Investigation of Human and Model Observer Performance of Mass Detection in a Prototype Digital Breast Tomosynthesis System

Seungyeon Choi,Dong Hoon Lee,Hee-Joung Kim,Young-Wook Choi,Sunghoon Choi 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.4

Task-based assessment of image quality using a theoretical observer model has recently gained attention in medical imaging fields. Observer models whose performance can suitably match that of a human observer under various imaging conditions have been considered a key concept for virtual clinical studies. This work focused on experimental study in which a prototype digital breast tomosynthesis (DBT) system, developed by the Korea Electrotechnology Research Institute, was used to compare the task-based Fourier metrics of a detectability index with the performance of human observers. Different angular ranges of ±7°, ±10.5°, ±14°, ±17.5°, ±21°, and ±24.5° were used to detect four different sizes of spheroidal masses with the same 15-projection samplings. A total of 16 human observers participated in the study. Human observer performance was measured using four-alternative forced choice (4AFC) tests for different detection tasks, including detecting spheroidal masses. To determine the task-based detectability index (d´), the non-prewhitening matched filter observer was calculated by analyzing the task function, local spatial resolution, and local noise of spheroidal masses. The percentage of signals correctly detected (Pc) with the 4AFC tests was then compared with the detectability index for tasks presented in 2D slices (d´^2slice). The average Pc for 16 human observers was 0.87 (range = 0.56--1). Results showed that Pc decreased as the angular range increased from ±7° to ±24.5° with different mass sizes. Our result also showed that the performance of the task-based theoretical model observer could reasonably estimate d´ for all inserted lesions of different sizes and acquired under different conditions, while presenting a trend similar to those of the human observers. Consequently, our study is expected to contribute to quantitative imaging performance analysis under various DBT imaging acquisition parameters.

Effective detective quantum efficiency of two detectors in a prototype digital breast tomosynthesis

Choi, Seungyeon,Choi, Sunghoon,Lee, Donghoon,Kim, Ye-seul,Choi, Young-Wook,Kim, Hee-Joung Elsevier 2019 Optik Vol.178 No.-

<P><B>Abstract</B></P> <P>Digital breast tomosynthesis (DBT) system is a novel imaging modality that strongly depends on the detector performance. The effective detective quantum efficiency (eDQE) is a newly accepted system of performance analysis metric that solves the disadvantages of conventional DQE evaluations, which do not consider clinical operating conditions. To evaluate the eDQE, we used the direct-conversion based Anrad detector and the indirect-conversion based Dexela detector. Our aim is to study the performance of such detectors when they are mounted on a prototype DBT system. The prototype DBT system consists of a CsI(Tl) scintillator/CMOS-based flat panel digital detector and an a-Se based direct conversion detector developed by the Korea Electrotechnology Research Institute (KERI). The performance of the two detectors was compared on the basis of scatter fraction, transmission factor, effective modulation transfer function (eMTF), and effective normalized noise power spectrum (eNNPS). As a result, the Dexela detector is characterized by a decreasing eNNPS trend as the spatial frequency increases, whereas the Anrad eNNPS looks almost independent of the spatial frequency. The eMTF was found to be higher in the Anrad detector compared to that in the Dexela one for all frequencies. The eDQE values at 1 cycle/mm (low frequency) were 0.11 and 0.17 for the Anrad and Dexela detectors, respectively, and the values of the spatial frequency <SUB> f e D Q E ( 0.1 ) </SUB> , corresponding to eDQE = 0.1, were 1.25 and 2.81 cycles/mm for the Anrad and Dexela detectors, respectively. The Dexela detector also presented a higher contrast-to-noise ratios (CNRs) for all different sizes of μCa groups, thus demonstrating overall better eDQE results in imaging performance compared to the Anrad detector.</P>

Energy-efficient hybrid FCDI-NF desalination process with tunable salt rejection and high water recovery

