• 제목/요약/키워드: kVCT

검색결과 22건 처리시간 0.024초

얼굴뼈 골절의 진단과 치료에 64채널 3D VCT와 Conventional 3D CT의 비교 (Comparison of 64 Channel 3 Dimensional Volume CT with Conventional 3D CT in the Diagnosis and Treatment of Facial Bone Fractures)

  • 정종명;김종환;홍인표;최치훈
    • Archives of Plastic Surgery
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    • 제34권5호
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    • pp.605-610
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    • 2007
  • Purpose: Facial trauma is increasing along with increasing popularity in sports, and increasing exposure to crimes or traffic accidents. Compared to the 3D CT of 1990s, the latest CT has made significant improvement thus resulting in higher accuracy of diagnosis. The objective of this study is to compare 64 channel 3 dimensional volume CT(3D VCT) with conventional 3D CT in the diagnosis and treatment of facial bone fractures. Methods: 45 patients with facial trauma were examined by 3D VCT from Jan. 2006 to Feb. 2007. 64 channel 3D VCT which consists of 64 detectors produce axial images of 0.625 mm slice and it scans 175 mm per second. These images are transformed into 3 dimensional image using software Rapidia 2.8. The axial image is reconstructed into 3 dimensional image by volume rendering method. The image is also reconstructed into coronal or sagittal image by multiplanar reformatting method. Results: Contrasting to the previous 3D CT which formulates 3D images by taking axial images of 1-2 mm, 64 channel 3D VCT takes 0.625 mm thin axial images to obtain full images without definite step ladder appearance. 64 channel 3D VCT is effective in diagnosis of thin linear bone fracture, depth and degree of fracture deviation. Conclusion: In its expense and speed, 3D VCT is superior to conventional 3D CT. Owing to its ability to reconstruct full images regardless of the direction using 2 times higher resolution power and 4 times higher speed of the previous 3D CT, 3D VCT allows for accurate evaluation of the exact site and deviation of fine fractures.

두경부암 환자의 MVCT를 이용한 치아 인공물 보정에 따른 선량평가 (Dose Evaluation of Dental Artifacts Using MVCT in Head and Neck)

  • 신충훈;윤인하;전수동;김정미;김호진;백금문
    • 대한방사선치료학회지
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    • 제31권2호
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    • pp.25-31
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    • 2019
  • 목 적: 본 연구는 두경부암 환자의 kVCT와 MVCT영상에서 치아 인공물의 체적을 비교하고, MVCT영상에서 치아체적을 얻은 후 kVCT영상에 배정하여 치아체적 및 주변 정상조직의 전자밀도 교정 후 치료계획체적(PTV) 선량변화를 평가하고자 하였다. 대상 및 방법: 본원의 Radixact® X9에서 세기조절방사선치료를 받은 5명의 두경부암 환자를 대상으로 하였다. 환자의 MVCT영상에서 치아 및 주변 정상조직의 체적을 그린 후 kVCT영상에 영상정합 후 역방향 전산화 치료계획을 실시하였다. 처방선량지수와 선량균질지수를 이용하여 PTV 선량을 평가하였다. 결 과: kVCT영상과 MVCT영상에서 얻은 금속 인공물의 체적을 비교한 결과 평균 3.49±2.61cc, 최대 7.43cc의 차이를 보였다. PTV는 내부 치아가 충분히 포함된 곳으로 제한하였으며, PTV 선량평가 결과 인공물을 보정하지 않은 kVCT의 전산화치료계획의 CI값의 평균은 0.86, MVCT영상을 통해 인공물을 보정 한 kVCT의 CI값은 평균 0.9로 평가되었다. 결 론: 금속 인공물의 보정 없이 전산화치료계획이 이루어졌을 때 PTV의 선량이 저평가 되어 선량 불확실성이 발생됨을 알 수 있었다.

