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SU-E-T-717: Surface Coating for Prevention of Metallic Seed Migration in Tissues

Medical Physics 2015年第6PART23期42卷 3501-3502页

作者： H Lee W Lee J Park Y Choy S Ye Program in Biomedical Radiation Sciences Department of Transdisciplinary Studies Graduate School of Convergence Science and Technology Seoul National University Seoul Korea Interdisciplinary Program in Bioengineering Seoul National University College of Engineering Seoul Korea Department of Biomedical Engineering Seoul National University College of Medicine Seoul Korea Department of Radiation Oncology Seoul National University Hospital Seoul Korea

Purpose: In radiotherapy, metallic implants often detach from their deposited sites and migrate to other locations. This undesirable migration could cause inadequate dose coverage for permanent brachytherapy and difficulties in image-guided radiation delivery for patients. To prevent migration of implanted seeds, we propose a potential strategy to use of a biocompatible and tissue-adhesive material called polydopamine. Methods: In this study, non-radioactive dummy seeds that have the same geometry and composition as commercial I-125 seeds were coated in polydopamine. Using scanning electron microscopy and X-ray photoelectron spectroscopy, the surface of the polydopamine-coated and non-coated seeds was characterized. The detachment stress between the two types of seeds and the tissue was measured. The efficacy of polydopamine-coated seed was investigated through in-vitro migration tests by tracing the seed location after tissue implantation and shaking for given times. The cytotoxicity of the polydopamine coating was also evaluated. Results: The results of the coating characterization have shown that polydopamine was successfully coated on the surface of the seeds. In the adhesion test, the polydopamine-coated seeds had 2.1-fold greater detachment stress than non-coated seeds. From the in-vitro test, it was determined that the polydopamine-coated seed migrated shorter distances than the non-coated seed. This difference was increased with a greater length of time after implantation. Conclusion: We suggest that polydopamine coating is an effective technique to prevent migration of implanted seeds, especially for permanent prostate brachytherapy.

关键词： Tissues Brachytherapy Dosimetry Metallic coatings Scanning electron microscopy Biocompatibility Image guided radiation therapy Medical imaging X-ray photoelectron spectroscopy

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Left atrial wall thickness and its relationship with reconnection after pulmonary vein isolation in patients with atrial fibrillation evaluated using a three-dimensional wall thickness map

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International Journal of Arrhythmia 2021年第1期22卷 1-13页

作者： Oh, Seil Joo, Yoon Ha Lee, Euijae Lee, So-Ryoung Cha, Myung-Jin Choi, Eue-Keun Lee, Jung Chan Lee, Whal Department of Internal Medicine Seoul National University College of Medicine and Seoul National University Hospital Seoul Republic of Korea Interdisciplinary Program in Bioengineering Seoul National University Seoul Korea Department of Biomedical Engineering Seoul National University College of Medicine Seoul Korea Department of Radiology Seoul National University Hospital Seoul Korea

The major cause of recurrence after pulmonary vein (PV) isolation for atrial fibrillation (AF) is PV reconnection, and thicker wall could be associated with reconnection. This study aimed to evaluate the wall thickness of the PV antrum in reconnection sites using a three-dimensional (3D) wall thickness map. A total of 91 patients who underwent a second ablation procedure due to AF recurrence were evaluated. The locations of the PV reconnection sites were confirmed in electroanatomical maps. A 3D atrial wall thickness (AWT) map was created using computed tomography scan data. The AWT values of the ablation lines of the index procedure were graded in each segment of the PV antrum: grade 1, 0.5 < AWT ≤ 1.0 mm; grade 2, 1.0 < AWT ≤ 1.5 mm; grade 3, 1.5 < AWT ≤ 2.0 mm; grade 4, 2.0 < AWT ≤ 2.5 mm; grade 5, AWT > 2.5 mm. A total of 281 PV reconnection sites among 1256 segments of the PV antrum in 79 patients were detected. The average AWT grades were 2.7 ± 1.0 and 2.2 ± 1.0 in the reconnected and non-reconnected segments, respectively (P < 0.01). Higher AWT grades were observed in the reconnected superior segments of the left superior PV, carina and inferior segments of the left inferior PV, superior and posterior segments of the right superior PV, and posterior and inferior segments of the right inferior PV. The reconnected segments of the PV antrum showed thicker myocardium than the non-reconnected ones in patients with recurrent AF after catheter ablation. A wall thickness map for PV isolation could be considered for customized ablation in order to reduce PV reconnection.

