• Asian Pacific Journal of Cancer Prevention
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• 제17권6호
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• pp.2979-2982
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• 2016

Background: High dose ionizing radiation can induce ovarian cancer, but the effect of low dose radiation on the development of ovarian cancer has not been extensively studied. We evaluated the effect of low dose radiation and total background radiation, and the radiation delivered to the ovaries during the treatment of rectosigmoid cancer and breast cancer on ovarian cancer incidence. Materials and Methods: Background radiation measurements are from Assessment of Variations in Radiation Exposure in the United States, 2011. Ovarian cancer incidence data are from the Centers for Disease Control and Prevention. Standardized incidence ratios (SIR) of ovarian cancer following breast cancer and rectosigmoid cancer are from Surveillance, Epidemiology, and End Results (SEER) data. Obesity data by US state are from the Centers for Disease Control and Prevention. Mean ages of US state populations are from the United States Census Bureau. Results: We calculated standardized incidence ratios (SIR) from Surveillance, Epidemiology, and End Results (SEER) data, which reveal that in 194,042 cases of breast cancer treated with beam radiation, there were 796 cases of ovarian cancer by 120+ months of treatment (0.41%); in 283, 875 cases of breast cancer not treated with radiation, there were 1,531 cases of ovarian cancer by 120+ months (0.54%). The difference in ovarian cancer incidence in the two groups was significant (p < 0.001, two tailed Fisher exact test). The small dose of scattered ovarian radiation (about 3.09 cGy) from beam radiation to the breast appears to have reduced the risk of ovarian cancer by 24%. In 13,099 cases of rectal or rectosigmoid junction cancer treated with beam radiation in the SEER data, there were 20 cases of ovarian cancer by 120+ months of treatment (0.15%). In 33,305 cases of rectal or rectosigmoid junction cancer not treated with radiation, there were 91 cases of ovarian cancer by 120+ months (0.27%). The difference in ovarian cancer incidence in the two groups was significant (p = 0.017, two tailed Fisher exact test). In other words, the beam radiation to rectum and rectosigmoid that also reached the ovaries reduced the risk of ovarian cancer by 44%. In addition, there was a significant inverse relationship between ovarian cancer in white women and radon background radiation (r = - 0.465. p = 0.002) and total background radiation (r = -0.456, p = 0.002). Because increasing age and obesity are risk factors for ovarian cancer, multivariate linear regression was performed. The inverse relationship between ovarian cancer incidence and radon background was significant (${\beta}=-0.463$, p = 0.002) but unrelated to age (${\beta}=-0.080$, p = 0.570) or obesity (${\beta}=-0.180$, p = 0.208). Conclusions: The reduction of ovarian cancer risk following low dose radiation may be the result of radiation hormesis. Hormesis is a favorable biological response to low toxin exposure. A pollutant or toxin demonstrating hormesis has the opposite effect in small doses as in large doses. In the case of radiation, large doses are carcinogenic. However, lower overall cancer rates are found in U.S. states with high impact radiation. Moreover, there is reduced lung cancer incidence in high radiation background US states where nuclear weapons testing was done. Women at increased risk of ovarian cancer have two choices. They may be closely followed (surveillance) or undergo immediate prophylactic bilateral salpingo-oophorectomy. However, the efficacy of surveillance is questionable. Bilateral salpingo-oophorectomy is considered preferable, although it carries the risk of surgical complications. The data analysis above suggests that low-dose pelvic irradiation might be a good third choice to reduce ovarian cancer risk. Further studies would be worthwhile to establish the lowest optimum radiation dose.

• 한국방사선학회논문지
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• 제9권2호
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• pp.117-120
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• 2015

주5일 근무제와 여가 생활의 증가로 인하여 캠핑을 하는 사람들이 지속적으로 증가 하고 있다. 따라서 다양한 캠핑장시설이 증가하고 있다. 사설 캠핑장의 경우 파쇄석이라 불리는 자갈 사이트와 일반 흙으로 된 사이트 등 다양한 사이트가 존재한다. 캠핑장은 야외 활동이 많은 곳이기 때문에 캠핑장내에서 측정되는 방사선량을 각각 다른 싸이트 별로 자연방사선량을 측정한 후에 분석하였다. 파쇄석으로 만들어진 장소보다는 흙으로 만들어진 싸이트에서 자연방사선량이 적게 측정되었으며, 인위적으로 만든 타프 그늘보다는 자연적으로 형성된 나무그늘이 자연 방사선량이 적게 측정되었다. 결론적으로 캠핑장소 선택시에서 자연방사선량을 피하려면 인위적으로 만든 캠핑장 보다는 나무가 많은 자연휴양림 장소가 캠핑하기 좋은 곳 이라고 알리고 싶다.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.1052-1060
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• 2023

The airborne radiation monitoring has been used in geophysics for more than forty years and now it also has its important role in emergency monitoring. The aircraft background and the cosmic gamma-rays contribute to the measured gamma spectrum on the aircraft board. This adverse effect should be eliminated before the data processing. The paper describes two semiparametric methods to estimate the full spectrum aircraft background and cosmic gamma-ray contribution from spectra measured at altitudes where terrestrial contribution is negligible. The methods only assume to know possible peak positions in spectra and their full width at half maximum, that can be easily obtained e.g. from terrestrial measurement. The methods were applied to real experimental data acquired on Mi-17 and Bell 412 helicopter boards. The IRIS airborne gamma-ray spectrometer, with 4×4 L NaI(Tl) crystals, produced by Pico Envirotec Inc., Canada, was used on helicopters' boards. To obtain valid estimate of the aircraft background and the cosmic contribution, the measurements over sea and large water areas were carried out. However, the satisfactory results over inland were also achieved comparing with those acquired over large water areas.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.275-278
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• 2002

