1.Establishment of Local Diagnostic Reference Levels for Pediatric Neck CT at Nine University Hospitals in South Korea
Jisun HWANG ; Hee Mang YOON ; Jae-Yeon HWANG ; Young Hun CHOI ; Yun Young LEE ; So Mi LEE ; Young Jin RYU ; Sun Kyoung YOU ; Ji Eun PARK ; Seok Kee LEE
Korean Journal of Radiology 2025;26(1):65-74
		                        		
		                        			 Objective:
		                        			To establish local diagnostic reference levels (DRLs) for pediatric neck CT based on age, weight, and water-equivalent diameter (WED) across multiple university hospitals in South Korea. 
		                        		
		                        			Materials and Methods:
		                        			This retrospective study analyzed pediatric neck CT examinations from nine university hospitals, involving patients aged 0–18 years. Data were categorized by age, weight, and WED, and radiation dose metrics, including volume CT dose index (CTDIvol) and dose length product, were recorded. Data retrieval and analysis were conducted using a commercially available dose-management system (Radimetrics, Bayer Healthcare). Local DRLs were established following the International Commission on Radiological Protection guidelines, using the 75th percentile as the reference value. 
		                        		
		                        			Results:
		                        			A total of 1159 CT examinations were analyzed, including 169 scans from Institution 1, 132 from Institution 2, 126 from Institution 3, 129 from Institution 4, 128 from Institution 5, 105 from Institution 6, 162 from Institution 7, 127 from Institution 8, and 81 from Institution 9. Radiation dose metrics increased with age, weight, and WED, showing significant variability both within and across institutions. For patients weighing less than 10 kg, the DRL for CTDIvol was 5.2 mGy. In the 10–19 kg group, the DRL was 5.8 mGy; in the 20–39 kg group, 7.6 mGy; in the 40–59 kg group, 11.0 mGy; and for patients weighing 60 kg or more, 16.2 mGy. DRLs for CTDIvol by age groups were as follows: 5.3 mGy for infants under 1 year, 5.7 mGy for children aged 1–4 years, 7.6 mGy for ages 5–9 years, 11.2 mGy for ages 10–14 years, and 15.6 mGy for patients 15 years or older. 
		                        		
		                        			Conclusion
		                        			Local DRLs for pediatric neck CT were established based on age, weight, and WED across nine university hospitals in South Korea. 
		                        		
		                        		
		                        		
		                        	
2.Establishment of Local Diagnostic Reference Levels for Pediatric Neck CT at Nine University Hospitals in South Korea
Jisun HWANG ; Hee Mang YOON ; Jae-Yeon HWANG ; Young Hun CHOI ; Yun Young LEE ; So Mi LEE ; Young Jin RYU ; Sun Kyoung YOU ; Ji Eun PARK ; Seok Kee LEE
Korean Journal of Radiology 2025;26(1):65-74
		                        		
		                        			 Objective:
		                        			To establish local diagnostic reference levels (DRLs) for pediatric neck CT based on age, weight, and water-equivalent diameter (WED) across multiple university hospitals in South Korea. 
		                        		
		                        			Materials and Methods:
		                        			This retrospective study analyzed pediatric neck CT examinations from nine university hospitals, involving patients aged 0–18 years. Data were categorized by age, weight, and WED, and radiation dose metrics, including volume CT dose index (CTDIvol) and dose length product, were recorded. Data retrieval and analysis were conducted using a commercially available dose-management system (Radimetrics, Bayer Healthcare). Local DRLs were established following the International Commission on Radiological Protection guidelines, using the 75th percentile as the reference value. 
		                        		
		                        			Results:
		                        			A total of 1159 CT examinations were analyzed, including 169 scans from Institution 1, 132 from Institution 2, 126 from Institution 3, 129 from Institution 4, 128 from Institution 5, 105 from Institution 6, 162 from Institution 7, 127 from Institution 8, and 81 from Institution 9. Radiation dose metrics increased with age, weight, and WED, showing significant variability both within and across institutions. For patients weighing less than 10 kg, the DRL for CTDIvol was 5.2 mGy. In the 10–19 kg group, the DRL was 5.8 mGy; in the 20–39 kg group, 7.6 mGy; in the 40–59 kg group, 11.0 mGy; and for patients weighing 60 kg or more, 16.2 mGy. DRLs for CTDIvol by age groups were as follows: 5.3 mGy for infants under 1 year, 5.7 mGy for children aged 1–4 years, 7.6 mGy for ages 5–9 years, 11.2 mGy for ages 10–14 years, and 15.6 mGy for patients 15 years or older. 
		                        		
