• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.57.1-57.8
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• 2019

Background: The relationship between the lateral deviation of chin and the upper and middle facial third asymmetry is still controversial. The purpose of this study is to evaluate the correlation of upper and middle facial third asymmetry with lateral deviation of chin using 3-dimensional computed tomography. The study was conducted on patients who underwent orthognathic surgery from January 2016 to August 2017. A total of 40 patients were included in this retrospective study. A spiral scanner was used to obtain the 3-dimensional computed tomography scans. The landmarks were assigned on the reconstructed 3-dimensional images, and their locations were verified on the axial, midsagittal, and coronal slices. The Pearson correlation analysis was performed to evaluate the correlation between chin deviation and difference between the measurements of distances in paired craniofacial structures. Statistical analysis was performed at a significance level of 5%. Results: In mandible, the degree of chin deviation was correlated with the mandibular length and mandibular body length. Mandibular length and mandibular body length are shorter on the deviated-chin side compared to that on the non-deviated side (mandibular length, r = -0.897, p value < 0.001; mandibular body length, r = -0.318, p value = 0.045). In the upper and middle facial thirds, the degree of chin deviation was correlated with the vertical asymmetry of the glenoid fossa and zygonion. Glenoid fossa and zygonion are superior on the deviated-chin side than on the non-deviated side (glenoid fossa, r = 0.317, p value = 0.046; zygonion, r = 0.357, p value = 0.024). Conclusion: Lateral deviation of chin is correlated with upper and middle facial third asymmetry as well as lower facial third asymmetry. As a result, treatment planning in patients with chin deviation should involve a careful evaluation of the asymmetry of the upper and middle facial thirds to ensure complete patient satisfaction.

• Progress in Medical Physics
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• v.16 no.1
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• pp.47-51
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• 2005

We report a case of an accidental extravasation of contrast material. A large-volume extravasation occurred in an adult during spiral contrast-enhanced CT. The amount of contrast material extravasated was 47 ml. The patient had a swelling of the dorsum right hand. The extravasation injury site was determined by CT scanning. The extavasation case was examined using five separate display techniques: axial, multi planar reformation (MPR), maximum intensity projection (MIP), volume rendering, and shaded-surfaced display (SSD). This paper introduces extravasation with the CT and the three-dimensional appearance.

• Journal of the Korean Society of Radiology
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• v.84 no.3
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• pp.520-535
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• 2023

Gastrointestinal (GI) bleeding is not a single disease but a symptom and clinical manifestation of a broad spectrum of conditions in the GI tract. According to its clinical presentation, GI bleeding can be classified into overt, occult, and obscure types. Additionally, it can be divided into upper and lower GI bleeding based on the Treitz ligament. Variable disease entities, including vascular lesions, polyps, neoplasms, inflammation such as Crohn's disease, and heterotopic pancreatic or gastric tissue, can cause GI bleeding. CT and conventional angiographies and nuclear scintigraphy are all radiologic imaging modalities that can be used to evaluate overt bleeding. For the work-up of occult GI bleeding, CT enterography (CTE) can be the first imaging modality. For CTE, an adequate bowel distention is critical for obtaining acceptable diagnostic performance as well as minimizing false positives and negatives. Meckel's scintigraphy can be complementarily useful in cases where the diagnosis of CTE is suboptimal. For the evaluation of obscured GI bleeding, various imaging modalities can be used based on clinical status and providers' preferences.

• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.53-59
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• 1999

The aim of this study is to improve the accuracy of field placement and junction between adjacent fields and block shielding through the use of a computed tomography(CT) simulator and virtual simulation. The information was acquired by assessment of Alderson Rando phantom image using CT simulator (I.Q. Xtra - Picker), determination of each field by virtual fluoroscopy of voxel IQ workstation AcQsim and colored critical structures that were obtained by contouring in virtual simulation. And also using a coronal, sagittal and axial view can determine the field and adjacent field gap correctly without calculation during the procedure. With the treatment planning by using the Helax TMS 4.0, the dose in the junction among the adjacent fields and the spinal cord and cribriform plate of the critical structure was evaluated by the dose volume histogram. The pilot image of coronal and sagittal view took about 2minutes and 26minutes to get 100 images. Image translation to the virtual simulation workstation took about 6minutes. Contouring a critical structure such as cribriform plate, spinal cord using a virtual fluoroscopy were eligible to determine a correct field and shielding. The process took about 20 minutes. As the result of the Helax planning, the dose distribution in adjacent field junction was ideal, and the dose level shows almost 100 percentage in the dose volume histogram of the spinal cord and cribriform plate CT simulation can get a correct therapy area due to enhancement of critical structures such as spinal cord and cribriform plate. In addition, using a Spiral CT scanner can be saved a lot of time to plan a simulation therefore this function can reduce difficulties to keep the patient position without any movements to the patient, physician and radiotherapy technician.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.37
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• pp.30.1-30.7
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• 2015

