A Study on the Effect of Heart rate based Left Ventricular Global Function on the Time of Contrast Enhancement

서충범(Choong-Beom Seo),남태현(Tae-Hyun Nam),채희창(Hee-Chang Chae),김성관(Seong-Gwan Kim),서은희(Eun-Hee Seo),대창민(Chang-Min Dae) 대한CT영상기술학회 2021 대한CT영상기술학회지 Vol.23 No.1

목적: 심장 기능 지표와 조영 증강 시간 간의 일정한 상관관계가 성립하는지 알아보고 이를 통해 심장의 기능에 따른 예상 조영 증강 시간을 구하고자 하였다. 대상 및 방법: 심장 기능 평가의 적정성을 확인하기 위해 팬텀 연구를 선행하였다. 임상 연구로 CCTA를 시행한 273명의 환자들을 대상으로 조영제 주입 속도에 따라 두 그룹으로 나누어 다양한 심장 기능을 측정하고 조영 증강 시간를 비교하는 후향적 연구를 진행하였다. 심장 기능 지표는 심박동수, 심박출량, 심장박출지수, 초당 심장박출지수, 좌심실 구혈률, 심박동수에 따른 초당 좌심실 구혈률을 사용하였다. 결과: 팬텀 연구에서 ECG 동조 관전류 변조로 측정한 용적의 변화율은 0.1 % 이하로 심장 기능 측정의 적정성을 확인하였다. 후향적 연구 결과 심장의 기능을 나타내는 지표들 중 심박동수에 따른 초당 좌심실 구혈률이 조영 증강 시간과 명확한 음의 상관관계(P<0.01)를 나타내고 가장 높은 신뢰도를 나타냈다. 이를 통해 조영 증강 시간과의 상관관계에서 회귀식을 통해 예상 조영 증강 시간을 도출하였으나 회귀식은 성립하지 않았다. 결론: 조영 증강 시간과 심박동수에 따른 초당 좌심실 구혈률은 명확한 상관관계를 가지나 다양한 인자의 복합적인 상호작용으로 이루어지는 조영 증강 시간을 심장의 기능만으로 예측할 수는 없었다. 추후 체내 순환 인자들의 영향에 대한 연구가 지속된다면 환자의 상태를 기반으로 한 조영 증강 검사가 가능할 것으로 사료된다. Purpose: It was intended to find out whether a constant correlation between the cardiac function and the contrast enhancement time was established and to obtain the estimated contrast enhancement time according to the cardiac function. Material and Method: A phantom study was preceded to verify the adequacy of cardiac function evaluation. A retrospective study of 273 patients who performed CCTA was conducted to measure cardiac function and compare contrast enhancement time. Cardiac functional indicators used Heart Rate, Cardiac Output, Cardiac Index, Cardiac Index per second, Left Ventricular Ejection Fraction, and Left Ventricular Ejection Fraction per second based on heart rate. Results: In the phantom study, the change rate of volume measured by ECG based tube current modulation was less than 0.1%. A retrospective study found the Left Ventricular Ejection Fraction per second based on heart rate showed a clear negative correlation with contrast enhancement time (P<0.01) and the highest reliability. Through this, the expected contrast enhancement time was derived from the regression equation in correlation with the contrast enhancement time, but the regression equation was not established. Conclusions: The contrast enhancement time and Left Ventricular Ejection Fraction per second based on heart rate were clearly correlated, but the contrast enhancement time, which consists of the complex interactions of various factors, could not be predicted by the cardiac function alone. If the study of the effects of circulating factors in the body continues, it is believed that contrast enhanced CT based on the patient s condition will be possible.

Evaluation of computer-aided detection and dual energy software in detection of peripheral pulmonary embolism on dual-energy pulmonary CT angiography

Lee, Choong Wook,Seo, Joon Beom,Song, Jae-Woo,Kim, Mi-Young,Lee, Ha Young,Park, Yang Shin,Chae, Eun Jin,Jang, Yu Mi,Kim, Namkug,Krauss, Bernard Springer-Verlag 2011 EUROPEAN RADIOLOGY Vol.21 No.1

A Pilot Trial on Pulmonary Emphysema Quantification and Perfusion Mapping in a Single-Step Using Contrast-Enhanced Dual-Energy Computed Tomography

Wook Lee, Choong,Beom Seo, Joon,Lee, Youngjoo,Jin Chae, Eun,Kim, Namkug,Joo Lee, Hyun,Jeon Hwang, Hye,Lim, Chae-Hun Lippincott Williams Wilkins, Inc. 2012 Investigative radiology Vol.47 No.1

