The Impact of COVID-19 on the Use of Radiology Resources in a Tertiary Hospital

Cho Jungheum,이승재,Gu Bon Seung,Jung Sang Hun,김혜영 대한의학회 2020 Journal of Korean medical science Vol.35 No.40

Background: The coronavirus disease 2019 (COVID-19) has escalated to be a global threat to public health. Analysis of the use of radiology resources may render us insight regarding the public health behavior during pandemic. We measured the influence COVID-19 had on the use of radiology resources in terms of the number of examinations performed, and turnaround time for portable radiography. Methods: This study was conducted at a tertiary hospital located in area where the prevalence of COVID-19 infection was low (0.01%). We compared the number of radiology examinations 1) before pandemic (in 2019) vs. during peak of pandemic (January to March 2020), and 2) before pandemic vs. after the peak of pandemic (April to June 2020) via t-tests. We repeated similar analyses for subgroups as follows: gender, age, department (outpatient, inpatient, emergency, screening), body parts, and modality. We also performed a survey of radiologic technologists regarding the turnaround time and rate-limiting step of portable radiography for patients with and without suspicion or confirmation of COVID-19. Results: Although not statistically significant, the daily number of examinations during the peak of pandemic decreased by 9 percentage points (2,638 vs. 2,413; difference [95% CI], −225 [−489, 38]; P = 0.094). The percentage change was especially notable for children, emergency, and screening department (25, 19, and 44 percentage points, respectively). After the peak of the pandemic, the number of examinations increased back to near the pre- pandemic level (2,638 vs. 2,588; −50 [−317, 218]; P = 0.71). The turnaround time for portable radiography tended to be longer for patients with suspicion or confirmation of COVID-19, with donning personal protective equipment being the major rate-limiting step. Conclusion: The number of examinations decreased during the pandemic, reflecting the tendency of the public to refrain from seeking medical care even in a community of low infection risk. Nevertheless, burden of healthcare providers may not have decreased as much, considering longer turnaround time required for COVID-19 related examinations.

Radiology Residents’ Independent Diagnosis of Appendicitis Using 2-mSv Computed Tomography: A Secondary Analysis of a Large Pragmatic Randomized Trial

Cho Jungheum,Kim Hae Young,Lee Seungjae,Park Ji Hoon,Lee Kyoung Ho 대한영상의학회 2023 Korean Journal of Radiology Vol.24 No.6

Objective: To compare the diagnostic performance and clinical outcomes of 2-mSv computed tomography (CT) and conventional-dose CT (CDCT), following radiology residents’ interpretation of CT examinations for suspected appendicitis. Materials and Methods: Altogether, 3074 patients with suspected appendicitis aged 15–44 years (28 ± 9 years, 1672 females) from 20 hospitals were randomly assigned to the 2-mSv CT (n = 1535) or CDCT (n = 1539) groups in a pragmatic trial from December 2013 and August 2016. Overall, 107 radiology residents participated in the trial as readers in the form of daily practice after online training for 2-mSv CT. They made preliminary CT reports, which were later finalized by attending radiologists via addendum reports, for 640 and 657 patients in the 2-mSv CT and CDCT groups, respectively. We compared the diagnostic performance of the residents, discrepancies between preliminary and addendum reports, and clinical outcomes between the two groups. Results: Patient characteristics were similar between the 640 and 657 patients. Residents’ diagnostic performance was not significantly different between the 2-mSv CT and CDCT groups, with a sensitivity of 96.0% and 97.1%, respectively (difference [95% confidence interval {CI}], -1.1% [-4.9%, 2.6%]; P = 0.69) and specificity of 93.2% and 93.1%, respectively (0.1% [-3.6%, 3.7%]; P > 0.99). The 2-mSv CT and CDCT groups did not significantly differ in discrepancies between the preliminary and addendum reports regarding the presence of appendicitis (3.3% vs. 5.2%; -1.9% [-4.2%, 0.4%]; P = 0.12) and alternative diagnosis (5.5% vs. 6.4%; -0.9% [-3.6%, 1.8%]; P = 0.56). The rates of perforated appendicitis (12.0% vs. 12.6%; -0.6% [-4.3%, 3.1%]; P = 0.81) and negative appendectomies (1.9% vs. 1.1%; 0.8% [-0.7%, 2.3%]; P = 0.33) were not significantly different between the two groups. Conclusion: Diagnostic performance and clinical outcomes were not significantly different between the 2-mSv CT and CDCT groups following radiology residents’ CT readings for suspected appendicitis.

