• 대한방사선기술학회지:방사선기술과학
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• 제41권2호
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• pp.115-122
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• 2018

We aims to perform comparative analysis on the dose area and image qualities varying on the slice thickness when using Automatic Exposure Controller (AEC) and manual exposure; thus, it wants to suggest a measure to reduce exposure dose by setting the optimal examination condition for each slice thickness. The method was to set the thickness as Thin, Normal, and Heavy adult and evaluate the dose area, spatial resolution, low contrast resolution, Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) according to each slice thickness by using the AEC and the manual exposure controller. The dose area according to each slice thickness all increased both when using the AEC and the manual exposure. However, the manual exposure showed lower dose area product than the AEC. Spatial resolutions and low contrast resolutions were all observed to be higher than the evaluation standard. Also, the SNR and CNR of each thickness all increased when using the AEC. When using the manual exposure, SNR and CNR increased in all cases other than the Heavy Adult. Consequently, the Thin and Normal Adult showed dose reduction about 2 times when using the manual exposure controller, while ensuring the image quality. Heavy adult was able to maintain good image quality by using AEC.

• Imaging Science in Dentistry
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• 제31권1호
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• pp.17-22
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• 2001

Purpose: To compare the film density of Insight dental X-ray film (Eastman Kodak Co., Rochester, NY, USA) with that of Ektaspeed Plus film (Eastman Kodak) under manual and automatic processing conditions. Materials and Methods : Insight and Ektaspeed Plus films were exposed at three different exposure conditions with an aluminum step wedge on the films under the three different exposure times. The exposed films were processed by both manual and automatic ways. The Base plus fog density and the optical density made by exposing step wedge were calculated using a digital densitometer (model 07-443, Victoreen Inc, Cleveland, Ohio, USA). The optical densities of the Insight and Ektaspeed film versus thickness of alumimun wedge at the same exposure time were plotted on the graphs. Statistical analyses were applied for comparing the optical densities of the two films. Results: The film density of both Insight films and Ektaspeed Plus films under automatic processing condition was significantly higher over the manual processing. The film density of Insight films was significantly higher than that of Ektaspeed Plus films on both automatic and manual processing conditions. Conclusion: The radiation exposure time can be reduced when using Insight over Ektaspeed Plus film. To take the full advantage of reducing exposure time, Insight film should be processed automatically.

• 대한방사선기술학회지:방사선기술과학
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• 제39권4호
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• pp.483-491
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• 2016

유방촬영 시 디지털 유방촬영 후 디지털 유방단층촬영을 한 60명 환자에 대한 촬영 조건을 분석하였다. 그 결과 디지털 유방단층촬영을 한 환자에 대한 피폭선량이 많음을 알았고 그 대책법으로 ACR 팬텀으로 촬영조건을 자동노출조건이 아닌 수동노출조건으로 변경하여 영상의 식별능과 환자피폭선량을 실험하였다. 그 결과 CC(Cranio-Caudal)촬영인 경우 촬영조건 중 kVp는 디지털 유방단층촬영 시 디지털 유방촬영보다 2kVp 높게 설정되어 있었다. 또 mAs는 디지털 유방단층촬영이 55.2% 감소되어 약 60mAs를 주는 것으로 나타났다. 이때 환자의 평균유선선량(AGD)은 디지털 유방촬영에서는 1.65mGy, 디지털 유방단층촬영에서는 1.87mGy로 디지털 유방단층촬영에서 0.22mGy 많이 받는 것으로 나타났다. 팬텀을 이용한 실험에서 kVp는 자동노출조건인 29kVp로 고정하고, mAs을 수동조건으로 감소시키면서 실험한 결과 mAs를 80% 줄여도 영상의 식별능 평가 기준인 10점 이상으로 영향이 없는 것으로 나타났다. 이때 평균유선선량(AGD)도 0.66mGy로 줄일 수 있었다. 디지털 유방촬영시행 후 디지털 유방단층촬영 시 자동노출조건을 그대로 적용하기 보다는 수동노출조건으로 mAs조건을 감소 시켰을 때 영상의 진단적 가치를 유지하면서 환자의 피폭선량경감에 효과가 있었다. 최근 디지털 유방단층촬영의 유용성이 높아지고 있는 만큼 본 연구에서 수동촬영조건의 가이드라인을 제시함으로서 진단적 가치를 높임과 동시에 환자피폭선량을 줄일 수 있을 것으로 사료된다.

