• Journal of Radiation Protection and Research
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• 제43권3호
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• pp.85-96
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• 2018

Background: A variety of inorganic scintillators have been developed and improved for use in radiation detection and measurement, and in situ gamma-ray spectrometry in the environment remains an important area in nuclear safety. In order to verify the feasibility of promising scintillators in an actual environment, a performance test is necessary to identify gamma-ray peaks and calculate the radioactivity from their net count rates in peaks. Materials and Methods: Among commercially available scintillators, $LaBr_3(Ce)$ scintillators have so far shown the highest energy resolution when detecting and identifying gamma-rays. However, the intrinsic background of this scintillator type affects efficient application to the environment with a relatively low count rate. An algorithm to subtract the intrinsic background was consequently developed, and the in situ calibration factor at 1 m above ground level was calculated from Monte Carlo simulation in order to determine the radioactivity from the measured net count rate. Results and Discussion: The radioactivity of six natural radionuclides in the environment was evaluated from in situ gamma-ray spectrometry using an $LaBr_3(Ce)$ detector. The results were then compared with those of a portable high purity Ge (HPGe) detector with in situ object counting system (ISOCS) software at the same sites. In addition, the radioactive cesium in the ground of Jeju Island, South Korea, was determined with the same assumption of the source distribution between measurements using two detectors. Conclusion: Good agreement between both detectors was achieved in the in situ gamma-ray spectrometry of natural as well as artificial radionuclides in the ground. This means that an $LaBr_3(Ce)$ detector can produce reliable and stable results of radioactivity in the ground from the measured energy spectrum of incident gamma-rays at 1 m above the ground.

• 대한방사선기술학회지:방사선기술과학
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• 제41권6호
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• pp.617-626
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• 2018

This study aims to provide the basic data helpful for the improvement of rights and interests of radiological technologists, by understanding the current working environment and if they get the proper reward through the analysis on the perception of appropriateness of current wage and job satisfaction of radiological technologists. Survey was conducted to evaluate the perception of satisfaction with job and wage system, work intensity, necessity of the radiological technologist limit system, and turnover in accordance. The appropriate starting salary was low in case of women and non-capital area, and when the age, academic background, career, and hospital size were lower. The appropriate wage was low in case of women and non-capital area, and when the academic background and hospital size were lower. The negative perception of the necessity to change the wage system was shown in university hospitals. Regarding the work intensity, in case of women and low career, and when the age, academic background, and hospital size were higher, the work intensity was perceived as high. When the academic degree and hospital size were lower, the positive perception of the radiological technologist limit was shown. The turnover intention was high in case of women, and when the age, academic background, career, and hospital size were lower. In order to increase the job satisfaction of radiological technologists, it would be necessary to the appropriate reward and the environment where they could concentrate on work.

• Nuclear Engineering and Technology
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• 제52권10호
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• pp.2361-2369
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• 2020

Compton cameras using large scintillators have been developed for high imaging sensitivity. These scintillator-based Compton cameras, however, mainly due to relatively low energy resolution, suffer from undesired background-radiation signals, especially when radioactive materials' activity is very low or their location is far from the Compton camera. To alleviate this problem for a large-size Compton camera, in the present study, a hybrid-type shielding system was designed that combines an active shield with a veto detector and a passive shield that surrounds the active shield. Then, the performance of the hybrid shielding system was predicted, by Monte Carlo radiation transport simulation using Geant4, in terms of minimum detectable activity (MDA), signal-to-noise ratio (SNR), and image resolution. Our simulation results show that, for the most cases, the hybrid shielding system significantly improves the performance of the large-size Compton camera. For the cases investigated in the present study, the use of the shielding system decreased the MDA by about 1.4, 1.6, and 1.3 times, increased the SNR by 1.2-1.9, 1.1-1.7, and 1.3-2.1 times, and improved the image resolution (i.e., reduced the FWHM) by 7-8, 1-6, and 3-5% for ¹³⁷Cs, ⁶⁰Co, and ¹³¹I point source located at 1-5 m from the imaging system, respectively.

