• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.229-236
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• 2016

Background: In order to manage the patient exposure dose in X-ray diagnosis, it is preferred to evaluate the entrance skin dose; although there are some evaluations about entrance skin dose, a small number of report has been published for direct measurement of patient. We think that a small-type optically stimulated luminescence (OSL) dosimeter, named nanoDot, can achieve a direct measurement. For evaluations, the corrections of angular and energy dependences play an important role. In this study, we aimed to evaluate the angular and the energy dependences of nanoDot. Materials and Methods: We used commercially available X-ray diagnostic equipment. For angular dependence measurement, a relative response of every 15 degrees of nanoDot was measured in 40-140 kV X-ray. And for energy dependence measurement, mono-energetic characteristic X-rays were generated using several materials by irradiating the diagnostic X-rays, and the nanoDot was irradiated by the characteristic X-rays. We evaluated the measured response in an energy range of 8.1-75.5 keV. In addition, we performed Monte-Carlo simulation to compare experimental results. Results and Discussion: The experimental results were in good agreement with those of Monte-Carlo simulation. The angular dependence of nanoDot was almost steady with the response of 0 degrees except for 90 and 270 degrees. Furthermore, we found that difference of the response of nanoDot, where the nanoDot was irradiated from the randomly set directions, was estimated to be at most 5%. On the other hand, the response of nanoDot varies with the energy of incident X-rays; slightly increased to 20 keV and gradually decreased to 80 keV. These results are valuable to perform the precise evaluation of entrance skin dose with nanoDot in X-ray diagnosis. Conclusion: The influence of angular dependence and energy dependence in X-ray diagnosis is not so large, and the nanoDot OSL dosimeter is considered to be suitable dosimeter for direct measurement of entrance surface dose of patient.

• 한국산학기술학회논문지
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• 제13권5호
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• pp.2291-2297
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• 2012

X-선 스펙트럼 데이터는 물질의 성분과 관련이 없는 신호(백그라운드, 노이즈)들을 포함 하고 있다. XRF는 스펙트럼에서 가우시안 형태의 피크 위치와 크기를 이용하여 시료의 성분을 분석하며, 시료의 성분을 정확히 분석하기 위해서는 노이즈와 백그라운드를 제거 하여야 한다. 백그라운드를 제거하기 위한 방법으로는 SNIP, Threshold, Morphology 방법 등을 적용하고 있으며, Threshold 기법을 중에서 블록별로 각기 다른 임계값을 적용하는 Interval Threshold기법이 하나의 임계값을 적용하는 Level Threshold 방법보다 더 좋은 성능을 발휘한다. 본 논문에서는 Interval Threshold를 적용하기 위하여 웨이블릿을 이용하여 블록을 분리하는 알고리즘을 제안하였다.

• 한국방사선학회논문지
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• 제14권4호
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• pp.425-431
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• 2020

COVID-19로 인해 수출용 컨테이너에 방사선 발생 장치를 설치한 경우 방사선실의 공간선량을 측정하고 검사실 내의 차폐벽의 효용성에 대하여 연구하고자 하였다. 측정 지점은 X-선관에서 검사자가 있는 뒤쪽으로 이동식 차폐벽을 사용하지 않았을 때를 12곳을 측정하였으며, 이와 대조군으로 이동식 차폐벽을 사용한 후 차폐벽 뒤에서 3곳을 측정하였다. 측정은 Survey Meter를 켜고 배후 방사선(Background)을 측정하였고, 배후 방사선(Background)에서 측정 Peak치 값을 빼서 산출하였다. 이동식 차폐벽 없이 X-선관 뒤, 50cm, 100cm, 200cm로 설정하여 12 곳을 측정하였고, 이동식 방사선 차폐벽을 사용하여 X-선관 뒤에서 3곳을 측정하여 이동식 방사선 차폐벽의 사용 전후의 선량값을 비교하였다. 이동식 차폐벽의 사용 여부에 따라 측정된 선량의 평균값을 대응표본 t 검정을 통하여 결과값 p < 0.05(양측)로 검증하였다. 측정값은 X-선관 뒤 좌측 50cm : 1.446μSv, X-선관 뒤 : 0.545μSv, X-선관 뒤 우측 50cm : 1.466μSv, 방사선 방어용 벽 뒤에서 측정값은 0.190μSv, 0.204μSv, 0.191μSv였다. 실측한 결과 검사실 내에서의 차폐벽으로 인한 검사자의 의료 피폭은 82.3%로 감소시킬 수 있었다. 선별 방사선 검사실에서의 직업 피폭을 감소시키기 위해서는 방사선 발생원으로부터 충분한 이격과 차폐벽의 사용을 권고하는 바이다.