The recognition of the natural background radiation is important not only for radiological education but also for the promotion of people's scientific view about radiation. We made a "room" on the web showing natural background radiation as part of a VRM (Virtual Radiation Museum). The "room" shows the video images of the tracks of charged particles from natural background radiation, alpha and beta ray track from known sources using a Large Scale Diffusion Cloud Chamber. The purpose of this study is to make clear the origin of a kind of track (named A-track) which is thick and easy to recognize with the length less than several cm in the cloud chamber, and to make numerical explanation of its counting rate. The study was carried out using a Large Scale Diffusion Cloud Chamber (Phywe, Germany) installed in the Niigata Science Museum. The Model RNC (Pylon Electronics, Canada) was used as Rn-222 source. Ra-226 activity in RNC was 111.6 Bq calibrated with NIST protocol. Rn-222 gas was injected into the cloud chamber. Continuous video recording with use of Digital Handycam (SONY, Japan) was carried out for 360 min. after injection of Rn-222 gas. The number of alpha-ray track (alpha track) in the video images was analyzed. The growth and decay curve of the total activity of Rn-222 and its alpha emitting progeny were calculated and compared with the count of the alpha tracks. As a result the alpha tracks formed by Rn-222 injection resemble A-Tracks. The relationship between A-track in the cloud chamber and atmospheric Rn is discussed.

• Journal of Radiation Protection and Research
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• 제35권3호
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• pp.96-98
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• 2010

Medical use of radiation is increasing in recent times and its influence on the population creates almost the same amount of annual natural background radiation in industrialized countries in particular. Thus, medical radiation has become a social issue. This paper is a brief report on the status of medical exposure in Korea by way of consulting from the radiation-related medical societies in Korea.

• Nuclear Engineering and Technology
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• 제38권1호
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• pp.99-108
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• 2006

SNU-RCCS is a water pool type RCCS (Reactor Cavity Cooling System) developed for VHTR (Very High Temperature Reactor) application by SNU (Seoul National University). Since radiation heat transfer is the major process of passive heat removal in a RCCS, it is important to determine the precise emissivity of the reactor vessel. Review studies have used a constant emissivity in the passive heat removal analysis, even though the emissivity depends on many factors such as temperature, surface roughness, oxidation level, wavelength, direction, atmosphere conditions, etc. Therefore, information on the emissivity of a given material in a real RCCS is essential in order to properly analyze the radiation heat transfer in a VHTR. The objectives of this study are to develop a method for compensation of the factors affecting the emissivity measurement using an infrared thermometer and to estimate the true emissivity from the measured emissivity via the developed method, especially in the SNU-RCCS environment. From this viewpoint, we investigated factors such as the attenuation effect of the window, filling gas, and the effect of background radiation on the emissivity measurements. The emissivity of the vessel surface of the SNU-RCCS facility was then measured using a sight tube. The background radiation was subsequently removed from the measured emissivity by solving a simultaneous equation. Finally, the calculated emissivity was compared with the measured emissivity in a separate emissivity measurement device, yielding good agreement with the emissivity increase with vessel temperature in a range of 0.82 to 0.88.

• Journal of Radiation Protection and Research
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• 제1권1호
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• pp.37-41
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• 1976

The background, beginnings and course of development of the radiation protection profession are outlined. Emphasis is on developments in the Western world, particularly the USA. It is shown that this profession has played a major role in producing a level of safety that would have been unbelievable a few decades ago.

• 대한방사선방어학회:학술대회논문집
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• 대한방사선방어학회 2011년도 추계 학술발표회 및 심포지엄
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• pp.266-267
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• 2011

• Current Optics and Photonics
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• 제1권5호
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• pp.440-455
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• 2017

In this paper, we carry out a performance analysis of a two-user free-space optical (FSO) communication system with photodetector multiplexing, in which the two users are defined as the primary user (PU) and secondary user (SU). Unlike common single-user FSO systems, our photodetector multiplexing FSO system deploys a shared detector at the receiver and enables PU and SU to send their own data synchronously. We conduct the performance analysis of this FSO system for two cases: (1) in the absence of background radiation, and (2) in the presence of background radiation. Decision strategies for PU and SU are presented according to the two scenarios above. Exact and approximate conditional symbol-error probability (SEP) expressions for both PU and SU are derived, in an ideal channel with no fading. Average SEP expressions are also presented in the no-background-radiation scenario. Additionally, in some particular cases where the power ratio tends to 0.5 or 1, approximate SEP expressions are also obtained. Finally, numerical simulations are presented under different conditions, to support the performance analysis.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2927-2934
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• 2023

The influence of the atmospheric radon background on the airborne gamma spectrum can seriously affect researchers' judgement of ground radiation information. However, due to load and endurance, unmanned aerial vehicle (UAV)-borne gamma-ray spectrometry is difficulty installing upward-looking detectors to monitor atmospheric radon background. In this paper, an advanced spectral-ratio method was used to correct the atmospheric radon background for a UAV-borne gamma-ray spectrometry in Inner Mongolia, China. By correcting atmospheric radon background, the ratio of the average count rate of U window in the anomalous radon zone (S5) to that in other survey zone decreased from 1.91 to 1.03, and the average uranium content in S5 decreased from 4.65 mg/kg to 3.37 mg/kg. The results show that the advanced spectral-ratio method efficiently eliminated the influence of the atmospheric radon background on the UAV-borne gamma-ray spectrometry to accurately obtain ground radiation information in uranium exploration. It can also be used for uranium tailings monitoring, and environmental radiation background surveys.