• 대한치과보철학회지
• /
• 제52권4호
• /
• pp.298-304
• /
• 2014

목적: 본 선행 연구는 recombinant human transforming growth factor-${\beta}2$ (rhTGF-${\beta}2$)/ poly lactic-co-glycolic acid (PLGA) 복합체를 타이타늄 임플란트에 처리하였을 때 골 유착에 미치는 영향을 알아보기 위해 시행된 것으로 토끼 모델을 사용하였다. 재료 및 방법: 8개의 임플란트를 300V에서 3분 동안 양극 산화하였다. 그 중 4개는 electrospray법으로 rhTGF-${\beta}2$/PLGA를 코팅하여 실험군으로 설정하였다. 4마리의 New Zealand rabbit의 tibiae에 1개씩의 실험군과 대조군 임플란트를 식립하였으며, 3주와 6주에 2마리씩 희생하여 micro-computed tomography(microCT) 촬영 후 분석하였다. 결과: Scanning electron microscope (SEM) 사진에서 rhTGF-${\beta}2$/PLGA 입자가 임플란트 표면에 균일하게 분산되어 있음을 확인하였다. MicroCT 분석 결과 통계적으로 유의하지는 않지만 rhTGF-${\beta}2$/PLGA를 처리한 임플란트가 bone volume/total volume (BV/TV)와 trabecular thickness (Tb.Th) 값이 더 높은 경향성을 보였으며, cross sectional view에서 더 많은 골이 형성되었음을 확인하였다. 결론: rhTGF-${\beta}2$/PLGA 표면처리된 임플란트가 주변 골의 양적 성장을 촉진시킬 수 있으며 임플란트 초기 골 유착을 증진시킬 수 있는 가능성을 보였다.

• 한국방사선학회논문지
• /
• 제16권4호
• /
• pp.387-394
• /
• 2022

갑상샘이 포함된 인체모형 팬텀을 이용하여 임상에서 많이 적용하는 NECK CT 프로토콜 중 관전압을 변화 적용하여 스캔 후 Raw data를 이용하여 FBP, ASIR-V, DLIR 재구성기법 적용 영상 획득하여 120 kVp FBP 재구성 영상 기준 DLIR 재구성기법의 유용성을 알아보았다. 그 결과 DLIR 재구성기법 적용 시 CTDIvol 이 감소하였으며, 특히 동일 관전압에서 FBP 적용보다 ASIR-V, DLIR 재구성 시 낮은 선량에서도 기준 스캔 조건으로 획득한 화질에 도달하였다. 또한, SNR, CNR 분석결과 DLIR 재구성 영상이 SNR, CNR 값이 높게 분석되었고, SSIM분석결과 100 kVp, DLIR 재구성 영상이 SSIM 지수가 1에 근사하게 측정되어 원본 영상에 대한 재구성 영상의 유사도가 높은 것으로 분석되었다(p>0.05). 본 연구결과를 활용하여 임상 영상 평가를 시행하여 보완하고 다양한 해부학적 구조에 적용 가능한 알고리즘을 추가 개발한다면 검사 선량을 현재 보다 낮추면서 화질을 유지할 수 있어 임상 적용 시 유용할 것으로 생각된다.