OBJECTIVES:: To know whether contrast-enhanced dual-energy computed tomography angiography (DECTA) can be used for simultaneous assessment of emphysema quantification and regional perfusion evaluation. MATERIALS AND METHODS:: We assessed 27 patients who had pulmonary emphysema and no pulmonary embolism on visual assessment of CT images, among 584 consecutive patients who underwent DECTA for the evaluation of pulmonary embolism. Virtual noncontrast (VNC) images were generated by modifying the “Liver VNC” application in a dedicated workstation. Using in-house software, the low-attenuation area below 950HU (LAA950), the 15th percentile attenuation (15pctlVNC) and the mean lung attenuation (MeanVNC) were calculated. The “Lung PBV” application was used to assess perfusion, and the low-iodine area below 5HU (LIA5), the 15th percentile iodine (15pctlIodine), and the mean iodine value (MeanIodine) were calculated from iodine map images. The correlation between VNC parameters and pulmonary function test data (available in 22 patients) and the correlation between VNC and iodine map parameters (all included 27 patients) were assessed. Color-coded map of VNC image were compared with iodine map images for the evaluation of regional heterogeneity. RESULTS:: We observed moderate correlations between LAA950 and predicted %FEV1 (rs = −0.47, P < 0.05), and 15pctlVNC and predicted %FEV1 (rs = 0.56, P < 0.05). We also observed significant correlations between LAA950 and LIA5 (rs = 0.48, P < 0.05), 15pctlVNC and 15pctlIodine (rs = 0.59, P = 0.001), and MeanVNC and MeanIodine (rs = 0.47, P < 0.05). On visual assessment of the regional heterogeneity, 82% of patients showed relatively good correlation between the areas of perfusion impairment on iodine map images and areas of emphysema on color-coded VNC images. CONCLUSIONS:: We observed moderate correlations between quantitative parameters on VNC images and pulmonary function test data, and also observed moderate correlations between the severity of parenchymal destruction, as determined from VNC images, and perfusion status, as determined from iodine maps. Therefore, the contrast-enhanced DECTA can be used for the emphysema quantification and regional perfusion evaluation by using the VNC images and iodine map, simultaneously.

에폭시 개질 한 다관능 아크릴레이트를 포함하는 충격 저항성이 향상된 불포화폴리에스터 SMC (Sheet Molding Compound) 소재제조 및 그의 물성연구

장정범 ( Jeong Beom Jang ),김태희 ( Taehee Kim ),김혜진 ( Hye Jin Kim ),이원주 ( Wonjoo Lee ),서봉국 ( Bongkuk Seo ),김용성 ( Yongsung Kim ),김창윤 ( Changyoon Kim ),임충선 ( Choong-sun Lim ) 한국접착및계면학회 2020 접착 및 계면 Vol.21 No.3

본 연구에서는 에폭시 수지를 개질 한 변성 아크릴레이트를 합성하였으며, 이를 기존의 유리섬유 복합소재에 사용하는 SMC 조성물에 5 phr - 15 phr을 첨가하여 SMC 소재를 제조하였다. SMC 프리프레그를 고온고압 (150 ℃, 10 bar)에서 컴프레션 몰딩방법으로 성형하여 유리섬유 복합소재를 제조하였으며, 제조된 복합소재를 가공하여 인장강도, 충격강도 등의 기계적 물성을 연구하였다. 실험결과 합성된 변성 아크릴레이트를 5 phr을 포함하는 복합소재가 합성 아크릴레이트를 포함하지 않는 binder 샘플보다 인장강도는 약 20%, 충격강도는 약 12% 향상함을 보였으며, 이는 합성 아크릴레이트가 폴리에스터와 반응할 수 있는 4개의 아크릴 기를 가짐으로써 가교반응을 강하게 하면서 기계적 강도가 향상됨을 확인하였다. In this study, epoxy-modified acrylate was synthesized. The synthesized acrylate was added to the composition for sheet molding compound (SMC) in the range of 5 phr to 15 phr. The prepared SMC prepreg was molded at high temperature and pressure to produce a glass fiber reinforced composite. Physical properties such as tensile and impact strength of the composite were measured, respectively. Experimental data show that the composite with 5 phr of synthesized acrylate has 20% improved tensile strength and 12% improved impact strength than that of the reference sample.

