• Tuberculosis and Respiratory Diseases
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• v.79 no.2
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• pp.91-97
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• 2016

Background: Chronic obstructive pulmonary disease (COPD) is sometimes complicated with pneumonia, but little is known about the risk factors that promote the development of pneumonia in COPD. These risk factors were evaluated in the present study. Methods: The data of 324 patients with COPD from a prospective multi-center observational cohort with obstructive lung disease were evaluated retrospectively. To identify risk factors for the development of pneumonia in COPD, the clinical and radiological data at enrollment and the time to the first episode of pneumonia were analyzed by Cox proportional hazard analysis. Results: The median follow-up time was 1,099 days and 28 patients (8.6%) developed pneumonia. The Cox analysis showed that post-bronchodilator forced expiratory volume in one second ($FEV_1$, % of predicted) and the computed tomography (CT) emphysema extent (inspiratory V950) were independent risk factors for the development of pneumonia (post-bronchodilator $FEV_1$: hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.94-1.00; p=0.048 and inspiratory V950: HR, 1.04; 95% CI, 1.01-1.07; p=0.01). Conclusion: Emphysema severity measured by CT and post-bronchodilator $FEV_1$ are important risk factors for the development of pneumonia in COPD.

• Journal of the Korea Safety Management & Science
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• v.12 no.4
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• pp.67-72
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• 2010

This study was done to provide basic data on the safety of professionals in medical imaging system by measuring the electromagnetic waves generated in the medical imaging system being used in medical organization. The studied medical imaging systems were general X-ray system, computed tomography(CT), ultrasonographic(USG) system, magnetic resonance imaging(MRI), PET-CT and fluoroscopic(R/F) system, and through these devices, electric field and magnetic field were measured and analyzed. As a result of the analysis, the measured values classified by the medical organizations were not much significant, but in the measurement by the medical imaging systems, there were high hazard elements in the sequential order of electric field PET-CT($17.7{\pm}22.9$)v/m, CT($10.3{\pm}8.7$)v/m, general X-ray system($8.8{\pm}8.8$)v/m, magnetic field general X-ray system($5.06{\pm}8.26$)mG, CT($2.71{\pm}4.53$)mG and PET-CT($0.74{\pm}0.34$)mG, the systems that adopted X-ray as main ray source, and the more aged the medical imaging systems, the greater the effects of electro-magnetic waves($10.6{\pm}15.93v/m$ for 5 years or more, $6.14{\pm}5.60v/m$ for 5 years or less). The effects of electromagnetic waves on medical imaging systems or facilities were not much when the notification of ministry of knowledge economy is considered, but in the overall perspective considering all the equipments and facility of the medical organization, such effects were significant. It is determined that sustainable safety managements of electric field and magnetic field must be done during process from medical imaging system installation to maintenance to rule out such factors.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2447-2453
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• 2023

The radioactivity concentrations of Naturally Occurring Radioactive Materials (NORM) i.e., ²²⁶Ra, ²³²Th, and ⁴K in various chemical fertilizers being used in the agricultural soil of Pakistan were determined utilizing gamma spectrometry by employing a High Purity Germanium (HPGe) detector. The radioactivity concentrations of ²²⁶Ra, ²³²Th, and ⁴K extended from 2.58 ± 0.8-265.7 ± 8.8 Bq kg^-1, 1.53 ± 0.14-76.6 ± 1.07 Bq kg^-1 and 36.5 ± 1.34-15606.7 ± 30.2 Bq kg^-1 respectively. The radiological hazard parameters such as internal and external indices and annual effective dose rates were calculated, while excessive lifetime cancer risk factors for the indoor and outdoor areas were found in the range from 0.3×10^-3 to 10.723×10^-3 and 0.03×10^-3 to 2.7948×10^-3 of most fertilizers, however, some values were slightly higher than the UNSCEAR (The United Nations Scientific Committee on the Effects of Atomic Radiation) recommended values for potash-containing fertilizers such as MOP (Muriate of Potash).

• Korean Journal of Radiology
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• v.21 no.8
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• pp.1007-1017
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• 2020

Objective: The purpose of our study was to investigate the predictive abilities of clinical and computed tomography (CT) features for outcome prediction in patients with coronavirus disease (COVID-19). Materials and Methods: The clinical and CT data of 238 patients with laboratory-confirmed COVID-19 in our two hospitals were retrospectively analyzed. One hundred sixty-six patients (103 males; age 43.8 ± 12.3 years) were allocated in the training cohort and 72 patients (38 males; age 45.1 ± 15.8 years) from another independent hospital were assigned in the validation cohort. The primary composite endpoint was admission to an intensive care unit, use of mechanical ventilation, or death. Univariate and multivariate Cox proportional hazard analyses were performed to identify independent predictors. A nomogram was constructed based on the combination of clinical and CT features, and its prognostic performance was externally tested in the validation group. The predictive value of the combined model was compared with models built on the clinical and radiological attributes alone. Results: Overall, 35 infected patients (21.1%) in the training cohort and 10 patients (13.9%) in the validation cohort experienced adverse outcomes. Underlying comorbidity (hazard ratio [HR], 3.35; 95% confidence interval [CI], 1.67-6.71; p < 0.001), lymphocyte count (HR, 0.12; 95% CI, 0.04-0.38; p < 0.001) and crazy-paving sign (HR, 2.15; 95% CI, 1.03-4.48; p = 0.042) were the independent factors. The nomogram displayed a concordance index (C-index) of 0.82 (95% CI, 0.76-0.88), and its prognostic value was confirmed in the validation cohort with a C-index of 0.89 (95% CI, 0.82-0.96). The combined model provided the best performance over the clinical or radiological model (p < 0.050). Conclusion: Underlying comorbidity, lymphocyte count and crazy-paving sign were independent predictors of adverse outcomes. The prognostic nomogram based on the combination of clinical and CT features could be a useful tool for predicting adverse outcomes of patients with COVID-19.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.184-190
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• 2014