		                        			Conclusion
		                        			Local DRLs for pediatric neck CT were established based on age, weight, and WED across nine university hospitals in South Korea. 
		                        		
		                        		
		                        		
		                        	
3.Establishment of Local Diagnostic Reference Levels for Pediatric Neck CT at Nine University Hospitals in South Korea
Jisun HWANG ; Hee Mang YOON ; Jae-Yeon HWANG ; Young Hun CHOI ; Yun Young LEE ; So Mi LEE ; Young Jin RYU ; Sun Kyoung YOU ; Ji Eun PARK ; Seok Kee LEE
Korean Journal of Radiology 2025;26(1):65-74
		                        		
		                        			 Objective:
		                        			To establish local diagnostic reference levels (DRLs) for pediatric neck CT based on age, weight, and water-equivalent diameter (WED) across multiple university hospitals in South Korea. 
		                        		
		                        			Materials and Methods:
		                        			This retrospective study analyzed pediatric neck CT examinations from nine university hospitals, involving patients aged 0–18 years. Data were categorized by age, weight, and WED, and radiation dose metrics, including volume CT dose index (CTDIvol) and dose length product, were recorded. Data retrieval and analysis were conducted using a commercially available dose-management system (Radimetrics, Bayer Healthcare). Local DRLs were established following the International Commission on Radiological Protection guidelines, using the 75th percentile as the reference value. 
		                        		
		                        			Results:
		                        			A total of 1159 CT examinations were analyzed, including 169 scans from Institution 1, 132 from Institution 2, 126 from Institution 3, 129 from Institution 4, 128 from Institution 5, 105 from Institution 6, 162 from Institution 7, 127 from Institution 8, and 81 from Institution 9. Radiation dose metrics increased with age, weight, and WED, showing significant variability both within and across institutions. For patients weighing less than 10 kg, the DRL for CTDIvol was 5.2 mGy. In the 10–19 kg group, the DRL was 5.8 mGy; in the 20–39 kg group, 7.6 mGy; in the 40–59 kg group, 11.0 mGy; and for patients weighing 60 kg or more, 16.2 mGy. DRLs for CTDIvol by age groups were as follows: 5.3 mGy for infants under 1 year, 5.7 mGy for children aged 1–4 years, 7.6 mGy for ages 5–9 years, 11.2 mGy for ages 10–14 years, and 15.6 mGy for patients 15 years or older. 
		                        		
		                        			Conclusion
		                        			Local DRLs for pediatric neck CT were established based on age, weight, and WED across nine university hospitals in South Korea. 
		                        		
		                        		
		                        		
		                        	
4.Establishment of Local Diagnostic Reference Levels for Pediatric Neck CT at Nine University Hospitals in South Korea
Jisun HWANG ; Hee Mang YOON ; Jae-Yeon HWANG ; Young Hun CHOI ; Yun Young LEE ; So Mi LEE ; Young Jin RYU ; Sun Kyoung YOU ; Ji Eun PARK ; Seok Kee LEE
Korean Journal of Radiology 2025;26(1):65-74
		                        		
		                        			 Objective:
		                        			To establish local diagnostic reference levels (DRLs) for pediatric neck CT based on age, weight, and water-equivalent diameter (WED) across multiple university hospitals in South Korea. 
		                        		
		                        			Materials and Methods:
		                        			This retrospective study analyzed pediatric neck CT examinations from nine university hospitals, involving patients aged 0–18 years. Data were categorized by age, weight, and WED, and radiation dose metrics, including volume CT dose index (CTDIvol) and dose length product, were recorded. Data retrieval and analysis were conducted using a commercially available dose-management system (Radimetrics, Bayer Healthcare). Local DRLs were established following the International Commission on Radiological Protection guidelines, using the 75th percentile as the reference value. 
		                        		