A Study on the Correlation of Left Atrial Volume Change according to Left Ventricular Contraction in Atrial Fibrillation

Sung Kwan Kim,Hee Chang Chae,Choong Beom Seo,Eun Hee Seo,Chang Min Dae,Tae Eun Kim 대한CT영상기술학회 2022 대한CT영상기술학회지 Vol.24 No.1

The purpose of this study was to increase accuracy and success rate of radiofrequency catheter ablation by analysis of left atrial volume change relative to left ventricular volume change and left atrial diameter change relative to left atrial volume change. 20 patients with normal heart rhythm were set as the control group, and 20 patients with diagnosed atrial fibrillation were set as the experimental group. The cardiac cycle was divided into 10 stages ranging from 0% to 90%, and left ventricular volume, left atrial volume, left atrial diameter, pulmonary vein diameter were measured for each group. the correlation between the left ventricular volume and the left atrial volume was analyzed, and the correlation between the left atrial volume and left atrial diameter was analyzed. The diameter of the pulmonary veins was measured. As a result of analyzing the correlation between left ventricular volume and left atrial volume through Spearman correlation, the control group showed a negative correlation.(P<0.001) The experimental group were not correlated.(P=0.075) As a result of analyzing the correlation between the left atrial volume and the left atrial diameter, both groups showed a positive correlation.(P<0.001) As a result of analyzing the diameter of the pulmonary vein by Wilcoxon signed-rank test, both groups showed a significant difference in the maximum diameter and the minimum diameter.(P<0.001) Because the volume and diameter of the left atrium in patients with atrial fibrillation change irregularly, the radiologist check all cardiac cycle and reconstruct to increase the accuracy and success rate of radiofrequency catheter ablation.

Quantitative Analysis of Deuterium Annealing Effect on Poly-Si TFTs by Low Frequency Noise and DC <tex> ${I}$</tex> – <tex> ${V}$</tex> Characterization

Kim, Do-Hyun,Lim, Sung Kwan,Bae, Hagyoul,Kim, Choong-Ki,Lee, Seung-Wook,Seo, Myungsoo,Kim, Seong-Yeon,Hwang, Kyu-Man,Lee, Geon-Beom,Lee, Byoung Hun,Choi, Yang-Kyu Institute of Electrical and Electronics Engineers 2018 IEEE transactions on electron devices Vol.65 No.4

<P>Deuterium (D<SUB>2</SUB>) annealing was applied to a poly-crystalline silicon thin-film transistor (poly-Si TFT) to improve reliability and performance. The field-effect electron mobility ( <TEX>$\mu $</TEX>) was extracted using the gate transconductance ( <TEX>${g}_{m}$</TEX>) method. It was found that <TEX>$\mu $</TEX> was improved before and after D<SUB>2</SUB> annealing. The interface trap density ( <TEX>${D}_{\text {it}}$</TEX>) as well as the oxide trap density ( <TEX>${N}_{\text {ot}}$</TEX>) in the poly-Si TFTs was quantitatively extracted using both conventional dc I–V characterization and analysis of low frequency noise (<I>LFN</I>). The profile of <TEX>${N}_{\text {ot}}$</TEX> along the depth direction was investigated before and after D<SUB>2</SUB> annealing using <I>LFN</I> characteristics. It was confirmed that <TEX>${D}_{\text {it}}$</TEX> as well as <TEX>${N}_{\text {ot}}$</TEX> was reduced by the D<SUB>2</SUB> annealing, resulting in a reduction in power spectral density and variation.</P>

Dual-energy Computed Tomography Characterization of Solitary Pulmonary Nodules

Chae, Eun Jin,Song, Jae-Woo,Krauss, Bernhard,Song, Koun-Sik,Lee, Choong Wook,Lee, Hyun Joo,Seo, Joon Beom Lippincott Williams Wilkins, Inc. 2010 Journal of thoracic imaging Vol.25 No.4

For the assessment of solitary pulmonary nodules (SPNs), a chest computed tomography (CT) is often performed as a combination of a nonenhanced and an enhanced scan. A nonenhanced scan is used for the detection of calcification in the SPN or lymph node, as the presence of calcification is one of the important determinants of benignity. An enhanced scan is informative in providing the degree and pattern of enhancement. In particular, the degree of enhancement of an SPN after iodine injection has been shown to be helpful in distinguishing malignant from benign nodules. Recently introduced dual-energy applications of dual-source CT simultaneously provide a virtual nonenhanced and an iodine-enhanced image from a single scan, after the administration of iodine contrast material. Therefore, a single enhanced dual-energy CT scan allows both measurement of the degree of enhancement and detection of calcifications. It may reduce radiation exposure to patients by avoiding baseline nonenhanced scans and may also reduce measurement error due to different regions of interest during the subtraction of a nonenhanced image from an enhanced image. This technique may have applications in contrast-enhanced dynamic CT and perfusion CT for the differentiation between benign and malignant lesions and the assessment of tumor angiogenesis. In this review article, we sought to address the usefulness of dual-energy CT for the assessment of SPN. In addition, we briefly review the physical principles of dual-energy CT and discuss potential future applications in patients with lung nodules.

