• Journal of the Korean Society of Radiology
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• v.84 no.2
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• pp.372-385
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• 2023

Breast cancer is one of the most common cancers and causes several complications in females. Currently, MRI is a necessary method for preoperative studies in patients with breast cancer. A high frequency of breast MRI can lead to an increase in the number of incidental extramammary findings. Moreover, it can provide accurate preoperative workup; therefore, the prognosis of patients can be improved. Herein, we provide several extramammary findings, including the mediastinum, lung, upper abdomen, bone, and soft tissue, correlating with US, chest CT, liver MRI, PET-CT, and bone scan.

• 대한핵의학회:학술대회논문집
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• 2005.11a
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• pp.329.1-329.1
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• 2005

• 대한핵의학회:학술대회논문집
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• 2001.11a
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• pp.30.2-30.2
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.383-383
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• 1999

• Journal of Korea Multimedia Society
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• v.19 no.8
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• pp.1371-1376
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• 2016

In this paper, an iterative method is proposed to perform attenuation correction and image reconstruction simultaneously for positron emission tomography, by using the time-of-flight information. Numerical simulation results are presented to demonstrate an improved performance of the proposed method in attenuation correction and image reconstruction.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.351-352
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• 2011

그래핀(Graphene)은 2차원 평면구조의 $sp^2$ 탄소 결합으로 이루어진 물질이다. 일반적으로 그래핀은 탄소 원자 한층 정도의 얇은 두께를 가지면서 강철의 100배 이상 높은 강도, 다이아몬드보다 2배 이상 뛰어난 열 전도성, 그리고 규소보다 100배 이상 빠른 전자이동도 등의 매우 우수한 특성을 지닌다. 그래핀을 합성하거나 얻는 방법에는, 기계적 박리법(Micro mechanical exfoliation), 산화흑연(graphite oxide)을 이용한 reduced graphene oxide(RGO)방법과 탄화 규소(SiC)를 이용한 epitaxial growth 방법 등이 있지만, 대 면적화가 어렵거나 구조적 결함이 큰 문제점이 있다. 반면, 탄화수소(hydrocarbon)를 탄소 공급원으로 하는 열화학 기상 증착법(Thermal chemical vapor deposition, TCVD)은 구조적 결함이 상대적으로 적으면서 대 면적화가 가능하다는 이점 때문에 최근 가장 많이 이용되고 있는 방법이다. TCVD를 이용, 니켈, 몰리브덴, 금, 코발트 등의 금속에서 그래핀 합성연구가 보고되었지만, 대부분 수 층(fewlayer)의 그래핀이 합성되었다. 하지만, 구리 촉매를 이용하는 것이 단층 그래핀 합성에 매우 효율적이라는 연구결과가 보고되었다. 구리의 경우, 낮은 탄소융해도(solubility of carbon) 때문에 표면에서 self limiting 과정을 통하여 단층 그래핀이 합성된다. 그러나 단층 그래핀 일지라도 면저항(sheet resistance)이 매우 높고, 이론적 계산값에 비해 전자이동도(electron mobility)가 낮게 측정된다. 이러한 원인은 구조적 결함에서 기인된 것으로써 산업으로의 응용을 어렵게 만들기 때문에 양질의 단층 그래핀 합성연구는 필수적이다[1,2]. 본 연구에서는 TCVD를 이용하여 구리 포일(25 ${\mu}m$, Alfa Aeser) 위에 메탄가스를 탄소공급원으로 하여 수소를 함께 주입하고, 메탄가스의 양과 합성시간, 열처리 시간을 조절하면서 균일한 단층 그래핀을 합성하였다. 합성된 그래핀을 $SiO_2$ (300 nm)기판위에 전사(transfer)후 라만 분광법(raman spectroscopy)과 광학 현미경(optical microscope)을 통하여 분석하였다. 그 결과, 열처리 시간이 증가할수록 촉매로 사용된 구리 포일의 grain size가 커짐을 확인하였으며, 구리 포일 위에 합성된 그래핀의 grain size는, 구리 포일의 grain size에 의존하여 커짐을 확인하였다. 또한 동일한 grain 내의 그래핀은 균일한 층으로 합성되었다. 이는 기계적 박리법, RGO 방법, epitaxial growth 방법으로 얻은 그래핀과 비교하여 매우 뛰어난 결정성을 지님이 확인되었다. 본 연구를 통하여 면적이 넓으면서도 결정성이 매우 뛰어난 양질의 단층 그래핀 합성 방법을 확립하였다.

