• Journal of Yeungnam Medical Science
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• v.13 no.1
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• pp.134-140
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• 1996

Recently many studies have shown the usefulness of computed tomogram in diagnosing abdominal mass when clinical and conventional radiologic examinations fail to reveal the nature of abdominal mass or the cause of abdominal distension. To evaluate the usefulness of CT in diagnosing neuroblastoma, we retrospectively analyzed computed tomographic findings of 16 neuroblastoma patients, who pathologically proved in Yeungnam University Hospital from 1986 to 1995. The age range of the patients studied were from 8months to 18years. The most frequent sith of origin was adrenal gland and the next was retroperitioneum. The presenting symptoms were palpable mass, abdominal distension, and abdominal pain. The viewpoints of this analysis were turnoral calcifications, midline cross, shape, margin, internal structure, contrast enhancement patterns, major vessel involvement, and lymph node involvement. Characteristic CT findings were as follows: Fine dense curvillinear calcification within the tumor(56%), midline cross(50%), lobulation(75%), well-circumscribed margin(56%), cystic degeneration(56%), heterogeneous contrast enhancement(69%). encasement of major vessels such as aorta, IVC and celiac trunk(50%), and paraaortic lymphadenopathy(87%). We conclude that these CT findings were very common and could be helpful in diagnosting and differentiation neuroblastoma in infant and children.

• Journal of the Korean Society of Radiology
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• v.9 no.6
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• pp.403-408
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• 2015

Hard X-ray has been widely used in medical and industrial fields because it can be applied to observe the inside of a sample. Computed tomography provides sectional images of the sample through the reconstruction of the projection images. The quality of sectional images strongly depends on that of projection images. Ring artifact appeared on the seconal image can be made by the abnormal pixels of the detector used. In this study, we examine the ring artifact ratio in the circle phantom as a function of detection error of the detector used in computed tomography. The ring artifact increased with the increment of detection error under parallel and fan beam geometries and strongly increased near the center of rotation. The corrections, dead pixel and flat field corrections, for the images taken with the detector are required before the image reconstruction process to reduce the ring artifact in the computed tomography.

• Journal of the Korean Society of Radiology
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• v.81 no.2
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• pp.250-271
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• 2020

Assessment of myocardial ischemia in patients with stable angina is important in deciding whether to treat coronary artery disease and in predicting clinical outcome. The fractional flow reserve is a standard reference for the diagnosis of myocardial ischemia, but this procedure has limitations because of its invasiveness. Coronary computed tomography angiography (CCTA) is now an established tool in the anatomic diagnosis of coronary artery disease; however, there are limits to the diagnosis of hemodynamically important stenosis that causes myocardial ischemia. In order to address this problem, studies using quantification of coronary atherosclerotic plaques, myocardial perfusion, and noninvasive calculation of fractional flow reserve based on CCTA have been actively conducted and recognized for their diagnostic value. In this review, several imaging techniques of CCTA used to assess myocardial ischemia are described.

• Proceedings of the Korean Magnestics Society Conference
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• 2015.11a
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• pp.58-58
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• 2015

• Tuberculosis and Respiratory Diseases
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• v.39 no.3
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• pp.236-241
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• 1992

Background: As well as fiberoptic bronchoscopy, chest computerized tomographic scan can now differentiate the benign from malignant causes and the obstructive from non-obstructive causes of lung collapse. This study was designed to evaluate the usefulness of chest CT scan and fiberoptic bronchoscopy in the diagnosis of middle lobe syndrome. Method: We reviewed the clinical features, roentgenographic changes, pathologic findings and bronchoscopic findings in 16 patients with middle lobe syndrome who were admitted to Severance Hospital during period of January, 1987 through January, 1992. Results: The male to female ratio was 1:1. The most common symptoms were cough and sputums. Crackle was the most common physical finding. Underlying disease was lung cancer, pulmonary tuberculosis and endobronchial tuberculosis in 3 each other, benign stenosis in 2, lung abscess, broncholithiasis, bronchial chondroma, pneumonia and nonspecific inflammation in 1 each other. Conclusion: We conclude that the combination of chest computerized tomogram and fiberoptic bronchoscopy was most desirable for the diagnosis of middle lobe syndrome.

