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RISS 인기검색어
- 검색키워드
- 저자 : Kim Dohyeon (검색결과 176 건)
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Feasibility study of shutter scan acquisition for region of interest ( ROI ) digital tomosynthesis
Kim, Dohyeon,Jo, Byungdu,Lee, Donghoon,Lee, Haenghwa,Choi, Sunghoon,Kim, Hyemi,Chao, Zhen,Choi, Seungyeon,Kim, Hee‐,Joung unknown 2018 Journal of applied clinical medical physics Vol.19 No.3
<P><B>Abstract</B></P><P>Dose reduction techniques have been studied in medical imaging. We propose shutter scan acquisition for region of interest (ROI) imaging to reduce the patient exposure dose received from a digital tomosynthesis system. A prototype chest digital tomosynthesis (CDT) system (LISTEM, Wonju, Korea) and the LUNGMAN phantom (Kyoto Kagaku, Japan) with lung nodules 8, 10, and 12 mm in size were used for this study. A total of 41 projections with shutter scan acquisition consisted of 21 truncated projections and 20 non‐truncated projections. For comparison, 41 projections using conventional full view scan acquisition were also acquired. Truncated projections obtained by shutter scan acquisition were corrected by proposed image processing procedure to remove the truncation artifacts. The image quality was evaluated using the contrast to noise ratio (CNR), coefficient of variation (COV), and figure of merit (FOM). We measured the dose area product (DAP) value to verify the dose reduction using shutter scan acquisition. The ROI of the reconstructed image from shutter scan acquisition showed enhanced contrast. The results showed that CNR values of 8 and 12 mm lung nodules increased by 6.38% and 21.21%, respectively, and the CNR value of 10 mm lung nodule decreased by 3.63%. COV values of the lung nodules were lower in a shutter scan image than in a full view scan image. FOM values of 8, 10, and 12 mm lung nodules increased by 3.06, 2.25, and 2.33 times, respectively. This study compared the proposed shutter scan and conventional full view scan acquisition. In conclusion, using a shutter scan acquisition method resulted in enhanced contrast images within the ROI and higher FOM values. The patient exposure dose of the proposed shutter scan acquisition method can be reduced by limiting the field of view (FOV) to focus on the ROI.</P>
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Kim, Dohyeon,Lee, Donghoon,Lee, Haenghwa,Kim, Hyemi,Chao, Zhen,Lee, Minjae,Kim, Hee-Joung Pergamon 2018 Radiation physics and chemistry Vol.152 No.-
<P><B>Abstract</B></P> <P>Recently, digital tomosynthesis systems have been actively investigated to reduce radiation dose in medical imaging. In this work, we present various beam modulation schemes for low-dose digital tomosynthesis; we compared the effects of the various acquisition schemes on image quality. A prototype chest digital tomosynthesis (CDT) system (LISTEM, Korea) and the LUNGMAN phantom (Kyoto Kagaku, Japan) with lung nodules were used in this study. A total of 81 projection data obtained through various beam modulation schemes over a 40° angular range were reconstructed using the filtered back projection (FBP) algorithm. The contrast noise ratio (CNR), structural similarity index (SSIM), and peak signal-to-noise ratio (PSNR) of the lung nodules were calculated to evaluate the image quality depending on the acquisition scheme. The reconstructed images obtained based on the proposed beam modulation schemes showed enhanced contrast in addition to a reduction of the area dose. It was determined that the beam modulation schemes affect the image quality. Among beam modulation schemes we investigated, the bunched view acquisition (outer focused) showed promising results within the region of interest (ROI). The reconstructed image obtained using the bunched view showed an increase of the CNR value by 63% compared to the conventional acquisition method. In addition, shutter scan acquisition showed promising results for the restoration information for the outside ROI. We determined that the beam modulation schemes in the prototype CDT system affect the image quality. It is also expected that the patient exposure dose can be reduced by modulating the beam size in the prototype CDT system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We have proposed three beam modulation schemes in a prototype chest digital tomosynthesis (CDT) system. </LI> <LI> We found that beam modulation schemes in the prototype CDT system affect the image quality. </LI> <LI> Patient exposure dose can be reduced by modulating the beam size in the prototype CDT system. </LI> </UL> </P>
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Kim, Suhee,Kim, Hyunwoo,Lee, Soo-Hyeon,Cho, Ilhan,Kang, Seongwoo,Bae, Junwoo,Kim, Woosun,Ahn, Soomin,Choi, Jihye,Kim, Sang-Ki,Do, Yoonjung,Yoo, Jae Gyu,Park, Jinho,Yu, DoHyeon 한국조명·전기설비학회 2017 한국조명·전기설비학회 학술대회논문집 Vol. No.