关键词： Catheter ablation Atrial fibrillation Pulmonary vein Wall thickness

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Surface force sensed by cells used for autonomous migration

Surface force sensed by cells used for autonomous migration

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IEEE SENSORS

作者： Juhee Hong Sujin Lee Misun Cha Junghoon Lee School of Mechanical and AeroSpace Engineering Seoul National University South Korea Interdisciplinary Program in Bioengineering Seoul National University South Korea Institute of Advanced Machinery and Design Seoul National University South Korea Seoul National University Gwanak-gu Seoul KR

In this study, we develop a platform for investigating the mechanical perceptual ability of a cell and monitor its migration guided by a pure surface gradient rigidity. The cells are cultured on a flexible substrate with variable mechanical stiffness with other conditions kept unvarying. The thickness polydimethylsiloxane (PDMS) layer on glass trench surface with thickness variation was used to create a rigidity gradient between stiff (2.5 ¿m) and soft (7.5 ¿m) regions. The changes of surface rigidity were 48.8% in normal direction (stiff: 2.9 N/m, soft: 1.4 N/m) and 25.5% in lateral direction (stiff: 1 N/m, soft: 0.8 N/m), respectively. A fabrication process of rigidity gradient composite layered micro-device was developed to minimize the topographical effect that may alter the patterns of cell attachment and migration. We cultured NIH 3T3 cells on the proposed flexible substrate coated with an extracellular matrix (ECM), and demonstrated that the cells were strongly affected by the mechanical rigidity of surface. The designed device can be used to facilitate our understanding of mechanotransduction in cells under a given environment.

关键词： Surface topography Cells (biology) Glass Fabrication Extracellular Electrochemical machining

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Segmented OctaSiPM for Dual-ended Readout of BGO to Improve Timing Resolution in Time-of-Flight PET

Segmented OctaSiPM for Dual-ended Readout of BGO to Improve ...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： M. Yi D. Lee A. Gola S. Merzi M. Penna J.S. Lee S. R. Cherry S.I. Kwon Department of Biomedical Engineering University of California Davis Davis California United States of America Interdisciplinary Program in Bioengineering College of Engineering Seoul National University Seoul Republic of Korea Fondazione Bruno Kessler Trento Italy Brightonix Imaging Inc Seoul Republic of Korea

ISBN: (数字)9798350388152

ISBN: (纸本)9798350388169

BGO has been highlighted as a cost-effective option for hybrid scintillator/Cherenkov radiator. However, effectively utilizing its improved timing resolution is hindered by challenges in managing the high detection fluctuation of Cherenkov photons and their spectral overlap with scintillation photons. Our previous study showed that the dual-ended readout and an adaptive timestamp method could enhance the detection of quasi-isotropically and simultaneously emitted Cherenkov photons in BGO. The OctaSiPM, developed by FBK, features a single pixel active area of 2.5 × 1.4 mm 2 and a 2 × 4 SiPM arrangement, offering a total active area of 5.3 × 5.8 mm 2 . In our recent investigation, when one end of a BGO crystal was coupled to two segmented pixels of the OctaSiPM, additional information about the initial photon density of the corresponding event could be provided. Thus, we hypothesize that the combination of the segmentation scheme and the dual-ended readout can provide multidimensional information on gamma events in BGO TOF-PET detectors. In the experimental setup, a Teflon-wrapped polished BGO crystal was read out from both ends using OctaSiPMs, followed by low-noise high-frequency amplification. Coincidence detection of gamma rays was conducted between a BGO detector and an LYSO:Ce:Mg reference detector. Relationship between segmented pixel time differences and top-bottom time differences revealed a unique pattern correlating with Cherenkov photon events. By selectively adjusting time windows, time difference distribution converged towards a single Gaussian distribution, enabling the selection of pure Cherenkov-triggered events. This marks the first instance of achieving a single Gaussian fitting from BGO data, underscoring the novelty and importance of our findings. Moreover, the analysis of initial photon counts provided insights into the likelihood of prompt Cherenkov photon detection and its temporal density.

