• 한국방사선학회논문지
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• 제12권1호
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• pp.107-114
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• 2018

고관절 시행에서 식립각도는 추후 환자의 운동범위나 힘의 분배조건에 따라 폴리에틸렌 라이너의 마모에도 영향을 미친다. 인공관절요소로부터 마모입자는 골괴사나 다른 생화학적으로 많은 합병증을 일으킨다. 이런 점에서 인공고관절에서 마모와 정렬각도를 수술 후 추시를 통해 측정하는 것은 중요하다. 특히 관절면의 마모를 측정하는 것은 그 량이 크지 않아 상당한 정밀도를 요구한다. 현재 널리 쓰이는 상용 소프트웨어는 재현성과 측정방법의 표준화가 되어 있지 않아 사용에 많은 어려움이 있다. 본 논문에서는 일반 병원의 방사선촬영 환경에서 CAD만 추가로 구비하면 행할 수 있는 인공관절면 마모와 식립각 측정법을 제시한다. 인공관절만의 X-ray영상을 이용한 본 방법의 정확도와 정밀도 평가를 수행하였다. 또한 실제 인공고관절환자의 X-ray영상을 가지고 2년추시에 따른 마모와 식립각을 측정하였다. 본 연구에서 제시한 CAD를 이용한 방법은 마모측정에서 정확도 0.06 mm, 정밀도 0.05 mm, 식립각은 $0.27^{\circ}$의 정밀도를 갖는다.

• 대한한방소아과학회지
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• 제22권2호
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• pp.155-170
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• 2008

Objectives : The purpose of this study was to have better data and to make efficient clinical reviews about children's growth based on two methods; X-ray of hand, and ultrasound of calcaneus. Methods : The study was composed of 100 patients(50 of boys and 50 of girls) who visited in department of pediatrics, O O university oriental hospital considering growth and their development. Bone age was measured by the TW3 method's RUS score in simple X-ray image of hand and bone density through ultrasonic image of calcaneus. To predict children's estimated height, their parent's height, bone age, and present height's percentile was measured. Results and Conclusions : 1. The bone age results from X-ray image of hand and ultrasonic image of calcaneus were correlated. Younger children have older bone age from hand's X-ray than the one from calcaneus's ultrasound. Older children have older bone age from calcaneus's ultrasound than one from hand's X-ray. 2. Predicted adult height by bone age(BH) of hand's X-ray and BH of calcaneus's ultrasound were correlated, but predicted adult height by inheritance(IH) was not correlated with others. 3. Bone age and predicted adult height were correlated with age, height, weight, BMI, and especially with age and height. 4. Measuring bone age by X-ray image of hand and ultrasonic image of calcaneus was simple and effective way of estimating children's growth and development.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.407-410
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• 2002

Monochromatic x-ray CT has several advantages over conventional CT, which utilizes bremsstrahlung white x-rays from an x-ray tube. There are several methods to produce such monochromatic x-rays. The most popular one is crystal diffraction monochromatization, which has been commonly used because of the fact that the energy spread is very narrow and the energy can be changed continuously. The alternative method is the use of fluorescent x-ray, which has several advantages such as large beam size and fast energy change. We have developed a parallel-beam and a fan-beam monochromatic x-ray CT, and compared some characteristics such as accuracy of CT numbers between those systems. The fan beam monochromatic x-rays were generated by irradiating target materials by incident white x-rays from a bending magnet beam line NE5 in 6.5 GeV Accumulation Ring at Tukuba. The parallel beam monochromatic x-rays were generated by using a silicon double crystal monochromator at the bending magnet beam line BL-20BM in Spring-8. A Cadmium telluride (CdTe) 256 channel array detector with 512mm sensitive width capable of operating at room temperature was used in the photon counting mode. A cylindrical phantom containing eight concentrations of gadolinium was used for the fan beam monochromatic x-ray CT system, while a phantom containing acetone, ethanol, acrylic and water was used for the parallel monochromatic x-ray CT system. The linear attenuation coefficients obtained from CT numbers of those monochromatic x-ray CT images were compared with theoretical values. They showed a good agreement within 3%. It was found that the quantitative measurement can be possible by using the fan beam monochromatic x-ray CT system as well as a parallel beam monochromatic X-ray CT system.