Decommissioning process of nuclear facilities consist of a sequence of problem solving activities, because there may exist not only working environments contaminated by radiological exposure but also industrial hazards such as fire, explosions, toxic materials, and electrical and physical hazards. Therefore, not a few countries in the world have been trying to develop appropriate counter techniques in order to guarantee safety and efficiency of the process. In spite of that, there still exists neither domestic nor international standard. Unfortunately, however, there are few workers who experienced decommissioning operations a lot in the past. As a solution, it is quite necessary to utilize experts' opinions for risk assessment in decommissioning process. As for an individual hazard factor, risk assessment techniques are getting known to industrial workers with advance of safety technology, but the way how to integrate those results is not yet. This paper aimed to find out an appropriate technique to integrate individual risk assessment results from the viewpoint of experts. Thus, on one hand the whole risk assessment activity for decommissioning operations was modeled as a sequence of individual risk assessment steps which can be classified into two activities, decontamination and dismantling, and on the other, a risk assessment structure was introduced. The whole model was inferred with Fuzzy theory and techniques, and a numerical example was appended for comprehension.

• Journal of Korean Neurosurgical Society
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• v.65 no.4
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• pp.558-571
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• 2022

Objective : The primary objective of this study was to identify predicting factors for local control (LC) of atypical meningioma, and we validated them with comparing the predicting factors for recurrence-free survival (RFS). We also examined the rate of LC after surgical resection with or without adjuvant treatment and RFS. Methods : Clinical and radiological records of patients with atypical meningiomas diagnosed at two institutes from January 2000 to December 2018 were reviewed retrospectively. Histopathological features were also reviewed using formalin-fixed paraffin embedded samples from pathological archives. Results : Of the 99 atypical meningiomas eligible for analysis, 36 (36.4%) recurred during the follow-up period (mean, 83.3 months; range, 12-232 months). The rate of 3-year LC and 5-year LC was 80.8% and 74.7%, respectively. The mean time-to-recurrence was 49.4 months (range, 12-150). The mean RFS was 149.3 months (95% confidence interval, 128.8-169.8 months) during the mean follow-up duration of 83.3 months (range, 12-232 months). Multivariate analysis using Cox proportional-hazard regression model showed that the extent of resection (hazard ratio [HR], 4.761; p=0.013), Ki67 index (HR, 8.541; p=0.004), mitotic index (HR, 3.275; p=0.044), and tumor size (HR, 3.228; p=0.041) were independently associated with LC. These factors were also statistically associated with RFS. In terms of radiotherapy after surgical resection, the recurrence was not prevented by immediate radiotherapy because of the strong effect of proliferative index on recurrence. Conclusion : The present study suggests that the extent of resection, proliferative index (according to Ki67 expression) and mitotic index, and tumor size are associated with recurrence of atypical meningiomas. However, our results should be further validated through prospective and randomized clinical trials to overcome the inborn bias of retrospective nature of the study design.

• Imaging Science in Dentistry
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• v.43 no.3
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• pp.179-184
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• 2013

Purpose: X-ray exposure should be clinically justified and each exposure should be expected to give patients benefits. Since dental radiographic examination is one of the most frequent radiological procedures, radiation hazard becomes an important public health concern. The purpose of this study was to investigate the attitude of Korean dentists about radiation safety and use of criteria for selecting the frequency and type of radiographic examinations. Materials and Methods: The study included 267 Korean dentists. Five questions related to radiation safety were asked of each of them. These questions were about factors associated with radiation protection of patients and operators including the use of radiographic selection criteria for intraoral radiographic procedures. Results: The frequency of prescription of routine radiographic examination (an example is a panoramic radiograph for screening process for occult disease) was 34.1%, while that of selective radiography was 64.0%. Dentists' discussion of radiation risk and benefit with patients was infrequent. More than half of the operators held the image receptor by themselves during intraoral radiographic examinations. Lead apron/thyroid collars for patient protection were used by fewer than 22% of dental offices. Rectangular collimation was utilized by fewer than 15% of dental offices. Conclusion: The majority of Korean dentists in the study did not practice radiation protection procedures which would be required to minimize exposure to unnecessary radiation for patients and dental professionals. Mandatory continuing professional education in radiation safety and development of Korean radiographic selection criteria is recommended.