최근 개발된 cone beam computed tomography의 흡수선량 및 유효선량 평가 (Absorbed and effective dose from newly developed cone beam computed tomography in Korea)

  • 이종녕;한원정;김은경
    • Imaging Science in Dentistry
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    • 제37권2호
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    • pp.93-102
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    • 2007
  • Purpose: Cone beam computed tomography (CBCT) provides a lower dose and cost alternative to conventional CT, promising to revolutionize the practice of oral and maxillofacial radiology. The purpose of this study was to evaluate the absorbed and effective doses of Implagraphy and VCT (Vatech Co., Hwasung, Korea) and compare them with those of panoramic radiography. Materials and Methods: Thermoluminescent dosimeter (TLD) chips were placed at 27 sites throughout the layers of Female ART Head and Neck Phantom for dosimetry. Implagraphy, VCT units, and Planmeca Proline XC panoramic unit were used for radiation exposures. Radiation weighted doses and effective doses were measured and calculated using 1990 and 2005 ICRP tissue weighting factors. Results: Effective doses in Sv (ICRP 2005, ICRP 1990) were 90.19, 61.62 for Implagraphy at maxillay molar area, 123.20, 90.02 for Implagraphy at mandibular molar area, 183.55, 139.26 for VCT and 40.92, 27.16 for panoramic radiography. Conclusion: Effective doses for VCT and Implagraphy were only about 2.2 to 4.5 times greater than those for panoramic radiography. VCT and Implagraphy, CBCT machines recently developed in Korea, showed moderately low effective doses.

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VCT탑재를 위한 엔진윤활시스템 평가 (Evaluation of Engine Lubrication System for Adapting Variable Cam Timing System)

  • 윤정의
    • Tribology and Lubricants
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    • 제22권1호
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    • pp.14-19
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    • 2006
  • VCT(Variable Cam Timing) system is one of very useful engine components to improve fuel economy and overcome emission regulation etc. In order to adapt the VCT to a base engine, many design mod ifications in the mechanical and lubrication fields are required. Especially, because the VCT performance itself depends on supplied oil flow rate and pressure, it is very important to evaluate the engine lubrication system in a viewpoint of supplied oil flow rate and pressure. In this paper, unsteady transient flow network analysis on the engine oil circuit system was carried out to do this.

표준 바닥재를 이용한 미끄럼 측정기의 검증방법 개선 및 활용방안 (A Study on the Improvement of Validation and Application for Slipmeters using Reference Surfaces)

  • 김정수
    • 한국안전학회지
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    • 제28권6호
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    • pp.73-78
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    • 2013
  • The purpose of this study was to evaluate three kinds of slipmeters (BOT, BPT, English XL) used on-site floor with ASTM F2508 which is comprised of four different standard surfaces(polished granite, glazed porcelain, vinyl composite tile ;VCT, and ceramic tile). ASTM F2508 has two criteria that decide which slipmeter is appropriate or not. The evaluated slipmeters were dreg sled, articulated sturt, and pendulum strike type. The test results revealed that two kinds of slipmeters(BOT, BPT) successfully ranked all four standard surfaces and differentiated among standard surfaces with varying degrees of slipperiness. Nevertheless, the measured value with BOT on the VCT, which was reported as slippery floor in previous study, was higher than its threshold(0.6). Although some slipmeter satisfy two criteria of ASTM F2508, they can underestimate the slip potential. So, another criteria is needed so as to reduce this problem. English XL couldn't properly measure slipperiness under the two kind of floors(glazed porcelain, VCT). So the slider of English XL was modified in order to meet two criteria of ASTM F2508.