• Safety and Health at Work
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• 제13권4호
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• pp.421-428
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• 2022

Background: The exposure to solar ultraviolet radiation is a significant risk factor generally underestimated by outdoor workers and employers. Several studies have pointed out that occupational solar exposure increased eye and skin diseases with a considerable impact on the lives and productivity of affected workers. The main purpose of this study was to evaluate the effectiveness against ultraviolet radiation of some measures recently undertaken for the protection of lifeguards in a coastal area of Tuscany. Methods: Different shading structures (gazebos and beach umbrella) were tested during a sunny summer's day on a sandy beach by means of two radiometers; the UV protection offered by some T-shirts used by lifeguards was also tested in the laboratory with a spectrophotometer. Results: The analysed shading structures strongly reduced the ultraviolet radiation by up to 90%, however a not always negligible diffuse radiation is also present in the shade, requiring further protective measures (T-shirt, sunglasses, sunscreen, etc.); the tested T-shirts showed a very good-excellent protection according to the Australian/New Zealand standard. Conclusion: Results obtained in this study suggest how the adoption and dissemination of good practices, including those tested, could be particularly effective as a primary prevention for lifeguards who are subjected to very high levels of radiation for long periods.

• Nuclear Engineering and Technology
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• 제55권10호
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• pp.3822-3830
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• 2023

The large-area Compton camera (LACC), featuring significantly high detection sensitivity, was developed for high-speed localization of gamma-ray sources. Due to the high gamma-ray interaction event rate induced by the high sensitivity, however, the multiplexer-based data acquisition system (DAQ) rapidly saturated, leading to deteriorated energy and imaging resolution at event rates higher than 4.7 × 10³ s^-1. In the present study, a new simultaneous multi-channel DAQ was developed to improve the energy and imaging resolution of the LACC even under high event rate conditions (10⁴-10⁶ s^-1). The performance of the DAQ was evaluated with several point sources under different event rate conditions. The results indicated that the new DAQ offers significantly better performance than the existing DAQ over the entire energy and event rate ranges. Especially, the new DAQ showed high energy resolution under very high event rate conditions, i.e., 6.9% and 8.6% (for 662 keV) at 1.3 × 10⁵ and 1.2 × 10⁶ s^-1, respectively. Furthermore, the new DAQ successfully acquired Compton images under those event rates, i.e., imaging resolutions of 13.8° and 19.3° at 8.7 × 10⁴ and 10⁶ s^-1, which correspond to 1.8 and 73 μSv/hr or about 18 and 730 times the background level, respectively.

• 지질공학
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• 제29권4호
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• pp.461-468
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• 2019

휴대용 감마선분광분석기를 이용하여 괴산지역 옥천하부천매암대(og2) 주변 일대 77개 지점에서 감마선량을 측정하였다. 전체 시료의 ⁴⁰K 함량은 1.8-8.8% 범위(평균 4.6%)로 Kgr에서 함량이 가장 높았으 며, eU의 함량 범위는 0.2-217.9 ppm (평균 16.7 ppm)인데 og2에서 가장 높았으며(중앙값 29.6 ppm)다. eTh의 함량 범위는 11.9-76.5 ppm (평균 29.5 ppm) 이었는데 Kgr의 평균 함량은 45.4 ppm으로 og1, og2, og3의 함량(26.6-30.6 ppm)보다 높았다. og2에 속하는 일부 고 우라늄 지점을 제외한 연구지역의 감마선량에 기여하는 방사성물질은 ⁴⁰K가 절대적이다. 연구지역의 옥외 유효선량률은 0.08-1.71 mSv/y (평균 0.28 mSv/y)의 범위로 나타났다. 유효선량률이 1 mSv를 넘는 지점은 함 우라늄 층이 협재된 og2의 덕평리지역 3지점이며 이를 제외한 나머지 대부분 지역은 정상적인 자연방사선지역에 해당한다.

