Neck Angiography 검사의 선량과 화질 : Dual Source Computed Tomography와 Multi-detector Computed Tomography의 비교

유흥준(Heung Joon Yoo),정성민(Seong Min Cheong),서동수(Dong Soo Suh) 대한전산화단층기술학회 2010 대한CT영상기술학회지 Vol.12 No.2

Purpose According to the development of devices from multi-detector computed tomography (MDCT) to dual source computed tomography(DSCT), protocol using DSCT with 140 kVp can be used in the examination of neck angiography. This can be considered to reduce beam hardening artifact at the portion of shoulder than when used single source CT with 120 kVp. for adapting to ALARA’s principle, we tried to make an optimal image quality with minimum dose and to compare with dose and image quality between DSCT and MDCT. Materials and methods Dose and image quality was compared and evaluated in each case of single source CT versus DSCT at examination of neck angiography. 16 channel MDCT(Somatom Sensation 16 Siemens, Germany) and DSCT(Somatom Definition Siemens, Germany) devices were utilized. Rando phantom(Model ART-200-5) and thermoluminescence dosimeter(TLD, GD352M, 12 mm) were used for measurement of dose according to protocol and organ’s dose figure. Lung-chest phantom(Model RS-330) was used for measuring the image quality. CTDⅣol was presented by monitor of CT device and TLD was located in sensitⅣe portion of radiation like thyroid, salⅣary gland, orbit. noise was assessed by making region of interest(ROI) in three sections of aortic arch level indicating severe artifacts. Also we compared an image using DSCT versus examination previously performed by 16 channel MDCT selecting a patient with similar body shape. Results CTDⅣol value bas decreased more as dual source compares in single source 16 MDCT. Organ dose(thyroid, salⅣary gland, and orbit) has been decreased in dual source in comparison with other source. In the image quality, noise has been decreased in DSCT in comparison with single source and 16 MDCT. In fact, that also reduced artifact. Conclusion Protocol using of dual source is useful than single source, when organ dose and noise result analysis has used Rando phantom.

CT 검사 시 촬영조건에 따른 Image Quality와 Dose에 관한 연구

유흥준(Heung Joon Yoo),권성옥(Seong Ohk Kwon) 대한CT영상기술학회 2008 대한CT영상기술학회지 Vol.10 No.1

Purpose To provide an advice on the patient dosimetry quantities without obstructing the medical purposes through the decrease in kVp and the use of Dose modulation program, Care dose 4D for tube current with patient screening by weight in CT examination. Materials and Methods Each weight group(51kg~60kg, 61kg~70kg, 71kg~80kg, 81kg~90kg) consists of 5 patients from total 20 patients with follow-up abdomen CT examination. CT values and noise according to the tube ctuTent were measured, and exposure dose and image quality were compared. Somatom Sensation 16 equipment was used for measurement. Dose modulation program, Care dose 4D was used for tube current, and tube voltage was measured using 100kVp at Pre Enhancement phase on the abdomen. Examination range was compared and analyzed by applying same FOV with the recently examined tube potential of 120kVp. Results In case of 120 kVp and 100 kVp by using Dose modulation program, Care dose 4D, CT values were decreased on the whole. However, the tendency of CT values of adjacent abdominal organs were measured similarly. 1his means that the contrast resolution is not greatly influenced by the lowered tube voltage of 100 kVp. When we measured the noise of the liver, the spleen, and the descending aorta according to the weight of the patient in the image quality measurement, as the weight of the patient decreases the noise ratio was also reduced as follows : from 0.76:1 to 0.88:1 for the liver, from 0.75:1 to 0.87:1 for the descending aorta, and from 0.73:1 to 0.85:1 for the spleen. Therefore, we can conclude that high quality image can be obtained using 100 kVp in the patient having a weight of 60 kg and the height of at least 165~175 cm. If the tube voltage was reduced from 120 kVp to 100 kVp, no tube current change was observed, and the CTDIvol value was decreased over 30%. Conclusion It would be very helpful in reducing radiation exposure to perform CT examination using optimal shooting condition according to the patient’s weight and physical constitution presented by the clinical trial results. Once the standard protocol is presented at the conference or public agency, We think that the radiation exposure of a patient can be greatly decreased by using optimal shooting condition for each hospital based on the protocol.