Experimental determination of the buckling load of rectangular plates using vibration correlation technique

  • Singhatanadgid, Pairod;Sukajit, Padol
    • Structural Engineering and Mechanics
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    • 제37권3호
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    • pp.331-349
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    • 2011
  • This study investigates the use of a vibration correlation technique (VCT) to identify the buckling load of a rectangular thin plate. It is proposed that the buckling load can be determined experimentally using the natural frequencies of plates under tensile loading. A set of rectangular plates was tested for natural frequencies using an impact test method. Aluminum and stainless steel specimens with CCCC, CCCF and CFCF boundary conditions were included in the experiment. The measured buckling load was determined from the plot of the square of a measured natural frequency versus an in-plane load. The buckling loads from the measured vibration data match the numerical solutions very well. For specimens with well-defined boundary conditions, the average percentage difference between buckling loads from VCT and numerical solutions is -0.18% with a standard deviation of 5.05%. The proposed technique using vibration data in the tensile loading region has proven to be an accurate and reliable method which might be used to identify the buckling load of plates. Unlike other static methods, this correlation approach does not require drawing lines in the pre-buckling and post-buckling regions; thus, bias in data interpretation is avoided.

Evaluation of Treatment Outcomes of Early-Stage Endometrial Cancer Radiotherapy: A Single Center Experience

  • Demiral, S.;Beyzadeoglu, M.;Sager, O.;Dincoglan, F.;Uysal, B.;Gamsiz, H.;Akin, M.;Turker, T.;Dirican, B.
    • Asian Pacific Journal of Cancer Prevention
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    • 제15권22호
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    • pp.9599-9602
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    • 2014
  • Background: Postoperative adjuvant radiotherapy (RT) in the management of early stage endometrial cancer (EC) is still controversial. Here we report our institutional experience with patients who received postoperative RT for stage I-II EC over a period of 35 years and assess potential predictors of local recurrence (LR), distant metastasis (DM), and overall survival (OS). Materials and Methods: A total of 188 patients undergoing postoperative RT for stage IA-II EC between 1977 and 2012 were evaluated. Some 96 received median 46 Gy whole pelvic radiotherapy (WPRT) (range: 40-60 Gy), 37 were given WPRT with vaginal cuff therapy (VCT), and 55 received only VCT either with brachytherapy (BT) or stereotactic body radiotherapy (SBRT). Chemotherapy was given to 5 patients with uterine papillary serous carcinoma (UPSC). Logistic regression analysis was used to assess the effect of clinicopathological factors on LR, DM, and OS. Results: Median follow-up time was 11 years (range: 1-35 years). At the time of analysis, 34 patients were not alive. Of the 15 patients with LR, 7 (46.7%) recurred in the vaginal stump, 5 (33.3%) in the pelvic region, and 3 (20%) in the paraaortic nodal region, while 12 had distant metastasis. UPSC histology (p=0.027), sole VCT (p=0.041), high histologic grade (p=0.034), and age ${\geq}71$ (p=0.04) were poor prognostic factors on univariate analysis. Conclusions: In our patients receiving radiotherapy for early-stage EC, grade III disease and age ${\geq}71$ were associated with shorter OS whereas UPSC histology was an independent predictor for both LR and DM.

Ultrastructure of Oocytes During Oogenesis and Oocyte Degeneration Associated with Follicle Cells in Female Sinonovacula constricta(BIVALVIA: PHARIDAE) in Western Korea

