• 대한방사선기술학회지:방사선기술과학
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• 제38권1호
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• pp.51-61
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• 2015

모든 방사선 검사는 검사를 결정하고 실행하는 과정에서 정당성이 확보되어야하고 피폭선량과 영상의 화질에 대한 최적화가 이루어져야 할 뿐만 아니라 ALARA의 원칙에 따라 최소의 방사선을 사용하여 최적의 임상 정보를 얻을 수 있어야 한다. CT 검사는 방사선 검사 중에서 많은 피폭을 환자에게 조사하는 검사이다. 특히 방사선 민감도가 높은 소아 환자의 CT 검사 있어서는 특별한 주의가 필요하다. 임상에서 CT선량에 대한 정확한 이해와 정보는 환자에게 불필요한 방사선 피폭을 줄이고 안전한 검사를 제공하기 위해 절대적으로 필요하다. 이에 본 연구에서는 여러 선행 연구의 고찰을 통하여 CT의 피폭선량에 대한 개념을 확인하고 CT장치의 선량 저감화를 위한 각 파라미터의 이해와 American Association of Physicists in Medicine (AAPM)report 204에서 소개하고 있는 환자의 사이즈에 따른 피폭선량의 보정방법인 Size-Specific Dose Estimates(SSDE)와 XR 25의 개념을 이해하고자 한다.

• Journal of the Korean Data and Information Science Society
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• 제17권4호
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• pp.1349-1364
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• 2006

An analytic approach that provides explicit estimates of risk on cataract and epilation data is evaluated by reasonableness of conceivable relative risk models regarding a simple, odds, logistic or Gompertz regression method, assuming a binomial distribution. In these analyses, we apply relative risk models with two thresholds between epilators and nonepilators from a highly characteristic lesion of which radiation cataract does not occur around 2 gray for a single acute exposure. The risk models are fitted to the data assuming 10 as a constant relative biological effectiveness of neutron. The likelihood of observing the entire data set in these models fitted is evaluated by an individual binary-response array. Estimation of a threshold with or without severe epilation and the 100 ($1-\alpha$)% confidence limits are derived from the maximum likelihood approach. The relative risk model with two thresholds can be expressed as a formula with structure of Background $\times$ RR, where RR includes threshold models with or without epilation. The radiosensitivity of ionizing radiation to cataracts has been examined for the relationship between epilators and nonepilators.

• 한국치위생학회지
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• 제20권3호
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• pp.269-279
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• 2020

Objectives: Previous studies have reported inconsistent findings in the association between dental diagnostic X-ray exposure and thyroid cancer. This study was a meta-analysis of case-control studies evaluating the association between exposure to dental radiation and the thyroid cancer risk. Methods: We searched the PubMed and EMBASE databases to identify studies on dental radiation and thyroid cancer risks that were published up to September 2018. Quality of studies was assessed using the Newcastle-Ottawa scale. A fixed-effects model was used to estimate pooled odds ratios (ORs) and 95% confidence intervals (CIs) using STATA 14.0. Potential publication biases were evaluated using Egger's test and Begg's funnel plot. Results: From the literature search, we included six case-control studies in this meta-analysis. The meta-analysis using the fixed-effects model found that dental X-ray exposure was associated with 2.34 times increased risk for thyroid cancer (OR=2.34, 95% CI=1.79-3.21). There was no heterogeneity in the data (p=0.662, I² =0%). Egger's test showed that there was no publication bias (p=0.532). Conclusions: This meta-analysis confirmed the association of dental X-ray exposure and thyroid cancer risk. The current results underscore the importance of applying safety regulations at dental clinics to protect thyroid glands during dental radiography examinations.