• Journal of Korean Neurosurgical Society
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• v.61 no.1
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• pp.19-27
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• 2018

Objective : The objectives of this study were to evaluate the immediate and long-term efficacy and safety of coil embolization for large or giant aneurysms. Methods : One hundred and fifty large or giant aneurysm cases treated with endovascular coil embolization between January 2005 and February 2014 at a single institute were included in this study. Medical records and imaging findings were reviewed. Statistical analysis was performed to evaluate prognostic factors associated with major recurrence (major recanalization or rupture) and delayed thromboembolism after selective coil embolization. Results : Procedure-related symptomatic complications occurred in five (3.3%) patients. The mean clinical and radiological follow-up periods were 38 months (range, 2-110) and 26 months (range, 6-108), respectively. During the follow-up period, the estimated recurrence rate was 4.6% per year. Multivariate analysis using Cox regression showed the degree of occlusion to be the only factor associated with recurrence (p=0.008, hazard ratio 3.15, 95% confidence interval 1.34-7.41). The patient's history of rupture in addition to the size and location of the aneurysm were not associated with recurrence in this study. Delayed infarction occurred in eight cases, and all were incompletely occluded. Conclusion : Although immediate postprocedural safety profiles were reasonable, longterm results showed recanalization and thromboembolic events to occur continuously, especially in patients with incomplete occlusion. In addition, incomplete occlusion was associated with delayed thromboembolic complications. Patients with incomplete occlusions should be followed carefully for delayed recurrence or delayed thromboembolic events.

• Journal of Gastric Cancer
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• v.4 no.3
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• pp.164-168
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• 2004

Purpose: The most feared complication of gastrointestinal tract operations is anastomotic leakage, not only because of the presumed individual surgeon's culpability but also because of the assumption that this event is often fatal. We have experienced 32 cases of anastomotic leakage after elective gastric resection during 8 years. The purpose of this study was to evaluate the result of their treatment. Materials and Methods: We evaluated the records of 1335 patients who had undergone elective gastric resection for an adenocarcinoma of stomach from January 1995 to October 2003 and conducted a retrospective, multivariate analysis. Results: Of the 1335 patients, 32 ($2.4\%$) sustained an anastomotic leakage. Anastomotic leakages usually developed on mean postoperative day $9.1\pm3.2$ (range:$1\∼18$ days).Overall, $31.3\%$ (10/32) of patients who sustained an anastomotic leakage died. The anastomotic leakages were identifed by radiological study or by operative finding at the site of the duodenal stump (20 patients), the esophagojejunostomy (7), the gastroduodenostomy (4), and the gastrojejunostomy (1). Fourteen patients ($43.8\%$) underwent a relaparotomy, a drainage procedure in the main, and 18 patients ($56.3\%$) were treated conservatively. The mortality rates were $42.9\%$ (6/14) and $22.2\%$ (4/18), respectively, but this difference was not statistically significant. A cox's proportional hazard analysis showed that a body-mass Index < 24 kg/m2 (odds ratio 5.55, $95\%$ CI: $0.69\∼44.82$) and non-enteral feeding (odds ratio 18.27, $95\%$ CI 2.22.150.69) were independent factors of mortality due to anastomotic leakage. Conclusion: Our observations show that anastomotic leakage after an elective gastric resection has a high risk of being fatal. Moreover, for a patient with a body-mass index lower than $24\;kg/m^{2}$ and/or non-enteral feeding, an anastomotic leakage after an elective gastric resection has a higher risk of being fatal.

• Journal of the Korean Society of Radiology
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• v.18 no.6
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• pp.613-620
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• 2024

This study aims to measure the level of indoor radon concentration in classrooms where college students take lectures and participate in activities, and use it as basic data for indoor radon management measures in school classrooms. To measure radon concentration, the study was conducted in a classroom at a university located in Gyeonggi-do, depending on the university classroom operating environment. Radon was measured using the RadoMon Kit (Betterlife Co., Ltd., Suwon, Korea). To measure radon concentration, the effective dose model presented in the United Nations Scientific Committee on the Effects of Radiation Effects Report 2000 (UNSCEAR (2000) was used. The effective dose was evaluated by applying a total of 1,200 hours of annual living time indoors in the classroom. The radon concentration in the classroom and laboratory was measured, the annual effective dose was evaluated, and the effective dose was converted by entering the radon concentration and factors using the personal radon dosimetry program provided by WISE. The radon concentration using the charcoal canister was 80.29 Bq/m³ in the classroom, and 90.28 Bq/m³ in the laboratory, indicating a high radon concentration in the laboratory. The annual effective dose and cumulative dose of radon concentration were measured at 1.21 mSv in the classroom and 1.36 mSv in the laboratory, and the dose rate was 1.008 µSv/h in the classroom and 1.134 µSv/h in the laboratory. The indoor radon concentration was measured at a level lower than the indoor radon concentration management standard, but from the viewpoint of optimization of protection, efforts should be made to keep the radon concentration as low as reasonably achievable and reduce the degree of health hazard, and continuous management is necessary.