Quantitative assessment of steroid amount in the tissue after epidural steroid injection: a new rabbit model

Jungheum Cho,Joon Woo Lee,Eugene Lee,Yusuhn Kang,Ha Ra Cho,Dong Yoon Kim,Myoung Jin Ho,Myung Joo Kang,Yong Seok Choi 대한통증학회 2019 The Korean Journal of Pain Vol.32 No.4

Background: To develop a rabbit epidural steroid injection (ESI) model for analyzing steroid retention in the tissue, and to assess the difference in steroid retention in the model according to the location and time elapsed after ESI. Methods: Fluoroscopy-guided ESI was performed using the interlaminar approach between the lowest two lumbar segments in 13 female New Zealand white rabbits. Four rabbits were allocated to each of three different groups according to the time of sacrifice: 3, 7, and 15 days post-ESI; the remaining rabbit was sacrificed immediately post-ESI to obtain baseline data. After sacrifice, two segments were harvested: the lowest two lumbar vertebrae and another two lumbar vertebrae immediately above these. The residual steroid amount (RSA) and residual steroid concentration (RSC) in the collected spinal columns were analyzed. A linear mixed model was used to compare RSAs and RSCs between the injected and adjacent segments, and among the number of days until sacrifice; P < 0.05 was considered statistically significant. Results: Both RSA and RSC of the injected segment were significantly higher than those of the adjacent segment (P < 0.001, both). The RSA and RSC significantly decreased over time (P = 0.009 and P = 0.016, respectively). Conclusions: The developed rabbit ESI model verified that significantly more steroid was retained at the injected segment than at the adjacent segment and the residual steroid decreased over time. This model could be useful not only for comparing current steroid medications, but also for developing new, better steroid formulations.

Quantitative assessment of steroid amount in the tissue after epidural steroid injection: a new rabbit model

Cho, Jungheum,Lee, Joon Woo,Lee, Eugene,Kang, Yusuhn,Cho, Ha Ra,Kim, Dong Yoon,Ho, Myoung Jin,Kang, Myung Joo,Choi, Yong Seok The Korean Pain Society 2019 The Korean Journal of Pain Vol.32 No.4

Background: To develop a rabbit epidural steroid injection (ESI) model for analyzing steroid retention in the tissue, and to assess the difference in steroid retention in the model according to the location and time elapsed after ESI. Methods: Fluoroscopy-guided ESI was performed using the interlaminar approach between the lowest two lumbar segments in 13 female New Zealand white rabbits. Four rabbits were allocated to each of three different groups according to the time of sacrifice: 3, 7, and 15 days post-ESI; the remaining rabbit was sacrificed immediately post-ESI to obtain baseline data. After sacrifice, two segments were harvested: the lowest two lumbar vertebrae and another two lumbar vertebrae immediately above these. The residual steroid amount (RSA) and residual steroid concentration (RSC) in the collected spinal columns were analyzed. A linear mixed model was used to compare RSAs and RSCs between the injected and adjacent segments, and among the number of days until sacrifice; P < 0.05 was considered statistically significant. Results: Both RSA and RSC of the injected segment were significantly higher than those of the adjacent segment (P < 0.001, both). The RSA and RSC significantly decreased over time (P = 0.009 and P = 0.016, respectively). Conclusions: The developed rabbit ESI model verified that significantly more steroid was retained at the injected segment than at the adjacent segment and the residual steroid decreased over time. This model could be useful not only for comparing current steroid medications, but also for developing new, better steroid formulations.

Appendiceal Visualization on 2-mSv CT vs. Conventional-Dose CT in Adolescents and Young Adults with Suspected Appendicitis: An Analysis of Large Pragmatic Randomized Trial Data

Cho Jungheum,Kim Youngjune,Lee Seungjae,Min Hooney Daniel,Ko Yousun,Chee Choong Guen,Kim Hae Young,Park Ji Hoon,Lee Kyoung Ho 대한영상의학회 2022 Korean Journal of Radiology Vol.23 No.4

