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

• 방사선산업학회지
• /
• 제8권2호
• /
• pp.123-132
• /
• 2014

After the nuclear accident of the Fukushima Dai-ichi Nuclear Power Plants (FDNPPs) on 11 March 2011, a large amount of radioactive materials has been released into the atmosphere and the ocean. A compartment model is used to evaluate the circulation characteristics and the spatiotemporal concentration distributions of radionuclides in the ocean. In the comparison with observed concentrations of $^{137}Cs$ in seawater, calculated concentrations by the compartment model were well agreed with them. On the basis of these results, we performed evaluation of the effective dose and the cancer risk. In the early stage of the accident, the effective doses from ingestion of the seafood near the Fukushima region were much higher than 1 mSv which is the value of the annual effective dose limit to individual recommended by the International Commission on Radiological Protection (ICRP). However, the effective doses by ingestion of the seafood decreased below 1 mSv as distance from the FDNPPs increased and time passed. In addition, it was estimated that the cancer risks by intake of the contaminated marine products were less than natural occurrence probability of cancer. Consequently, it was inferred that the health risk due to the $^{137}Cs$ was low after since mid-term period of the accident.

• 대한방사선기술학회지:방사선기술과학
• /
• 제44권3호
• /
• pp.205-210
• /
• 2021

The purpose of this study was to analyze the spatial dose according to the distance by location of medical workers when using a mobile X-ray fluoroscopy device in the operating room through a simulation experiment. The MCNPX program was used for the simulation, and the location of medical workers was set around the operating table, and the spatial dose distribution according to the distance and changes in imaging conditions was evaluated. As a result, The highest score was 2.74×10^-4 mGy, 2.72×10^-4 mGy, and 1.18×10^-4 mGy based on the 10 cm distance from the operating table. Spatial dose depending on the distance 100cm, A point 5.15×10^-5 mGy is decreased 19% of 10cm, D point 5.12×10^-5 mGy, 19 % of 10cm, and G pint, 1.73×10^-5 mGy is reduced by 15% of 10cm. Based on this study, medical-related workers directly or indirectly participating in surgery carry potential risks of radiation exposure during surgery, but there are difficulties in radiation protection due to the nature of their work. Therefore, efforts to reduce exposure suitable for the operating room environment will be required.

• Journal of Radiation Protection and Research
• /
• 제38권4호
• /
• pp.214-227
• /
• 2013

MDCT의 등장과 함께 병적 증상이 없는 개인이 조기검진을 위해 CT검사를 하는 예가 꾸준히 증가하고 있다. 이러한 검사의 임상적 효용성과 방사선에 의한 암 발생위험에 대한 여러 가지 논란을 살펴보았다. 1. 저선량흉부CT(LDCT)를 이용한 폐암의 조기 검진 효용성을 보기 위해 설계된 무작위배정대조검사(randomized controlled trial)인 NLST(National Lung Screening Trial)의 분석 결과, CT선별검사가 선별검사를 하지 않은 그룹의 사망률 1.67%를 1.33%로, 20% (p=0.004) 감소시키는 것으로 나타났다. CT선별검사군에서 양성결과를 보인 사람의 96.4%는 위양성(false-positive)이었다. 그리고 방사선에 의한 폐암의 ERR (excess radiation risk)은 다른 고형암과는 달리 나이와 함께 감소하지 않으며, 더욱이 흡연 위험과 방사선 위험이 상승작용을 하여 폐암 검진 대상인 고위험군에게 더욱 위험할 수 있는 것으로 평가되었다. 따라서 방사선에 의한 위험이 NLST에서 관측한 이득을 상쇄할 수도 있다. 아직은 최적의 전략이 확립되지 않은 상태이므로 임상에서 광범위하게 적용하기에는 한계가 있다. 2. 대장CT검사(CT colonography)는 10 mm보다 큰 용종의 검출에는 정확도가 뛰어나지만 이보다 작은 경우에는 민감도와 특이도가 급격히 감소하고, 용종이 발견되어 제거하고자 하는 경우 다시 기존의 대장내시경을 이용해야 하는 불편함이 있다. 현재 대장CT검사 1회 시행의 평균유효선량은 약 8-10 $mS{\nu}$로 보고되어, 만약 이 검사가 많은 사람들을 대상으로 일상적으로 행해지면 공중보건에 영향을 미칠 수 있다. 따라서 집단검진 방법으로 정착하기 위해서 는 용종 크기 6-10 mm 범위에서 높은 민감도와 특이도를 확립하고, 하제를 사용하지 않는 방법을 개발하여야 하며, 선량을 더 감소시킬 수 있는 최적화된 전략을 세워 표준화하여야만 한다. 3. 전신CT검사는 그 효용성이 검증된 선행연구가 없는 상태이다. 이 검사는 약 90%의 검사자들에게서 최소한 하나 이상의 이상소견을 확인하였지만 그 중 약 2%만이 임상적으로 중요한 질환으로 판명되었다. 전신CT검사 1회 시행으로 인한 평균유효선량은 약 12 $mS{\nu}$이며 45세부터 75세까지 매년 검사를 받는 경우 LAR (lifetime attributable risk)이 1.9%로 보고되었다. 현재 의학계의 어떤 단체도 이 검사를 권고하고 있지 않다. 현재까지 CT선별검사는 정당화에 대한 충분한 논의를 위해 심도 있는 다양한 연구가 필요하며 최적화된 프로토콜이 확립된 후 이용하는 것이 바람직하다.

