• 한국인공지능학회지
• /
• 제9권2호
• /
• pp.1-5
• /
• 2021

Although CT has an advantage in describing the three-dimensional anatomical structure of the human body, it also has a disadvantage in that high doses are exposed to the patient. Recently, a deep learning-based image reconstruction method has been used to reduce patient dose. The purpose of this study is to analyze the dose reduction and image quality improvement of deep learning-based reconstruction (DLR) on the adult's chest CT examination. Adult lung phantom was used for image acquisition and analysis. Lung phantom was scanned at ultra-low-dose (ULD), low-dose (LD), and standard dose (SD) modes, and images were reconstructed using FBP (Filtered back projection), IR (Iterative reconstruction), DLR (Deep learning reconstruction) algorithms. Image quality variations with respect to varying imaging doses were evaluated using noise and SNR. At ULD mode, the noise of the DLR image was reduced by 62.42% compared to the FBP image, and at SD mode, the SNR of the DLR image was increased by 159.60% compared to the SNR of the FBP image. Based on this study, it is anticipated that the DLR will not only substantially reduce the chest CT dose but also drastic improvement of the image quality.

• 한국의학물리학회:학술대회논문집
• /
• 한국의학물리학회 2002년도 Proceedings
• /
• pp.322-323
• /
• 2002

Partial volume averaging effect of PET data influences on the accuracy of quantitative measurements of regional brain metabolism because spatial resolution of PET is limited. The purpose of this study was to evaluate the accuracy of partial volume correction carried out on $^{18}$ F-PET images using Hoffman brain phantom. $^{18}$ F-PET Hoffman phantom images were co-registered to MR slices of the same phantom. All the MR slices of the phantom were then segmented to be binary images. Each of these binary images was convolved in 2 dimensions with the spatial resolution of the PET. The original PET images were then divided by the smoothed binary images in slice-by-slice, voxel-by-voxel basis resulting in larger PET image volume in size. This enlarged partial volume corrected PET image volume was multiplied by original binary image volume to exclude extracortical region. The evaluation of partial volume corrected PET image volume was performed by region of interests (ROI) analysis applying ROIs, which were drawn on cortical regions of the original MR image slices, to corrected and original PET image volume. From the ROI analysis, range of regional mean values increases of partial volume corrected PET images was 4 to 14%, and average increase for all the ROIs was about 10% in this phantom study. Hoffman brain phantom study was useful for the objective evaluation of the partial volume correction method. This MR-based correction method would be applicable to patients in the. quantitative analysis of FDG-PET studies.

• Korean Journal of Radiology
• /
• 제21권9호
• /
• pp.1095-1103
• /
• 2020

Objective: The present study aimed to investigate whether quantitative dual-energy computed tomography (DECT) parameters offer an incremental risk stratification benefit over the CT ventricular diameter ratio in patients with acute pulmonary embolism (PE) by using propensity score analysis. Materials and Methods: This study was conducted on 480 patients with acute PE who underwent CT pulmonary angiography (CTPA) or DECT pulmonary angiography (DE CT-PA). This propensity-matched study population included 240 patients with acute PE each in the CTPA and DECT groups. Altogether, 260 (54.1%) patients were men, and the mean age was 64.9 years (64.9 ± 13.5 years). The primary endpoint was all-cause death within 30 days. The Cox proportional hazards regression model was used to identify associations between CT parameters and outcomes and to identify potential predictors. Concordance (C) statistics were used to compare the prognoses between the two groups. Results: In both CTPA and DECT groups, right to left ventricle diameter ratio ≥ 1 was associated with an increased risk of all-cause death within 30 days (hazard ratio: 3.707, p < 0.001 and 5.573, p < 0.001, respectively). However, C-statistics showed no statistically significant difference between the CTPA and DECT groups for predicting death within 30 days (C-statistics: 0.759 vs. 0.819, p = 0.117). Conclusion: Quantitative measurement of lung perfusion defect volume by DECT had no added benefit over CT ventricular diameter ratio for predicting all-cause death within 30 days.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2013년도 자성 및 자성재료 국제학술대회
• /
• pp.106-107
• /
• 2013