Objective: We compared appendiceal visualization on 2-mSv CT vs. conventional-dose CT (median 7 mSv) in adolescents and young adults and analyzed the undesirable clinical and diagnostic outcomes that followed appendiceal nonvisualization. Materials and Methods: A total of 3074 patients aged 15–44 years (mean ± standard deviation, 28 ± 9 years; 1672 female) from 20 hospitals were randomized to the 2-mSv CT or conventional-dose CT group (1535 vs. 1539) from December 2013 through August 2016. A total of 161 radiologists from 20 institutions prospectively rated appendiceal visualization (grade 0, not identified; grade 1, unsure or partly visualized; and grade 2, clearly and entirely visualized) and the presence of appendicitis in these patients. The final diagnosis was based on CT imaging and surgical, pathologic, and clinical findings. We analyzed undesirable clinical or diagnostic outcomes, such as negative appendectomy, perforated appendicitis, more extensive than simple appendectomy, delay in patient management, or incorrect CT diagnosis, which followed appendiceal nonvisualization (defined as grade 0 or 1) and compared the outcomes between the two groups. Results: In the 2-mSv CT and conventional-dose CT groups, appendiceal visualization was rated as grade 0 in 41 (2.7%) and 18 (1.2%) patients, respectively; grade 1 in 181 (11.8%) and 81 (5.3%) patients, respectively; and grade 2 in 1304 (85.0%) and 1421 (92.3%) patients, respectively (p < 0.001). Overall, undesirable outcomes were rare in both groups. Compared to the conventional-dose CT group, the 2-mSv CT group had slightly higher rates of perforated appendicitis (1.1% [17] vs. 0.5% [7], p = 0.06) and false-negative diagnoses (0.4% [6] vs. 0.0% [0], p = 0.01) following appendiceal nonvisualization. Otherwise, these two groups were comparable. Conclusion: The use of 2-mSv CT instead of conventional-dose CT impairs appendiceal visualization in more patients. However, appendiceal nonvisualization on 2-mSv CT rarely leads to undesirable clinical or diagnostic outcomes.

메모리 아티팩트 기반의 공격 기술 탐지 규칙 정규화 및 활용 방안

진필근(Philgeun Jin),김동현(Donghyun Kim),방수민(Sumin Bang),박정흠(Jungheum Park),이상진(Sangjin Lee),박아란(ARan Park),조병모(Byoungmo Cho),이화성(Hwaseong Lee) 한국디지털포렌식학회 2021 디지털 포렌식 연구 Vol.15 No.1

최근 보안 분야에서는 다양한 공격 기술을 효과적으로 탐지하고 대응하기 위한 연구개발이 활발하게 이루어지고 있다. 대부분의 기존 솔루션들은 운영체제 동작 과정에서 발생하는 이벤트들을 실시간으로 모니터링하거나 보조 저장장치에 저장되는 아티팩트들을 주기적으로 확인하는 등의 방법을 활용하고 있다. 하지만, 다양한 솔루션들이 실제 환경에 적용되고 있음에도 불구하고 악성코드들을 완벽하게 방어하지 못하는 상황이기 때문에, 기존 방어 기술의 기능적 한계점을 보완하기 위한 새로운 관점의 탐지 방법을 연구할 필요가 있다. 이에, 본 논문에서는 시스템 메모리를 대상으로 악성코드가 실행될 때 생성되는 다양한 아티팩트들의 특징을 활용한 공격 기술 탐지 방안을 제안한다. 구체적으로, MITRE ATT&CK에서 분류한 공격 기술들을 체계적으로 탐지하기 위해서 EQL(Event Query Language)을 활용하여 메모리 아티팩트를 공격 탐지 규칙으로 정규화하고 이를 활용하는 프로토타입 시스템을 개발한다. Recently, research and development has been actively conducted in the security field to effectively detect and respond to various attack techniques. Most existing solutions utilize methods such as monitoring events that occur during operating system operations in real time or periodically checking artifacts stored on secondary storage devices. However, it is necessary to study new perspective detection methods to supplement functional limitations of existing defense techniques, as various solutions are not fully protected against malicious codes despite being applied in real-world environments. Thus, in this paper, we propose a novel perspective attack technique detection method that utilizes the characteristics of various memory (RAM) artifacts generated by the execution of malicious code. Specifically, to systematically detect attack techniques classified by MITRE ATT&CK, this work normalizes attack detection rules for memory artifacts using Event Query Language (EQL), and develops a prototype system based on it.

Windows 10 내의 hiberfil.sys 파일에 대한 포렌식 활용 방안

방수민(Sumin Bang),진필근(Philgeun Jin),김동현(Donghyun Kim),박정흠(Jungheum Park),이상진(Sangjin Lee),박아란(Aran Park),조병모(Byoungmo Cho),정일훈(Ilhoon Jung) 한국디지털포렌식학회 2021 디지털 포렌식 연구 Vol.15 No.1