• 대한방사선기술학회지:방사선기술과학
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• 제28권2호
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• pp.111-115
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• 2005

X-선을 이용하여 의료영상을 생성하는 시스템은 X-선 발생장치, 피사체, 영상전달매체 등의 여러 가지 차이에 따라 영상의 질이 결정된다. 즉, X-선 발생에서 최종영상에 이르기까지 화질에 영향을 미치는 요소가 다양하다는 것이다. 따라서 임상에서 영상을 생성하는 사용자는 최종영상에서 계속적인 영상의 평가와 관찰이 필요하다. 의료영상을 평가하는 방법에는 여러 가지가 있지만, 그 중 실질 또는 실효해상도를 측정하는 방법으로 MTF 측정방법이 적절하다고 할 수 있다. 따라서 본 연구에서는 X-선 필름을 이용하여 MTF를 계산하는 방법을 탈피하고, 디지털 의료영상의 MTF를 측정할 수 있는 소프트웨어(Borland C++ builder 소프트웨어와 LEAD tools 소프트웨어를 이용한 프로그램)를 이용하여 X-선 장비의 노후화 정도에 따른 MTF 특성을 측정하였다. 측정결과, 사용연수와 사용횟수가 오래된 X-선 발생장치는 최신 장치에 비해 해상력(resolution)과 선예도(sharpness) 등의 화질이 저하되는 것을 MTF 그래프를 통해 확인할 수 있었다. 또한, 디지털 의료영상에서도 간단하고 쉽게MTF를 측정할 수 있는 방법을 얻을 수 있었다.

• 천문학회지
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• 제35권3호
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• pp.111-121
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• 2002

We have measured the correlation functions of the optically selected clusters of galaxies in the Abell and the APM catalogs, and of the X-ray clusters in the X-ray-Brightest Abell-type Clusters of galaxies (XBACs) catalog and the Brightest Clusters Sample (BCS). The same analysis method and the same method of characterizing the resulting correlation functions are applied to all observational samples. We have found that the amplitude of the correlation function of the APM clusters is much higher than what has been previously claimed, in particular for richer subsamples. The correlation length of the APM clusters with the richness R $\ge$ 70 (as defined by the APM team) is found to be $r_0 = 25.4_{-3.0}^{+3.1}\;h^{-1}$ Mpc. The amplitude of correlation function is about 2.4 times higher than that of Croft et al. (1997). The correlation lengths of the Abell clusters with the richness class RC $\ge$ 0 and 1 are measured to be $r_0 = 17.4_{-1.1}^{+1.2}$ and $21.0_{-2.8}^{+2.8}\;h^{-1}$ Mpc, respectively, which is consistent with our results for the APM sample at the similar level of richness. The richness dependence of cluster correlations is found to be $r_0= 0.40d_c + 3.2$ where $d_c$ is the mean intercluster separation. This is identical in slope with the Bahcall & West (1992)'s estimate, but is inconsistent with the weak dependence of Croft et al. (1997). The X-ray bright Abell clusters in the XBACs catalog and the X-ray selected clusters in the BCS catalog show strong clustering. The correlation length of the XBACs clusters with $L_x {\ge}0.65{\times} 10^{44}\;h^{-2}erg\;s^{-1}$ is $30.3_{-6.5}^{+8.2}\;h^{-1}$ Mpc, and that of the BCS clusters with $L_x {\ge}0.70{\times} 10^{44}\;h^{-2}erg\;s^{-1}$ is $30.2_{-8.9}^{+9.8}\;h^{-1}$ Mpc. The clustering strength of the X-ray clusters is much weaker than what is expected from the optical clusters.

• 한국정밀공학회지
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• 제32권4호
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• pp.387-394
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• 2015

We analyze heat generation as well as temperature distribution induced by accelerated electron impact on a target in a closed x-ray tube. For the sake of accuracy, we use Monte carlo analysis. This method gives accurate energy deposit in a medium with additional information such as secondary and backscattered electron as well as their paths. A Tungsten coated layer is divided by small rectangular cell which accumulate energy loss of primary electron beam. The cells and their accumulated energy datum are used for the input of finite element analysis. The Maximum temperature rising and temperature distribution were analyzed by transient heat analysis. Some temperature parameters such as target size and coating thickness were varied to investigate temperature sensitivity. Temperatures were compared each other to find primary variable that affect temperature rising on the x-ray target. The results will be helpful in development highresolution x-ray tube and related industries.

• 대한방사선기술학회지:방사선기술과학
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• 제22권1호
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• pp.13-20
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• 1999

This study is to calculate the exposed radiation dose using Bit method, NDD calculation method and monogram method without dosimeter. In addition, we can calculate the radiation dose from x-ray film density as a film badge. The authors examined the entrance skin dose from $2{\sim}3$ intercostal chest x-ray film density. We also studied the relationship between film density and equivalent dose in the each screen film system under the different radiation quality and the poor geometry condition of grid ratio. As results, we established the deductive method to define the entrance skindose from chest x-ray film density. The error range was found in the range $-13%{\sim}+l7%$ for between deductive entrance skindose and the $2{\sim}3$ intercostal chest x-ray film density to actual detective radiation dose with dosimeter.