• 한국의학물리학회:학술대회논문집
• /
• 한국의학물리학회 2006년도 제33회 추계학술대회 발표논문집
• /
• pp.48-48
• /
• 2006

• 대한영상의학회지
• /
• 제83권3호
• /
• pp.750-750
• /
• 2022

• 대한방사선기술학회지:방사선기술과학
• /
• 제39권3호
• /
• pp.399-406
• /
• 2016

비전리-방사선의 일종인 근적외선은 비침습적이고, 비전리성을 가지며, 생체 내 높은 투과성을 가지는 전자기파로, 진단을 위한 의료영상분야에 전 세계적으로 관심이 증가하여 그 활용 가능성이 활발히 연구되어지고 있다. 그러나 현재 국내에서 근적외선 의료영상의 활용은 극히 제한되어 있으며, 큰 관심을 가지고 있지 못하여, 새롭게 형성되는 근적외선 기반 의료영상 분야의 방사선사의 대응 역량의 강화가 필요시 된다. 본 연구에서는 근적외선의 특징 및 영상화 원리를 간략히 소개하고, 이를 이용한 최신의 연구 주제 및 세계적인 연구 동향을 소개함으로서 국내 방사선사의 역량을 강화하고자 한다. 특히, 임상적 활용 가능성이 매우 높은 상처 및 당뇨발등의 연구 주제에 대해서 소개하여, 이 분야의 발전을 가속화 시키는데 기여하고자 한다.

• IEIE Transactions on Smart Processing and Computing
• /
• 제4권5호
• /
• pp.305-310
• /
• 2015

We propose a new concept for a depth of interaction (DOI) positron emission tomography (PET) detector based on dual-ended-scintillator (DES) readout for small animal imaging. The detector consists of lutetium yttrium orthosilicate (LYSO) arrays coupled with orthogonal wavelength-shifting (WLS) fibre placed on the top and bottom of the arrays. On every other line, crystals that are 2 mm shorter are arranged to create grooves. WLS fibre is inserted into these grooves. This paper describes the design and performance evaluation of this PET detector using Monte Carlo simulations. To investigate sensitivity by crystal size, five types of PET detectors were simulated. Because the proposed detector is composed of crystals with three different lengths, degradation in sensitivity across the field of view was also explored by simulation. In addition, the effect of DOI resolution on image quality was demonstrated. The simulation results proved that the devised PET detector with excellent DOI resolution is helpful for reducing the channels of sensors/electronics and minimizing gamma ray attenuation and scattering while maintaining good detector performance.

• 한국환경성돌연변이발암원학회지
• /
• 제25권2호
• /
• pp.76-81
• /
• 2005

25-Hydroxycholesterol (cholest-5-ene-3, 25-diol, 25-OHC) showed the cytotoxicity on HeLa human cervix and NCI-H460 human lung cancer cells, $0.5{\mu}M\;of\;50\%$ inhibitory concentration. We studied 25-OHC as the possibility of radiation sensitizer. The combination effect of 25-OHC and y-irradiation measured using flow cytometer with propidium iodide stained cells. The combined treatment of 25-OHC and $\gamma-irradiation$ did not show significant enhancing effects on Hela and NCI-H460 cells.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제10권6호
• /
• pp.556-563
• /
• 2005

Homogentisic acid was found to scavenge intracellular reactive oxygen species (ROS), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and thus prevented lipid peroxidation in human fibroblast (Wl 38) cells. The radical scavenging activity of homogentisic acid was found to protect Wl 38 cells against hydrogen peroxide $(H_2O_2)$ induced oxidative stress, via the activation of extracellular signal regulated kinase (ERK) protein. Homogentisic acid increased the activity of catalase. Hence, from the present study, it is suggested that homogentisic acid protects Wl 38 cells against $H_2O_2$ damage by enhancing the intracellular antioxidative activity.