Windows 운영체제는 다양한 전원 및 절전 옵션을 제공하며 옵션 선택에 따라 휘발성 메모리 데이터를 보조기억장치 내에 hiberfil.sys 파일로 저장한다. 특히 ‘빠른 시작’ 옵션이 활성화되어 있는 경우, 시스템 종료를 하면 종료 직전 휘발성 메모리에 적재되어 있던 Windows 커널 및 드라이버의 메모리 영역이 보조기억장치에 백업되기 때문에 메모리 데이터를 활성 상태가 아닌 비활성 상태에서 확보할 수 있게 되었다. 이에 비활성 시스템에서도 hiberfil.sys 파일을 통해 메모리 포렌식을 할 수 있는 가능성이 생겨났다. 이러한 가능성을 바탕으로 본 논문에서는 메모리 데이터의 커널 영역에서 관리되는 파일시스템 드라이버 관련 객체들을 기반으로 시스템 종료 직전 행해진 외부 저장 장치로의 파일 복사 흔적을 추적하는 방안을 제시한다. Windows provides a variety of power saving options and store volatile memory data as the hiberfil.sys file in a auxiliary memory according to option selection. Especially, when the "fast start" option is activated, the memory area of the Windows kernel and driver loaded in the volatile memory just before the end of the system is backed up in the auxiliary memory, so that the memory data can be secured in not only the active system but also the inactive state. This has led to the possibility of memory forensics through memory data obtained from the hiberfil.sys file in the inactive system. Based on this possibility, in this paper, we propose a method to track file copy traces to external storage devices that were performed just before the end of the system based on file system driver-related objects managed in the kernel area of memory data.

Simultaneous improvements in self-cleaning and light-trapping abilities of polymer substrates for flexible organic solar cells

Jeong, Eunwook,Zhao, Guoquing,Song, Myungkwan,Yu, Seung Min,Rha, Jongjoo,Shin, Jongmoon,Cho, Young-Rae,Yun, Jungheum The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.5

<P>Organic solar cells (OSCs) supported on mechanically flexible and optically transparent polymer substrates have been receiving increased attention owing to their noticeable merits of low cost, light weight, and flexible design that are unattainable by their existing counterparts supported on rigid glass substrates. However, technical issues such as relatively low photon-to-electron conversion efficiencies and long-term stabilities of OSCs on polymer substrates require the enhancement and maintenance of the efficiency of OSCs. In this study, a simple, direct vacuum deposition strategy was used to fabricate a multifunctional silica nanoparticle array (SNA) layer on polymer substrates for improving and maintaining the light harvesting efficiencies of OSCs; this induces simultaneous and significant enhancements in the light-scattering and contaminant-repelling (or self-cleaning) properties of the substrate. The SNA layer led to improved light scattering features, representing haze transmittances ranging from 3.4% to 80.4% in the visible spectral range with strong influences of its geometrical features on the hydrophobic/oleophobic characteristics of the substrate. Any contaminant-induced reduction in the performance of OSCs could be successfully prevented by the strong contaminant-repelling feature, characterized by high contact angles (>150°) and low sliding angles (<15°) for water and ethylene glycol, without compromising the optical transparency of the polymer substrate. A combination of the SNA layer and oxide/metal/oxide (OMO) electrode coating on each side of the polymer substrate provides a promising solution to improve the performance of OSCs. The power conversion efficiency was enhanced by 13.31% compared to that of an OSC based on the same polymer substrate without the SNA layer.</P>

Wafer-Scale Integration of Highly Uniform and Scalable MoS₂ Transistors

Kim, Yonghun,Kim, Ah Ra,Zhao, Guoqing,Choi, Sun Young,Kang, Soo Cheol,Lim, Sung Kwan,Lee, Kang Eun,Park, Jucheol,Lee, Byoung Hun,Hahm, Myung Gwan,Kim, Dong-Ho,Yun, Jungheum,Lee, Kyu Hwan,Cho, Byungjin American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.42

<P>Molybdenum disulfide with atomic-scale flatness has application potential in high-speed and low-power logic devices owing to its scalability and intrinsic high mobility. However, to realize viable technologies based on two-dimensional materials, techniques that enable their large-area growth with high quality and uniformity on wafer cale is a prerequisite. Here, we provide a route toward highly uniform growth of a wafer-scale, four-layered MoS2 film on a 2 in. substrate via a sequential process consisting of the deposition of a molybdenum trioxide precursor film by sputtering followed by postsulfurization using a chemical vapor deposition process. Spatial spectroscopic analyses by Raman and PL mapping validated that the as-synthesized MoS2 thin films exhibit high uniformity on a 2 in. sapphire substrate. The highly uniform MoS2 layers allow a successful integration of devices based on 4200 MoS2 transistor arrays with a yield of 95% because of their extreme homogeneity on Si wafers. Moreover, a pulse electrical measurement technique enabled investigation of the inherent physical properties of the atomically thin MoS2 layers by minimizing the charge-trapping effect. Such a facile synthesis method can be possibly applied to other 2D transition metal dichalcogenides to ultimately realize the chip integration of device architectures with all 2D-layered building blocks.</P>