• 대한방사선기술학회지:방사선기술과학
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• 제42권1호
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• pp.25-30
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• 2019

Whole Spine Scanography (WSS) using the Digital Radiography (DR) system is an examination that requires whole body X-ray exposure, which involves more exposure to radiation for patients than other general radiographies. This can affect the occurrence of breast cancer. This research measured radiation dose when breasts were shield and not shield using the Auto Exposure Control (AEC) mode. The radiation dose without a shield was 1.540 mGy, and that using a collimator was measured 0.506 mGy. Moreover, 0.733 mGy was measured when 1 shield (0.3 mm) was used, and $0.523{\mu}Gy$ when 5 of them (1.5 mm) were used. The results showed that the radiation dose with 5 shields and the radiation dose with a collimator were similar. Moreover, 0.233 mGy was measured when 8 shields (2.4 mm) were used. The standard deviation were 0.081 when using collimator and 0.014 when 5 shields were used. Also, when 8 shields were used, it was found to be 0.002. Most patients who go under a scoliosis test are children or young people who are highly sensitive to radiation. In the research results, the case where the organs sensitive to radiation, women's breasts, were shielded showed more distinct differences compared to without shields. It is considered that using shields can provide more constant shield than using a collimator and lower the risk of breast cancer caused by exposure to radiation.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제25권1호
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• pp.87-91
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• 2022

Ingestion of foreign bodies (FBs) is a common phenomenon among young children. Plain radiography is the first step diagnostic modality to detect the radio-opaque FBs. And computed tomography has been recommended by several guidelines as useful modalities for diagnosing ingested FBs. However, there is a risk of radiation exposure, making it burdensome to use in asymptomatic patients. Ultrasound (US) is not a commonly used technique for diagnosing ingested foreign bodies. However, US can provide real-time imaging with good resolutions without radiation exposure in pediatric patients. Herein, we report two pediatric cases of metallic foreign body ingestion that were successfully diagnosed using US for localizing foreign bodies. This study indicates that US may be used as an alternative method for detecting the localization of metallic foreign bodies in the gastrointestinal tract without exposure of radiation, particularly in pediatric patients.

• Journal of Radiation Protection and Research
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• 제40권3호
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• pp.155-161
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• 2015

Radon is a naturally occurring radioactive gas and a major indoor contribution of exposure to ionizing radiation in dwellings. $^{222}Rn$ is a health hazard gas what is responsible for thousand lung cancer deaths every year. In this study, indoor radon concentrations present in thirty representative houses in Mahallat city, Iran, were determined in order to estimate lung cancer risk associated with residential radon exposure. Long-term passive method, using CR-39, was used to measure the radon concentration. The results showed an association between the age of the dwellings and the indoor radon concentration that was found, in that the concentration of radon tended to increase as the age of the dwelling also increased. The indoor radon concentrations were calculated to be within the range of $23{\pm}2$ to $350{\pm}26Bq{\cdot}m^{-3}$, with an average of $158Bq{\cdot}m^{-3}$. The annual effective dose from inhaled radon and its decay products was calculated between $0.8{\pm}0.1$ and $12.3{\pm}0.9mSv{\cdot}y^{-1}$, with an average of $5.5mSv{\cdot}y^{-1}$. By taking into consideration the EPA recommendation and ICRP statement, the average annual risk of lung cancer from inhaled radon was calculated as 0.09%, 0.06%, 0.01%, and 0.03% for current smokers (CS), those who had ever smoked (ES), never smokers (NS) and the general population, respectively.

• Journal of Radiation Protection and Research
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• 제47권2호
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• pp.67-76
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• 2022

Background: We conducted a cross-sectional study of residents within and outside Fukushima Prefecture to clarify their perceptions of the need for smartphone applications (apps) for explaining exposure doses. The results will lead to more effective methods for identifying target groups for future app development by researchers and municipalities, which will promote residents' understanding of radiological situations. Materials and Methods: In November 2019, 400 people in Fukushima Prefecture and 400 people outside were surveyed via a web-based questionnaire. In addition to basic characteristics, survey items included concerns about radiation levels and intention to use a smartphone app to keep track of exposure. The analysis was conducted by stratifying responses in each region and then cross-tabulating responses to concerns about radiation levels and intention to use an app by demographic variables. The intention to use an app was analyzed by binomial logistic regression analysis. Text-mining analyses were conducted in KH Coder software. Results and Discussion: Outside Fukushima Prefecture, concerns about the medical exposure of women to radiation exceeded 30%. Within the prefecture, the medical exposure of women, purchasing food products, and consumption of own-grown food were the main concerns. Within the prefecture, having children under the age of 18, the experience of measurement, and having experience of evacuation were significantly related to the intention to use an app. Conclusion: Regional and individual differences were evident. Since respondents differ, it is necessary to develop and promote app use in accordance with their needs and with phases of reconstruction. We expect that a suitable app will not only collect data but also connect local service providers and residents, while protecting personal information.