• 한국콘텐츠학회논문지
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• 제19권8호
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• pp.276-283
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• 2019

본 연구는 자동노출제어장치(Automatic Exposure Control, AEC)와 수동노출 이용 시 입사표면선량(Entrance Surface Dose, ESD)과 Entropy를 분석하여 자동노출제어장치의 유용성에 대해 알아보고자 하였다. 실험방법은 Skull, Chest, Abdomen, Pelvis 부위에 대하여 란도팬텀(Rando Phantom)에 반도체 선량계를 위치시켜 선량을 측정하였고, 동시에 획득한 DICOM(Digital Imaging and Communications in Medicine) 파일을 Matlab으로 Entropy 분석을 하였다. 그 결과 자동노출제어장치 이용 시 모든 부위의 입사표면선량이 수동노출보다 낮았고 Entropy 수치는 높았으며, paired t-test는 p<0.05로 유의한 차이가 있음을 알 수 있었다. 결론적으로 자동노출제어장치의 사용은 X선 검사 시 발생할 수 있는 불필요한 방사선량과 정보의 손실량을 줄여서 피폭선량과 영상 화질의 최적화에 기여할 수 있는 유용한 방법이 될 수 있다.

• International Journal of Contents
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• 제7권4호
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• pp.103-107
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• 2011

The effective dose and the organ absorbed dose, which are given to a breast in the cases of using and not using the bismuth breast protection shield for the protection of a breast with the coronary artery CT angiography, have been measured and compared for the manual exposure control (MEC)and the automatic exposure control (AEC). In the cases of using and not using the bismuth breast protection shield, it has been found that the measured dose shows the reduction of about 23 to 26% for the MEC and about 22 to 25% for the AEC when the shield is used compared to the case of not using it. By comparing the shield and non-shield cases for the AEC and the MEC, it can be said that the value measured by carrying out the scanning process with the AEC mode has decreased by about 24 to 30% compared to the case of applying the MEC mode. Such a result shows that it is recommended to use the AEC mode for the reduction of the patient's exposure dose during the CT examination.

• 대한방사선기술학회지:방사선기술과학
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• 제35권4호
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• pp.293-298
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• 2012

디지털 유방촬영술은 유방의 두께 및 유선조직의 밀도에 따라 노출조건이 자동으로 이루어지는 자동노출제어장치를 사용하고 있는데 이는 피폭선량을 증가시키는 원인이 되기도 한다. 이 연구에서는 디지털 유방확대촬영술에서 영상의 질을 유지하며 불필요한 방사선 피폭을 줄이기 위한 최적의 방사선량 촬영조건을 알아보았다. 자동노출방식을 사용할 경우 가장 좋은 영상화질을 얻을 수 있었으나 평균유선선량 역시 가장 높았다. 수동노출방식의 경우 자동노출방식의 55 % 정도의 mAs 값만으로도 기준 팬텀영상 점수와 신호대잡음비를 얻을 수 있으며 평균유선선량은 55 % 이하로 줄일 수 있었다. 위와 같은 결과를 참고로 하면 디지털 유방확대촬영 시 자동노출방식보다는 수동노출방식을 이용함으로써 불필요한 환자의 피폭선량을 줄일 수 있을 것이라 생각된다.

• 한국콘텐츠학회논문지
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• 제13권4호
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• pp.290-299
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• 2013

건강검진 목적으로 심장 CT검사를 시행한 198명의 대상자 중 수동노출조절 방법(n=123)의 대조군과 자동노출조절 방법(n=75)의 실험군으로 BMI에 따라 Grade 1(BMI < 23kg/$m^2$), Grade 2(23 $$\leq_-$$ BMI < 25kg/$m^2$), Grade 3(25 $$\leq_-$$ BMI < 30kg/$m^2$), Grade 4(30 $$\leq_-$$ BMI kg/$m^2$)로 분류하고 영상의 질을 객관적, 주관적 평가로 분석하였고 방사선량을 비교하였다. 자동노출조절 방법을 사용하였을 때 모든 Grade에서 관전압이 유의하게 감소하였고, $CTDI_{vol}$, effective dose 값은 Grade 2에서는 통계적으로 유의하지 않게 감소하였으나 Grade 1, 3, 4에서는 유의하게 감소하였다(p<0.05). SNR은 Grade 1에서 유의하게 감소하였고 Grade 3에서는 유의하게 증가하였지만(p<0.05) Grade 2와 4에서는 유의한 차이가 없었다(p>0.05). CNR은 Grade 1에서 유의하게 감소하였고(p<0.05), Grade 2, 3, 4에서는 유의한 차이는 없었다(p>0.05). 영상의 주관적인 평가에서도 두 그룹간의 모든 Grade에서 유의한 차이가 없었다(p>0.05). 결론적으로 자동노출조절 방법은 수동노출조절 방법에 비해 영상의 주관적 평가는 변하지 않으면서도 피폭선량을 줄일 수 있는 유용한 방법으로 나타났다.