Arrhythmia 환자의 Coronary Computed Tomography Angiography에서 ECG-triggered FLEX Scan Mode 사용 시 선량과 영상의 질에 대한 연구

유흥준(Heung Joon Yoo),김민정(Min Jung Kim),박정훈(Jung Hoon Park) 대한CT영상기술학회 2013 대한CT영상기술학회지 Vol.15 No.1

서론 : 본 연구의 목적은 부정맥이 있는 환자를 대상으로 DSCT를 이용한 CCTA 검사에서 Retrospective ECG-gated helical scan mode와 Adaptive Cardio Sequence 기능을 갖고 있는 ECG-triggered FLEX scan mode를 통해 검사하였을 경우의 선량과 영상의 질을 비교 분석하여 임상에서의 유용성을 평가하고자 한다. 대상 및 방법 : 2012년 2월부터 2012년 12월까지 본원에서 CCTA 검사를 시행한 환자 중에서 심전도 동조 시 부정맥을 보이는 63명의 환자를 대상으로 하였으며, 33명은 ECG-triggered FLEX scan mode를 사용 하였고, 30명은 Retrospective ECG-gated helical scan mode를 사용하여 검사를 시행하였다. 각 mode별 유효 선량과 영상의 질을 비교 분석하였다. 결과 : 유효 선량의 평균값은 retrospective ECG-gated helical scan mode에서는 5.67mSv, ECG-triggered FLEX scan mode에서는 3.55mSv 였다. 평균적으로, ECG-triggered FLEX scan mode에서 선량이 37% 더 낮았다(P=0.002). ECG-triggered FLEX scan mode 그룹에서 영상의 질이 높이 평가 되었으며, 환자의 부정맥 패턴에 따라서는 심방세동에서 만큼은 ECG-triggered FLEX scan mode보다 retrospective ECG-gated helical scan mode에서 영상의 질이 더 높게 평가 되었으나, 통계학적 차이는 보이지 않았다. 결론 : 부정맥이 있는 환자의 CCTA 검사에서 advanced arrhythmia rejection 알고리즘을 이용한 ECG-triggered FLEX scan mode로 검사하였을 경우 retrospective ECG-gated helical scan mode로 검사 했을 때보다 피폭선량을 효과적으로 줄이면서도 영상의 질을 유지할 수 있다. Purpose : To determine clinical usefulness of ECG-triggered FLEX scan mode for patients with irregular heart rhythm in CCTA by comparing radiation dose and image quality with retrospective ECG-gated helical scan mode. Materials and methods : We selected 63 patients who showed arrhythmia in ECG monitoring in CCTA from February to December 2012. We divided these patients into two groups and performed CCTA using retrospective ECG-gated helical scan mode(n=33) and ECG-triggered FLEX scan mode(n=30). Then, we compared effective dose and image quality between two groups. Results : In retrospective ECG-gated helical scan mode, mean value of effective dose was 5.67 mSv and in ECG-triggered FLEX mode, 3.55 mSv, respectively. On average, radiation dose in ECG-triggered FLEX scan mode was 37% lower(P=0.02). Subjective score of image quality was higher in ECG-triggered FLEX scan mode groups except atrial fibrillation case. However, there was no statistical significance. Conclusion : In case of performing CCTA for patients having arrhythmia, radiation dose in ECGtriggered FLEX scan mode with advanced arrhythmia rejection algorhythm is 37% lower than that in retrospective ECG-gated helical scan mode without deteriorating image quality.