Background: The inferior alveolar nerve (IAN) may be injured during extraction of the mandibular third molar, causing severe postoperative complications. Many methods have been described for evaluating the relative position between the mandibular third molar and the inferior alveolar canal (IAC) on panoramic radiography and computed tomography, but conventional radiography provides limited information on the proximity of these two structures. The present study assessed the benefits of three-dimensional computed tomography (3D-CT) prior to surgical extraction of the mandibular third molar, to prevent IAN damage. Methods: This retrospective study included 4917 extractions in 3555 patients who presented for extraction of the mandibular third molars. The cases were classified into three groups, according to anatomical relationship between the mandibular third molars and the IAC on panoramic radiography and whether 3D-CT was performed. Symptoms of IAN damage were assessed using the touch-recognition test. Data were compared using the chi-square test and Fisher's exact test. Results: Among the 32 cases of IAN damage, 6 cases were included in group I (0.35 %, n = 1735 cases), 23 cases in group II (1.1 %, n = 2063 cases), and 3 cases in group III (0.27 %, n = 1119 cases). The chi-square test showed a significant difference in the incidence of IAN damage between groups I and II. No significant difference was observed between groups I and III using Fisher's exact test. In the 6 cases of IAN damage in group I, the mandibular third molar roots were located lingual relative to the IAC in 3 cases and middle relative to the IAC in 3 cases. The overlap was ${\geq}2mm$ in 3 of 6 cases and 0-2 mm in the remaining 3 cases. The mean distance between the mandibular third molar and IAC was 2.2 mm, the maximum distance 12 mm, and the minimum distance 0.5 mm. Greater than 80 % recovery was observed in 15 of 32 (46.8 %) cases of IAN damage. Conclusions: 3D-CT may be a useful tool for assessing the three-dimensional anatomical relationship and proximity between the mandibular third molar and IAC in order to prevent IAN damage during extraction of mandibular third molars.

• Journal of Veterinary Clinics
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• v.27 no.3
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• pp.273-283
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• 2010

The objective of this study was to measure densities in various areas of the normal canine lung with computed tomography (CT) depending on influences of gravity and the degree of lung inflation and to determine optimal positions and positive end expiratory pressure of canine lung for CT scanning. In each eight normal Beagle and Shihtzu dogs, a respiratory breathhold maneuver without spontaenous breathing at different positive end expiratory pressure (PEEP) of 0 mmHg, 10 mmHg and 20 mmHg was applied with the position of right and left lateral recumbency, sternal recumbency, and dorsal recumbency and spiral-CT scans of the total lung were acquired. Slices were selected at three levels through the apex, middle and basal lung at the aortic arch, carina and just above the diaphragm and lung density was measured in the dorsal, ventral, and lateral portions of the peripheral lung field. Lung density in dependent areas was higher than in nondependent areas (p < 0.05) regardless of species, positions, anatomic locations at the PEEP of 0 mmHg and 10 mmHg. However, no significant difference of lung density was found at PEEP of 20 mmHg in both species except the dorsal recumbency in Shihtzu dogs. This density gradient in the dependent areas is strongly influenced by PEEP (p < 0.05). In the four positions on the CT gantry, the lung density at the dependent and nondependent location of the lung was greater at the aortic arch than at the base (p < 0.05). Lung density decreased on identical location according to increase of PEEP (p < 0.05). There was no significant difference between right and left lung density at sternal and dorsal recumbency and no significant difference of the dorsal, ventral, and lateral portions of lung density at the right and left recumbency under identical pressure. It is implied that during chest CT scan with 20 mmHg of positive end expiratory pressure with right or left lateral recumbency, canine lung density do not influenced by gravity or anatomic location.

• Geotechnical Engineering
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• v.9 no.2
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• pp.41-54
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• 1993

This paper presents the two and three -dimensional stability analysis of nonhom- ogeneous, c-o soil slopes. Potential failure surface is assumed as a logspiral curve refracted in boundaries of layers. In 3-D analysis, rotational soil mass is assumed with a cylindroid central part terminated with plane ends. Seismic force is considered by sesmic intensity. The program developed in this study is compared with the program PCSTABLS. The ratio of three-dimensional minimum factor of safety to two-dimensional case is examined and factor of safety changes are showed for the ratio of cylindroid length to slope height and numbers of slice. On such bases the following conclusions may by made : (1) The program developed in this program is less conservative than the program PCSTABLS. (2) The value of F2 of this study shows the larger differences than that of PCSTABLS with increasing friction angle (3) Factors of safety computed for 3-D geometry differ considerablely from ordinary 2-D factors of safety. Since Fb/F2 exceeds unity, three -dimensional effects tend to increase the factor of safety. (4) As the ratio of three - dimensional failure width of slope height, b/H increase, the value of Fb/Ff decreases and approaches 1.0 when bye is 14. (5) In calculating the factor of safety using the developed program the number of slices is suitable with the ranges of 30-40

