• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.147-151
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• 2019

In chest and abdomen CT scans, the radiation exposure doses by scattering lines were measured at the eyeball and thyroid. Radiation exposure was investigated by using shielding devices. The chest and abdomen CT scan protocols used in the real examination were applied to measure and compare radiation doses before and after the use of shielding devices at the eyeball and the thyroid. The radiaton doses were measured with OSLD dosimeters. Barium, tungsten sheets, goggles and neck shields were used to protect the scattered X-ray. The chest CT scans showed respectively 3.01 mSv and 6.21 mSv at the eyeball and the thyroid by the scattered X-ray. The abdomen CT scans showed 0.55 mSv and 3.22 mSv for the eyeball and the thyroid respectively. Barium and tungsten sheets had 11% to 13% protection rates at the eyeball and the thyroid for chest CT scan, and 34% to 49% reduction in radiation dose for the abdomen CT scan. Because of the significant radiation dose, which causes cataracts and thyroid cancer by the repeated and continuous radiation exposure, for the chest and the abdomen CT scans, it is required to use shielding devices to reduce radiation dose for examinations.

• The Journal of Korean Society for Radiation Therapy
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• v.18 no.2
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• pp.75-80
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• 2006

Purpose: In radiation therapy, precise calculation of dose toward malignant tumors or normal tissue would be a critical factor in determining whether the treatment would be successful. The Radiation Treatment Planning (RTP) system is one of most effective methods to make it effective to the correction of dose due to CT number through converting linear attenuation coefficient to density of the inhomogeneous tissue by means of CT based reconstruction. Materials and Methods: In this study, we carried out the measurement of CT number and calculation of mass density by using RTP system and the homemade inhomogeneous tissue Phantom and the values were obtained with reference to water. Moreover, we intended to investigate the effectiveness and accuracy for the correction of inhomogeneous tissue by the CT number through comparing the measured dose (nC) and calculated dose (Percentage Depth Dose, PDD) used CT image during radiation exposure with RTP. Results: The difference in mass density between the calculated tissue equivalent material and the true value was ranged from $0.005g/cm^3\;to\;0.069g/cm^3$. A relative error between PDD of RTP and calculated dose obtained by radiation therapy of machine ranged from -2.8 to +1.06%(effective range within 3%). Conclusion: In conclusion, we confirmed the effectiveness of correction for the inhomogeneous tissues through CT images. These results would be one of good information on the basic outline of Quality Assurance (QA) in RTP system.

• Journal of radiological science and technology
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• v.35 no.2
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• pp.125-132
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• 2012

In this study a group of experts and clinical radiological technologists were surveyed to evaluate the clinical importance of current subjects in the radiological sciences. For the data collection and analysis, an open-ended questionnaire was distributed to the group of experts, and a multiple choice questionnaire was distributed to radiological technologists. Subjects were classified into 9 groups for analysis of the importance of subjects, and in regard to the questionnaire design for measurement of variables, departments and type of hospital were set up as independent variables, and the 9 groups of subjects were set up as dependent variables. As a result, clinical radiological technologists perceived Diagnostic Imaging Technology and practical courses, including general radiography, CT and MRI, as the most clinically necessary subjects, and the group of experts placed most weight on basic courses for the major. The result of this study suggests that the curriculum should be revised in a way that combines theory and practice in order to foster radiological technologists capable of adapting to the rapidly changing healthcare environment.

• Journal of the Korean Society of Earth Science Education
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• v.14 no.2
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• pp.80-94
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• 2021

In this study, teaching-learning activities were developed based on computational thinking (CT) in high school Earth Science I Solid Earth domain. And their effects and implications were examined. To this end, 8 sessions unplugged activities based on problem solving were developed, and applied it to 65 high school students. As a results, significant changes have been were confirmed in both student's perception about CT and CT. After that, based on student's responses to self-reports and interview, the affecting factors for perception about CT and CT in the earth science problem solving process were investigated. In addition, implication that should be considered in terms of design and progress of teaching-learning based on CT were derived. Based on these results, the necessity and operation of teaching-learning activities was suggested for developing CT through various subjects including earth science.

• Journal of the Korean Geotechnical Society
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• v.32 no.1
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• pp.55-62
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• 2016

This study presents the numerical results of soil-water characteristic curve for sandy soil by pore network model. The Jumunjin sand is subjected to the high resolution 3D X-ray computed tomographic imaging and its pore structure is constructed by the web of pore body and pore channel. The channel radius, essential to the computation of capillary pressure, is obtained based on the skeletonization and Euclidean Distance transform. The experimentally obtained soil-water characteristic curve corroborates the numerically estimated one. The pore channel radius defined by minimum radii of pore throat results in the slightly overestimation of air entry value, while the overall evolution of capillary pressure resides in the acceptable range. The relative permeability computed by a series of suggested models runs above that obtained by pore network model at high degree of saturation.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.2
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• pp.85-95
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• 2010

Purpose: The degradation of an image quality and error of the beam dose calculation can be caused because the metal artifact is generated during the CT simulation of head and neck patient. The usability of the gantry tilt scan for reducing the metal artifact tries to be appraised. Materials and Methods: The inferior $20^{\circ}$ gantry tilt scan was made in order to reduce the metal artifact and $0^{\circ}$ reconstruction image was acquired. The AAPM CT performance Phantom was used in order to compare the CT number of the reconstructed image and Original image. the difference of volume was compared by using the acrylic phantom. The homogeneity of the CT number was evaluated the Intensity volume Histogram (IVH) as in order to evaluate an influence by the metal artifact. A dose was evaluated as the Dose Volume Histogram (DVH). Results: in the comparison of the CT number and volume, the difference showed up less than 0.5%. As to the comparison of IVH, in the gantry tilt scan, influence by an artifact was reduced and the homogeneity of the CT number was improved. The comparison of DVH result reduced the mean dose error of the both sides parotid 0.2~6%. Conclusion: In the Head & Neck radiation therapy, It is difficult and to distinguish tumor and normal tissue and the error of dose is generated by the metal artifact. The delineation of the exact organization was possible if the Gantry tilt scan was used. The CT number homogeneity was improved and the error of dose could be reduced. The Gantry tilt scan confirmed in the Head & Neck radiation therapy to be very useful in the exact radiation therapy.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.2
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• pp.131-137
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• 2016