• 대한디지털의료영상학회논문지
• /
• 제12권2호
• /
• pp.127-132
• /
• 2010

In this study, the correlation among the changes of Modulation Transfer Function(MTF) in the noise and high-contrast resolution and the change of Contrast to noise ratio(CNR) in the low-contrast resolution will be examined to investigate the estimation of image quality according to the type of algorithms. The image data obtained by scanning American Association of Physicists in Medicine(AAPM) phantom was applied to each algorithm and the exposure condition of 120 kVp, 250 mAs, and then the CT number and noise were measured. The MTF curved line of the high-contrast resolution was calculated with Point Spread Function(PSF) by using the analysis program by Philips, resulting in 0.5 MTF, 0.1 MTF and 0.02 MTF respectively. The low-contrast resolution was calculated with CNR and the uniformity was measured to each algorithm. Since the measurement value for the uniformity of the equipment was below ${\pm}$ 5 HU, which is the criterion figure, it was found to belong to the normal range. As the algorithm got closer from soft to edge, the standard deviation of CT number increased, which indicates that the noise increased as well. As for MTF, 0.5 MTF, 0.1 MTF and 0.02 MTF were all sharp algorithms, and as the algorithm got closer from soft to edge, it was possible to distinguish more clearly with the naked eye. On the other hand, CNR gradually decreased, because the difference between the contrast hole CT number and the acrylic CT number was the same while the noise of hole increased.

• 한국의학물리학회지:의학물리
• /
• 제13권4호
• /
• pp.229-233
• /
• 2002

CdZnTe 검출기를 제작하고 CT/SPECT 조합영상 시스템에 설치하여 엑스선 및 감마선검출기로서의 응용가능성을 타진해 보았다. 검출기의 크기는 10$\times$10$\times$5 ㎣ 이었다. 양극은 4$\times$4 픽셀로 설계하였으며 각 픽셀의 크기는 $1.5\times$l.5 $\textrm{mm}^2$ 이었다. 음극은 Au로 전극을 만들어 주었다. 시스템의 성능을 조사하기 위해서 방사선촬영용 분해능팬텀과 호프만 뇌 팬텀을 사용하였다. X선 영상에서 고광자방출율을 만족시키기 위해서 shapping time은 50ns 로 하었으며, 3$\times$$10^{5}$ counts/s 까지 선형성이 유지되었다. Tc-99m의 140 keV 감마선에 대한 에너지 분해능은 50 ㎱와 2 $\mu\textrm{s}$ shaping time을 걸어주었을 때 각각 10.4%와 5.3%이었다. CT와 SPECT의 공간분해능은 각각 1 mm와 9 mm 이었다. 광피이크 효율은 50 ㎱와 2 $\mu\textrm{s}$일 때 각각 41.0%와 72.5%이었다.

• Imaging Science in Dentistry
• /
• 제51권4호
• /
• pp.341-350
• /
• 2021

Purpose: The use of micro-computed tomography (micro-CT) scans in biomedical and dental research is growing rapidly. This study aimed to explore the scientific literature on approaches and applications of micro-CT in restorative dentistry. Materials and Methods: An electronic search of publications from January 2009 to March 2021 was conducted using ScienceDirect, PubMed, and Google Scholar. The search included only English-language articles. Therefore, only studies that addressed recent advances and the potential uses of micro-CT in restorative and preventive dentistry were selected. Results: Micro-CT is a tool that enables 3-dimensional imaging on a small scale with very high resolution. In this method, there is no need for sample preparation or slicing. Therefore, it is possible to examine the internal structure of tissue and the internal adaptation of materials to surfaces without destroying them. Due to these advantages, micro-CT has been recommended as a standard imaging tool in dental research for many applications such as tissue engineering, endodontics, restorative dentistry, and research on the mineral density of hard tissues and bone growth. However, the high costs of micro-CT, the time necessary for scanning and reconstruction, computer expertise requirements, and the enormous volume of information are drawbacks. Conclusion: The potential of micro-CT as an emerging, accurate, non-destructive approach is clear, and the valuable research findings reported in the literature provide an impetus for researchers to perform future studies focusing on employing this method in dental research.

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

• Journal of the Korean Data and Information Science Society
• /
• 제26권1호
• /
• pp.179-185
• /
• 2015

최근 고가의료장비의 도입으로 진단기술이 빠르게 발전하고 있으나 이에 따른 건강보험 재정의 부담이 크게 늘어 이에 대한 적절한 관리와 효율적 운영에 대한 정책이 필요하다. 이에 따라 본 연구에서는 의사결정나무분석 모형을 사용하여 CT 의료장비의 검사빈도에 영향을 미치는 요인을 파악하여 효율적 운영에 대한 방안을 제시한다.