<P>Acute lymphocytic leukemia (ALL) is uncommon lymphoid malignancy in dogs, and its diagnosis is challenging. A 14-year-old spayed female mixed breed dog was transferred to a veterinary medical teaching hospital for an immediate blood transfusion. The dog showed lethargy, pale mucous membranes, and a weak femoral pulse. Complete blood count revealed non-regenerative anemia and severe leukopenia with thrombocytopenia. ALL was tentatively diagnosed based on the predominance of immature lymphoblasts on blood film examination. For confirmation of lymphoid malignancy, PCR for antigen receptor rearrangement (PARR) on a peripheral blood sample and flow cytometry analysis were performed after blood transfusion. Flow cytometry analysis revealed that lymphocyte subsets were of normal composition, but PARR detected a T-cell malignancy. The dog was diagnosed with ALL and survived 1 wk after diagnosis. In conclusion, after blood transfusion, flow cytometry was not a reliable diagnostic method for an ALL dog, whereas PARR could detect lymphoid malignancy. Our results suggest that PARR should be the first-line diagnostic tool to detect canine lymphoid malignancy after a blood transfusion.</P>
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Kim, Dohyeon,Jo, Byungdu,Park, Su-Jin,Kim, Hyemi,Kim, Hee-Joung Korean Society of Medical Physics 2016 의학물리 Vol.27 No.3
Sparse angular sampling has been studied recently owing to its potential to decrease the radiation exposure from computed tomography (CT). In this study, we investigated the analytic reconstruction algorithm in sparse angular sampling using the sinogram interpolation method for improving image quality and computation speed. A prototype of the spectral CT system, which has a 64-pixel Cadmium Zinc Telluride (CZT)-based photon-counting detector, was used. The source-to-detector distance and the source-to-center of rotation distance were 1,200 and 1,015 mm, respectively. Two energy bins (23~33 keV and 34~44 keV) were set to obtain two reconstruction images. We used a PMMA phantom with height and radius of 50.0 mm and 17.5 mm, respectively. The phantom contained iodine, gadolinium, calcification, and lipid. The Feld-kamp-Davis-Kress (FDK) with the sinogram interpolation method and Maximum Likelihood Expectation Maximization (MLEM) algorithm were used to reconstruct the images. We evaluated the signal-to-noise ratio (SNR) of the materials. The SNRs of iodine, calcification, and liquid lipid were increased by 167.03%, 157.93%, and 41.77%, respectively, with the 23~33 keV energy bin using the sinogram interpolation method. The SNRs of iodine, calcification, and liquid state lipid were also increased by 107.01%, 13.58%, and 27.39%, respectively, with the 34~44 keV energy bin using the sinogram interpolation method. Although the FDK algorithm with the sinogram interpolation did not produce better results than the MLEM algorithm, it did result in comparable image quality to that of the MLEM algorithm. We believe that the sinogram interpolation method can be applied in various reconstruction studies using the analytic reconstruction algorithm. Therefore, the sinogram interpolation method can improve the image quality in sparse-angular sampling and be applied to CT applications.