• Journal of the Korean Society of Radiology
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• v.9 no.1
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• pp.31-37
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• 2015

The cases of radiographic inspection for medical diagnosis in Korea have been continuously increasing year after year, which pays particularly more attention to CT which occupies over the half of medical radiation exposure. To find an effective alternative for reducing radiation exposure, the researchers conducted comparative experiments using some shields made of bismuth, aluminum 6mm, and silicone 22mm. These shielding materials have been used to reduce the entrance surface dose (ESD) on lenses, maintaining the CT number, noise, and uniformity in brain CT scanning which forms the largest part in CT scanning these days. These experiments showed that the doses in the spiral scan parallel to IOML and the conventional scan in Bismuth were 26.41% and 17.52%, respectively; in Aluminum 18.24% and 9.39%; in Silicone 19.47% and 14.39% lower than compared with those in the cases without any shields. In the items of the CT number, noise, and uniformity, the bismuth shield satisfied exceedingly the standards of the phantom image test while aluminum and silicone were within. To keep the graphic quality and get good shielding effect, we recommend the silicone shield which can be manufactured and purchased with ease.

• Tuberculosis and Respiratory Diseases
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• v.83 no.2
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• pp.157-166
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• 2020

Background: Infectious conditions may increase the risk of venous thromboembolism. The purpose of this study was to evaluate the risk factor for combined infectious disease and its influence on mortality in patients with pulmonary embolism (PE). Methods: Patients with PE diagnosed based on spiral computed tomography findings of the chest were retrospectively analyzed. They were classified into two groups: patients who developed PE in the setting of infectious disease or those with PE without infection based on review of their medical charts. Results: Of 258 patients with PE, 67 (25.9%) were considered as having PE combined with infectious disease. The sites of infections were the respiratory tract in 52 patients (77.6%), genitourinary tract in three patients (4.5%), and hepatobiliary tract in three patients (4.5%). Underlying lung disease (odds ratio [OR], 3.69; 95% confidence interval [CI], 1.926-7.081; p<0.001), bed-ridden state (OR, 2.84; 95% CI, 1.390-5.811; p=0.004), and malignant disease (OR, 1.867; 95% CI, 1.017-3.425; p=0.044) were associated with combined infectious disease in patients with PE. In-hospital mortality was higher in patients with PE combined with infectious disease than in those with PE without infection (24.6% vs. 11.0%, p=0.006). In the multivariate analysis, combined infectious disease (OR, 4.189; 95% CI, 1.692-10.372; p=0.002) were associated with non-survivors in patients with PE. Conclusion: A substantial portion of patients with PE has concomitant infectious disease and it may contribute a mortality in patients with PE.

• Journal of the Korean Society of Radiology
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• v.7 no.4
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• pp.307-311
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• 2013

This study examined the change of artifact volume by analyzing the level of image change associated with the setting of threshold through 3D imaging in scan parameter(slice thickness and helical pitch) and 3D image reconstruction to explore whether the presence of pathology was fully distinguished when CT was taken by lower dose than the existent dose to reduce exposure. Furthermore, this study attempted to investigate Scan Parameter acceptable in CT to reduce exposure dose. For materials and methods, silicon was used to produce samples. Five spherical samples were produced at 10-millimeter intervals(50, 40, 30, 20, and 10 mm) in diameter and were fixed at 120 Kvp of tube voltage and 50 mA of tube current. Varied slab thickness((1.0, 2.0, 3.0, 5.0, and 7.0mm) and Helical Pitch(1.5, 2.0, 3.0) were scanned. The image at an interval of 1.0, 2.0, 3.0, 5.0, and 7.0mm was transmitted to the workstation. Threshold(-200, -50, 50 ~ 1,000) was changed using the volume rendering technique, 3D image was reconstructed, and artifact volume was measured. In conclusion, 1.5 of Helical Pitch showed the least change of volume and 3.0 of helical pitch showed the greatest reduction of volume change. The experiment suggested that as slice thickness was increased, artifact volume was decreased more than actual measurement. Furthermore, in the 3D image reconstruction, when the range of threshold was set as -200 ~1,000, artifact volume was changed the least. Based on the results, it is expected to have an effect of reducing exposure dose.