关键词： Microwave integrated circuits Image segmentation Image resolution Fluctuations Semiconductor detectors Gamma-rays Crystals

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Dynamic Threshold Discriminator - Mutual Learning for Scalable Time Stamping Neural Networks

Dynamic Threshold Discriminator - Mutual Learning for Scalab...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： S. Bae M. Yi J.S. Lee Seoul National University Graduate School Interdisciplinary Program in Bioengineering Seoul Republic of Korea Seoul National University Graduate School Integrated Major in Innovative Medical Science Seoul Republic of Korea Department of Nuclear Medicine Seoul National University Seoul Republic of Korea

The precision of emission image estimation relies on accurate interaction time estimation, which is becoming increasingly possible with neural network-based time stamping methods. In order to expand the use of these methods to multiple detector systems and facilitate mutual training, we leverage the inherent variance-bias characteristics of scintillator detectors. Our neural network, called the Dynamic Threshold Discriminator (DTD), is designed to estimate appropriate thresholds for given waveforms rather than estimating time stamps directly to exploit the characteristic. We assessed the feasibility of DTD using experimental data and compared it to classical time stamping methods (LED, CFD, LED with energy correction) and a neural network-based time stamping method. The proposed method showed a 12% lower coincidence timing resolution compared to LED with energy correction for a 500 keV energy window even without energy information and demonstrated robust performance regardless of the digitizer's sampling rate.

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Development of exosome membrane materialsfused microbubbles for enhanced stability and efficient drug delivery of ultrasound contrast agent

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Acta Pharmaceutica Sinica B 2023年第12期13卷 4983-4998页

作者： Yongho Jang Jeehun Park Pilsu Kim Eun-Joo Park Hyungjin Sun Yujin Baek Jaehun Jung Tai-kyong Song Junsang Doh Hyuncheol Kim Department of Chemical and Biomolecular Engineering Sogang UniversitySeoul 04107Republic of Korea Research Institute of Advanced Materials(RIAM) Institute of Engineering ResearchSeoul National UniversitySeoul 08826Republic of Korea Department of Electronic Engineering Sogang UniversitySeoul 04107Republic of Korea Biomedical Research Institute&Department of Radiology Seoul National University HospitalSeoul 03080Republic of Korea Interdisciplinary Program in Bioengineering Seoul National UniversitySeoul 08826Republic of Korea Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Institute of Engineering Research Bio-MAX InstituteSeoul National UniversitySeoul 08826Republic of Korea Department of Biomedical Engineering Sogang UniversitySeoul 04107Republic of Korea

Lipid-coated microbubbles are widely used as an ultrasound contrast agent,as well as drug delivery ***,the two main limitations in ultrasound diagnosis and drug delivery using microbubbles are the short half-life in the blood system,and the difficulty of surface modification of microbubbles for active *** exosome,a type of extracellular vesicle,has a preferentially targeting ability for its original *** this study,exosome-fused microbubbles(Exo-MBs)were developed by embedding the exosome membrane proteins into *** a result,the stability of Exo-MBs is improved over the conventional *** the same principle that under the exposure of ultrasound,microbubbles are cavitated and self-assembled into nano-sized particles,and Exo-MBs are self-assembled into exosome membrane proteins-embedded nanoparticles(Exo-NPs).The Exo-NPs showed favorable targeting properties to their original cells.A photosensitizer,chlorin e6,was loaded into Exo-MBs to evaluate therapeutic efficacy as a drug *** higher therapeutic efficacy of photodynamic therapy was confirmed,followed by cancer immunotherapy from immunogenic cell *** have therefore developed a novel ultrasound image-guided drug delivery platform that overcomes the shortcomings of the conventional ultrasound contrast agent and is capable of simultaneous photodynamic therapy and cancer immunotherapy.