Ca scoring을 통한 Coronary artery의 Scan Parameter 최적화를 위한 연구

유흥준(Heung Joon Yoo),최성민(Seong Min Choi),홍성두(Seong Doo Hong) 대한CT영상기술학회 2012 대한CT영상기술학회지 Vol.14 No.2

목적 Coronary artery 검사 시 Ca scoring scan을 먼저 시행하였으며, scan 시 AEC(Auto exposure control) program에 의해 측정된 mAs/rot. 값의 차이를 바탕으로 영상의 질을 유지하면서 효율적인 검사 조건을 만들기 위함이다. 대상 및 방법 Dual Sauce CT(Somatom definition, Siemens, Erlangen, Germany, 2006년) 장비를 사용하여 2010년 11월부터 2011년 3월까지 본원에 방문한 Coronary artery 검사 환자 중 Heart Rate 70회 이하, Heart에 특이한 질환이 없는 남성 113명을 대상으로 하였다. 실험 방법으로서는 Ca scoring scan 시 AEC program에 의한 mAs/rot. 값의 차이를 바탕으로 kVp와 mAs/rot. 값을 설정하여 scan 후 Ascending Aorta, RCA(Right coronary artery), LM(Left main coronary artery) 에서의 CT number는 300HU 이상, SD값 15±5를 기준으로 하여 수치를 비교 분석하였다. 결과 Ca scoring scan을 통한 113명의 mAs/rot. 값의 평균은 69.82mAs/rot 이며, 이 값을 바탕으로 각 mAs/rot.에 따른 적절한 영상의 질을 유지할 수 있는 kVp 값과 mAs/rot를 구해 scan한 결과 Ascending aorta에서의 CT No 값은 평균 443.4(St Dev: 89.1)이며, SD 값은 평균 16.3(St Dev: 2.48)이다. RCA에서의 평균 CT No 값은 430.48(St Dev: 86.5)이고, SD 값은 평균 16.35(St Dev: 3.9)이다. LM에서의 평균 CT No 값은 412.7(St Dev: 82.35)이며, SD 값은 평균 11.5(St Dev: 4.34)으로 나타나 각각 기준 범위에서 벗어나지 않았다. 이때의 펑균 DLP(mGYcm) 값은 401.815 mGYcm(St Dev: 162.6)으로 나타났다. 결론 Ca scoring scan 시 AE program에 의한 mAs/rot. 값의 차이를 바탕으로 구해진 kVp와 mAs/rot.로 scan하였을 경우 영상의 질을 저하하지 않으면서 환자마다 적절한 선량으로 Over Dose를 줄임으로써 피폭선량으로 낮출 수 있었다. I. Purpose Coronary artery examinations were performed first, Ca scoring scan, scan at AEC (Auto exposure control) program as measured by the difference in values based on mAs while maintaining image quality is to create an efficient test conditions. II. Meterial and Methods Dual Souce CT(Somatom definition, Siemens, Erlangen, Germany, 2006 years) using equipment from November 2010 to March 2011 Coronary artery examination of the patients visited our hospital Heart Rate 70 times or less, Heart disease is not unusual for 113 men were enrolled in this study. We scanned with kVp and mAs/rot. setting based on mAs/rot. values from AEC program in Ca scoring sam. Then we compared and analyzed CT number and SD values of ascending aorta, RCA(Right coronary artery), and LM(Left main coronary artery) with the criteria values(CT number of 300 HU and SD values of 15±5). III. Result Ca scoring scan through the 113mAs value is an average 69.82mAs/rot. Based on this value according to each ref mAs to maintain adequate image quality can be examined appointed kVp and mAs/rot. values. Ascending aorta in the CT No average value 443.4(St Dev: 89.l) and, SD the average 16.3(St Dev: 2.48). The average value of CT No RCA 430.48(St Dev: 86.5) and, SD the average 16.35(St Dev: 3.9) and LM values of the average CT No 412.7(St Dev: 82.35) and, SD the average 11.5(St Dev: 4.34) appear to deviate from the reference range were, respectively, The average of the DLP(mGYcm) value 401.815 mGYcm (St Dev: 162.6), respectively. IV. Conclusions When Ca scoring scan, Using AEC program, Calculated kVp and mAs/rot. based on the difference of reference mAs/rot. were not degrade image quality. therefore It can be maintain proper respective patient dose without degrade image quality.

