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Eom, Jisoo,Kim, Burnyoung,Kim, Wonhyung,Lee, Seungwan Elsevier 2018 OPTIK -STUTTGART- Vol.174 No.-
<P><B>Abstract</B></P> <P>Due to various factors, the number of chronic obstructive pulmonary disease (COPD) patients continues to grow. In addition, the mortality from COPD is increasing because of the difficult in the early detection of COPD. Both of radiologic and respiratory examinations should be performed for detecting COPD. But, since the conventional respiratory test uses spirometer, there is the air leakage between mouth and measurement machine, which reduces the accuracy and reproducibility of measurement. Also, it is difficult to apply respiratory examinations to all ages because the long respiration is needed. In this study, we confirmed the feasibility of material decomposition for pulmonary function test by combining dual-energy X-ray imaging based on a photon-counting detector. Non-radioactive Xe was used for determining pulmonary region. The RMSEs and contrast of each material in decomposition images were analyzed to quantitatively evaluate an accuracy of material decomposition images, and the volume including each material was calculated from material decomposition images. Results showed the high accuracy of material decomposition and volume measurements. The average RMSE values of PMMA, lung, and non-radioactive Xe were 0.07, 0.28, and 0.08%. The percentage errors of volume measurements for pure PMMA, lung, non-radioactive Xe, and total lung were 2.72, 8.46, 4.06, and 3.72%, respectively. Therefore, the diagnosis of COPD can be simplified through the material decomposition imaging using non-radiologic Xe, and the pulmonary function can be evaluated by decomposing the actual gas exchange volume form the total lung volume.</P>
몬테카를로 시뮬레이션을 이용한 광자계수검출기 기반 이중에너지 스펙트럼 유방촬영에서 가중 영상 감산법을 통한 물질분리
엄지수(Eom Jisoo),강순철(Kang Sooncheol),이승완(Lee Seungwan) 대한방사선과학회(구 대한방사선기술학회) 2017 방사선기술과학 Vol.40 No.3
유방촬영술은 유방암의 조기검진을 위해 시행되는 대표적인 검사이다. 하지만 유방 구성물질의 물리적 특성에 의존하는 유방촬영상은 병변의 악성 또는 양성 여부에 대한 정보 제공이 불가능하다. 이중에너지 영상 감산법을 시행하는 경우 유방촬영상에서 특정 물질에 대한 정보를 추출할 수 있지만 피폭선량을 증가시킬 뿐만 아니라 물질 분리의 정확도를 감소시키는 단점이 있다. 본 연구에서는 물질의 선감약계수를 적용한 유방팬텀을 모사하여 광자 계수검출기 기반 이중에너지 유방촬영에서 특정 물질에 대한 가중함수를 적용하여 분리의 정확도를 향상시킬 수 있는 기술을 제안하였다. 그리고 유방팬텀영상으로부터 물질분리의 정확도를 평가하기 위해 대조도 및 잡음 특성을 분석하였다. 분석 결과 이중에너지 가중 영상 감산법의 악성종양에 대한 대조도는 일반적인 유방촬영과 이중에너지 영상 감산법에 비해 각각 0.98, 1.06배로 큰 차이가 없다. 그렇지만 이중에너지 가중 영상 감산법 적용 시 양성종양에 대한 대조도가 0에 근사하기 때문에 양성종양에 대한 악성종양의 상대적인 대조도가 13.54배로 크게 향상된 것으로 확인되었다. 따라서 본 연구에서 제안하는 이중에너지 가중 영상 감산법은 유방촬영 진단의 정확도 향상에 기여할 수 있을 것이다. Mammography is commonly used for screening early breast cancer. However, mammographic images, which depend on the physical properties of breast components, are limited to provide information about whether a lesion is malignant or benign. Although a dual-energy subtraction technique decomposes a cer-tain material from a mixture, it increases radiation dose and degrades the accuracy of material decomposition. In this study, we simulated a breast phantom using attenuation characteristics, and we pro-posed a technique to enable the accurate material decomposition by applying weighting factors for the du-al-energy mammography based on a photon-counting detector using a Monte Carlo simulation tool. We al-so evaluated the contrast and noise of simulated breast images for validating the proposed technique. As a result, the contrast for a malignant tumor in the dual-energy weighted subtraction technique was 0.98 and 1.06 times similar than those in the general mammography and dual-energy subtraction techniques, respectively. However the contrast between malignant and benign tumors dramatically increased 13.54 times due to the low contrast of a benign tumor. Therefore, the proposed technique can increase the ma-terial decomposition accuracy for malignant tumor and improve the diagnostic accuracy of mammography.
