• 핵의학기술
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• 제27권2호
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• pp.111-127
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• 2023

Purpose: Gallium-68 (⁶⁸Ga) is increasingly used in nuclear medicine imaging for various conditions such as lymphoma and neuroendocrine tumors by labeling tracers like Prostate Specific Membrane Antigen (PSMA) and DOTA-TOC. However, compared to Fluorine-18 (¹⁸F) used in conventional nuclear medicine imaging, ⁶⁸Ga has lower spatial resolution and relatively higher Signal to Background Ratio (SBR). Therefore, this study aimed to investigate the optimized parameters and reconstruction methods for PET/CT imaging using the ⁶⁸Ga radiotracer through model-based image evaluation. Materials and Methods: Based on clinical images of ⁶⁸Ga-PSMA PET/CT, a NEMA/IEC 2008 PET phantom model was prepared with a Hot vs Background (H/B) ratio of 10:1. Images were acquired for 9 minutes in list mode using DMIDR (GE, Milwaukee WI, USA). Subsequently, reconstructions were performed for 1 to 8 minutes using OS-EM (Ordered Subset Expectation Maximization) + TOF (Time of Flight) + Sharp IR (VPFX-S), and BSREM (Block Sequential Regularized Expectation Maximization) + TOF + Sharp IR (QCFX-S-400), followed by comparative evaluation. Based on the previous experimental results, images were reconstructed for BSREM + TOF + Sharp IR / 2 minutes (QCFX-S-2min) with varying β-strength values from 100 to 700. The image quality was evaluated using AMIDE (freeware, Ver.1.0.1) and Advanced Workstation (GE, USA). Results: Images reconstructed with QCFX-S-400 showed relatively higher values for SNR (Signal to Noise Ratio), CNR (Contrast to Noise Ratio), count, RC (Recovery Coefficient), and SUV (Standardized Uptake Value) compared to VPFX-S. SNR, CNR, and SUV exhibited the highest values at 2 minutes/bed acquisition time. RC showed the highest values for a 10 mm sphere at 2 minutes/bed acquisition time. For small spheres of 10 mm and 13 mm, an inverse relationship between β-strength increase and count was observed. SNR and CNR peaked at β-strength 400 and then decreased, while SUV and RC exhibited a normal distribution based on sphere size for β-strength values of 400 and above. Conclusion: Based on the experiments, PET/CT imaging using the ⁶⁸Ga radiotracer yielded the most favorable quantitative and qualitative results with a 2 minutes/bed acquisition time and BSREM reconstruction, particularly when applying β-strength 400. The application of BSREM can enhance accurate quantification and image quality in ⁶⁸Ga PET/CT imaging, and an optimization process tailored to each institution's imaging objectives appears necessary.

• Korean Journal of Radiology
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• 제22권3호
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• pp.425-434
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• 2021

Objective: To investigate the potential value of ¹⁸F-fluorodeoxyglucose (FDG) PET/CT in predicting the survival of patients with primary tracheal malignant tumors. Materials and Methods: An analysis of FDG PET/CT findings in 37 primary tracheal malignant tumor patients with a median follow-up period of 43.2 months (range, 10.8-143.2 months) was performed. Cox proportional hazards regression analyses were used to assess the associations between quantitative ¹⁸F-FDG PET/CT parameters, other clinic-pathological factors, and overall survival (OS). A risk prognosis model was established according to the independent prognostic factors identified on multivariate analysis. A survival curve determined by the Kaplan-Meier method was used to assess whether the prognosis prediction model could effectively stratify patients with different risks factors. Results: The median survival time of the 37 patients with tracheal tumors was 38.0 months, with a 95% confidence interval of 10.8 to 65.2 months. The 3-year, 5-year and 10-year survival rate were 54.1%, 43.2%, and 16.2%, respectively. The metabolic tumor volume (MTV), total lesion glycolysis (TLG), maximum standardized uptake value, age, pathological type, extension categories, and lymph node stage were included in multivariate analyses. Multivariate analysis showed MTV (p = 0.011), TLG (p = 0.020), pathological type (p = 0.037), and extension categories (p = 0.038) were independent prognostic factors for OS. Additionally, assessment of the survival curve using the Kaplan-Meier method showed that our prognosis prediction model can effectively stratify patients with different risks factors (p < 0.001). Conclusion: This study shows that ¹⁸F-FDG PET/CT can predict the survival of patients with primary tracheal malignant tumors. Patients with an MTV > 5.19, a TLG > 16.94 on PET/CT scans, squamous cell carcinoma, and non-E1 were more likely to have a reduced OS.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2013년도 하계학술대회
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• pp.274-277
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• 2013