• Journal of Gastric Cancer
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• v.9 no.4
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• pp.177-185
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• 2009

Purpose: Preoperative clinical staging of gastric cancer is very important for determining the treatment plans and predicting the prognosis. The previous reports regarding the accuracy of computed tomography or endoscopic ultrasound for the preoperative staging of gastric cancer have shown various outcomes. We analyzed the diagnostic performance of CT and EUS, which are important staging tools for the staging of TN gastric cancer. Materials and Methods: We retrospectively analyzed 1,174 patients who underwent gastrectomy for gastric cancer at Seoul National University Bundang Hostpital from May, 2003 to December, 2007. We derived the Kappa value to examine the agreement of the preoperative staging obtained from CT and EUS with the pathological staging. Results: The mean age of the 1,174 patients was $59.31{\pm}11.98$ years. Six hundred thirty seven patients had early gastric cancer and 536 had advanced gastric cancer. The diagnostic performance between CT and EUS for the T staging showed no significant difference between CT and EUS for the kappa values. The kappa values showed moderate agreement at 0.4039 (P=0.021) and 0.4201 (P=0.026), respectively. This suggests that there is no difference between the two examinations for the overall T staging. Analysis of the discrimination of mucosal and submucosal lesions with EUS showed an accuracy of 58.92% and a Kappa value of 0.206 (P<0.001), suggesting fair agreement and a lower diagnostic performance than expected. To differentiate lesions with stages higher than or equal to T2 or T3 from the lesion with stages lower than T2 or T3, respectively, adoption of the higher stage from the CT staging or the EUS staging showed a larger AUC of 0.84 than that from either stage alone. The CT-derived node stage had the higher diagnostic performance (68.55%) than that of the EUS-derived node stage (60.82%) for the node staging. Conclusion: The CT-derived stage and EUS-derived stage showed comparable results for determining the T stage of gastric cancer. Yet the higher stage of the two stages from CT and EUS most accurately discriminated between those lesions with stages higher than T2 and those lesions with stages lower than T2.

• Radiation Oncology Journal
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• v.20 no.2
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• pp.165-171
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• 2002

Purpose : In order to perform craniospinal irradiation (CSI) in the supine position on patients who are unable to lie in the prone position, a new simulation technique using a CT simulator was developed and its availability was evaluated. Materials and Method : A CT simulator and a 3-D conformal treatment planning system were used to develop CSI in the supine position. The head and neck were immobilized with a thermoplastic mask in the supine position and the entire body was immobilized with a Vac-Loc. A volumetrie image was then obtained using the CT simulator. In order to improve the reproducibility of the patients' setup, datum lines and points were marked on the head and the body. Virtual fluoroscopy was peformed with the removal of visual obstacles such as the treatment table or the immobilization devices. After the virtual simulation, the treatment isocenters of each field were marked on the body and the immobilization devices at the conventional simulation room. Each treatment field was confirmed by comparing the fluoroscopy images with the digitally reconstructed radiography (DRR)/digitally composite radiography (DCR) images from the virtual simulation. The port verification films from the first treatment were also compared with the DRR/DCR images for a geometrical verification. Results : CSI in the supine position was successfully peformed in 9 patients. It required less than 20 minutes to construct the immobilization device and to obtain the whole body volumetric images. This made it possible to not only reduce the patients' inconvenience, but also to eliminate the position change variables during the long conventional simulation process. In addition, by obtaining the CT volumetric image, critical organs, such as the eyeballs and spinal cord, were better defined, and the accuracy of the port designs and shielding was improved. The differences between the DRRs and the portal films were less than 3 mm in the vertebral contour. Conclusion : CSI in the supine position is feasible in patients who cannot lie on prone position, such as pediatric patienta under the age of 4 years, patients with a poor general condition, or patients with a tracheostomy.

• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.495-502
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• 2019

A typical cerebrovascular disease among cerebrovascular diseases is vascular diseases such as cerebral infarction, cerebral hemorrhage, cerebral aneurysm, cerebrovascular stenosis. If the disease occurs and causes cerebral damage, it may be difficult to recover completely. So that, Must continue to perform health care through examination early. In particular, Because most cerebrovascular disease examining use radiation equipment and Thus this study was to find out how to select about the optimal examining method and X-ray dose decrease method among different examining method though comparison and analysis for the entrance surface dose (ESD) on cerebrovascular examining with Trance Femoral Cerebral angiography (TFCA) and Cerebral Computed Tomographic Angiography (CCTA). Also, want to find out how to select about the optimal examining method for worried patient that contrast medium side effect though measuring and evaluating for contrast usage. Data were collected from 70 patients (43 males and 27 females) who underwent CCTA at Yeosoo region hospital from June 2018 to December 2018 and 61 patients (34 males and 27 females) who underwent TFCA at Pyeongtaek region hospital from June 2018 to November 2018. ESD analysis method collected retrospective data though M-view and PACS PLUS program, Used contrast usage measuring method did reality measuring method. In the analysis using SPSS, the ESD of TFCA was $245.74{\pm}71.91$, which was $32.05{\pm}7.74$ lower than the dose of $277.79{\pm}79.65$ of CCTA ESD, and statistically significant at t = 3.249, p = 0.017 (p<0.05). As a result of the comparison of the total amount of contrast agent, the mean contrast agent used in TFCA was $55.05{\pm}17.68ml$, which was about 14.95 smaller than the amount of contrast agent used in CCTA, and statistically significant t = -4.548, p<0.001. In conclusion, the ESD of TFCA was statistically significantly lower than that of CCTA, and also the used contrast usage was significantly tiny than that of CCTA. Therefore, Select the method to increase the utilization of TFCA for cerebral disease examining, we can consider X-ray dose decrease method at the same time as to decrease side effect of contrast medium.

• Journal of the Korean Society of Radiology
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• v.81 no.3
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• pp.644-653
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• 2020

Purpose We aimed to analyze postoperative multidetector CT (MDCT) of acquired spondylolysis and spondylolisthesis after posterior lumbar laminectomy. Materials and Methods We enrolled 74 patients, from 2003 to 2017, who underwent posterior lumbar laminectomy with both pre and postoperative MDCT. The patients were categorized into the following two groups: group 1 without fusion and group 2 with fusion. We analyzed laminectomy width, level and location of spondylolysis or spondylolisthesis, facet changes, and fatty infiltration of paraspinal muscles on postoperative MDCT. Results Incidence of spondylolysis or spondylolisthesis was 4 of 20 patients in group 1 and 2 of 54 patients in group 2. The laminectomy width (%) was defined as the percentage of the width of laminectomy to total lamina length. Mean laminectomy width (%) in patients with spondylolysis or spondylolisthesis was 54.0 in group 1 and 53.2 in group 2, in contrast to that in patients without spondylolysis or spondylolisthesis, which was 35.0 in group 1. The spondylolysis was observed at the level of the laminectomy and below pars interarticularis in group 1 and below the fusion mass at isthmic region in group 2. Conclusion MDCT facilitates the diagnosis of postsurgical acquired spondylolysis and spondylolisthesis and demonstrates typical location of spondylolysis. Greater laminectomy width has been associated with occurrence of acquired spondylolysis and spondylolisthesis.

• Journal of the Korean Society of Radiology
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• v.11 no.4
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• pp.241-246
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• 2017

The existing fractal compression method is effective in generating an artificial shape by approximating its partial regions to a domain block by re-dividing the whole image into a domain region and dividing it into several domain blocks, but it is difficult to implement a computer. In this study, it is difficult to approximate a complex block such as a large-sized block and an affine transformation because a large amount of calculation is required in searching for a combination of similar blocks through a transformation, so a large amount of coding time is required.