Kang, Sooncheol,Eom, Jisoo,Kim, Burnyoung,Lee, Seungwan Elsevier 2017 OPTIK -STUTTGART- Vol.140 No.-
<P><B>Abstract</B></P> <P>Energy-integrating detectors (EIDs) are hard to reflect information of multi-energy X-rays due to its detection mechanism. On the other hand, photon-counting detectors (PCDs) are able to selectively acquire spectral information using energy thresholds. This characteristic of the PCDs allows the K-edge imaging technique, which is able to increase the contrast of high atomic number materials, such as iodine, gadolinium, and gold. Especially, the characteristics of gold can provide benefits for clinical applications because gold has minimal toxicity and a high K-edge absorption energy of 80.7 keV. In this study, a spectral CT system using a cadmium zinc telluride (CZT)-based PCD was designed by a Monte Carlo simulation tool. Phantoms were simulated to obtain gold K-edge and conventional CT images, and different reconstruction filters were used for investigating the noise property. The obtained images were evaluated by measuring contrast-to-noise ratios (CNRs). The results of this study showed that the CNRs of gold K-edge CT images were higher than those of conventional CT images, and a noise suppression filter improved the CNRs of gold K-edge CT images. It was concluded that gold has a high performance as a contrast agent, and the gold K-edge CT imaging enable the excellent material decomposition.</P>
Kim, Burnyoung,Kang, Sooncheol,Eom, Jisoo,Lee, Seungwan Elsevier 2018 OPTIK -STUTTGART- Vol.171 No.-
<P><B>Abstract</B></P> <P>Recently, cone-beam computed tomography (CBCT) equipped with image-guided radiation therapy (IGRT) has been used to precisely identify the location of target lesion. However, the treatment accuracy for respiratory-sensitive regions is still low due to long scanning time and target motion, and the imaging dose is also relatively high compared to other imaging systems. These issues can be solved by using 4D IGRT with digital tomosynthesis (DT). Also, an application of graphics processing unit (GPU) computing can reduce reconstruction time. The purpose of this study was to develop a 4D DT imaging technique for IGRT and compare image quality between 3D DT and 4D DT. And, we also compared reconstruction time between CPU and GPU computing. Projections were separately obtained through 3 phases for simulating 4D DT imaging. We measured profile, normalized root-mean-square error (NRMSE), contrast-to-noise ratio (CNR), noise-power spectrum (NPS) and figure-of-merit (FOM). NRMSEs and CNRs of 4D DT images were averagely 0.56 and 0.74 times lower than those of 3D DT images, respectively. The NPSs of 4D DT images were higher than 3D DT images. The FOMs of 4D DT images were averagely 1.65 times higher than 3D DT images. The GPU computing reduced reconstruction time in 3D and 4D imaging by a factor of 0.11 and 0.56, respectively. As a results, the 4D DT imaging enables the high-precision IGRT for respiratory-sensitive regions, and the real-time 4D imaging would be possible by using the GPU computing.</P>
건설 안전용 지오펜스 감시를 위한 이동형 CCTV 연구
강애띠 ( Kang Aetti ),김상우 ( Kim Sangwoo ),백은진 ( Baek Eunjin ),이지수 ( Lee Jisoo ),엄세민 ( Eom Semin ),함성일 ( Ham Sungil ) 한국건축시공학회 2023 한국건축시공학회 학술발표대회 논문집 Vol.23 No.1
Frequent accidents occur when workers at construction sites leave the safety zone, and particularly in the past 5 years, 9 fatal accidents occurred at the Korea Railroad Corporation due to train accidents on other tracks during track work. With the Severe Accident Punishment Act taking effect in January 2022, it is a priority to secure a safe work environment for workers at industrial (construction) sites. Therefore, there is a need to manage workers’ departure from the safety zone (construction zone) and to facilitate communication within the construction zone. In this study, a mobile edge computing CCTV system is proposed that uses geofencing to determine whether workers are working in the danger zone, which can judge and respond in real-time to the ever-changing field environment. The proposed system is mobile and flexible, rather than server-based fixed CCTV. However, since it is designed mainly based on images, it has limitations in recognition rate depending on the environment such as distance, viewing angle, and illumination. As a way to compensate for this, it is required to develop more reliable equipment by combining technologies such as LiDAR and Radar.