Examination of the optimal temporal resolution required for computed tomography coronary angiography

13301甲第3941号博士（保健学）金沢大学博士論文要旨Abstract 要約Outline 以下に掲載：Radiological Physics and Technology 6(2) pp.453-460 2013. Springer. 共著者：Kazuya Ohashi, Katsuhiro Ichikawa, Masaki Hara, Tatsuya Kawai, Hiroshi Kunitomo, Ryo Higashide, Yuta Shibamot

筋芽細胞に対する亜鉛の効果および作用機序に関する研究

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 松田 良一, 東京大学教授 石浦 章一, 東京大学教授 八田 秀雄, 東京大学准教授 坪井 貴司, 東京大学教授 石井 直方University of Tokyo(東京大学

Application of a variable filter for presampled modulation transfer function analysis with the edge method

We devised a new noise filtering method to reduce the noise in the line spread function (LSF) for presampled modulation transfer function (MTF) analysis with the edge method. A filter was designed to reduce noise effectively using a position-dependent filter controlled by the boundary frequency b for low-pass filtering, which is calculated by 1/2d (d: distance from the LSF center). In this filtering process, strong filters with very low b can be applied to regions distant from the LSF center, and the region near the LSF center can be maintained simultaneously by a correspondingly high b. Presampled MTF accuracies derived by use of the proposed method and an edge spread function (ESF)-fitting method were compared by use of simulated ESFs with and without noise, resembling a computed radiography (CR) and an indirect-type flat panel detector (FPD), respectively. In addition, the edge images of clinical CR, indirect-type FPD, and direct-type FPD systems were examined. For a simulated ESF without noise, the calculated MTFs of the variable filtering method agreed precisely with the true MTFs. The excellent noise-reduction ability of the variable filter was demonstrated for all simulated noisy ESFs and those of three clinical systems. Although the ESF-fitting method provided excellent noise reduction only for the CR-like simulated ESF with noise, its noise elimination performance could not be demonstrated due to the lesser robustness of the fitting. © 2015, Japanese Society of Radiological Technology and Japan Society of Medical Physics.発行後1年より全文公

Economical Wet Extraction of Lipid from labyrinthula Aurantiochytrium limacinum by Using Liquefied Dimethyl Ether

Recently, a simple method for the extraction of lipids from wet biomass using liquefied dimethyl ether (DME) without drying, cell disruption, or heating was proposed. Here, the versatility of this method was evaluated for labyrinthula Aurantiochytrium limacinum (A. limacinum). The liquefied DME was passed through the extractor that filled by A. limacinum at different time intervals. The extraction of lipids from A. limacinum of moisture-rich microorganism was successfully achieved, the yield of lipid was 46.1 wt% of the dry weight of the sample. In comparison, the yields of lipid were 21.3 wt%, 43.6 wt% and 50.7 wt% when supercritical carbon dioxide (SCCO2), hexane-Soxhlet and Bligh-Dyer (BD) extraction methods were applied as extractants, respectively. However, the drying and cell-disruption process were required in SCCO2, hexane-Soxhlet, and BD extraction methods

Suzaku observations of the Hydra A cluster out to the virial radius

We report Suzaku observations of the northern half of the Hydra A cluster out to ~1.4 Mpc, reaching the virial radius. This is the first Suzaku observations of a medium-size (kT ~3 keV) cluster out to the virial radius. Two observations were conducted, north-west and north-east offsets, which continue in a filament direction and a void direction of the large-scale structure of the Universe, respectively. The X-ray emission and distribution of galaxies elongate in the filament direction. The temperature profiles in the two directions are mostly consistent with each other within the error bars and drop to 1.5 keV at 1.5 r_500. As observed by Suzaku in hot clusters, the entropy profile becomes flatter beyond r_500, in disagreement with the r^1.1 relationship that is expected from accretion shock heating models. When scaled with the average intracluster medium (ICM) temperature, the entropy profiles of clusters observed with Suzaku are universal and do not depend on system mass. The hydrostatic mass values in the void and filament directions are in good agreement, and the Navarro, Frenk, and White universal mass profile represents the hydrostatic mass distribution up to ~ 2 r_500. Beyond r_500, the ratio of gas mass to hydrostatic mass exceeds the result of the Wilkinson microwave anisotropy probe, and at r_100, these ratios in the filament and void directions reach 0.4 and 0.3, respectively. We discuss possible deviations from hydrostatic equilibrium at cluster outskirts. We derived radial profiles of the gasmass- to-light ratio and iron-mass-to-light ratio out to the virial radius. Within r_500, the iron-mass-to-light ratio of the Hydra A cluster was compared with those in other clusters observed with Suzaku.Comment: 16 pages, 15 figures; Accepted for publication in PAS

Assessment of temporal resolution of multi-detector row computed tomography in helical acquisition mode using the impulse method

The purpose of this study was to propose a method for assessing the temporal resolution (TR) of multi-detector row computed tomography (CT) (MDCT) in the helical acquisition mode using temporal impulse signals generated by a metal ball passing through the acquisition plane. An 11-mm diameter metal ball was shot along the central axis at approximately 5m/s during a helical acquisition, and the temporal sensitivity profile (TSP) was measured from the streak image intensities in the reconstructed helical CT images. To assess the validity, we compared the measured and theoretical TSPs for the 4-channel modes of two MDCT systems. A 64-channel MDCT system was used to compare TSPs and image quality of a motion phantom for the pitch factors P of 0.6, 0.8, 1.0 and 1.2 with a rotation time R of 0.5s, and for two R/. P combinations of 0.5/1.2 and 0.33/0.8. Moreover, the temporal transfer functions (TFs) were calculated from the obtained TSPs. The measured and theoretical TSPs showed perfect agreement. The TSP narrowed with an increase in the pitch factor. The image sharpness of the 0.33/0.8 combination was inferior to that of the 0.5/1.2 combination, despite their almost identical full width at tenth maximum values. The temporal TFs quantitatively confirmed these differences. The TSP results demonstrated that the TR in the helical acquisition mode significantly depended on the pitch factor as well as the rotation time, and the pitch factor and reconstruction algorithm affected the TSP shape. © 2015 Associazione Italiana di Fisica Medica.Embargo Period 12 month