• Safety and Health at Work
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• 제10권2호
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• pp.141-150
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• 2019

Background: Evidence on associations between occupational diesel exhaust and gasoline exposure and colorectal cancer is limited. We aimed to assess the effect of workplace exposure to diesel exhaust and gasoline on the risk of colorectal cancer. Methods: This case-control study included 181,709 colon cancer and 109,227 rectal cancer cases diagnosed between 1961 and 2005 in Finland, Iceland, Norway, and Sweden. Cases and controls were identified from the Nordic Occupational Cancer Study cohort and matched for country, birth year, and sex. Diesel exhaust and gasoline exposure values were assigned by country-specific job-exposure matrices. Odds ratios and 95% confidence intervals were calculated by using conditional logistic regression models. The results were adjusted for physical strain at work and occupational exposure to benzene, formaldehyde, ionizing radiation, chlorinated hydrocarbons, chromium, and wood dust. Results: Diesel exhaust exposure was associated with a small increase in the risk of rectal cancer (odds ratio - 1.05, 95% confidence interval 1.02-1.08). Gasoline exposure was not associated with colorectal cancer risk. Conclusion: This study showed a small risk increase for rectal cancer after workplace diesel exhaust exposure. However, this finding could be due to chance, given the limitations of the study.

• Journal of Radiation Protection and Research
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• 제41권1호
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• pp.57-70
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• 2016

Background: Since the terminology 'radioactive consumer product' is not quite familiar to the public and is often considered as negative and detrimental things, the educational curriculum is essential for establishing reliability of nuclear energy related and for the development of better communication strategy of radiation risk with the public. To provide base data which is valuable for establishing efficient curriculum of education and training about radiation safety, it is necessary to apprehend the different level of awareness of radiation exposures classified by various consumer products. Materials and Methods: On November 2014, a question investigation about asking awareness level of radiation exposure from various consumer products was done for university students who are highly educated. The object students are studied at a four-year-course universities which is located at Daejeon City. Results and Discussion: Although the average awareness level is comparatively low, the awareness of senior students, who major in radiation, nuclear related departments and male students are relatively high. On the other hand, the awareness of freshman, sophomore, junior students, who do not major in radiation, nuclear related departments and female students are relatively low. It is necessary to provide various information to avoid unnecessary concerns and misconceptions about radiation exposure. Conclusion: This paper will be an instrument for efficient establishment of curriculum of education and training related with radiation safety.

• Journal of Radiation Protection and Research
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• 제42권2호
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• pp.130-140
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• 2017

Background: With the need for a domestic level 3 probabilistic safety assessment (PSA), it is essential to develop a Korea-specific code. Health effect assessments study radiation-induced impacts; in particular, long-term health effects are evaluated in terms of cancer risk. The objective of this study was to analyze the latest cancer risk models developed by foreign organizations and to compare the methodology of how they were developed. This paper also provides suggestions regarding the development of Korean cancer risk models. Materials and Methods: A review of cancer risk models was carried out targeting the latest models: the NUREG model (1993), the BEIR VII model (2006), the UNSCEAR model (2006), the ICRP 103 model (2007), and the U.S. EPA model (2011). The methodology of how each model was developed is explained, and the cancer sites, dose and dose rate effectiveness factor (DDREF) and mathematical models are also described in the sections presenting differences among the models. Results and Discussion: The NUREG model was developed by assuming that the risk was proportional to the risk coefficient and dose, while the BEIR VII, UNSCEAR, ICRP, and U.S. EPA models were derived from epidemiological data, principally from Japanese atomic bomb survivors. The risk coefficient does not consider individual characteristics, as the values were calculated in terms of population-averaged cancer risk per unit dose. However, the models derived by epidemiological data are a function of sex, exposure age, and attained age of the exposed individual. Moreover, the methodologies can be used to apply the latest epidemiological data. Therefore, methodologies using epidemiological data should be considered first for developing a Korean cancer risk model, and the cancer sites and DDREF should also be determined based on Korea-specific studies.