• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.6
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• pp.22-30
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• 1979

A new circular ring position camera tomographic system termed "Oscillatory Dichotomic Ring" system is proposed and its performance is simulated. It is basically a circular ring system, composed of two half rings, which has the capability of scanning so that any sampling intervals can be obtained. Since finer sampling means poorer photon statistcs, simulations with varous signal dependent statistical noise effects, ray sampling and arrangement as well as related artifacts peculiar to the proposed Dichotomic Ring system are made.

• Computers and Concrete
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• v.21 no.4
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• pp.367-376
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• 2018

This study reports the results of nondestructive monitoring of macro void developments in mortars manufactured with both ordinary Portland cement and sulfate resistant cement. Two types of curing were utilized; tap water curing and another curing environment that contains 5% $Na_2(SO_4)$ solution. Being the primary objective of this study, macro void developments of the mortar specimens were monitored by X-ray Medical Computerized Tomography. Compressive strength tests and water absorption tests were conducted on specimens that were kept in both curing environments for a duration of 560 days. Data analyses yielded consistent results among the three tests used in this experimental study. Macro void ratios of mortars decreased at the beginning of experiments for a certain period; afterwards, macro void ratios increased. The objective of this study was accomplished as anticipated since X-CT image analysis was able to nondestructively monitor macro void development process in cement mortars.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.23 no.1
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• pp.159-164
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• 1993

Cystic hygroma is a special form of lymphangioma. It most often occurs in the neck of children. We observed a 14-year-old male whose chief complaint was a abnormal swelling of the right mandibular angle area. The computerized tomography showed the well-defined nonenhancing cystic mass on right submandibular gland area and anterior triangle of the neck. The histopathologic fidings exhibited the multiloculatedfluid-filled cysts, which are lined a flattened layer of endothelial cells with foci of lymphocytes found lying adjacent to the lining. After evaluation of above findings, the mass was diagnosed as a cystic hygroma in the neck.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1990.10a
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• pp.23-25
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• 1990

In this paper, a system to measure tree degradation of three dimensional phenomena in organic insulating materials using image processing system is discussed. Using a computerized tomography method, volume of tree immediately after tree initiation, as well as changes in the configuration of the tree were measured, which up to now have been difficult to measure. The specimens used an acrylic acid resin. As a result, it was possible to record the cross sections of the tree, and to describe the volume of the tree by the three dimensional measurement.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.22 no.2
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• pp.189-192
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• 2019

Gastric duplication cysts (GDCs) are rare congenital anomalies. Presentation of GDCs varies from an asymptomatic abdominal mass to fulminant or massive gastrointestinal (GI) bleeding. Herein, we describe a case of a GDC in a 10-month-old infant presenting with unexplained massive GI hemorrhage and hematemesis. An abdominal ultrasound was negative, while computerized tomography was, initially, inaccessible. Through a series of repeated esophagogastroduodenoscopies, we documented penetration of the GDC into the gastric cavity that was later confirmed by computerized tomography. The patient was treated successfully with surgical resection.

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.3
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• pp.181-190
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• 1998

A computerized tomography system was developed using the X-ray source that has diameter of 5 micrometer. The system is used for the nondestructive testing of specimens with diameter below 20 mm. The convolution back projection algorithm was adopted for the reconstruction of cross sectional image, and the shape of the X-ray beam was let parallel beam or fan beam to compare each resultant image. Our CT system was constructed to operate based on the personal computer. The sectional images of the fabricated specimens were reconstructed and analyzed. The reconstructed images well coincided with real images taken with optical microscope and gave us enough reports on the defects in the ceramic specimen. The resolution of the system regarded as about $20{\sim}30$ micrometers.

• Journal of Korean Neurosurgical Society
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• v.58 no.1
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• pp.9-13
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• 2015

Objective : To improve pedicle screw placement accuracy with minimal radiation and low cost, we developed specially designed K-wire with a marker. To evaluate the accuracy of thoracolumbar pedicle screws placed using the novel guide-pin and portable X-rays. Methods : Observational cohort study with computerized tomography (CT) analysis of in vivo and in vitro pedicle screw placement. Postoperative CT scans of 183 titanium pedicle screws (85 lumbar and 98 thoracic from T1 to L5) placed into 2 cadavers and 18 patients were assessed. A specially designed guide-pin with a marker was inserted into the pedicle to identify the correct starting point (2 mm lateral to the center of the pedicle) and aiming point (center of the pedicle isthmus) in posteroanterior and lateral X-rays. After radiographically confirming the exact starting and aiming points desired, a gearshift was inserted into the pedicle from the starting point into the vertebral body through the center of pedicle isthmus. Results : Ninety-nine percent (181/183) of screws were contained within the pedicle (total 183 pedicle screws : 98 thoracic pedicle screws and 85 lumbar screws). Only two of 183 (1.0%) thoracic pedicle screws demonstrated breach (1 lateral in a patient and 1 medial in a cadaver specimen). None of the pedicle breaches were associated with neurologic or other clinical sequelae. Conclusion : A simple, specially designed guide-pin with portable X-rays can provide correct starting and aiming points and allows for accurate pedicle screw placement without preoperative CT scan and intraoperative fluoroscopic assistance.