The Study of the Usefulness of Breathing method using Straw for Larynx CT Examination

채희창(Hee-Chang Chae),남태현(Tae-Hyun Nam),서충범(Choong-Beom Seo),김성관(Seong-Gwan Kim),권순안(Soon-Ahn Kwon),대창민(Chang-Min Dae) 대한CT영상기술학회 2019 대한CT영상기술학회지 Vol.21 No.2

목적: 후두 CT검사에서 후두부의 움직임 인공물을 제한하기 위해 보조기구를 이용한 호흡법의 유용성에 대해 연구하고자 하였다. 대상 및 방법: 연구를 위해 64 MDCT와 3D 워크스테이션을 사용하였다. 빨대를 다른 세 가지 각도로 적용한 두경부 팬텀을 스캔하였다. CT number와 noise를 측정하기 위해 4곳의 해부학적 위치에 관심영역을 설정하였다. CT number와 noise의 기준값은 ±5%로 설정하였다. 임상 연구는 성문상부, 성문부, 성문하부의 면적 평가와 성문부분에서의 성문각의 변화, 이상동의 확장 및 후두실의 묘출능력을 측정하였다. 5점 척도로 정성적으로 평가하였다. 결과: 팬텀 연구에서 측정된 CT number와 noise는 기준값인 ±5%를 만족하였다. 임상 연구에서 정량적 평가 결과 성문상부 및 성문하부의 변화율은 각 각 22.6%, 8.7% 증가하였으나, 성문부는 18.2% 감소하였다. 성문각의 변화율은 10.1% 감소하였다. 이상동은 28.1% (좌), 26.2% (우) 증가하였다. 후두실은 실험군 50명에서 나타났다. 정성적 평가에서 빨대를 이용한 호흡법을 사용하였을 때 motion artifact가 발생하지 않았다. 결론: 빨대를 이용한 호흡법은 충분한 진단학적 정보를 제공할 수 있을 뿐만 아니라, 후두의 고품질 영상이 병기 결정에 도움을 주어 적절한 치료 방법의 선택에 도움이 될 것이다. Purpose: The study purpose was to investigate the usefulness of straw-blow method to limit the motion artifact of the larynx. Material and Method: 64 MDCTs and a 3D workstation were used for this study. In phantom study, we scan a head phantom with three different angles of straw. We set area of interests at the four anatomical location to measure CT number and noise. The reference value of CT number and noise is set to ±5%. In clinical study, assessment of supraglottis, glottis, subglottis and the glottic angle, the vertical distance of the pyriform sinus and the appearance of laryngeal ventricle were measured. In addition, five points scale method was used as a qualitative analysis. Results: In phantom study, measured CT number and noise were satisfied reference value of ±5%. In clinical study, quantitative assessment results showed that the change rate of supraglottis and subglottis area increased by 22.6% and 8.7%, while the glottis area decreased by 18.2%. The rate of change in the glottic angle decreased by 10.1%. the pyriform sinus increased by 28.1% (left) and 26.2% (right). the laryngeal ventricle was shown that 50 cases in the experimental group. Qualitative evaluation showed that motion artifact didn’t occur with straw-blow method. Conclusions: Straw-blow technique can provide sufficient diagnostic information. Furthermore, high quality image of larynx will be helpful for decision-making of appropriate treatment plan.

관상동맥 CT 혈관조영술에서 ECG Window Acquisition 단위 변환을 통한 선량 및 화질 평가에 관한 연구

조장우(Jang-Woo Jo),채희창(Hee-Chang Chae),서충범(Choong-Beom Seo),서은희(Eun-Hee Seo),대창민(Chang-Min Dae),김태은(Tae-Eun Kim) 대한CT영상기술학회 2022 대한CT영상기술학회지 Vol.24 No.2