Choi, Seungyeon,Chang, Barsa,Kang, Ji Hyun,Diallo, Mamadou S.,Choi, Jang Wook Elsevier 2017 Journal of membrane science Vol.541 No.-

<P><B>Abstract</B></P> <P>Seawater and brackish water constitute ~ 97% of the water on Earth. Therefore, future water shortages could be alleviated if we develop more efficient and cost-effective desalination technologies. Reverse osmosis (RO) has been established as the best available technology for commercial seawater (SW) desalination during the last two decades. Because the standard SWRO membrane element is designed to achieve a very high salt (NaCl) rejection (> 99%) with a low water recovery (~ 15%), current SWRO desalination plant design is based on the staging of arrays of RO membrane elements to achieve an overall water recovery of ~ 50% with an energy consumption of 3–4kWhperm<SUP>3</SUP> of water treated. Moreover, SWRO desalination plants generate substantial amounts of brines that must be disposed of. In addition, SWRO desalination plants require post-treatment including remineralization. Here, we report an energy-efficient hybrid desalination process for high salinity brackish water. This new desalination process couples flow capacitive deionization (FCDI) with nanofiltration (NF). Our experiments and energy calculations using a 10000ppm NaCl solution as model brackish water show that the energy consumption of the new FCDI-NF unit (0.460kWh_totalm<SUP>−3</SUP>) is lower by 16–20% than the best reported energy consumption (0.571kWhm<SUP>−3</SUP>) and the 1-stage practical minimum energy consumption (0.550kWhm<SUP>−3</SUP>) of a brackish water reverse osmosis (BWRO) unit treating the same feed at 70% water recovery, while final total dissolved solids (TDS) are in the drinking water range.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Flow capacitive deionization (FCDI) is coupled with nanofiltration (NF). </LI> <LI> The performance of FCDI is improved by using polyurethane sponge as a water path. </LI> <LI> FCDI-NF yields drinkable water for 10000ppm NaCl feed with 70% water recovery. </LI> <LI> Energy consumption comparison between FCDI-NF and BWRO unit is performed. </LI> <LI> The energy consumption of FCDI-NF unit is lower than 1-stage BWRO unit by 16–20%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Development of a prototype chest digital tomosynthesis (CDT) R/F system with fast image reconstruction using graphics processing unit (GPU) programming

Choi, Sunghoon,Lee, Seungwan,Lee, Haenghwa,Lee, Donghoon,Choi, Seungyeon,Shin, Jungwook,Seo, Chang-Woo,Kim, Hee-Joung Elsevier 2017 Nuclear Instruments & Methods in Physics Research. Vol.848 No.-

<P><B>Abstract</B></P> <P>Digital tomosynthesis offers the advantage of low radiation doses compared to conventional computed tomography (CT) by utilizing small numbers of projections (~80) acquired over a limited angular range. It produces 3D volumetric data, although there are artifacts due to incomplete sampling. Based upon these characteristics, we developed a prototype digital tomosynthesis R/F system for applications in chest imaging. Our prototype chest digital tomosynthesis (CDT) R/F system contains an X-ray tube with high power R/F pulse generator, flat-panel detector, R/F table, electromechanical radiographic subsystems including a precise motor controller, and a reconstruction server. For image reconstruction, users select between analytic and iterative reconstruction methods. Our reconstructed images of Catphan700 and LUNGMAN phantoms clearly and rapidly described the internal structures of phantoms using graphics processing unit (GPU) programming. Contrast-to-noise ratio (CNR) values of the CTP682 module of Catphan700 were higher in images using a simultaneous algebraic reconstruction technique (SART) than in those using filtered back-projection (FBP) for all materials by factors of 2.60, 3.78, 5.50, 2.30, 3.70, and 2.52 for air, lung foam, low density polyethylene (LDPE), Delrin<SUP>®</SUP> (acetal homopolymer resin), bone 50% (hydroxyapatite), and Teflon, respectively. Total elapsed times for producing 3D volume were 2.92s and 86.29s on average for FBP and SART (20 iterations), respectively. The times required for reconstruction were clinically feasible. Moreover, the total radiation dose from our system (5.68mGy) was lower than that of conventional chest CT scan. Consequently, our prototype tomosynthesis R/F system represents an important advance in digital tomosynthesis applications.</P>