CT(Computed Tomography)영상에서 선량과 화질은 중요한 요소이다. 선량은 환자에게 직접적으로 악영향을 끼치는 요소이며, 화질은 환자의 병변을 판단하는데 매우 중요하게 작용한다. 반복적 재구성 알고리즘을 이용하면 저선량 영상에서도 고화질의 영상을 얻을 수 있는지 FBP와 정량적, 정성적으로 비교하였다. 촬영 프로토콜은 관전압 80, 100, 120kVp에서 관전류를 동일하게 200mA로 촬영하여 획득하였으며, 정량적 평가를 위해 SD(Standard Deviation), SNR(Signal to Noise Ratio), MTF(Modulation Transfer Function)를 측정하여 분석하였다. 선량은 80kVp일 때 가장 낮았으며, 120kVp일 때 가장 높았다. 80kVp의 영상을 Toshiba 사(社)의 AIDR 3D(Adaptive Iterative Reduction integrated into $^{SURE}Exposure$)로 재구성하고, 120kVp의 영상에 FBP로 재구성한 다음 정량적 비교를 한 결과 AIDR 3D를 적용한 영상의 SD가 낮게 나왔으며, SNR이 높게 나타났고, MTF 곡선은 유사하게 나타났다. 그리고 FWHM(Full Width at Half Maximum) 값의 오차가 거의 없었다. 결론적으로 AIDR 3D는 저선량에서도 높은 화질을 나타냄을 확인하였다.

• Archives of Plastic Surgery
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• 제32권5호
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• pp.589-592
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• 2005

Since G.N. Hounsfield's clinical use of computed tomography in 1971, digital imaging technique using computers has shown an eye opening progress. Progress has made 3-dimensional understanding of not only facial bones but muscles and other connective tissues possible through 3-dimensional reconstruction of preexisting tomographical images. Also, quantitative analysis of density, distance, volume has become possible, allowing objective analysis of preoperative and postoperative states through imaging. The authors measured the masseter muscle volume of 20 normal individuals and 8 female patients through 3-D reconstructive CT imaging and made a statistical analysis of the measurements. The method used in our study may be applied to the diagnosis of disease causing the change of the facial volume and presurgical design as a useful tool to provide objective information on the evaluation of surgery outcome.

• Food Science and Biotechnology
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• 제27권6호
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• pp.1811-1821
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• 2018

Obesity is generally caused by quantitative changes in adipocyte differentiation and fat metabolism. Only a few studies have been determined the effect of red beans extract on obesity and plasma cholesterol concentration. We have been studied the functional activities of red-bean extracts including anti-oxidative effect against DNA and cell damages. Histological study including micro CT analysis showed that the accumulation of fat in hepatocytes and intestines was significantly decreased in red bean extract treated group. In addition, plasma cholesterol and triglyceride levels were decreased in blood samples. In addition, it was confirmed that the red bean extract inhibited the expression of $PPAR{\gamma}$, Fabp4 and RETN genes, which regulate total adipocyte differentiation and lipid metabolism. Red bean extract inhibits the expressions of transcription factors associated with adipocyte differentiation in a dose-dependent manner, thereby inhibiting fat accumulation and decreasing blood lipid levels in obese mice induced by high fat diet.

• 대한방사선기술학회지:방사선기술과학
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• 제44권2호
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• pp.91-100
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• 2021

High-Resolution thoracic CT (HRCT) is a scanning protocol in which thin slice thickness and sharpness algorithm are utilized to enhance image resolution for diagnosis and assessment of interstitial lung disease (ILD). This examination is sometimes performed in both supine and prone position to improve sensitivity to early changes of these conditions. Anatomical structures (the size of lung field and heart and descending aorta) of 150 patients who underwent HRCT were retrospectively compared. HRCT had been conducted in two positions (supine and prone). Data were divided into five groups according to patient body weights (from 40 to more than 80kg, 10kg intervals, 60 patients/each group). Quantitative analysis was utilized in Image J program. In the supine position defined as the control group, the average values of lung fields and heart size and aorta were compared with the prone position defined as the experimental group. The size of the lungs was found to be higher in the supine position, and it was confirmed that there was a statistically significant difference in patients over 70 kg (p<0.05). In addition, both sizes of the heart and descending aorta were larger in prone position, but in the case of the heart, there was no correlation with the presence or absence of ILD disease (p>0.05). Also, the area of prone in the descending aorta was higher than supine position, but there was no statistically significant difference between supine and prone position (p>0.05). In conclusion, when the severity of ILD disease was severe, there was no statistically significant difference in the area difference between supine and prone position, so it is considered that it will be helpful in diagnostic decision.