关键词： Exosomes Microbubbles Photodynamic therapy Ultrasound Sonoporation Cancer immunotherapy Drug delivery

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Analysis of blood and dialysate flow in a hemodialyzer by perfusion computed tomography

Analysis of blood and dialysate flow in a hemodialyzer by pe...

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World Congress on Medical Physics and Biomedical Engineering: Diagnostic and Therapeutic Instrumentation, Clinical Engineering

作者： Kim, J.C. Kim, J.H. Kim, H.-C. Kang, E. Ronco, C. Kim, H.C. Institute of Medical and Biological Engineering College of Medicine Seoul National University Seoul Korea Republic of Interdisciplinary Program in Bioengineering Major Seoul National University Seoul Korea Republic of Department of Radiology Seoul National University Hospital Seoul Korea Republic of Department of Internal Medicine Chung-Ang University Hospital Seoul Korea Republic of Vincenza Italy Department of Biomedical Engineering College of Medicine Seoul National University 28 Yeongeon-dong Jongno-gu Seoul 110-744 Korea Republic of

ISBN: (纸本)9783642038846

Perfusion computed tomography (PCT) is a means to rapidly and easily evaluate cerebral perfusion in patients presenting with acute stroke symptoms, which pro-vides insights into capillary-level hemodynamics. In this study, we used PCT to analyze the 3-dimensional blood and dialysate flow in a low-flux hemodialyzer equipped with a standard fiber bundle. The dynamic CT studies were performed with 64-channel multi-detector row CT (MDCT) at a dialysate flow rate of 500 ml/min and a 1.0 ml/sec injection rate of contrast agent. Central volume principle was used to calculate hydro-dynamic parameters by deconvolution of time-density curves (TDCs). Functional maps of PCT parameters quantitatively described the blood and dialysate flow maldistribution, varia-tions in fiber packing, and perfusion pressure distribution in a hemodialyzer. PCT was able to overcome the limitations of conventional imaging techniques for analyzing dialysate flow distributions in hollow-fiber dialyzers. Therefore, PCT is a quantitative analysis method to provide better insights into hemodynamics of hollow-fiber dialyzers and is expected to contribute to optimization of artificial kidneys. © 2009 Springer-Verlag.

关键词： Computerized tomography

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Recent technological advances in lab-on-a-chip for bone remodeling

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Biosensors and Bioelectronics: X 2023年 14卷

作者： Kim, Seoyeon Rajendran, Arun Kumar Amirthalingam, Sivashanmugam Kim, Jung Hun So, Kyoung-Ha Hwang, Nathaniel S. School of Chemical and Biological Engineering Institute of Chemical Processes Seoul National University Seoul08826 Korea Republic of Institute of Chemical Processes Seoul National University Seoul08826 Korea Republic of Institute of Engineering Research Seoul National University Seoul08826 Korea Republic of Bio-MAX/N-Bio Institute of Bioengineering Seoul National University Seoul08826 Korea Republic of Interdisciplinary Program in Bioengineering Seoul National University Seoul08826 Korea Republic of