Development of a chest digital tomosynthesis r/f system and implementation of low‐dose gpu‐accelerated compressed sensing (cs) image reconstruction

Choi, Sunghoon,Lee, Haenghwa,Lee, Donghoon,Choi, Seungyeon,Lee, Chang‐,Lae,Kwon, Woocheol,Shin, Jungwook,Seo, Chang‐,Woo,Kim, Hee‐,Joung Published for the American Association of Physicis 2018 Medical physics Vol.45 No.5

Studies on a new solid-liquid Cs separation using the ionic liquid extraction system in comparison with the conventional adsorption

Cho, Seungyeon,Choi, Jungweon,Choi, Sang-June,Oh, Wonzin Springer-Verlag 2019 JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY Vol.319 No.1

단백질-리간드 결합 친화력 예측을 위한 VAE기반 데이터 증강 기법

최승연(Seungyeon Choi),서상민(Sangmin Seo),최종환(Jonghwan Choi),박상현(Sanghyun Park) 한국정보과학회 2022 한국정보과학회 학술발표논문집 Vol.2022 No.12

스페이스 마케팅의 전략적 요소를 적용한 백화점 라이프스타일 브랜드 공간 VMD에 관한 연구

최승연 ( Choi Seungyeon ),이정교 ( Lee Jeonggyo ) 한국공간디자인학회 2022 한국공간디자인학회논문집 Vol.17 No.7