Synthetic Peptide-conjugated Titanium Alloy for Enhanced Bone Formation In Vivo

Yoo, Jeong Joon,Park, Yoon-Jeong,Rhee, Sang-Hoon,Chun, Heung Jae,Kim, Hee Joong Informa Healthcare 2012 Connective tissue research Vol.53 No.5

<P>There are growing demands for bioactive titanium implants that could shorten the healing period, promote faster rehabilitation, and thereby increase the success rate of treating patients with poor bone quality. A synthetic receptor-binding peptide mimicking bone morphogenetic protein-2 (BMP-2) was covalently linked to a titanium alloy with two types of topography—machined (TiMA) and rough (TiGB)—by using a chemical conjugation process. In vivo osseointegration capacity was evaluated chronologically using histomorphometric analysis at 2, 4, and 8 weeks after implantation in the distal femurs of rabbits. In the histologic examinations, peri-implant bone formation was more active around TiGB than TiMA. Compared to the control groups (nonconjugated TiMA and TiGB) at 2, 4, and 8 weeks, the peptide-conjugated groups (TiMA-P and TiGB-P) had more mature new bone, thicker trabeculae, more rapid bone maturation, and higher affinity index (percentage of new bone contact length) in histomorphometric analysis. Particularly, differences in the affinity index between the peptide-conjugated and nonconjugated groups were more pronounced at the early phase of peri-implant healing (2 and 4 weeks). However, at 8 weeks, enhanced bone formation was less prominent according to peptide conjugation, especially in specimens with a rough surface. The titanium alloys in the rabbit femurs led to a significant increase of bone growth when modified with bioactive peptides, especially during the early phase of bone healing. These results confirm that biochemical modifications of titanium surfaces can enhance the rate of bone healing compared with that of untreated titanium surfaces.</P>

LOCAL SPECTRAL PROPERTIES OF QUASI-DECOMPOSABLE OPERATORS

Yoo, Jong-Kwang,Oh, Heung Joon Chungcheong Mathematical Society 2016 충청수학회지 Vol.29 No.4

In this paper we investigate the local spectral properties of quasidecomposable operators. We show that if $T{\in}L(X)$ is quasi-decomposable, then T has the weak-SDP and ${\sigma}_{loc}(T)={\sigma}(T)$. Also, we show that the quasi-decomposability is preserved under commuting quasi-nilpotent perturbations. Moreover, we show that if $f:U{\rightarrow}{\mathbb{C}}$ is an analytic and injective on an open neighborhood U of ${\sigma}(T)$, then $T{\in}L(X)$ is quasi-decomposable if and only if f(T) is quasi-decomposable. Finally, if $T{\in}L(X)$ and $S{\in}L(Y)$ are asymptotically similar, then T is quasi-decomposable if and only if S does.

Transcriptional Activities of Two Different forms of Human TFIIS

Yoo, Ook Joon,Cho, Nam Young,Hahn, Bum Soo,Baek, Kwang Hee,Park, Heung Rok 한국유전학회 1993 Genes & Genomics Vol.15 No.2

Transcription Factor IIS(TFIIS) exerts influence on the transcript elongation by RNA polymerase II. Two different cDNA clones of human TFIIS have been found. If we compare the amino acid sequence in the coding region of these two clones, we can find one of the cDNA clone carry extra 21 amino acids at the N-terminal region of TFIIS. To identify the functional role of these additional amino acid sequence, we have expressed and purified two different forms of TFIIS in E. coli. The results of the comparison between these two proteins in the transcription elongation activities indicate that 21 amino acid sequence is not crucial for the function of TFIIS in our in vitro assay system. But we cannot rule out the possibility of their functional role(s) in vivo.