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( Dohyeon Lee ),( Sungmin Park ),( Sunho Park ),( Daun Kim ),( Woochan Kim ),( Hoon Seonwoo ),( Sujin Kim ),( Jangho Kim ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1
Biocompatible capsules have recently been highlighted as novel delivery platforms of any “materials” (e.g., drug, food, agriculture pesticide) to address current problems of living systems such as humans, animals, and plants in academia and industry for agriculture, biological, biomedical, environmental, food applications. For example, biocompatible alginate capsules were proposed as a delivery platform of biocontrol agents (e.g., bacterial antagonists) for an alternative to antibiotics, which will be a potential strategy in future agriculture. Here, we proposed a new platform based on biocompatible alginate capsules that can control the movements as an active target delivery strategy for various applications including agriculture and biological engineering. In this study, we developed large-scale iron oxide nanoparticle-incorporated alginate capsules and investigated the movement performances of capsules under magnetic fields. The capsules described in this work were generated from ionically cross-linked alginate, and various concentrations of iron oxide nanoparticles were inserted into the capsules. It was found that the sizes of large scale alginate capsules could be controlled via various working conditions such as concentrations of alginate solutions and iron oxide nanoparticles. As a proof of concept work, we showed that the iron oxide particles-incorporated large scale alginate capsules could be moved by the magnetic fields, which would be a strategy as active target delivery platforms for agriculture and biological engineering.
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( Sujin Kim ),( Sunho Park ),( Daun Kim ),( Woochan Kim ),( Dohyeon Lee ),( Sungmin Park ),( Jangho Kim ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1
Living cells are exposed to complex and functional microenvironment including soluble macromolecules, biophysical cues, and interactions between cell-cell and cell-extracellular matrix (ECM). This suggests that the design and manipulation of engineered cellular microenvironments is of great important in a wide variety of biological applications such as fundamental biology, therapeutic and diagnostic research, stem cells and regenerative medicine, and developing in vitro disease models. In this work, we described the development of nanoscale engineered biomimetic systems for animal tissue engineering. Specifically, we showed the nanoscale patterned scaffolds inspired by the unique architectures of native animal tissues and ECMs that can provide cells the in vivo-like topographical cell environment, and their applications for better understanding of the function of living animal cells and tissue regeneration without complex surgical treatments.
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( Daun Kim ),( Woochan Kim ),( Sunho Park ),( Dohyeon Lee ),( Sungmin Park ),( Sujin Kim ),( Jangho Kim ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1
The various surfaces in nature have great potential in both the academia and the industry. In particular, the lotus leaves surface exhibit a unique surface consisting of evenly distributed micro and nanoscale structures (i.e., called as ‘lotus effect’ (superhydrophobic property)). For these reasons, many studies were performed about the lotus effect to design and manipulation of engineering platforms or devices. With this consideration, various natural leaves have unique micro and nanoscale structures that can have controlled hydrophilic and hydrophobic properties. Here, we report on the tunable replication of surface topographies of natural leaves of common camellia, fragrant plantain, and lotus onto thin polymeric films using a capillarity-directed soft lithography technology. To this end, the surfaces of natural leaves were first replicated using polydimethylsiloxane (PDMS) as molds. The poly(ε-caprolactone) (PCL) film was then coated on the glass using spin-coating technique. Finally, the PCL-based unique micro- and nanostructures of natural leaves were generated using PDMS molds. The micro and nanostructure, chemical composition, wettability was characterized using scanning electron microscopy, atomic force microscope, Fourier transform infrared spectroscopy, X-ray diffraction, and contact angle measurement.
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Engineering nanowrinkled microfibers composed of eggshell membrane and graphene
Park, Sunho,Choi, Kyoung Soon,Kim, Woochan,Lee, Dohyeon,Kim, Daun,Kim, Myung-Sun,Kim, Kyunghoon,Kim, Jangho Elsevier 2018 Materials letters Vol.229 No.-
<P><B>Abstract</B></P> <P>We present a facile method for designing and manipulating eggshell membrane-based nanowrinkled microfibers (EMNMs) using graphene and a spin-coating technique. Graphene is simply spin-coated on the eggshell membrane to form multiscale structures of nanowrinkled microfibers. We demonstrate that the EMNMs combine the unique properties of the raw eggshell membrane and graphene, such as micro- and nanoscale hierarchical morphologies, specific crystalline structures, and surface wettability. We also show that the properties of the EMNMs can be controlled by adjusting the concentration of graphene.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nanowrinkled microfibers composed of eggshell membrane and graphene are fabricated. </LI> <LI> The properties of the prepared nanowrinkled microfibers are investigated. </LI> <LI> The microfiber properties can be controlled by adjusting the graphene concentration. </LI> </UL> </P>
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