• Journal of the Korean Physical Society
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• v.73 no.12
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• pp.1904-1907
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• 2018

We designed a depth-encoding positron emission tomography (PET) detector by using a bottom and side readout method with a cross-arranged scintillator array. To evaluate the characteristics of the novel detector module, we used the DETECT2000 simulation tool to perform the optical photon transport in the crystal array. The detector module consists of an $M(column){\times}N(row)$ cross-arranged crystal array composed of M/3 sub-arrays consisting of $N{\times}3$ crystals. The second column of the sub-array is arranged perpendicular to the first and the third columns. The crystal is optically coupled to the crystals of the other columns; however, the surfaces between the crystals in the same column are treated as reflectors. A $6{\times}5$ crystal array consisting of two sub-arrays was considered for proof of concept. The two multi-pixel photon counter (MPPC) arrays are coupled to the bottom and one side of the crystal array, respectively. The x-y position is determined by the bottom MPPC array, and the side MPPC array gives depth information. All pixels in the x-y plane and the z direction were clearly distinguished.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.703-705
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• 2005

본 논문에서는 기울기 크기 기반의 3차원 영역확장 알고리즘을 사용하여 small animal PET(Positron Emission Tomography) 영상으로부터 종양을 분할하는 연구를 수행하였다. 픽셀 값의 범위가 다양하고 저해상도의 특성을 갖는 PET영상으로부터 대상영역을 정확하게 분할하기 위해서 전처리(preprocessing)과정으로 영상 픽셀값의 분포를 펼쳐줌으로써 영상의 가시화를 높이는 히스토그램 스트레칭(histogram stretching) 기법을 적용하고 대상영역과 픽셀값이 유사한 인접영역과의 경계를 찾기 위해 가우시안의 1차 미분 함수를 사용하여 계산된 기울기 크기(gradient magnitude) 기반의 3차원 영역확장(region growing) 알고리즘을 제안한다. 제안한 알고리즘은 영역확장의 결과에 가장 큰 영향을 미치는 적절한 동질성 기준의 선택으로 대상영역의 분할을 성공적으로 수행하여 일반적인 영역확장의 단점을 보완하였다.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.1
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• pp.33-37
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• 2022

Translocator protein (TSPO) is associated with neurodegeneration diseases, and the development of potent ligands with high affinity to TSPO was valuable study for many scientists. Specially, pyrazolo[1,5-a]pyrimidine moiety has been employed for development of new TSPO ligands with good properties. In this highlight review, the development of [¹⁸F]F-DPA as a promising TSPO ligand as PET tracer is described.

• 대한핵의학회:학술대회논문집
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• 2002.05a
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• pp.45-53
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• 2002

Positron Emission Tomography(PET) was introduced as a research tool in the 1970s and it took about 20 years before PET became an useful clinical imaging modality. In the USA, insurance coverage for PET procedures in the 1990s was the turning point, I believe, for this progress. Initially PET was used in neurology but recently more than 80% of PET procedures are in oncological applications. I firmly believe, in the 21st century, one can not manage cancer patients properly without PET and PET is very important medical imaging modality in basic and clinical sciences. PET is grouped into 2 categories : conventional(c) and gamma camera $based_{(CB)}$ PET. $_{CB}PET$ is more readily available utilizing dual-head gamma cameras and commercially available FDG to many medical centers at low cost to patients. In fact there are more $_{CB}PET$ in operation than cPET in the USA. $_{CB}PET$ is inferior to cPET in its performance but clinical studies in oncology is feasible without expensive infrastructures such as staffing, rooms and equipments. At Ajou university Hospital, CBPET was installed in late 1997 for the first time in Korea as well as in Asia and the system has been used successfully and effectively in oncological applications. Ours was the fourth PET operation in Korea and I believe this may have been instrumental for other institutions got interested in clinical PET. The fellowing is a brief description of our clinical experience of FDG CBPET in oncology.

• 대한위암학회:학술대회논문집
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• 2004.11a
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• pp.44-44
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• 2004

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.7 no.2
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• pp.127-131
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• 2021

Neuroendocrine tumor is one of popular diseases, and somatostatin receptor antagonists have been considered as promising agents for neuroendocrine tumors. Imaging of somatostatin receptor is useful approach on the diagnosis and therapy of neuroendocrine tumors. Thus, several radiolabeled somatostatin derivatives have been developed by scientists, and used for patients with neuroendocrine tumors. In particular, some radiopharmaceuticals for neuroendocrine tumors were approved by FDA. In this highlight review, the development of important radiolabeled somatostatin derivatives is described.

• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1942-1942
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• 2024

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.3
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• pp.111-115
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• 2011

PET/CT(Positron Emission Tomography/Computed Tomography) is an examination combining morphological and functional information in one examination. The purpose of this study is to see the lowest CT dose for attenuation correction in the PET/CT maintaining good image quality when considering CT scan dose to the patients. We injected $^{18}F$-FDG and water into the cylinder shaped phantom, and obtained emission images for 3 mins and transmission images(140 kVp, 8 sec, 10~200 mA for transmission images), and reconstructed the images to PET/CT images with Iterative method. Data(Maximum, Minimum, Average, Standard Deviation) were obtained by drawing a circular ROI(Region Of Interest) on each sphere in each image set with Image J program. And then described SD according to the CT and PEC/CT images as graphes. Through the graphes, we got the relationships of mA and quality of images. SDs according to CT graph were 16.25 at 10 mA, 7.26 at 50 mA, 5.5 at 100 mA, 4.29 at 150 mA, and 3.83 at 200 mA, i.e. the higer mA, the better image quality was presented. SDs according to PET/CT graph were 1823.2 at 10 mA, 1825.1 at 50 mA, 1828.4 at 100 mA, 1813.8 at 150 mA, and 1811.3 at 200 mA. Calculated SDs at PET/CT images were maintained. This means images quality is maintained having nothing to do with mA of high and low.

• Radiation Oncology Journal
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• v.29 no.4
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• pp.243-251
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• 2011

Purpose: To evaluate the prognostic value of metabolic tumor volume (MTV) and maximum standardized uptake value (SUVmax) on initial positron emission tomography-computed tomography (PET-CT) and investigate the clinical value of SUVmax for early detection of locoregional recurrent disease after postoperative radiotherapy in patients with locally advanced head and neck squamous cell carcinoma (HNSCC). Materials and Methods: A total of 100 patients with locally advanced HNSCC received primary tumor excision and neck dissection followed by adjuvant radiotherapy with or without chemotherapy. The MTV and SUVmax were measured from primary sites and neck nodes. The prognostic value of MTV and SUVmax were assessed using initial staging PET/CT (study A). Follow-up PET/CT scan available after postoperative concurrent chemoradiotherapy or radiotherapy were evaluated for the SUVmax value and correlated with locoregional recurrence (study B). A receiver operating characteristic (ROC) curve analysis was used to define a threshold value of SUVmax with the highest accuracy for recurrent disease assessment. Results: High MTV (>41 mL) is negative prognostic factor for disease free survival (p = 0.041). Postradiation SUVmax was significantly correlated with locoregional recurrence (hazard ratio, 1.812; 95% confidence interval, 1.361 to 2.413; P < 0.001). A cutoff value of 5.38 from follow-up PET/CT was identified as having maximal accuracy for detecting locoregional recurrence by ROC analysis. Conclusion: MTV at staging work-up was significantly associated with disease free survival. The SUVmax value from follow-up PET/CT showed high diagnostic accuracy for the detection of locoregional recurrence in postoperatively irradiated HNSCC.

• Korean Journal of Radiology
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• v.20 no.8
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• pp.1293-1299
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• 2019

Objective: The purpose of this study was to evaluate the diagnostic performance of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) for chronic empyema-associated malignancy (CEAM). Materials and Methods: We retrospectively reviewed the ¹⁸F-FDG PET/CT images of 33 patients with chronic empyema, and analyzed the following findings: 1) shape of the empyema cavity, 2) presence of fistula, 3) maximum standardized uptake value (SUV) of the empyema cavity, 4) uptake pattern of the empyema cavity, 5) presence of a protruding soft tissue mass within the empyema cavity, and 6) involvement of adjacent structures. Final diagnosis was determined based on histopathology or clinical follow-up for at least 6 months. The abovementioned findings were compared between the ¹⁸F-FDG PET/CT images of CEAM and chronic empyema. A receiver operating characteristic (ROC) analysis was also performed. Results: Six lesions were histopathologically proven as malignant; there were three cases of diffuse large B-cell lymphoma, two of squamous cell carcinoma, and one of poorly differentiated carcinoma. Maximum SUV within the empyema cavity (p < 0.001) presence of a protruding soft tissue mass (p = 0.002), and involvement of the adjacent structures (p < 0.001) were significantly different between the CEAM and chronic empyema images. The maximum SUV exhibited the highest diagnostic performance, with the highest specificity (96.3%, 26/27), positive predictive value (85.7%, 6/7), and accuracy (97.0%, 32/33) among all criteria. On ROC analysis, the area under the curve of maximum SUV was 0.994. Conclusion: ¹⁸F-FDG PET/CT can be useful for diagnosing CEAM in patients with chronic empyema. The maximum SUV within the empyema cavity is the most accurate ¹⁸F-FDG PET/CT diagnostic criterion for CEAM.