• Journal of Advanced Marine Engineering and Technology
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• 제31권5호
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• pp.622-629
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• 2007

Some worker is occupationally exposed to cold and freezing environment. The cold stimuli in the working environment impose physiological and psychological loads on workers to decrease the task performance. The purpose of this study is to investigate the cold stimuli of cold and freezing stores widely used in Busan can make an effect on human's physiological responses and task performance, experimentally and analytically. In the experiment, 5 workers are selected as subjects, and then their skin temperatures of hand and ear, heart rates, blood pressure, and ring test performances in cold($3^{\circ}C$) and freezing($-22^{\circ}C$) stores were measured for 21 minutes and analyzed by using statistical method. It is observed that a physiological variation and the task performance are significantly influenced by an exposure time as well as a strength of cold stimuli. Also, it is suggested the exposure limiting times for the useful manual work and the performance predict model of the ring tasks. The result of this study will be useful for a fundamental data of which design the standard task time of manual tasks and solve the job placement problem of worker selection and placement in cold environment.

• Safety and Health at Work
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• 제14권4호
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• pp.488-491
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• 2023

This study aims to ascertain occupations potentially at greatest risk of exposure to SARS-CoV-2 based on pre-lockdown working conditions in France. We combined two French population-based surveys documenting workplace exposures to infectious agents, face-to-face contact with the public, and working with colleagues just before the pandemic. Then, for each 87-level standard French occupational grouping, we estimated the number and percentage of the French working population reporting these occupational exposure factors, by gender, using survey weights. As much as 40% (11 million) of all workers reported at least two exposure factors. Most of the workers concerned were in the healthcare sector. However, army/police officers, firefighters, hairdressers, teachers, cultural/sports professionals, and some manual workers were also exposed. Women were overrepresented in certain occupations with potentially higher risks of exposure such as home caregivers, childminders, and hairdressers. Our gender-stratified matrix can be used to assign prelockdown work-related exposures to cohorts implemented during the pandemic.

• Toxicological Research
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• 제24권2호
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• pp.119-127
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• 2008

The objectives of this study were to examine the lung injury and inflammation caused by manual metal arc stainless steel(MMA-SS) welding fume inhalation and to evaluate the recovery process. Sprague-Dawley rats were exposed to MMA-SS welding fumes for 2 h per day in a whole-body exposure chamber, with a total suspended particulate(TSP) concentration of $51.4{\pm}2.8mg/m^3$(low dose) or $84.6{\pm}2.9mg/m^3$(high dose) for 30 days. The animals were sacrificed after 30 days of exposure as well as after a 30-day recovery period. To assess the inflammatory or injury responses, cellular and biochemical parameters as well as cytokines were assayed in the bronchoalveolar lavage fluid(BALF). MMA-SS welding fume exposure led to a significant elevation in the number of alveolar macrophages(AM) and polymorphonuclear cells(PMN). Additionary, the values of $\beta$-n-acetyl glucosaminidase($\beta$-NAG) and lactate dehydrogenase(LDH) in the BALF were increased in the exposed group when compared to controls. After 30 days of recovery from exposure, a significant reduction in inflammatory parameters of BALF was observed between the exposed and recovered groups. Slight, but significant elevations were noted in the number of AM and PMN in the recovered groups, and AM that had been ingested fume particles still remain in the lungs. In conclusion, these results indicated that welding fumes induced inflammatory responses and cytotoxicity in the lungs of exposed rats. Fume particles were not fully cleared from lungs even after a 30-day recovery period.