Purpose : The bladder volume change was measured using ultrasonography for helping decrease the side effects and other organ variations in the location of radiation therapy for cervical cancer patients. An experiment was performed targeting patients who were treated with radiation therapy at PNUH within the period from September to December 2015. Materials and Methods : To maintain the bladder volume, each patient was instructed to drink 500 cc water before and after CT simulation, 60 minutes before the dry run. Also, the bladder volume was measured in each patient CT scan, and a 3D conformal therapy plan was designed. The bladder volumes measured before and after the CT simulation, dry run, and radiation treatment planning were compared and analyzed. Results : The average volume and average error of the bladder that were obtained from the measurement based on the CT scan images had the lowest standard deviation in the CT simulation. This means that the values that were obtained before and after the CT simulation were statistically relevant and correlative. Moreover, the bladder volume measured via ultrasonography was larger size, the average volume in the CT scan. But the values that were obtained Dry run and after the CT simulation were not statistically relevant. Conclusion : Drinking a certain amount of water helps a patient maintain his/her bladder volume for a dry run. Even then, it is difficult to maintain the bladder volume for the dry run. Also, whether or not the patients followed the directions for the dry run correctly is important.

• Journal of Veterinary Clinics
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• v.25 no.2
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• pp.96-101
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• 2008

This study was performed to quantify the pleural effusion in radiography, ultrasonography and computed tomography(CT) and to evaluate and compare the usefulness of these methods. Normal saline of 10 ml/kg was infused into the pleural space until a final loading volume of 60 ml/kg body weight was reached in six Beagle dogs. The radiographic examination was performed for the detection and quantification of pleural effusion. On the ultrasonographic study, the maximum perpendicular distance was measured between the surface of the lung and the thoracic wall to evaluate pleural effusion. On the CT image, pleural effusion was evaluated as the perpendicular distance to the thoracic surface in the maximum pleural effusion volume on any transverse images with soft tissue window. Statistical analysis was performed using linear regression test. The volume of pleural effusion and measurements of radiography and ultrasonography had no statistical relationship. However, a significant correlation was identified between the volume of pleural effusion and the depth at right ($r^2=0.715$), left ($r^2=0.745$), and mean right and left depth ($r^2=0.844$) on the CT images. All of the thoracic radiographs, ultrasonography, and CT are useful in recognition of pleural effusion. In quantification of pleural effusion, the CT measurement method is superior to radiographic and ultrasonographic measurements.

• Clinical and Experimental Pediatrics
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• v.46 no.7
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• pp.679-686
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• 2003

Purpose : Ataxia telangiectasia mutated(ATM) is involved in DNA damage responses at different cell cycle checkpoints, and signalling pathways associated with regulation of apoptosis in response to ionizing radiation(IR). However, the signaling pathway that underlies IR-induced apoptosis in ATM cells has remained unknown. The purpose of this study was, therefore, to investigate the apoptotic pathway that underlies IR-induced apoptosis in a CT-26 cells expressing dominant negative ATM (DN-ATM). Methods : We generated a replication-deficient recombinant adenovirus encoding the DN-ATM(Ad/DN-ATM) or control adenovirus encoding no transgene(Ad/GFP) and infected adenovirus to CT-26 cells. After infection, we examined apoptosis and apoptotic pathway by [$^3H$]-thymidine assay, DNA fragmentation, and Western immunoblot analysis. Results : DN-ATM gene served as the creation of AT phenotype in a CT-26 cells as revealed by decreased cell proliferations following IR. In addition, IR-induced apoptosis was regulated through the reduced levels of the anti-apoptotic protein Bcl-2, the increased levels of the apoptotic protein Bax, and the activation of caspase-9, caspase-3, and PARP. Conclusion : These results indicate that the pathway of IR-induced apoptosis in CT-26 cells expressing DN-ATM is mediated by mitochondrial signaling pathway involving the activation of caspase 9, caspase 3, and PARP.

• Journal of Veterinary Clinics
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• v.27 no.1
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• pp.42-45
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• 2010

Inflammatory sinonasal disease was diagnosed in five dogs and two cats with clinical signs of nasal discharge and epistaxis. Survey radiography and CT were performed in all of patients. CT scan of the rostral cranium was performed with a thickness of 2 or 5 mm. Nasal cytology and culture from nasal smear were performed immediately after CT examination. Remarkable increase of opacity in the nasal cavities and frontal sinuses was observed in only 3 cases. On CT images, the cavitating lesions were isodense in nasal cavity (7 cases), frontal sinuses (3 cases), and nasopharynx (2 cases) with destruction of the nasal septum (4 cases), maxillary turbinates (5 cases), maxilla (3 cases), and hard palate (3 cases). The lesions were enhanced after intravenous contrast administration in 5 cases and were not enhanced in 2 cases. Inflammatory cells were observed in nasal cytology. Most of the cultures from nasal smear were bacteria. CT is useful to diagnose sinonasal disease and is more accurate in demonstrating the extent and character of lesions of nasal cavity than radiography.