• 전자공학회논문지
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• 제52권10호
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• pp.97-107
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• 2015

디지털 엑스레이 기기로부터 처음 획득된 엑스레이 영상은 데이터 범위가 일반 영상에 비해 넓고 밝기 레벨이 고르지 못하다. 특히 흉부 엑스레이 영상의 경우 다양한 이유로 촬영하기 때문에 갈비뼈와 혈관, 척추 뼈 등 특성이 다른 모든 부위들을 자연스럽게 개선할 필요가 있다. 이러한 엑스레이 영상의 경우 일반 영상과 특성이 다르기 때문에 기존의 화질 개선 알고리즘으로는 진단에 적합한 화질을 얻을 수 없다. 따라서 본 논문은 특정 밝기에 밀집된 정보들의 히스토그램 범위를 확장시키고, 주파수 대역 별 가중치 조절을 통한 선명도 개선 및 고주파 성분의 특성을 이용한 영상 융합 기법을 통해 최종적으로 영상의 대비를 적절하게 개선하는 흉부 엑스레이 영상용 화질 개선 방법을 제안한다. 또한 기존의 기법들과 비교하여 흉부 엑스레이 영상을 보다 자연스럽게 개선하는 것을 확인하고 discrete entropy와 saturation을 통해 정량적 평과 결과를 보인다.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.111-115
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• 2016

Background: The scattered photons cause reduction of the contrast of radiographic image and it results in the degradation of the quality of the image. In order to acquire better quality image, an anti-scattering x-ray gird should be equipped in radiography system. Materials and Methods: The X-ray anti-scattering grid of the inclined type based on the hybrid concept for that of parallel and focused type was tested by MCNP code. The MCNPX 2.7.0 was used for the simulation based test. The geometry for the test was based on the IEC 60627 which was an international standard for diagnostic X-ray imaging equipment-Characteristics of general purpose and mammographic anti-scatter grids. Results and Discussion: The performance of grids with four inclined shielding material types was compared with that of the parallel type. The grid with completely tapered type the best performance where there were little performance difference according to the degree of inclination. Conclusion: It was shown that the grid of inclined type had better performance than that of parallel one.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1994년도 춘계학술발표회 프로그램 및 초록
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• pp.66-66
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• 1994

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2023년도 춘계학술발표대회
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• pp.687-688
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• 2023

Bone age assessment is a crucial task in pediatric radiology for assessing growth and development in children. In this paper, we explore the potential of Vision Transformer, a state-of-the-art deep learning model, for bone age assessment using X-ray images. We generate heatmap outputs using a pre-trained Vision Transformer model on a publicly available dataset of hand X-ray images and show that the model tends to focus on the overall hand and only the bone part of the image, indicating its potential for accurately identifying the regions of interest for bone age assessment without the need for pre-processing to remove background noise. We also suggest two methods for extracting the region of interest from the heatmap output. Our study suggests that Vision Transformer holds great potential for bone age assessment using X-ray images, as it can provide accurate and interpretable output that may assist radiologists in identifying potential abnormalities or areas of interest in the X-ray image.