• 한국정보통신학회논문지
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• 제5권4호
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• pp.829-840
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• 2001

본 연구는 디지털 화상처리기술의 대표적인 응용분야로서 주목받고 있는 X선 사진을 대상으로 한 계산기 지원진단에 관한 연구의 일종으로서, 폐의 중요한 질환중 하나인 폐기종의 진단을 지원하는 계산기 시스템에 관한 연구이다. 구체적인 내용으로서는 흉부X선 사진으로부터 말초혈관을 자동추출하고, 추출된 혈관을 토대로 여러가지의 특징량을 구하여, 최종적으로 폐기종의 병세진행도를 정량평가하는 시스템에 관한 연구이다. 혈관 도형을 추출하여 병의 진행 정도를 정량적으로 평가하기 위해 본 연구에서 제안한 평가방법을 10장의 X선 사진에 설정된 189개의 관심영역에 적용하여, 의사의 평가치와 본 연구의 제안방법에 의한 평가치를 비교·검토함으로써 그 유효성을 검증하였다.

• Journal of Radiation Protection and Research
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• 제20권2호
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• pp.129-136
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• 1995

중저준위 에너지 범위에서 방사선관리용측정기기의 에너지의존성에 대한 연구를 위하여 ISO에서 는 ISO표준 X선장을 발간하였으며, 또한 ANSI에서도 개인방사선측정 기기의 성능시험을 위하여 ANSI X선장을 제시 하였다. 그러나 X선 스펙트럼의 측정은 많은 시간이 소요될 뿐만 아니라 특히 측정 X선 스펙트럼에 unfolding이 수행된다면 매우 어려운 작업이 된다. 따라서 이론적인 방법에 의해 스펙트럼을 계산 예측하고 그 평균에너지 및 선량환산인자를 계산하는 것은 X선 실험제작에 필요한 시간, 노력 및 비용을 최소화 할 수 있을 것이다. 따라서 본 연구에서는 ISO Narrow series 및 ANSI X선장에 대하여 이론적으로 스펙트럼을 계산하였으며, 그에 의한 평균에너지와 선량당량혼산인자를 계산하였다. 본 계산에 의한 평균에너지 및 선량환산인자는 측정스펙트럼에 의한 ISO 및 X선장의 값과 잘 일치하였다.

• Journal of the Korean Wood Science and Technology
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• 제45권6호
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• pp.836-845
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• 2017

Gravimetric method is usually used to evaluate air-dry density, which is governing physical or mechanical properties of wood. Although it had high evaluation accuracy, the method is time consuming process. Thus, this study was conducted to estimate air-dry density of wood with high accuracy by using polychromatic X-ray and digital detector as alternative of gravimetric method. To quantify polychromatic X-ray projection for evaluating air-dry density, Lambert-Beer's law with the integral value of probability function was used. The integral value was used as weighting factor in the law, and it was determined by conducting simple test at various penetration depths and tube voltage. Mass attenuation coefficient (MAC) of wood also calculated by investigating polychromatic X-ray projection according to species, penetration depth and tube voltage. The species had not an effect on change of MAC. Finally, an air-dry density of wood was estimated by applying the integral value, MAC and Lambert-Beer's law to polychromatic X-ray projection. As an example, the relation of the integral value (${\alpha}$) according to penetration depth (t, cm) at tube voltage of 35 kV was ${\alpha}=-0.00091t{\times}0.0184$ while the regression of the MAC (${\mu}$, $cm^2/g$) was ${\mu}=0.5414{\exp}(-0.0734t)$. When calculation of root mean squared error (RMSE) was performed to check the estimation accuracy, RMSE at 35, 45 and 55 kV was 0.010, 0.013 and $0.009g/cm^3$, respectively. However, partial RMSE in relation to air-dry density was varied according to tube voltage. The partial RMSE below air-dry density of $0.41g/cm^3$ was $0.008g/cm^3$ when tube voltage of 35 kV was used. Meanwhile, the partial RMSE above air-dry density of $0.41g/cm^3$ decreased as tube voltage increased. It was conclude that the accuracy of estimation with polychromatic X-ray and digital detector was quite high if the integral value and MAC of wood were determined precisely or a condition of examination was chosen properly. It was seemed that the estimation of air-dry density by using polychromatic X-ray system can supplant the gravimetric method.