  • Chung, Ee-Yung;Ko, Cheol-Hwan;Kang, Hee-Woong;Choi, Ki-Ho;Jun, Je-Cheon
    • Animal cells and systems
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    • 제12권4호
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    • pp.313-319
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    • 2008
  • The ultrastructure of oocytes during oogenesis and oocyte degeneration associated with follicle cells in female Sinonovacula constricta(Lamarck, 1818) were investigated by electron microscope observations. Ovarian follicles are surrounded by a matrix of vesicular connective tissue cells(VCT cells). VCT cells contain large quantities of glycogen particles and several lipid droplets in their cytoplasm. It is suggested that VCT cells act as a source of nutrients for vitellogenesis during oogenesis. In early vitellogenic oocytes, several coated vesicles, which appear at the basal region of the oocyte, lead to the formation of membrane-bound vesicles via endocytosis. The uptake of nutritive materials in coated vesicles formed by endocytosis appears through the formation of coated pits on the oolemma during vitellogenesis. During the late stage of oogenesis, yolk precursors(yolk granules), mitochondria and lipid droplets are present in the cytoplasm of late vitellogenic oocytes. In particular, proteinaceous yolk granules containing several different components are intermingles and form immature yolk granules. In the mature oocyte, small immature yolk granules are intermingled and form large mature yolk granules. Vitellogenesis occurs through a process of autosynthesis, involving combined activity of the Golgi complex, mitochondria and rough endoplasmic reticulum in the cytoplasm of vitellogenic oocytes. The process of heterosynthesis is where extraovarian precursors are incorporated into oocytes by endocytosis at the basal region of early vitellogenic oocytes before the formation of the vitelline coat. Follicle cells appear to play an important role in vitellogenesis and oocyte degeneration. The functions of attached follicle cells to the oocyte during oocyte degeneration are phagocytosis and digestion of phagosomes originating from oocyte degeneration. After digestion of phagosomes, it is assumed that the function of follicle cells can permit a transfer of yolk precursors necessary for vitellogenesis and allows for the accumulation of glycogen and lipid during oocyte degeneration, which can be employed by vitellogenic oocytes. Follicle cells of S. constricta may possess a lysosomal system for induction of oocyte breakdown and might resorb phagosomes in the cytoplasm for nutrient accumulation during oocyte degeneration.

Barriers to Health Service Utilization Among Iranian Female Sex Workers: A Qualitative Study

  • Asadi-AliAbadi, Mehran;Abolghasemi, Jamileh;Rimaz, Shahnaz;Majdzadeh, Reza;Rostami-Maskopaee, Fereshteh;Merghati-Khoei, Effat
    • Journal of Preventive Medicine and Public Health
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    • 제51권2호
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    • pp.64-70
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    • 2018
  • Objectives: In most countries around the world, sex work is an illegal activity. Female sex workers (FSWs) in Iran hide their identities, and they are known to be a hard-to-reach population. Despite free access to HIV testing, fewer than half of FSWs receive HIV testing. The purpose of this study was to characterize the reasons for which FSWs do not seek testing at drop-in centers (DICs) and voluntary counseling and testing (VCT) centers in Iran. Methods: A qualitative study was conducted in 2016. The participants were 24 FSWs who received services at VCT centers and DICs for vulnerable females in the north of Iran and 9 males who were the clients of FSWs. In this study, we made use of purposive sampling and carried out a thematic analysis. Results: We found 4 major and 6 minor themes. The major themes were: fear of being infected (with HIV), stigma, indifference, and knowledge. Conclusions: Despite the significant efforts made by the government of Iran to establish and expand DICs for vulnerable females, the number of FSWs receiving services at these centers has not been very considerable. Consequently, by introducing and implementing training programs for peer groups, it may be possible to take steps toward establishing strategic programs for the control and prevention of HIV/AIDS.

부하추종 운전시 보론 보충 수량 결정에 관한 연구 (A Study on Determination of Boron Makeup Flow Rate During the Load Follow Operation)

  • Song, Yong-Mann;Lee, Un-Chul;Chung, Chang-Hyun
    • Nuclear Engineering and Technology
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    • 제20권1호
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    • pp.1-8
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    • 1988
  • 상업용 발전소의 가동시, 출력 변화에 의해 1차 계통 보론 농도의 변화가 요구되었을 때 CVCS보충 시스템에서의 보충 유량이 연속 방정식과 질량 평형 방정식을 이용하여 측정된다. 이를 위하여, 1차 계통, 가압기, 그리고 volume control tank가 각각 질량과 보론 농도를 가진 control volume으로 그리고 1차측과 가압기, CVCS를 연결하는 파이프들이 시간 지연 요소로 모델화 되었다. 14-2-6-2 (출력변화 100-50-100) 부하 추종운전의 경우(7호기 EOL에서)를 이 모델을 이용하여 계산하였다.

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