• Radiation Oncology Journal
• /
• 제22권1호
• /
• pp.1-10
• /
• 2004

비소세포성 폐암에서 국소 진행성 병변(병기 3)이 3분의 1을 차지한다. 이 중 완전 절제가 가능한 소수의 환자를 제외하고 대부분의 환자에서 근치적 방사선치료가 전통적으로 시행되어 왔다. 하지만 근치적 방사선치료 후 장기 생존율은 극히 불량하고, 대개의 경우 원격 전이 또는 국소 재발로 사망하게 된다. 지난 20년간, 집합적 요법으로 국소 진행성 비소세포성 폐암 치료효과의 향상이 있었다. 그중 화학방사선요법이 가장 흔히 사용되었고, 화학요법과 방사선치료를 병용하는 순서에 따라 다음 두 가지 기본적 방법이 있다. 즉, 순차적 요법과 동시 요법이 그것이다. 순차적 병용 요법은 유도 화학요법 완료 후 방사선 치료를 진행하는 순서로 주로 시행되었다. 근거로는 방사선 치료전 유도 화학요법 사용 으로 종양의 크기를 줄여 국소제어율을 높이고, 보이지 않는 미세 전이 병변을 제거하여 원격 전이를 감소시키는 데 있다. 방사선 단독 치료와 비교하여 순차적 화학방사선요법으로 중앙생존기간과 장기생존율의 향상을 보고한 여러 연구가 있다. 재발 양상을 분석한 보고에 따르면, 방사선치료 단독과 비교하여 순차적 병용요법이 원격전이율은 감소시키나, 국소 재발률에는 영향이 없었다. 화학요법과 방사선치료를 동시 시행하는 동시병용요법에 대한 많은 보고가 있다. 근거로는 화학요법을 방사선과 동시 투여함으로써 화학요법에 의한 종양세포 방사선 감작효과를 기대할 수 있고, 순차적요법과 비교하여 전체 치료기간을 단축하여 국소제어율을 향상시킬 수 있다. 기대했던 대로 동시 병용요법 후 국소 제어율 향상과 이로 인한 생존율 증가가 관찰되었다. 하지만 방사선 치료 단독과 비교하여 원격 전이율에는 차이가 없었고, 이는 급성 부작용, 특히 급성 식도염 위험을 줄이기 위해 대다수의 연구에서 관찰되듯이 화학요법의 강도를 줄인 때문으로 생각된다. 상기한 바와 같이 집합적 치료가 방사선 단독 요법과 비교하여 생존율의 향상에 기여하였고, 현재 새 표준 치료로 정착되었으나, 이의 치료효과는 아직도 실망스러우며, 최적 치료 개발을 위한 연구는 계속되어야 한다. 본 보고에서 국소 진행 비소세포성 폐암에서 집합적 치료에 대한 현 논점을 검토하고자 한다.

• 한국분무공학회지
• /
• 제20권2호
• /
• pp.107-113
• /
• 2015

To date, the demand for Combined Cycle Power Plant (CCPP) has been continuously increased to overcome the problem of air pollution and lack of energy. In particular, the underground CCPP is exposed to substantial fire and explosion risks induced by gas leakage. The present study conducted numerical simulations to examine the fire behavior and gas leakage characteristics for a restricted region including gas turbine and other components used in a typical CCPP system. The commercial code of FLUENT V.14 was used for simulation. From the results, it was found that flammable limit distribution of leakage gas affects fire behavior. Especially, the flame is propagated in an instant in restricted region with LNG gas. In addition, consequence analysis factors such as critical temperature and radiation heat flux are introduced. These results would be useful in making the safety guidelines for the underground CCPP.