• Journal of Korean Neurosurgical Society
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• v.49 no.2
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• pp.107-111
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• 2011

Objective : The aim of this study was to evaluate the utility of volume-rendered helical computerized tomography (CT) angiography focusing tracheostomy tube and innominate artery for prevention of tracheoinnominate artery fistula. Methods : The authors retrospectively analyzed 22 patients with tracheostomy who had checked CT angiography. To evaluate the relationship between tracheostomy tube and innominate artery, we divided into three categories. First proximal tube position based on cervical vertebra, named "tracheostomy tube departure level (TTDL)". Second, distal tube position and course of innominate artery, named "tracheostomy tube-innominate artery configuration (TTIC)". Third, the gap between the tube and innominate artery, named "tracheostomy tube to innominate artery gap (TTIG)". The TTDL/TTIC and TTIG are based on 3-dimensional (3D) reconstruction around tracheostomy and enhanced axial slices of upper chest, respectively. Results : First, mean TTDL was $6.8{\pm}0.6$. Five cases (23%) were lower than C7 vertebra. Second, TTIC were remote to innominate artery (2 cases; 9.1 %), matched with it (14 cases; 63.6%) or crossed it (6 cases; 27.3%). Only 9% of cases were definitely free from innominate artery injury. Third, average TTIG was $4.3{\pm}4.6$ mm. Surprisingly, in 6 cases (27.3%), innominate artery, trachea wall and tracheostomy tube were tightly attached all together, thus have much higher probability of erosion. Conclusion : If low TTDL, match or crossing type TTIC with reverse-L shaped innominate artery, small trachea and thin TTIG are accompanied all together, we may seriously consider early plugging and tube removal.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.3
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• pp.363-372
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• 2003

Supernumerary teeth are found frequently in the dental office causing many dental complications. They are one of the many dental abnormalities that may occur during tooth development. Inversely impacted supernumerary teeth in the midpalatal area are especially important clinically because they occur with high frequency and many complications. Though many previous clinical and radiographical studies exist, the sample numbers were small and the evaluation of shape, location, and effects to its surrounding tissue may not be accurate due to the solitary use of intraoral radiographs or panoramic radiographs. Among the patients who visited department of pediatric dentistry, yonsei dental hospital, from July, 1998 to June, 2002, those with inversely impacted supernumerary teeth took computerized tomography for a more accurate diagnosis. Their dental chart, panoramic radiograph and computerized tomography were evaluated for this study. The number, form, convexity, location, distance, and complications of inversely impacted supernumerary teeth in the midpalatal area were recorded. This study show that when the supernumerary teeth is tuberculated with a curved root and is in close proximity to the adjacent teeth, it causes complications such as eruption disturbance, rotation, displacement of adjacent teeth, and diastema. Such factors must be considered in making decisions for diagnosis and treatment.

• Journal of Yeungnam Medical Science
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• v.18 no.1
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• pp.123-137
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• 2001

Background: The purpose of this study is to evaluate the accuracy of measurements obtained from 3-dimensional computerized tomography and 3-dimensional cephalogram constructed by using the frontal and lateral cephalogram of six human dry skulls. Materials and Methods: After CT scans and each cephalograms were taken, 3-dimensional coordinates (X, Y, Z) of landmarks were obtained using computer programs. In this study, the accuracy of both methods were determined by means of 14 linear measurements compare with caliper measurements. Results: The standard deviation of landmarks of 3-dimensional CT and 3-dimensional cephalogram were 0.23 mm, and 0.30 mm in X axis, 0.27 mm and 0.25 mm in Y axis, and 0.27 mm and 0.31 mm in Z axis. In both methods, the standard deviation were less than 0.5 mm in all landmarks, and the most of landmarks showed less than 1 mm in range. Concerning the accuracy, the mean difference between 3-dimensional CT and manual measurements was 0.33 mm, and 1.13 mm between 3-dimensional cephalogram and manual measurements. The distance between RGo and LGo showed the largest difference (2.03 mm). There were highly significant, and large correlation with manual measurements in both methods (p<0.01). Conclusion: It is concluded that closeness of repeated measures to each skulls reveal the precision of both methods. Computerized tomography and cephalogram for 3-dimensional measurement of maxillofacial structure are equivalent in quality to caliper measurements.