• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.929-937
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• 2023

Human equivalent phantoms manufactured using 3D printers are cheaper and can be manufactured in a short time than conventional human phantoms. However, many phantoms are manufactured with less than 100 % of Infill Density, one of the 3D printer output setting variables. Therefore, this study compared the Bone Phantom CT number, which differs from the ratio of five Infill Density produced using a 3D printer, to the CT number of the actual human body Bone. In addition, the usefulness of the manufactured phantom was evaluated by producing a 100 % elbow joint phantom with Infill Density and setting the Infill Density to 100 % through CT number comparison for each tissue on computed tomography (CT). As a result, the Bone Phantom printed with 100 % Infill Density did not show the most statistically significant difference from the CT number value of the actual human Bone, and the CT number of each tissue did not show a statistically significant difference from the CT number value of each tissue of the actual human elbow joint.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.869-875
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• 2021

The purpose of this study is to derive a formula for calculating the effective energy of an X-ray beam generated by a CT simulator. Under 90, 120, and 140 kVp X-ray beams, the CT number calibration insert part of the AAPM CT performance phantom was scanned 5 times with a CT simulator. The CT numbers of polyethylene, polystyrene, water, nylon, polycarbonate, and acrylic were measured for each CT slice image. The average value of CT number measured under a single tube voltage and the linear attenuation coefficients corresponding to each photon energy calculated from the data of the National Institute of Standards and Technology were linearly fitted. Among the obtained correlation coefficients, the photon energy having the maximum value was determined as the effective energy. In this way, the effective energy of the X-ray beam generated at each tube voltage was determined. By linearly fitting the determined effective energies(y) and tube voltages(x), y=0.33026x+30.80263 as an effective energy calculation formula was induced.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.619-625
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• 2022

In the field of imaging medicine, computed tomography is one of the most common test methods and one of the most frequently used test methods in hospitals. However, it is accompanied by a very high radiation exposure compared to other test methods. In order to reduce exposure, CT scans should be performed only when absolutely necessary, and even if the tests are performed because they are absolutely necessary, a protocol that serves the purpose of the test and allows the test to be performed in a small dose should be used. In this study, we wanted to learn about the most up-to-date radiation dose usage information used by the region's leading general hospitals and develop a diagnostic reference level (DRL). In the experimental results, the Head CT and Abdomen CT tests showed that DLP was higher than the NRPB (U.K) and Korean DRL. The DLP values used by Chest CT were low for all 3 types of CT devices. The hospital found that efforts to reduce exposure should be made during CT examinations, and in particular, Head CT and Abdomen CT determined that efforts to reduce exposure were necessary.

• Journal of radiological science and technology
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• v.20 no.1
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• pp.15-20
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• 1997

Unlike conventional CT scan, the helical CT scan uses continuous rotating CT equipment with a slip ring to move the patient's coach at a constant speed while continuously scanning. Slice sensitivity profiles in the Z-position(SSPz) using the conventional X-ray CT have a shape similiar to a rectangular wave, which slightly spreads out into plains below the mountain. However, in the helical CT, with an expansion of the base, the rectangular shape collapses and a mouatain-like shape can be seen. We need to investigate the fellowing factors in helical CT scanning;the ability to scan along the axis of the body, effective slice width, slice shape and the precision of coach velocity, Helical scanning with sprial X-ray track is different from the conventional scanning in terms of the principle of image reconstruction performed. We believe that the problems in helical scanning can be solved by understanding new the special parameters such as the bed moving speed and the interval of image reconstruction.

• Tuberculosis and Respiratory Diseases
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• v.65 no.4
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• pp.339-342
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• 2008

Early CT findings of transient radiographic progression (TRP) during treatment of active pulmonary tuberculosis including subpleural, interlobular or intralobular septal thickening and micronodules are shown in the present case. Late CT findings of TRP are subpleural, enhancing nodular infiltration with internal low attenuation. These CT features accompanied by a lack of clinical worsening in young patients taking antituberculous medication due to pulmonary tuberculosis can help to differentiate TRP from other disease entities.

• Journal of radiological science and technology
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• v.6 no.1
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• pp.3-19
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• 1983

• 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.

• Radiation Oncology Journal
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• v.4 no.2
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• pp.179-181
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• 1986

Computed tomography (CT) adds a new dimension in the study of body contour, organs, and tissues as well as various pathologic conditions. This modality provides a great degree of accuracy in radiation therapy Planning (RTP). However, CT images are usually taken on a small reduced format so that possible errors can be made during inputting the CT data into an automatic planner. Authors have designed a simple inexpensive magnifying device of CT images to obviate errors created by reduced image.

• Journal of the Korean Society of Radiology
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• v.15 no.3
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• pp.293-299
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• 2021

In order to reduce the irresistible radiation exposure of patients who perform periodic examinations using a CT among various scan parameters a method to reduce patient dose was investigated through changes in the tube voltage close to X-ray penetrating power. As a result of the experiment 100 kVp was applied instead of 120 kVp which is commonly used in clinical practice and CTDI decreased by about 41% during scan. In addition the degree of change in image quality was measured as 1046.1±3.7 HU for CT value and 71.4±7.9 for Pixel value and statistical analysis showed no significant difference (0.05

• Journal of radiological science and technology
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• v.35 no.1
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• pp.35-44
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• 2012

The goal of this study is to awaken about risk occurred by CT examination. For radio-technologists working at 'S medical center' located in Seoul, we investigated a recognition about dose and risk CT and normal X-ray examination according by working experience in hospital, experience about CT examination and radiation source. For subjects of investigation, radio-technologists working at 'S medical center' located in Seoul helped us. We collected 131 questionnaires for a test of hypothesis. Cronbach @ coefficients of questionnaires were 0.825988 and 0.767161 and a rejection rate of p-value was below 0.05. SAS 9.1(SAS Institute Inc., Cary, NC, USA.) statistic package was used for hypothesis test. We used Mann-Whitney test, Kruskai-Wallis test, Two sample T-test, Two sample T-test with Bonferroni's Correction and One-way ANOVA methods. P-values of hypothesis about dose of CT and normal X-ray examination were 0.2291 ~ 0.9663. p-values of hypothesis about risk were 0.1924 ~ 1.0000. All of hypothesis is over rejection rate(<0.05). This study shows that radio-technologists of S medical center recognized that CT has higher dose and risk than general X-ray examination.