• Asian Journal for Public Opinion Research
• /
• 제5권1호
• /
• pp.1-14
• /
• 2017

The Fukushima nuclear accident caused by an earthquake and a subsequent tsunami on March 11, 2011 has seriously impacted the environment surrounding the Fukushima Daiichi nuclear power plant. While all the residents near the plant were evacuated from the area deemed uninhabitable after the accident, residents of the neighboring area outside of the evacuation zone still seem to live in fear of invisible radiation. To understand Fukushima residents' thinking about the environmental risks that accompany a nuclear disaster, we utilize a poll of the residents of Fukushima conducted in 2013. Based on the survey data, we reveal factors that seem to strongly affect their knowledge and concerns about nuclear power plants. The results of the multivariate analysis show the importance of the following two factors: (1) confidence in mass media, and (2) trust in institutions in charge of administering the accident, especially the central government, the Nuclear and Industrial Safety Agency, and Tokyo Electric Power Company. We conclude that the more people trust mass media and particular institutions, the more likely it is that they are have an elevated sense of anxiety and fear of the presence of nuclear plants.

• Nuclear Engineering and Technology
• /
• 제47권7호
• /
• pp.827-837
• /
• 2015

Following a severe accident in a nuclear power plant, iodine is a major contributor to the potential health risks for the public. Because the amount of iodine released largely depends on its volatility, iodine's behavior in containment has been extensively studied in international programs such as International Source Term Programme-Experimental Program on Iodine Chemistry under Radiation (EPICUR), Organization for Economic Co-operation and Development (OECD)-Behaviour of Iodine Project, and OECD-Source Term Evaluation and Mitigation. Korea Institute of Nuclear Safety (KINS) has joined these programs and is developing a simplified, stand-alone iodine chemistry model, RAIM (Radio-Active Iodine chemistry Model), based on the IMOD methodology and other previous studies. This model deals with chemical reactions associated with the formation and destruction of iodine species and surface reactions in the containment atmosphere and the sump in a simple manner. RAIM was applied to a simulation of four EPICUR tests and one Radioiodine Test Facility test, which were carried out in aqueous or gaseous phases. After analysis, the results show a trend of underestimation of organic and molecular iodine for the gas-phase experiments, the opposite of that for the aqueous-phase ones, whereas the total amount of volatile iodine species agrees well between the experiment and the analysis result.

• Clinical and Experimental Pediatrics
• /
• 제63권11호
• /
• pp.422-428
• /
• 2020

In today's world, most children are exposed to various manmade electromagnetic fields (EMFs). EMFs are electromagnetic waves less than 300 GHz. A developing child's brain is vulnerable to electromagnetic radiation; thus, their caregivers' concerns about the health effects of EMFs are increasing. EMF exposure is divided into 2 categories: extremely low frequencies (ELFs; 3-3,000 Hz), involving high-voltage transmission lines and in-house wiring; and radiofrequencies (RFs; 30 kHz to 300 GHz), involving mobile phones, smart devices, base stations, WiFi, and 5G technologies. The biological effects of EMFs on humans include stimulation, thermal, and nonthermal, the latter of which is the least known. Among the various health issues related to EMFs, the most important issue is human carcinogenicity. According to the International Agency for Research on Cancer's (IARC's) evaluation of carcinogenic risks to humans, ELFs and RFs were evaluated as possible human carcinogens (Group 2B). However, the World Health Organization's (WHO's) view of EMFs remains undetermined. This article reviews the current knowledge of EMF exposure on humans, specifically children. EMF exposure sources, biological effects, current WHO and IARC opinions on carcinogenicity, and effects of EMF exposures on children will be discussed. As well-controlled EMF experiments in children are nearly impossible, scientific knowledge should be interpreted objectively. Precautionary approaches are recommended for children until the potential health effects of EMF are confirmed.

• Nuclear Engineering and Technology
• /
• 제53권7호
• /
• pp.2277-2288
• /
• 2021

To regulate the safety protocols in nuclear facilities, radioactive aerosols have been extensively researched to understand their health impacts. However, most measured particle-size distributions remain at low resolutions, with the particle sizes ranging from nanometer to micrometer. This study combines the high-resolution detection of 500 size classes, ranging from 6 nm to 10 ㎛, for aerodynamic diameter distributions, with a regional lung deposition calculation. We applied the new approach to characterize particle-size distributions of aerosols generated during the plasma arc cutting of simulated non-radioactive steel alloy wastes. The high-resolution measured data were used to calculate the deposition ratios of the aerosols in different lung regions. The deposition ratios in the alveolar sacs contained the dominant particle sizes ranging from 0.01 to 0.1 ㎛. We determined the distribution of various metals using different vapor pressures of the alloying components and analyzed the uncertainties of lung deposition calculations using the low-resolution aerodynamic diameter data simultaneously. In high-resolution data, the changes in aerosols that can penetrate the blood system were better captured, correcting their potential risks by a maximum of 42%. The combined calculations can aid the enhancement of high-resolution measuring equipment to effectively manage radiation safety in nuclear facilities.