医学物理
Online ISSN : 2186-9634
Print ISSN : 1345-5354
ISSN-L : 1345-5354
23 巻, 4 号
選択された号の論文の5件中1~5を表示しています
  • 大島 まり, 高木 清, 早川 基治
    2003 年 23 巻 4 号 p. 209-214
    発行日: 2003/12/31
    公開日: 2012/09/24
    ジャーナル フリー
    The paper aims to investigate the relationship between aneurysm's geometry and hemodynamics in order to predict rupture and creation of cerebral aneurysms. The authors have been developing a numerical simulation system, which consists of medical image based geometric modeling, grid generation, finite element fluid simulation, and scientific visualization. The simulation was conducted for 20 cases of the middle cerebral artery (MCA) aneurysms (17 unruptured aneurysms and 3 ruptured aneurysms). The wall shear stress distributions and flow patters are compared with respect to the aspect ratio. The results show that as the aspect ratio becomes larger, the wall shear stress distribution in the aneurysm becomes smaller.
  • Katsuyoshi Tabushi, Tadashi Tamiya, Akira Maruhashi, Shuji Koyama, Mit ...
    2003 年 23 巻 4 号 p. 215-220
    発行日: 2003年
    公開日: 2012/09/24
    ジャーナル フリー
    A system for observing blue light of Cherenkov radiation was constructed using a Co-60 γ-ray irradiation unit. However, there was some doubt that the observed light was not Cherenkov light, but scintillation. Therefore, the radiation from water was compared with that from a scintillator. The difference between both luminosities was examined using photographs taken in a dark irradiation room with mirrors and a camera. The radiation from the scintillator was much stronger than that from water.The differences between luminosities of the light radiated in the beam direction, at right angles to the beam and in the reverse beam direction were examined for both radiations. The luminosity from water showed very definite anisotropy, while that from the scintillator was almost isotropic. Furthermore, the light radiated in the beam direction from water was the strongest, and the strengths of the light radiated in the three directions from the scintillator were almost equivalent to each other. It was confirmed that the radiation from water irradiated by Co-60 γ-rays was indeed Cherenkov light. The anisotropy of the radiated Cherenkov light and the isotropy of the scintillation were clearly observed in the photographs.
  • 安田 成臣, 阿部 慎司, 西村 克之, 佐藤 斉, 富田 哲也, 村石 浩, 神崎 孝之, 稲田 哲雄, 遊佐 顕, 金井 達明, 河内 ...
    2003 年 23 巻 4 号 p. 221-231
    発行日: 2003年
    公開日: 2012/09/24
    ジャーナル フリー
    The relative electron density resolution was discussed by the Wiener spectrum in the heavy ion CT image. The two dimensional (2D) Wiener spectrum in the CT image was obtained from the one dimensional (1D) Wiener spectrum of the measured residual range distribution of the water phantom for a single projection angle, and the relative electron density resolution in the CT image was calculated from the 2D Wiener spectrum. To examine the usefulness of this method, the relative electron density resolution was also estimated by other two methods; the calculation using the Wiener spectrum of the reconstructed image of the water phantom, and the estimation by the reconstructed image of the electron density resolution phantom. The result of the first method was similar to those of the other two methods. Therefore, it is useful to estimate the relative electron density resolution by the 1D Wiener spectrum of the measured residual range distribution of the water phantom for a single projection angle.
  • Mitsuhiro Matsumoto, Seiichi Ota, Shinichi Inoue, Yuji Ogata, Shuji Ya ...
    2003 年 23 巻 4 号 p. 232-242
    発行日: 2003/12/31
    公開日: 2012/09/24
    ジャーナル フリー
    Dose audit is an important topic in radiology and variations in dose attributable to sex have not been fully investigated. The primary purpose of our study was to determine the entrance surface dose (ESD) for men and women, from which we established an easy estimation equation for ESD, using the body mass index (BMI) as a variable.
    From April 2000 to March 2002,15424 patients (8586 men,6838 women; m ean age,58 years old; age range,20 to 90 years old) were recruited in this study. Estimated equation of ESD was obtained from the dispersion data of BMI and ESD. Welch's ttest was used as the test of significance. P values evaluated levels of significance at 5%. Analysis for correlation coefficients was used for Peason's correlation coefficient test. And, we also performed a simple regression analysis.
    The results of the simple regression equation with BMI as variable (y: ESD [mGy], x: BMI [kg/m2]), and the median values of ESD were as follows: for chest PA, men,0.22, y = 0.0145×-0.0876, women,0.20, y = 0.0126×-0.0704; for abdomen AP, men,2.12, y = 0.2707×-3.7206, women,1.65, y=0.2561×-3.7989; for pelvis AP, men,1.87, y = 0.0517×+0.8753, women,1.77, y = 0.0674×+ 0.4775; for lumbar spine AP, men,3.08, y = 0.3462×-4.1416, women,2.66, y = 0.2525×-2.8131; and for lumbar spine lateral, men,9.31, y = 0.6012×-3.7216, women,7.42, y = 0.3147×+0.3384. The results of ESD had a significant difference between sexes (P<0.05). Chest PA, abdomen AP, lumbar spine AP, and lumbar spine lateral each had a good correlation between ESD and BMI (r: 0.4 to 0.8). We successfully obtained the estimation equ ation using BMI as variable.
  • 横山 秀克, 佐藤 敏幸, 尾形 健明, 土橋 宣昭, 宍戸 文男
    2003 年 23 巻 4 号 p. 243-249
    発行日: 2003年
    公開日: 2012/09/24
    ジャーナル フリー
    An ESR/NMR resonator for hybrid imaging system was fabricated. It consisted of an ESR resonator, a bridged loop-gap resonator (inner diameter,43 mm; axial length,10 mm), and an NMR resonator, an LC circuit of a solenoid coil (inner diameter,60mm; axial length,10 mm) and variable capacitor. The former was located inside the latter. The resonant frequencies of ESR and NMR were 730 and 27 MHz, respectively. An ESR/NMR hybrid spectrometer was constructed for homodyne detection and lock in detection of ESR and NMR signals. By using the ESR/NMR resonator and spectrometer, CW-ESR, CW-NMR, and pulsed NMR measurements of a phantom that included a physiological saline solution containing a nitroxide radical could be made at the magnetic field of 26 mT and 640 mT.
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