선시 술의 특성상 시술자에 대한 직무피폭의 관리 및 감시가 중요하다. 개인선량계를 통해 측정되는 방사선 방호 실용량인 심부선량은 중재방사선시술의 경우 균질한 방사선장에 의해 전신에 고르게 노출되는 경우가 아니므로 유효선량을 항 상 대표할 수는 없다. 따라서 본 연구에서는 C-arm을 이용한 대표적인 중재방사선시술에 대해 수학적 모의피폭체와 몬테카를로 방법을 이용한 계산과 개인선량계를 이용한 실측을 통해 개인선량당량과 장기별 선량을 평가하고자 하였 다. 주요 장기별 선량평가 결과는 개인선량계로 측정된 선량 값보다 낮았으나, 갑상선과 같은 장기는 전신 연조직 선량 보다 상당히 높은 것으로 평가되었다. 중재방사선시술자에 대한 적절한 방사선방호를 위해 납치마의 착용과 같은 전신 방호와 더불어 갑상선 방호와 같은 추가적인 방호조치가 고려되어야 할 것이다.

Medical operations and diagnosis using interventional radiology techniques have been increased. The management and monitoring of occupational radiation exposure to the staff of interventional radiology become important, specially because they stand in close proximity to the patient. The operational radiation protection quantity, Hp(10) which can be obtained from personal dosimeter do not always represent the effective dose to the staff. So, in this study, to estimate the critical organ doses to the staff of interventional radiology, Monte Carlo calculations with mathematical human phantom and dose measurements with personal dosimeters were carried out for the major interventional radiology procedures using C -arm. Results showed that the values of Hp(10) measured by personal dosimeters were higher than critical organ doses which were calculated. And the calculated dose to thyroids was much higher than those of other critical organ doses. For the proper radiation protection of the medical staff of interventional radiology, additional radiation protection for thyroids as well as for whole body shielding like wearing a lead apron should be considered.

원자력안전법에는 방사성동위원소 등의 취급에 관하여 방사성동위원소취급자일반면허, 특수면허 및 감독자면허 등 3 종의 면허가 있다. 이들 면허시험 응시자격은 학력과 교육훈련을 포함한 경력으로 구분된다. 원자력안전위원회는 경력 의 내용 및 산출방법을 정하여 고시한다. 본 논문에서는 과거에 운영된 방사선취급감독자면허 교육과정 종료 후 시행 된 교육만족도 및 운영에 관한 설문조사 자료를 분석하여 개선점을 도출하였다. 교육과정을 개선하기 위하여 학습평가 를 도입하여 운영하였으며, 개선된 교육과정과 기존 교육과정을 만족도 측면에서 비교하여 기술하였다. 학습평가를 도입한 교육과정은 기존 교육과정에 비해 만족도, 현업적용도 등에서 4.0점(5.0 만점 기준) 이상의 평가 결과를 나타냈 다. 이러한 결과를 바탕으로 방사선취급감독자면허 교육과정뿐만 아니라 방사성동위원소취급자일반면허 교육과정에도 학습평가를 적용하는 것이 바람직하다고 본다.

Nuclear Safety Act had described the three types of licenses on radioisotope handling, such as a general license, a special license and a supervisory license. Applicants should be qualified by careers and qualifications for the education and training to acquire the licenses. In particular, the information on the estimation for the career is notified by Nuclear Safety and Security Commission(NSSC). In this paper, we suggest an improvement by analyzing survey data at the end of the education course on a license for the supervisor of radiation handling. We applied the learning evaluation to improve the education course. The level of satisfaction with the improved curriculum was compared with the existing curriculum. The improved curriculum with the learning evaluation has shown high grades of performance, i.e. above 4.0 points (full mark: 5.0 points) on the level of satisfaction and field application. The learning evaluation should be applied to the basic education course on a general license for radioisotope handling.