• Journal of Radiation Protection and Research
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• 제29권4호
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• pp.231-236
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• 2004

시료중의 방사능 분포를 영상으로 획득할 수 있는 2차원 디지털 방사선 검출기인 Imaging Plate(IP) 검출기는 주로 산업용 라디오그라피, 의료진단, X-선 회절실험 등에서도 광범위하게 사용되고 있다. 본 연구에서는 IP 검출기의 여러 종류의 방사선에 대한 높은 감도 우수한 공간 분해능, 넓은 선형범위와 스크린의 높은 균질성을 이용하여 시료중의 방사능을 측정할 수 있는 가능성에 대해 조사하였다. 먼저 IP 검출기를 이용하여 면적선원의 표면균질도 측정에 적용하였다. 상용 기준 면적선원$(^{241}Am)$의 방사능 분포에 대한 영상을 얻어서 표면 균질도를 비 파괴적이고 신속하게 측정하였다. 다음으로 IP 검출기를 극저준위 방사능 측정에 적용하여 방사능 측정가능성에 대해 연구하였다. 이를 위해 IP 검출기의 스크린 균질도, 배경방사선 차폐효과, 선형범위 조사, fading 시간을 조사하였다. 극저준위 방사능 측정을 위해 감자 바나나 무 당근에 포함되어 있는 $^{40}K$ 자연방사능을 선택하여 측정하였다. 기준선원을 사용하여 IP 효율교정을 수행하였다.

• Journal of Radiation Protection and Research
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• 제44권3호
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• pp.110-117
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• 2019

Background: This study aimed to estimate occupational doses and patient peak skin doses (PSDs) during interventional radiology procedures. Materials and Methods: We examined data from brain embolization (n = 30), hepatic chemoembolization (n = 50), and uterine embolization (n = 12). The PSDs were measured using radiochromic film around the patient's head (group 1) or abdominal/pelvic region (group 2). Acquisition technical data and kerma-area products (KAP) were also recorded. Occupational doses were measured using $Instadose^{TM}$ dosimeters near the left eye region (LER), chest, and left ankle. Results and Discussion: The third quartile (median) KAP values were $408.1(235.3)Gy{\cdot}cm^2$ for group 1 and $584.4(449.4)Gy{\cdot}cm^2$ for group 2. The average PSDs were greatest during vascular procedures, reaching 1,004.4 (786.4) mGy, and the highest PSD was 2,352.6 mGy (during hepatic chemoembolization). The third quartile (median) occupational doses were 0.35 (0.21) mSv at the LER, 0.25 (0.15) mSv at the chest, and 1.47 (0.64) mSv at the left ankle. Occupational doses at the LER were higher than at the chest, which highlights the importance of protective glasses and suspended shields. The occupational doses at the ankle region were also high, which highlights the importance of using a lead-lined curtain attached to the table. Conclusion: The results indicate that physicians can reach, for eye region, the weekly occupational dose limit after around 15 procedures, even when using proper protection. The average PSD values were below the threshold for tissue reactions, although the complexity of these procedures emphasises the importance of considering related risks.

• 치위생과학회지
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• 제15권2호
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• pp.172-181
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• 2015