BISHOP'S PROPERTY (${\beta}$) AND SPECTRAL INCLUSIONS ON BANACH SPACES

Yoo, Jong-Kwang,Oh, Heung-Joon The Korean Society for Computational and Applied M 2011 Journal of applied mathematics & informatics Vol.29 No.1

Let T ${\in}$ L(X), S ${\in}$ L(Y), A ${\in}$ L(X, Y) and B ${\in}$ L(Y, X) such that SA = AT, TB = BS, AB = S and BA = T. Then S and T shares the same local spectral properties SVEP, Bishop's property (${\beta}$), property $({\beta})_{\epsilon}$, property (${\delta}$) and and subscalarity. Moreover, the operators ${\lambda}I$ - T and ${\lambda}I$ - S have many basic operator properties in common.

Fabrication of a large scanning micromirror array using vertical combdrive actuator

하준근(Joon-Geun Ha),전진아(Jin-A Jeon),서정은(Jung-Eun Seo),유병욱(Byung-Wook Yoo),진주영(Joo-Young Jin),박일흥(Il-Heung Park),박재형(Jae-Hyoung Park),김용권(Yong-Kweon Kim) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7

In this paper, a 2-degree-of-freedom (DOF) Micro-electro-mechanical systems(MEMS) scanning micromirror array is fabricated, which has a large area mirror, a large actuation displacement and high fill factor. Each mirror is designed for independent actuation to two axis. The mirrror is designed as leverage structure in order to achieve large actuation angle with electrostatic actuator. To achieve this, a vertical combdrive actuator is fabricated with leverage structure. The tilting angles are 9.87 ° and 9.76 ° for each axis at the voltage of 150 V. The high fill factor is accomplished by fabricating actuator under the mirror plate. The array is composed of 9 single mirrors with 3 by 3 matrices, of which the size is 1 ㎜ by 1 ㎜. The fill factor of mirror array is 84 %.

Isolation Yield and Osteogenic Potential of Human Bone Marrow Stromal Cells Obtained from Different Sites

( Jeong Joon Yoo ),( Won Chul Choi ),( Heung Jae Chun ),( Hee Joong Kim ) 한국조직공학·재생의학회 2010 조직공학과 재생의학 Vol.7 No.1

The majority of studies on human bone marrow stromal cells (hBMSCs) have been performed using bone marrow obtained from the iliac crests of healthy donors. If hBMSCs could be isolated from bone marrow aspirated at sites exposed during operation, and these hBMSCs had an osteogenic potential comparable with those obtained from the iliac crest, hBMSCs acquisition could be simplified and donor site morbidity could be obviated. To compare the isolation yields and the osteogenic potentials of hBMSCs obtained from different sites in same donors, fresh bone marrow was obtained from the iliac crests and greater trochanters of 36 donors undergoing total hip arthroplasty. During the isolation procedure and initial culture, the numbers of nucleated cells, colony forming unit-fibroblasts (CFU-Fs), alkaline phosphatase (ALP)-positive CFU-Fs, and total numbers of hBMSCs harvested at day 20 after seeding were measured. Osteogenic differentiation potentials were investigated by measuring ALP activity and calcium content in osteogenic medium. The isolation yield of hBMSCs, their populations in nucleated cells, and ALP-positive populations were significantly lower for bone marrow aspirated from the greater trochanter. However, no significant difference was observed in the osteogenic differentiation potentials of hBMSCs obtained from the two aspiration sites. These results suggest that although the absolute number of hBMSCs in greater trochanter derived marrow is smaller than that in marrow obtained from the iliac crest, that hBMSCs obtained from these sites have similar osteogenic potentials. These findings indicate that the greater trochanter can be used as an alternative site for harvesting hBMSCs.