		                        			Results:
		                        			A total of 1159 CT examinations were analyzed, including 169 scans from Institution 1, 132 from Institution 2, 126 from Institution 3, 129 from Institution 4, 128 from Institution 5, 105 from Institution 6, 162 from Institution 7, 127 from Institution 8, and 81 from Institution 9. Radiation dose metrics increased with age, weight, and WED, showing significant variability both within and across institutions. For patients weighing less than 10 kg, the DRL for CTDIvol was 5.2 mGy. In the 10–19 kg group, the DRL was 5.8 mGy; in the 20–39 kg group, 7.6 mGy; in the 40–59 kg group, 11.0 mGy; and for patients weighing 60 kg or more, 16.2 mGy. DRLs for CTDIvol by age groups were as follows: 5.3 mGy for infants under 1 year, 5.7 mGy for children aged 1–4 years, 7.6 mGy for ages 5–9 years, 11.2 mGy for ages 10–14 years, and 15.6 mGy for patients 15 years or older. 
		                        		
		                        			Conclusion
		                        			Local DRLs for pediatric neck CT were established based on age, weight, and WED across nine university hospitals in South Korea. 
		                        		
		                        		
		                        		
		                        	
5.Establishment of Local Diagnostic Reference Levels for Pediatric Neck CT at Nine University Hospitals in South Korea
Jisun HWANG ; Hee Mang YOON ; Jae-Yeon HWANG ; Young Hun CHOI ; Yun Young LEE ; So Mi LEE ; Young Jin RYU ; Sun Kyoung YOU ; Ji Eun PARK ; Seok Kee LEE
Korean Journal of Radiology 2025;26(1):65-74
		                        		
		                        			 Objective:
		                        			To establish local diagnostic reference levels (DRLs) for pediatric neck CT based on age, weight, and water-equivalent diameter (WED) across multiple university hospitals in South Korea. 
		                        		
		                        			Materials and Methods:
		                        			This retrospective study analyzed pediatric neck CT examinations from nine university hospitals, involving patients aged 0–18 years. Data were categorized by age, weight, and WED, and radiation dose metrics, including volume CT dose index (CTDIvol) and dose length product, were recorded. Data retrieval and analysis were conducted using a commercially available dose-management system (Radimetrics, Bayer Healthcare). Local DRLs were established following the International Commission on Radiological Protection guidelines, using the 75th percentile as the reference value. 
		                        		
		                        			Results:
		                        			A total of 1159 CT examinations were analyzed, including 169 scans from Institution 1, 132 from Institution 2, 126 from Institution 3, 129 from Institution 4, 128 from Institution 5, 105 from Institution 6, 162 from Institution 7, 127 from Institution 8, and 81 from Institution 9. Radiation dose metrics increased with age, weight, and WED, showing significant variability both within and across institutions. For patients weighing less than 10 kg, the DRL for CTDIvol was 5.2 mGy. In the 10–19 kg group, the DRL was 5.8 mGy; in the 20–39 kg group, 7.6 mGy; in the 40–59 kg group, 11.0 mGy; and for patients weighing 60 kg or more, 16.2 mGy. DRLs for CTDIvol by age groups were as follows: 5.3 mGy for infants under 1 year, 5.7 mGy for children aged 1–4 years, 7.6 mGy for ages 5–9 years, 11.2 mGy for ages 10–14 years, and 15.6 mGy for patients 15 years or older. 
		                        		
		                        			Conclusion
		                        			Local DRLs for pediatric neck CT were established based on age, weight, and WED across nine university hospitals in South Korea. 
		                        		
		                        		
		                        		
		                        	
6.Mortality Burden Due to Short-term Exposure to Fine Particulate Matter in Korea
Jongmin OH ; Youn-Hee LIM ; Changwoo HAN ; Dong-Wook LEE ; Jisun MYUNG ; Yun-Chul HONG ; Soontae KIM ; Hyun-Joo BAE
Journal of Preventive Medicine and Public Health 2024;57(2):185-196
		                        		
		                        			 Objectives:
		                        			Excess mortality associated with long-term exposure to fine particulate matter (PM2.5) has been documented. However, research on the disease burden following short-term exposure is scarce. We investigated the cause-specific mortality burden of short-term exposure to PM2.5 by considering the potential non-linear concentration–response relationship in Korea. 
		                        		
		                        			Methods:
		                        			Daily cause-specific mortality rates and PM2.5 exposure levels from 2010 to 2019 were collected for 8 Korean cities and 9 provinces. A generalized additive mixed model was employed to estimate the non-linear relationship between PM2.5 exposure and cause-specific mortality levels. We assumed no detrimental health effects of PM2.5 concentrations below 15 μg/m3. Overall deaths attributable to short-term PM2.5 exposure were estimated by summing the daily numbers of excess deaths associated with ambient PM2.5 exposure. 
		                        		