본 연구는 치과위생사의 방사선안전 관리 실태 및 방사선 위해 불안감에 대하여 조사하고 영향을 미치는 요인들을 분석하여 방사선 안전 관리 수준을 향상하고 나아가 방사선 취급에 대한 올바른 인식 전환과 불안감을 줄이는데 기여하고자 실시하였다. 구조화된 설문지를 이용하여 2014년 9월 1일부터 10월 31일까지 전라북도 일부 지역 치과의원에 근무하는 치과위생사를 대상으로 수집된 자료를 분석하여 다음과 같은 결론을 얻었다. 방사선안전 관리에 대한 교육은 교육받지 않았다는 응답자(63.0%)가 교육받은 응답자(37.0%)보다 높게 나타났고 방사선안전 관리 지식도는 총 5점 중 평균점수는 $3.74{\pm}0.83$으로 평균보다 높았으며, 방사선안전 관리 행위 실천은 평균점수가 $2.58{\pm}1.11$로 평균보다 낮았다. 방사선 위해 불안감은 평균점수는 $3.88{\pm}0.92$로 높았으며, 임신 중일 때 태아의 건강 문제가 염려된다는 $4.43{\pm}0.71$로 가장 높게 나타났다. 방사선안전 관리 지식에 영향을 미치는 것은 '하루 방사선 총 촬영 횟수'에서 유의한 차이가 있었고(p<0.05), 방사선안전 관리행위 실천에 영향을 미치는 것은 '연령대', '최종학력', '한 달 소득', '근속연수', '업무영역', '현재 직위', '현재 방사선 촬영 여부'에 따라 유의한 차이가 있었다(p<0.05). 또한, 방사선안전 관리 지식은 방사선안전 관리행위 실천과 음의 상관관계(r=-0.232), 방사선 위해 불안감과는 양의 상관관계를 보였다(r=0.262). 대상자의 방사선 위해 불안감 영향은 방사선안전 관리 지식이 높을수록(${\beta}=0.252$, p<0.001), 방사선 촬영 업무 기간이 짧을수록(${\beta}=-0.341$, p<0.05) 유의하게 영향을 미치는 요인으로 나타났다. 이상의 연구결과로 치과위생사는 방사선 안전 관리에 관한 지식은 있으나 행위 실천이 부진한 실태와 방사선 위해에 대한 높은 불안감을 개선하기 위한 대책이 필요할 것으로 생각된다. 또한, 향후 환자와 진료 종사자의 방사선 피폭에 대한 정신적, 신체적 위해를 예방하여 방사선에 대한 안전 관리 수준을 향상하게 시켜 진료환경을 개선하고 나아가 방사선 취급에 대한 올바른 인식 전환을 위한 방안이 마련되어야 할 것이다.

• Journal of Ecology and Environment
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• 제47권3호
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• pp.85-102
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• 2023

Background: Ecophysiological characteristics of Rosa rugosa were analyzed under different environmental factors from May to October 2022. Photosynthesis, chlorophyll fluorescence, chlorophyll content, leaf water content (LWC), osmolality, carbohydrate content, and total ion content were measured to compare the physiological characteristics of R. rugosa at two study sites (i.e., in large pots and in the Goraebul coastal sand dune area). Results: When R. rugosa was exposed to high temperatures, photosynthetic parameters including net photosynthetic rate (P_N) and stomatal conductance (g_s) in both experiment areas declined. In addition, severe photoinhibition occurs when R. rugosa is continuously exposed to high photosynthetically active radiation (PAR), and because of this, relatively low Y(II) (i.e., the quantum yield of photochemical energy conversion in photosystem II [PSII]) and high Y(NO) (i.e., the quantum yield of non-regulated, non-photochemical energy loss in PSII) in the R. rugosa of the pot were observed. As the high Y(NPQ) (i.e., the quantum yield of regulated non-photochemical energy loss in PSII) of R. rugosa in the coastal sand dune, they dissipated the excessed photon energy through the non-photochemical quenching (NPQ) mechanism when they were exposed to relatively low PAR and low temperature. Rosa rugosa in the coastal sand dune has higher chlorophyll a and carotenoid content. The high chlorophyll a + b and low chlorophyll a/b ratios seemed to optimize light absorption in response to low PAR. High carotenoid content played an important role in NPQ. As a part of the osmotic regulation in response to low LWCs, R. rugosa exposed to high temperatures and continuously high PAR used soluble carbohydrates and ions to maintain high osmolality. Conclusions: We found that F_v/F_m was lower in the potted plants than in the coastal sand dune plants, indicating the vulnerability of R. rugosa to high temperatures and PAR levels. We expect that the suitable habitat range for R. rugosa will shrink and move to north under climate change conditions.