• 정보교육학회논문지
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• 제19권2호
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• pp.225-232
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• 2015

본 연구에서는 스크래치 프로그래밍 수업이 초등예비교사에게 미치는 영향을 컴퓨팅 사고력과 블룸의 텍사노미를 활용한 인지적 평가를 통해 확인하고자 하였다. 이를 위해 한 학기 동안 스크래치 프로그래밍 수업을 진행하고 예비교사의 객관적인 프로그래밍 능력을 평가하기 위해 인지적 평가 문항을 블룸의 텍사노미를 기반하여 측정하였다. 또한 초등예비교사들의 컴퓨팅 사고(Computational Thinking) 개념, 수행, 관점에 초점을 둔 설문을 실시하는 한편 팀프로젝트를 가지고 산출물 기반 인터뷰(Artifact-based Interview)를 실시하고 팀프로그래밍 경험을 정성적으로 분석하였다. 본 연구는 프로그래밍 수업을 통한 예비교사의 컴퓨팅 사고를 양적 및 질적으로 보다 포괄적으로 평가하였다는 점에서 의미가 있다. 또한 프로그래밍 능력을 블룸의 텍사노미 체계에 의해 객관적으로 평가해 봄으로써 향후 예비교사 프로그래밍 수업 설계에 대한 평가 측면의 시사점을 제시하고 있다.

• 한국컴퓨터그래픽스학회논문지
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• 제22권4호
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• pp.11-19
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• 2016

본 논문에서는 복부 CT 영상에서 다중 확률 아틀라스 기반 형상제한 그래프-컷을 사용한 신실질 자동 분할 방법을 제안한다. 제안 방법은 다음의 세 단계로 구성된다. 첫째, 신실질의 다양한 형상정보를 이용하기 위해 피질기반 유사정합을 통한 다중 확률 아틀라스를 생성한다. 둘째, 최대사후확률 추정을 통해 그래프-컷의 초기 씨앗을 추출하고, 형상제한 그래프-컷을 통해 신실질을 분할한다. 셋째, 확률 아틀라스의 정합 오차를 줄이고 분할 정확도를 높이기 위해, 정합 및 분할을 반복적으로 수행한다. 제안방법의 성능을 평가하기 위해 정성적 평가 및 정량적 평가를 수행하였다. 실험결과 제안방법이 신실질과 유사한 밝기값을 갖는 주변 영역으로의 누출을 방지하여 개선된 분할 정확도를 보여준다.

• 한국정보통신학회논문지
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• 제13권10호
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• pp.2163-2170
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• 2009

흉부 컴퓨터단층영상에서의 얻어진 폐 영상은 볼륨과 형태 등의 정량적인 정보들로서 진단과 수술 계획 등에 있어서 필연적 정보를 제공한다. 일반적인 영상분할은 이미지를 구성 요소영역이나 목적물에 따라 나누는 방법이다. 그러나 재분할을 하는 단계에서 최종영상은 에너지 최소화를 해결하는 정도에 의존하며, 분할은 응용대상의 관심 영역에서 객체나 물체의 경계에서 정지하게 된다. 가변형 능동모델은 컴퓨터 비젼, 영상처리 분야에서 광범위하게 사용되고 있다. 또한 영역 분할은 현재까지 많은 연구가 되고 있으며, Xu에 의해서 GVF라는 새로운 형태의 외부힘이 제안되고 있다. 본 논문에서 제안하는 알고리듬은 흉부 컴퓨터단층영상에서 실질을 자동 분할하기 위해서 에너지 최소화 방법을 사용하고, 영역분할을 위해 개선된 가변형 능동모델을 제안한다. 알고리듬은 정확한 영역분할을 위해서 기존 방법과 다른 개선된 외부힘을 정의하는 것이다. 임상의 실험은 흉부 컴퓨터단층영상에서 진단에 필요로 하는 폐 실질의 분할이 성공적인 결과를 나타내었다.

• 대한방사선기술학회지:방사선기술과학
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• 제36권2호
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• pp.141-148
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• 2013

CT 검사 시 뇌출혈의 부위는 심각한 정도에 따라 인지하기 어려운 경우도 있으며, 응급상황에서 숙련이 되지 않은 의료진에게는 부담을 준다. 응급상황에서 검사와 동시에 뇌출혈부위를 자동으로 빨리 파악하고 정량적인 정보를 제공하는 보조적인 역할은 필요하며, 컴퓨터를 이용한 자동 검출 및 인식 시스템은 출혈부위 진단에 매우 큰 도움을 줄 수 있다. 본 연구에서는 출혈부위를 문턱치값 처리, 모폴로지 연산, 원형률 계산을 접목하여 뇌 출혈부위의 자동검출에 성공하였고 검출 후보군에서 잘 못 선정된 영역을 판정하기위한 주성분분석을 이용한 분류기 개발에 성공하였다. 개발된 시스템을 응급상황의 뇌출혈 환자에게 적용한다면 의료진에게 수술계획을 위한 유용한 정보가 될 것으로 사료된다.