(연구배경 및 목적) 최근의 팬데믹과 급속한 발전에 의해 소비자들의 패션이나 인테리어 등의 영역에 대한 인식이 변화되어 자신의 취향과 개성을 드러내기 시작했다. 이러한 배경에서 새로운 형식의 취향을 갖는 소비자들에게 새로운 삶의 방식을 제안하는 라이프스타일 브랜드들이 등장했다. 라이프스타일 브랜드 공간은 여러 영역의 상품군을 다루는 만큼 단순히 상품들을 진열하고 판매하는 공간이 아닌 소비자들의 니즈를 충족시키고 감성을 자극할 수 있으면서 브랜드의 아이덴티티를 전달하고 메시지, 즉 스토리텔링으로 공감될 수 있는 공간으로 꾸며져야 한다. 이에 본 연구는 스페이스 마케팅의 전략적 요소 특성을 적용한 라이프스타일 브랜드 공간의 사례 분석을 통해서 전략적 요소를 추출하고 효율적인 VMD 전략을 도출하는 것에 목적이 있다. (연구 방법) 본 연구는 스페이스 마케팅과 VMD의 주요 개념과 특성에 대한 이론적 고찰을 바탕으로 라이프스타일 브랜드 공간의 사례 분석을 통해 스페이스 마케팅의 전략적 요소를 적용한 브랜드 공간 VMD 특성에 대해 도출하는 방식으로 진행된다. 사례로 선정한 공간은 총 4곳이며, 현장 방문, 인터넷 자료 조사, 선행 연구 고찰 등의 방법을 통해 결과를 도출한다. (결과) 10 꼬르소꼬모와 프레드 시갈은 해당 브랜드만의 개성과 이미지가 뚜렷하게 드러났고, 상품의 진열이나 연출 요소 역시 소비자들의 감성을 자극해 호기심과 흥미를 이끌어내기 충분했다. 이에 비해 더 콘란샵과 아르켓은 공간에 차별화된 요소나 특성이 없었기 때문에 상대적으로 매력성이 낮게 나왔다. 또한 프레드 시갈은 모든 공간을 잘 활용하여 상품들이 눈에 잘 들어오고 동선 또한 편리했기 때문에 공간의 기능성이 높았다. 각 브랜드마다 제안하는 상품들과 전체적인 공간 연출이 브랜드의 정체성과 이미지에 적합했기 때문에 적합성은 대부분의 브랜드에서 높게 나타났고, 전달성은 브랜드별로 상품들을 분류해놓고 브랜드마다 설명을 적어 상품 정보를 확실하게 전달하고 신뢰성을 주었던 10 꼬르소꼬모가 가장 높은 점수로, 매장의 규모에 비해 상품과 브랜드에 대한 설명이 부족했던 더 콘란샵은 비교적 낮은 점수로 나타났다. (결론) 라이프스타일 브랜드 공간에는 브랜드만의 아이덴티티와 브랜드가 추구하는 이미지를 전달할 수 있는 차별화된 요소가 있어야 소비자들의 감성과 호기심을 자극할 수 있다. 또한 여러 브랜드의 상품들을 모아놓은 공간이기 때문에 각각의 브랜드와 상품에 대한 기본적인 정보를 제공하면 소비자들에게 신뢰를 주고 이해도를 높일 수 있어 더욱 호감을 가지게 된다. 따라서 라이프스타일 브랜드 공간에는 이러한 요소들이 포함되어야 소비자들을 만족시킬 수 있다. (Background and Purpose) With the recent coronavirus pandemic and rapid development, consumers’ perception of fashion and interior design has changed, and they have begun to express their preferences and individuality more openly. Against this background, a lifestyle brand that suggests a new way of life for consumers who have new forms of preferences has emerged. The lifestyle brand space should be where consumers can meet their needs, stimulate their emotions, convey brand identity, and empathize with messages or storytelling rather than simply displaying and selling products. Therefore, this study aims to extract strategic elements and derive an efficient VMD strategy through a case analysis of the lifestyle brand space by applying the strategic element characteristics of space marketing. (Method) Based on theoretical considerations of key concepts and characteristics of space marketing and VMD, this study was conducted by deriving brand space VMD characteristics that apply strategic elements of space marketing through case analysis of lifestyle brand space. A total of four spaces were selected as examples, and results were derived through field visits, Internet data surveys, and prior research. (Results) It was observed that 10 Corso Como and Fred Segal clearly showed their individuality and image, and the display and production elements of the products were sufficiently interesting to stimulate consumers' sensibility and arouse their curiosity and interest. Conversely, The Conran Shop and ARKET were relatively less attractive to consumers because there were no differentiated elements or characteristics in the space. Additionally, Fred Seagal made good use of all the spaces, and the functionality of the space was high because the products were visible and the flow line was convenient. The product and overall space production proposed by each brand matched the brand’s identity and image; therefore, the suitability was high in most brands. In terms of communicability, 10 Corso Como, which categorized products by brand and provided reliable information by writing explanations by brand, received the highest score, and The Conran Shop, which did not provide an explanation for products and brands, received relatively low scores. (Conclusions) In the lifestyle brand space, consumers’ sensibilities and curiosity can be stimulated only if there are differentiated elements that convey the identity of the brand and the image that the brand pursues. Furthermore, since the space is a collection space of commodities of a plurality of brands, basic information on each brand and commodity can be provided to engender trust among consumers, enhance their understanding, and further give them a favorable impression. Therefore, consumers can be satisfied when these elements are included in the lifestyle brand space.

사용자 편의성을 고려한 법안검색 시스템

최승연(Seungyeon Choi),김준석(Junseok Kim),김광호(Gwangho Kim),김철민(Cheolmin Kim),김장원(Jangwon Gim) 한국정보기술학회 2022 Proceedings of KIIT Conference Vol.2022 No.12

공공데이터를 이용한 응급환자 이송 지원 서비스

최승연(Seungyeon Choi),박준혁(JunHyuk Park),김장원(Jangwon Gim) 한국정보기술학회 2022 Proceedings of KIIT Conference Vol.2022 No.6