• The Korean Journal of Nuclear Medicine
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• v.33 no.1
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• pp.65-75
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• 1999

Purpose: The aim of this study is to demonstrate the feasibility of 2-[fluorine-18] fluoro-2-deoxy-D-glucose (F-18-FDG) whole body scan (FDG W/B Scan) using dual-head gamma camera equipped with ultra high energy collimator in patients with various cancers, and compare the results with those of coincidence imaging. Materials and Methods: Phantom studies of planar imaging with ultra high energy and coincidence tomography (FDG CoDe PET) were performed. Fourteen patients with known or suspected malignancy were examined. F-18-FDG whole body scan was performed using dual-head gamma camera with high energy (511 keV) collimators and regional FDG CoDe PET immediately followed it Radiological, clinical follow up and histologic results were correlated with F-18-FDG findings. Results: Planar phantom study showed 13.1 mm spatial resolution at 10 cm with a sensitivity of 2638 cpm/MBq/ml. In coincidence PET, spatial resolution was 7.49 mm and sensitivity was 5351 cpm/MBq/ml. Eight out of 14 patients showed hypermetabolic sites in primary or metastatic tumors in FDG CoDe PET. The lesions showing no hypermetabolic uptake of FDG in both methods were all less than 1 cm except one lesion of 2 cm sized metastatic lymph node. The metastatic lymph nodes of positive FDG uptake were more than 1.5 cm in size or conglomerated lesions of lymph nodes less than 1cm in size. FDG W/B scan showed similar results but had additional false positive and false negative cases. FDG W/B scan could not visualize liver metastasis in one case that showed multiple metastatic sites in FDG CoDe PET. Conclusion: FDG W/B scan with specially designed collimators depicted some cancers and their metastatic sites, although it had a limitation in image quality compared to that of FDG CoDe PET. This study suggests that F-18-FDG positron imaging using dual-head gamma camera is feasible in oncology and helpful if it should be more available by regional distribution of FDG.

• Journal of Chest Surgery
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• v.32 no.4
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• pp.388-393
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• 1999

Background: Correct preoperative staging of esophageal cancer is a prerequisite for adequate treatment. We prospectively compared the accuracy of positron emission tomography (PET) with [fluorine-18]FDG in the staging of esophageal cancer to that of computed tomography (CT). Material and Method: The findings of FDG PET and of chest CT including lower neck and the upper abdomen of 20 biopsy-proven squamous cell carcinoma patients (male, 19; female, 1; mean age, 61) were compared with the pathologic findings obtained from a curative esophagectomy with lymph node dissection. Result: The sensitivities of FDG PET and CT for diagnosis of primary tumor were the same, 90.0% (18/20). Both FDG PET and CT failed to show the primary tumor in 2 of 20 patients; one had a 1cm sized carcinoma in situ and the other had T1 stage cancer. By using the results of the pathologic examinations of 193 removed lymph node groups, we calculated the diagnostic sensitivities, specificities and accuracies of PET and CT (*$\chi$2 p < 0.005). Sensitivity** Specificity Accuracy* PET 55.6%(30/54) 97.1%(135/139) 85.5%(165/193) CT 13.0%(7/54) 98.6%(137/139) 74.6%(144/193) One of four patients with a false-positive for PEThad had active pulmonary tuberculosis. Among the 24 tumor involved lymph node groups, PET failed to show tumor metastasis in 5 lymph node groups abutting the tumor and in 14 lymph node groups located where the decay correction was not performed. Conclusion: Based on the above findings, it is suggested that [F-18]FDG-PET is superior to CT in the detection of nodal metastases and in the staging of patients with esophageal cancer.

• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.175-181
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• 2017

The purpose of this study is to evaluate the breast tool to improve the diagnostic value of the image in the breast examination. Breast tool was made of using FRP. And then it was compared by radioactivity counting rate and image. In the evaluation of the Breast tool, the left and right counts per $1{\mu}Ci$ are 185 counts and 189 counts, respectively. The image obtained in the prone position was close to the circle. To increase diagnostic value of image, it is considered to use Breast-tool in the breast examination.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.249-255
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• 2022

Positron emission tomography for small animals has very high spatial resolution for imaging very small organs. To achieve good spatial resolution, the system must be constructed using very small scintillation pixels. When a detector is constructed using very small scintillation pixels, the size of the applicable array varies depending on the photosensor pixel. In a previous study, a study was conducted to find the maximum scintillation pixel arrangement according to the size of the photosensor. In this study, a detector with a light guide was designed to configure the detector using a more extended array of scintillation pixels, and try to find the maximum arrangement in which all scintillation pixels are imaged. The detector was designed using DETECT2000, which can simulate a detector made of a scintillator. Simulations were performed by configuring the detectors from an 11 × 11 scintillation pixel array to a 16 × 16 array. After obtaining a flood image by collecting the light generated from the scintillation pixel with a photosensor, the largest arrangement without overlap was found through image analysis. As a result, the largest arrangement in which all scintillation pixels could be distinguished without overlapping was a 15 × 15 arrangement.