• 한국의상디자인학회지
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• 제17권3호
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• pp.13-27
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• 2015

The purpose of this study is to understand the general process from textile design till fashion design and to understand the relation between the body structure by using the x-ray technique. The research method was to see background of the anatomic feature and human skeletal X-ray projection through historical aspect of publications, the Internet, and paper. In terms of production, in order to present a design that takes into account the unique silhouette of the human body without distorting the shape of the human skeleton, X-ray images that were reconstituted using a computer graphic tool (Photoshop CS) were reproduced into the fabric as intense images through the digital Textile Printing technique that is capable of expressing fine and delicate details, and applied into the design. An original design was developed that emphasized the impression of the human body being projected and the shape of the human skeleton realistically expressed in terms of silhouette and detail. The results are as follows: First, Body has a anatomic formative characteristic and its formativeness becomes as a great motive for the artistic expression and thereby it becomes more unique and available for new design expression. Second, Using the 'body frame' as the motive of the research, there's mainly tried to make an unique expression. Third, according to reconstructing human skeletal X-ray projection by using Adobe Photoshop CS2, it can be expressed strong and unique design. Forth, DTP which is being used as an essential technique, expresses the body frame realistically and being used the special type of functional product and silk. Likewise by discovering the diverse formativeness of our body frame and reflecting the sense of humanity into the pieces there's been able to make and develop an unique fashion design. I sincerely hope there is a hug progress in this research in this area.

• 천문학회지
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• 제37권5호
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• pp.517-525
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• 2004

We present an update on our proposal that during the 'quasar era' (1.5 $\le$ z $\le$ 3), powerful radio galaxies could have played a major role in the enhanced global star-formation, and in the widespread magnetization and metal pollution of the universe. A key ingredient of this proposal is our estimate that the true cosmological evolution of the radio galaxy population is likely to be even steeper than what has been inferred from flux-limited samples of radio sources with redshift data, when an allowance is made for the inverse Compton losses on the cosmic microwave background which were much greater at higher redshifts. We thus estimate that a large fraction of the clumps of proto-galactic material within the cosmic web of filaments was probably impacted by the expanding lobes of radio galaxies during the quasar era. Some recently published observational evidence and simulations which provide support for this picture are pointed out. We also show that the inverse Compton x-ray emission from the population of radio galaxies during the quasar era, which we inferred to be largely missing from the derived radio luminosity function, is still only a small fraction of the observed soft x-ray background (XRB) and hence the limit imposed on this scenario by the XRB is not violated.

• Journal of Chest Surgery
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• 제31권7호
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• pp.730-734
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• 1998

배경: 기흉 환자를 수술하기 전에 폐기포의 위치, 숫자, 크기와 모양을 파악하기 위하여 단순 흉부 X선 사진이나 흉부 컴퓨터 단층 촬영등을 이용한다. 단순 흉부 X선 사진은 간편하고 저렴하나 정확도가 낮고, 흉부 컴퓨터 단층 촬영은 정확하나 비용이 많이든다. 그러나 흉강조영술을 이용하면, 폐기포의 상태를 비교적 저렴하고 정확히 파악할수 있으리라 예상되어, 이를 확인하기 위하여 본 임상 실험을 계획하였다. 대상 및 방법: 대상은 개흉이나 흉강내시경을 이용하여 폐기포 절제를 시행한, 원발성 자연 기흉 환자 22명이었다. 수술전에 단순 흉부 X선 사진과 흉강조영술을 시행하여, 이를 수술시의 폐기포의 소견과 비교하였다. 결과: 흉강조영술의 Sensitivity는 75%로 단순 흉부 X선 사진의 30%에 비하여 높았고, 정확도(Accuracy)도 72.7%로 단순 흉부 X선 사진의 36.4%에 비하여 높았다. 그러나 Specificity는 흉강조영술이 50%로 단순 흉부 X선 사진의 100%에 비하여 낮았다. 검사로인한 합병증은 없었다. 결론: 결론적으로 기흉의 수술전 검사로서 흉강조영술은 단순 흉부 X선 사진에 비하여 높은 진단적 가치를 지녔으며, 안전하게 이용될 수 있으리라 생각된다.