		                        			Results:
		                        			Of the 2 749 704 recorded deaths, 2 453 686 (89.2%) were non-accidental, 591 267 (21.5%) were cardiovascular, and 141 066 (5.1%) were respiratory in nature. A non-linear relationship was observed between all-cause mortality and exposure to PM2.5 at lag0, whereas linear associations were evident for cause-specific mortalities. Overall, 10 814 all-cause, 7855 non-accidental, 1642 cardiovascular, and 708 respiratory deaths were attributed to short-term exposure to PM2.5. The estimated number of all-cause excess deaths due to short-term PM2.5 exposure in 2019 was 1039 (95% confidence interval, 604 to 1472). 
		                        		
		                        			Conclusions
		                        			Our findings indicate an association between short-term PM2.5 exposure and various mortality rates (all-cause, non-accidental, cardiovascular, and respiratory) in Korea over the period from 2010 to 2019. Consequently, action plans should be developed to reduce deaths attributable to short-term exposure to PM2.5. 
		                        		
		                        		
		                        		
		                        	
7.Clinical Characteristics and Risk of Hypoxemia Development in Women Infected with SARS-CoV-2 during Pregnancy
Yujin SOHN ; Hee Kyoung CHOI ; Jisun YUN ; Eui Hyeok KIM ; Young Keun KIM
Yonsei Medical Journal 2024;65(1):27-33
		                        		
		                        			 Purpose:
		                        			There is limited information on the clinical characteristics and prognosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection during pregnancy. The clinical features and risk factors for hypoxemia development were investigated in pregnant women with coronavirus disease-2019 (COVID-19). 
		                        		
		                        			Materials and Methods:
		                        			From August 2020 to February 2022, we performed a retrospective cohort study of 410 pregnant women with COVID-19. The clinical characteristics and prognoses were compared between pregnant COVID-19 patients requiring oxygen and those who did not. 
		                        		
		                        			Results:
		                        			Of 410 patients, 100 (24.4%) required oxygen therapy. Among them, fever [163 (52.6%) vs. 81 (81.0%), p<0.001] and cough [172 (56.4%) vs. 73 (73.0%), p=0.003] were more frequently observed than in non-oxygen group. The proportion of unvaccinated women was higher in oxygen group than in non-oxygen group [264 (85.2%) vs. 98 (98.0%), p=0.003]. During the Omicron wave, patients were more likely to have no oxygen requirement [98 (31.6%) vs. 18 (18.0%), p=0.009]. The risk of hypoxemic respiratory difficulty increased if SARS-CoV-2 infection occurred during the third trimester [adjusted odds ratio (aOR) 5.083, 95% confidence interval (CI): 1.095–23.593, p=0.038] and C-reactive protein (CRP) was elevated (≥1.0 mg/dL) at admission (aOR 5.878, 95% CI:3.099–11.146, p<0.001). The risk was higher in unvaccinated patients (aOR 5.376, 95% CI: 1.193-24.390, p=0.028). However, the risk was lower in patients during the Omicron wave (aOR 0.498, 95% CI: 0.258–0.961, p=0.038). 
		                        		
		                        			Conclusion
		                        			A quarter of SARS-CoV-2-infected women developed hypoxemic respiratory difficulty during pregnancy. SARSCoV-2 infection during the third trimester, CRP elevation at admission, and no vaccination increased the risk of hypoxemia in pregnant women. 
		                        		
		                        		
		                        		
		                        	
8.Burnout among Nurses in COVID-19 Designated Units Compared with Those in General Units Caring for Both COVID-19 and Non-COVID-19 Patients
Kyung Ah WOO ; Eun Kyoung YUN ; JiSun CHOI ; Hye Min BYUN
Journal of Korean Academy of Nursing Administration 2023;29(4):374-384
		                        		
		                        			 Purpose:
		                        			This study aimed to examine the differences in COVID-19 work-related characteristics, workload, anxiety, stress, and burnout between nurses working in the COVID-19 designated units and those in the general units caring for both COVID-19 and non-COVID-19 patients and to identify factors related to burnout in these two nurse groups. 
		                        		