본 연구의 목적은 동 리듬 환자와 심방세동 환자의 관상동맥 CT 혈관조영술에서 기존의 상대적 지연 스캔 단위를 절대적 지연 스캔 단위로 변환함으로써, 영상의 화질 저하 없이 선량을 최소화 할 수 있는 방법이 무엇인지 알아보고자 하였다. 연구대상 및 방법은 흉부 팬텀과 ECG simulator를 이용하여 동 리듬과 불규칙한 심박수를 만들어 팬텀 연구를 진행하였다. 임상연구는 동 리듬 환자 90명과 심방세동 환자 76명을 대상으로 진행하였다. 절대적 지연 스캔은 환자의 평균 심박수를 기준으로 단위 변환 후 검사를 진행하였다. 관심영역 설정 후 정량적 화질 평가를 하였으며, 임상 연구에서는 관찰자 2명이 정성적 평가를 진행하였다. Dose information에 기록된 CTDIvol 및 DLP로 선량 평가를 진행하였다. 팬텀 연구 결과 동 리듬, 심방세동군 모두 대조군과 실험군 사이의 정량적 화질 평가 값의 유의한 차이를 보이지 않았다. 불규칙한 심박수 79에서 실험군의 CTDIvol은 대조군 대비 18% 감소하였으며, DLP는 대조군 대비 17.4% 감소하였다.(P<0.05) 임상 연구 결과 모든 관심영역에서 대조군과 실험군 사이의 정량적 화질 평가 값에서 유의한 차이를 보이지 않았다. 동 리듬 환자의 대조군과 실험군 사이의 CTDIvol, DLP는 유의한 차이를 보이지 않았다. 심방세동 환자의 실험군 CTDIvol은 대조군 대비 33% 감소하였으며, DLP는 대조군 대비 30% 감소하였다.(P<0.05) 결론적으로 심방세동 환자의 관상동맥 CT 혈관조영술 검사 시 환자의 평균 심박수를 기준으로 ECG window acquisition 단위를 milliseconds로 변환 후 검사 범위를 설정하여 검사한다면, 영상 화질의 변화를 최소화하며 환자선량 감소에 큰 도움이 될 것으로 사료된다. The purpose of this study was to evaluate radiation dose and image quality compared to those of the relative delay scan when using an absolute delay scan after converting the ECG window acquisition unit in coronary CT angiography. We used chest phantom and ECG simulator through the phantom study. Patient study was conducted on 90 sinus rhythm patients and 76 atrial fibrillation patients. The absolute delay scan was performed after unit conversion based on the average heart rate. After setting the region of interest, quantitative evaluation of image quality was made, qualitative evaluation was made by two observers. The dose was evaluated using the CTDIvol and DLP. There were no significant differences in quantitative values in terms of the phantom study. At an irregular heart rate 79, the CTDIvol of the experimental group decreased by 18% compared to the control group, the DLP decreased by 17.4% compared to the control group.(P<0.05) As a result of patient study, there were no significant differences in quantitative values in terms of the patient study. The CTDIvol of the artrial fibrillation experimental group decreased by 33% compared to the control group, the DLP decreased by 30% compared to the control group.(P<0.05) As a result, when examining coronary CT angiography of patients with atrial fibrillation, it will help reduce the patient’s dose without affecting the image quality if the scan range is set after converting the ECG window acquisition unit to milliseconds based on the average heart rate.

Nano-electromechanical Switch Based on a Physical Unclonable Function for Highly Robust and Stable Performance in Harsh Environments

Hwang, Kyu-Man,Park, Jun-Young,Bae, Hagyoul,Lee, Seung-Wook,Kim, Choong-Ki,Seo, Myungsoo,Im, Hwon,Kim, Do-Hyun,Kim, Seong-Yeon,Lee, Geon-Beom,Choi, Yang-Kyu American Chemical Society 2017 ACS NANO Vol.11 No.12

<P>A physical unclonable function (PUF) device using a nano-electromechanical (NEM) switch was demonstrated. The most important feature of the NEM-switch-based PUF is its use of stiction. Stiction is one of the chronic problems associated with micro- and nano-electromechanical system (MEMS/NEMS) devices; however, here, it was utilized to intentionally implement a PUF for hardware-based security. The stiction is caused by capillary and van der Waals forces, producing strong adhesion, which can be utilized to design a highly robust and stable PUF. The probability that stiction will occur on either of two gates in the NEM switch is the same, and consequently, the occurrence of the stiction is random and unique, which is critical to its PUF performance. This uniqueness was evaluated by measuring the interchip Hamming distance (interchip HD), which characterizes how different responses are made when the same challenge is applied. Uniformity was also evaluated by the proportion of “1” or “0” in the response bit-string. The reliability of the proposed PUF device was assessed by stress tests under harsh environments such as high temperature, high dose radiation, and microwaves.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2017/ancac3.2017.11.issue-12/acsnano.7b06658/production/images/medium/nn-2017-066583_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn7b06658'>ACS Electronic Supporting Info</A></P>