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ABSTRACT: The present study investigates the mechanical properties of three embolization microspheres (E-ms): tris-acryl gelatin microspheres (TG-ms), acrylamido polyvinyl alcohol microspheres (APVA-ms), and polyphosphazene-coated polymethylmethacrylate microspheres (PP-PMMA-ms). Compression and relaxation tests were performed on monolayers of particles and their Young's moduli and relaxation half times (RHTs) were determined. The elasticity of E-ms was evaluated by applying Hertz theory with the assumptions of incompressibility and a Poisson's ratio of 0.5. The Young's moduli of TG-ms, APVA-ms, and PP-PMMA-ms were 39.6±5.05 kPa, 18.8±4.00 kPa, and 13.6±1.98 kPa, respectively. The RHTs of TG-ms, APVA-ms, and PP-PMMA-ms were 52.3±5.56 s, 59.1±8.16 s, and 31.0±7.01 s, respectively. TG-ms have a high rigidity and deform slightly under a sustained compression since they have a high elasticity. PP-PMMA-ms are soft and deform a lot under sustained compression. They are more viscous than the other two microspheres. APVA-ms have intermediate material properties, having the same low rigidity as PP-PMMA-ms and being more elastic than TG-ms.
Journal of the mechanical behavior of biomedical materials. 11/2011; 4(8):2161-7.
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ABSTRACT: Embolic agents are used in vascular interventional radiology to occlude arteries under pathological conditions. The present study was performed to investigate the material properties of two microspherical embolic agents (MSEAs), tris-acryl gelatin microspheres (TGMS) and superabsorbent polymer microsphere (SAP-MS), using a loading-unloading compression test. The results demonstrated that for both TGMS and SAP-MS, the stress-strain relationship appeared to be linear up to 25% deformation. Therefore, one can reasonably treat TGMS and SAP-MS as linearly elastic materials for this range of deformation and apply the Hertz contact theory for analysis of the Young's modulus. The Young's moduli of TGMS and the SAP-MS obtained by applying Hertz theory under the assumption of a Poisson's ratio of 0.5 were 19.33 +/- 4.97 kPa and 9.64 +/- 2.46 kPa, respectively (mean +/- SD, P<0.001, Mann-Whitney U-test), indicating that TGMS showed higher stiffness than SAP-MS. The effects of a difference in these mechanical characteristics of embolic agents on the performance of interventional radiology were discussed from a viewpoint of their flowing behavior and clinical aspects.
Journal of the mechanical behavior of biomedical materials. 10/2010; 3(7):497-503.
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ABSTRACT: The gravity sag view(GSV)is a lateral radiograph taken in the same position when the posterior sag sign is observed. The purpose of this study was to standardize the radiography technique for GSV by adjusting lateral rotation. To confirm the benchmark and correction angle(CA)for the GSV position, we assessed three-dimensional(3D)CT of the GSV position of the knee using normal volunteers. The benchmark is established at the 3-point of the leg and adjusting the CA of the knee is established by estimating from Rosenberg technique radiography. This helped not only to correct external rotation in the initial radiography but also to correct rotation for repeat radiography. Our method is quantitative and highly reproducible, and it increases the success rate in adjusting lateral radiography of the knee.
Nippon Hoshasen Gijutsu Gakkai zasshi 05/2007; 63(4):412-9.
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Hiroko Kou,
Hajime Harauchi,
Hodaka Numasaki,
Yu Kumazaki,
Yasuhiro Okura,
Akihiro Takemura,
Takashi Kondou,
Masatoshi Ishibashi, Kuniyuki Hidaka,
Tokuo Umeda,
Kiyofumi Haneda,
Kiyonari Inamura
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ABSTRACT: The purposes of this study were first to develop a system which statistically tests results of radiotherapy and which automatically acquires an optimal discrete-valued attribute by dividing and grouping continuous-valued attributes, and second to find the optimal range of values such as tumor dose by taking account of the conditions and statistics in ROGAD (Radiation Oncology Greater Area Database), a multi-institutional database in Japan. Our ultimate goal is to assist clinical decision making for every patient. In this research, two algorithms for acquiring a boundary value were developed without detecting false boundaries or accidental errors of acquired boundaries. The resolution of detected discrete-valued attributes and speed of convergence were confirmed to be practical. The optimal range of given tumor dose with the best reaction and with the fewest complications is expected to be clarified.
Igaku butsuri: Nihon Igaku Butsuri Gakkai kikanshi = Japanese journal of medical physics: an official journal of Japan Society of Medical Physics 02/2003; 23(3):163-72.
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ABSTRACT: The purpose of this study is to evaluate the influence of MPEG-2 compression scheme on coronary angiography and to search the highest compression ratio at which no significant effect to accuracy of assessment of stenosis severity occurs. Forty-Four digital cine angiographies were used. Three cardiologists participated in a subjective study in which they read both uncompressed images and compressed images. Furthermore, an objective study was carried out to measure vessel stenosis ratio by using software. The influence of compression was evaluated by kappa statistics in case of subjective study and by both systematic error and random error in case of objective study. Kappa statistics between uncompressed image and compressed image at a ratio of 80:1 was significantly lower than that of other compression ratios such as 40:1. Similar results were obtained in objective evaluation. In this report, the authors provide the baseline for further studies on observer performance for motion images.
Journal of Digital Imaging 01/2003; 15(4):210-5. · 1.25 Impact Factor