		                        			Methods:
		                        			The study was conducted using data from 192 nurses in the COVID-19 designated units and 340 nurses in the general units from two general hospitals. The data were collected using self-report, structured questionnaires.Independent t-test, chi-squared test, and logistic regression analysis were performed.  
		                        		
		                        			Results:
		                        			There were no significant differences observed in workload and burnout between the two groups. For nurses in the general units, workload, stress, adequacy of the number of patients assigned, and the experience of temporary, floating staff were significant factors associated with burnout, while only clinical experience in the current unit was a significant factor among those in the COVID-19 units.  
		                        		
		                        			Conclusion
		                        			Findings indicate significant differences in factors related to burnout between the two nurse groups. Thus, substantial support and strategies tailored to the working environments of each nursing unit are required to prevent burnout among nurses caring for COVID-19 patients. 
		                        		
		                        		
		                        		
		                        	
9.Establishment of the Korea National Health and Nutrition Examination Survey air pollution study dataset for the researchers on the health impact of ambient air pollution
Myung-Jae HWANG ; Jisun SUNG ; Miryoung YOON ; Jong-Hun KIM ; Hui-Young YUN ; Dae-Ryun CHOI ; Youn-Seo KOO ; Kyungwon OH ; Sungha YUN ; Hae-Kwan CHEONG
Epidemiology and Health 2021;43(1):e2021015-
		                        		
		                        			
		                        			To provide a nationwide representative dataset for the study on health impact of air pollution, we combined the data from the Korea National Health and Nutrition Examination Survey with the daily air quality and weather data by matching the date of examination and the residential address of the participants. The database of meteorological factors and air quality as sources of exposure data were estimated using the Community Multiscale Air Quality model. The linkage dataset was merged by three ways; administrative district, si-gun-gu (city, county, and district), and geocode (in latitude and longitude coordinate units) based on the participants’ residential address, respectively. During the study period, the exposure dataset of 85,018 individuals (38,306 men and 46,712 women) whose examination dates were recorded were obtained. According to the definition of exposure period, the dataset was combined with the data on short-term, mid-term, and long-term exposure to air pollutants and the meteorological indices. Calculation of the daily merged dataset’s average air pollution linked by si-gun-gu and geocode units showed similar results. This study generated a daily average of meteorological indices and air pollution exposure dataset for all regions including rural and remote areas in Korea for 11 years. It is expected to provide a platform for the researchers studying the health impact of air pollution and climate change on the representative population and area, which may facilitate the establishment of local health care plans by understanding the residents’ health status at the local as well as national level.
		                        		
		                        		
		                        		
		                        	
10.Establishment of the Korea National Health and Nutrition Examination Survey air pollution study dataset for the researchers on the health impact of ambient air pollution
Myung-Jae HWANG ; Jisun SUNG ; Miryoung YOON ; Jong-Hun KIM ; Hui-Young YUN ; Dae-Ryun CHOI ; Youn-Seo KOO ; Kyungwon OH ; Sungha YUN ; Hae-Kwan CHEONG
Epidemiology and Health 2021;43(1):e2021015-
		                        		
		                        			
		                        			To provide a nationwide representative dataset for the study on health impact of air pollution, we combined the data from the Korea National Health and Nutrition Examination Survey with the daily air quality and weather data by matching the date of examination and the residential address of the participants. The database of meteorological factors and air quality as sources of exposure data were estimated using the Community Multiscale Air Quality model. The linkage dataset was merged by three ways; administrative district, si-gun-gu (city, county, and district), and geocode (in latitude and longitude coordinate units) based on the participants’ residential address, respectively. During the study period, the exposure dataset of 85,018 individuals (38,306 men and 46,712 women) whose examination dates were recorded were obtained. According to the definition of exposure period, the dataset was combined with the data on short-term, mid-term, and long-term exposure to air pollutants and the meteorological indices. Calculation of the daily merged dataset’s average air pollution linked by si-gun-gu and geocode units showed similar results. This study generated a daily average of meteorological indices and air pollution exposure dataset for all regions including rural and remote areas in Korea for 11 years. It is expected to provide a platform for the researchers studying the health impact of air pollution and climate change on the representative population and area, which may facilitate the establishment of local health care plans by understanding the residents’ health status at the local as well as national level.
		                        		
		                        		
		                        		
		                        	
            
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