• 한국의학물리학회:학술대회논문집
• /
• 한국의학물리학회 2002년도 Proceedings
• /
• pp.379-381
• /
• 2002

A single CdZnTe detector is tested for suitability in a prototype CT/ SPECT system designed to acquire both emission and transmission data. The detector has the size of 1${\times}$l-cm$^2$ with 4${\times}$4 1.5${\times}$l.5mm$^2$ pixellated anodes. Since the detector is smaller than imaged object, we translated it in an arc centered at the x-ray tube to image larger objects. Pulse counting electronics with very short shaping time (50 ns) are used to satisfy high photon rates in x-ray imaging, and response linearity up to 3${\times}$10$\^$5/ counts per second per detector element is achieved. The energy resolution of 122-keV gamma-ray is measured to be 14%. We have characterized the system performance by scanning a radiographic resolution phantom .and the Hoffman brain phantom. The spatial resolution of CT and SPECT are about 1 mm and 7 mm, respectively.

• International Journal of Precision Engineering and Manufacturing
• /
• 제9권2호
• /
• pp.63-68
• /
• 2008

Hard and brittle materials, such as Ni- and Ti-based alloys, glass, and ceramics, are very useful in aerospace, marine, electronics, and high-temperature applications because of their extremely versatile mechanical and chemical properties. One Ni-based alloy, Inconel 718, is a precipitation-hardenable material designed with exceptionally high yield strength, ultimate tensile strength, elastic modulus, and corrosion resistance with outstanding weldability and excellent creep-rupture properties at moderately high temperatures. However, conventional machining of this alloy presents a challenge to industry. Ultrasonic vibration cutting (UVC) has recently been used to cut this difficult-to-machine material and obtain a high quality surface finish. This paper describes an experimental study of the UVC parameters for Inconel 718, including the cutting force components, tool wear, chip formation, and surface roughness over a range of cutting conditions. A comparison was also made between conventional turning (CT) and UVC using scanning electron microscopy observations of tool wear. The tool wear measured during UVC at low cutting speeds was lower than CT. UVC resulted in better surface finishes compared to CT under the same cutting conditions. Therefore, UVC performed better than CT at low cutting speeds for all measures compared.

• 한국산학기술학회논문지
• /
• 제18권7호
• /
• pp.84-91
• /
• 2017

본 연구는 컴퓨터 단층촬영 영상에서 제거할 수 없는 의료용 고밀도 물질을 Somatom Definition Flash(Siemens, Enlarge, Germany.)와 GE 64-MDCT (Discovery 750 HD, GE HEALTHCARE, Milwaukee, USA.)스캔 후 획득한 팬텀영상 데이터와 이미 촬영된 Raw 데이터영상을 이용하여 IMAR 알고리즘과 MAR 알고리즘 적용 및 재구성한 후 CT 재구성영상의 CT Number 변화율을 정량적으로 분석하였다. 그 결과 팬텀영상의 모든 의료용 고밀도 물질은 IMAR 알고리즘과 MAR 알고리즘 적용 시 CT Number의 변화와 영상의 차이가 있는 것으로 나타났지만(p<0.05). Stainless Steel 재질은 Black streak artifact에서 MAR 또는 IMAR 알고리즘 적용 시 재구성 영상의 변화와 CT Number의 변화차이가 없는 것으로 분석되었다(p>0.05). 또한 이미 촬영된 Raw 데이터영상 분석결과 IMAR 알고리즘 적용 시 적용 전에 비하여 영상 CT Number 변화가 있어, IMAR 알고리즘 적용은 Attenuation deviation에 영향을 미치는 것을 알 수 있었다. 이 결과를 바탕으로 향후 Implant시술 후 추적 CT검사 시 수술부위 및 주변조직의 상태를 관찰하는데 유용할 것으로 사료된다.