Lab-on-a-chip (LOC) is a three-dimensional cell culture platform with a microfluidic flow that biomimics the physiological system of various organs. LOC emerged as a future replacement technology for in vitro cell-based models and in vivo animal models, gaining popularity in the field of physiology, pharmacology, and biology. Nowadays, sensors are incorporated into the LOC system to monitor real-time parameters of the cell and its microenvironment in response to biophysical and/or biochemical stimuli and maturation. A considerable amount of studies has been conducted to detect the mechanical, physical, electrical, and metabolic parameters of engineered organs. This paper aims to provide a comprehensive insight into how the biosensor-implemented LOC platform can be utilized for the analysis of tissue recapitulating systems with a focus on bone remodeling. We describe chip design, basic principles of sensors, and ongoing recent efforts to perform in-line analysis of engineered organoids. This review also presents various imaging techniques used as analytical tools for visualizing LOC. © 2023 The Author(s)

关键词： Biosensors

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Emulating Scanning Process for Stochastic Bone Scan Denoising

Emulating Scanning Process for Stochastic Bone Scan Denoisin...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： S. Bae J.S. Lee Seoul National University Interdisciplinary Program in Bioengineering Seoul Republic of Korea Seoul National University Integrated Major in Innovative Medical Science Seoul Republic of Korea Department of Nuclear Medicine Seoul National University Seoul Republic of Korea Brightonix Imaging Inc Seoul Republic of Korea

ISBN: (数字)9798350388152

ISBN: (纸本)9798350388169

Improving the quality of low-dose nuclear medicine images can reduce radiation exposure and acquisition time, and deep learning is a major trend in this area. Due to the nature of deterministic denoising, restored images are often blurred. In this study, we used the Generative Accumulation of Photons (GAP) method to stochastically denoise bone scan images by emulating the scanning process. The effectiveness of the method was evaluated using 99mTc MDP and DPD bone scan images from Seoul National University Hospital and compared with well-established deterministic denoising schemes - low-dose image to low-dose image training (Noise2Noise, N2N) and low-dose image to full-dose image supervised training (Noise2Full, N2F). The mean of stochastically sampled full-dose images using GAP showed higher structural similarity index measure (SSIM) and peak signal-to-noise ratio (PSNR) compared to N2F and N2N denoising results, along with good perceptual metrics calculated using Learned Perceptual Image Patch Similarity (LPIPS). For denoising $50 \%$ dose images, GAP achieved SSIM of 0.938, PSNR of 36.76 dB, and LPIPS of 0.039. Additionally, for denoising 20% dose images, GAP achieved SSIM of 0.891, PSNR of 34.34 dB, and LPIPS of 0.086 (average of 41 images).

关键词： Training Semiconductor device measurement Nuclear medicine Microwave integrated circuits PSNR Semiconductor detectors Noise reduction

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Estimation of Sleep Posture using a Patch-type Accelerometer based Device

Estimation of Sleep Posture using a Patch-type Accelerometer...

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Annual International Conference of the IEEE Engineering in Medicine and Biology Society

作者： Heenam Yoon Suhwan Hwang Dawoon Jung Sangho Choi Kwangmin Joo Jaewon Choi Yujin Lee Do-Un Jeong Kwangsuk Park the Interdisciplinary Program in Bioengineering Seoul National University Seoul 110-799 Korea the Department of Neuropsychiatry and the Center for Sleep and Chronobiology Seoul National University Hospital Seoul 110-744 Korea the Department of Biomedical Engineering College of Medicine Seoul National University Seoul 110-799 Korea

ISBN: (纸本)9781424492695

In this study, we developed a sleep posture estimation algorithm using 3-axis accelerometer signals measured from a patch-type sensor. Firstly, we inspected the characteristics of accelerometer signals for different sleep postures. Based on the results, we established decision rules to estimate 5 postures containing supine, left, right lateral, prone postures, and non-sleep postures such as sitting and standing. The algorithm was tested by the data from thirteen subjects during night time PSG. As a result, the algorithm estimated sleep postures with an average agreement of 99.16%, and cohen's kappa of 0.98 compared with reference sleep postures determined by position sensor and video recording. The proposed method with the device could be used as supportive purpose in routine PSG study and out-of-hospital environment.

关键词： PSG Estimation Patch-type Accelerometer

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