RADIOISOTOPES
Online ISSN : 1884-4111
Print ISSN : 0033-8303
ISSN-L : 0033-8303
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Volume 57, Issue 5
Displaying 1-8 of 8 articles from this issue
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Articles
  • Consideration to Shielding Design Calculation of Radiation Oncology Electron Linac Facility whose Energy is Greater than 10MeV
    Koji OISHI, Kazuaki KOSAKO, Yuki KOBAYASHI, Issei SONOKI, Takashi NAKA ...
    2008 Volume 57 Issue 5 Pages 277-286
    Published: 2008
    Released on J-STAGE: May 29, 2008
    DOIhttps://doi.org/10.3769/radioisotopes.57.277
    JOURNAL FREE ACCESS
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    In the electron linac facility for radiation oncology whose energy is greater than 10 MeV, there occurs photonuclear reaction and photoneutrons are emitted from the target. As far as radiation dose from the target is concerned, the dose of photoneutrons is small and can be ignored. However, shielding calculations considering only photons from the target have been performed and found out that the measured dose was greater than the calculated ones by about two orders of magnitude. The neutrons were also observed at the end of primary shield. The measurement of radiation field around the shield was performed and clarified that the photoneutrons were produced in the iron of the shield and capture gamma-rays were also emerged in the second layer of concrete shield. The behavior was verified by using Monte-Carlo calculation code MCNPX and very good agreement was obtained between measured and calculated results. It is concluded that the Monte-Carlo calculation code is very effective for the shielding design calculation in the electron linac facility where the photonuclear reaction occurs
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  • Development of a Real-time Autoradiography System to Analyze the Movement of the Compounds Labeled with β-ray Emitting Nuclide in a Living Plant
    Hiroki RAI, Satomi KANNO, Yoshitake HAYASHI, Tomoyuki OHYA, Naoto NIHE ...
    2008 Volume 57 Issue 5 Pages 287-294
    Published: 2008
    Released on J-STAGE: May 29, 2008
    DOIhttps://doi.org/10.3769/radioisotopes.57.287
    JOURNAL FREE ACCESS
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    Real-time imaging analysis in a living plant allows studying the mechanism of chemical transport or signal transduction more in detail. We present the real-time autoradiography system to analyze the movement of β-ray emitters in a living plant. The system was consisted of a FOS (a fiber optic plate deposited with CsI(Ti) scintillator) and a GaAsP imaging intensifier unit. Though the resolution is about the same as that of an imaging plate(IP), the sensitivity was more than 10 times higher than that of an IP. Using this system, 32P movement in a young leaf of soybean was analyzed when 32P was supplied from the root.
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  • A Statistical Approach to Estimate Soil-soil Solution Distribution Coefficient of Radiostrontium
    Nao ISHIKAWA, Tomoyuki TAKAHASHI, Shigeo UCHIDA, Keiko TAGAMI
    2008 Volume 57 Issue 5 Pages 295-303
    Published: 2008
    Released on J-STAGE: May 29, 2008
    DOIhttps://doi.org/10.3769/radioisotopes.57.295
    JOURNAL FREE ACCESS
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    Soil-soil solution distribution coefficient (Kd) is one of the important parameters in radiation dose assessment models for the environmental transfer of radionuclides. Since Kd value varies with soil properties, development of a method for estimation of Kd using some soil properties is useful. In this study, we estimated Kd values of radioactive strontium using selected soil properties. We determined Kd values of Sr for 142 agricultural field soil samples collected throughout Japan and measured such soil properties as pH, cation exchangeable content, exchangeable Ca, clay content, concentrations of major and trace elements in soil, and concentrations of elements and ions in water soluble fractions. The relationship between Kd of Sr and each soil property was calculated using a product-moment correlation test. Then, we developed a method using multiple linear regression analysis to estimate Kd values of Sr based on soil properties. Our results showed that pH, exchangeable Ca, Ca concentration in soil, and Ca concentration in water soluble fraction were the most important factors that contributed to estimation of Kd values.
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Note
  • Terrestrial Gamma Ray Dose Rates in Andesitic Terrains
    Susumu MINATO
    2008 Volume 57 Issue 5 Pages 305-311
    Published: 2008
    Released on J-STAGE: May 29, 2008
    DOIhttps://doi.org/10.3769/radioisotopes.57.305
    JOURNAL FREE ACCESS
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    Air absorbed dose rate data taken at 31 sites have been analyzed in order to understand the characteristics of dose rate levels in andesitic terrains. The dose rate increased with increasing K2O content of rock. The following three models were tested to interpret this trend, i.e., crystallization-differentiation of basaltic magma, mixing of basaltic and felsic magmas and partial melting of mantle materials. A semi-empirical formula expressing the dose rate as a function of K2O content was derived based on the above models.
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Materials(Data)
  • Gamma-ray Dose Rate in Air on the Subway Lines in Tokyo Metropolitan Area
    Masayuki OGAWA, Masahiro HOSODA, Masahiro FUKUSHI, Susumu OGASHIWA
    2008 Volume 57 Issue 5 Pages 313-320
    Published: 2008
    Released on J-STAGE: May 29, 2008
    DOIhttps://doi.org/10.3769/radioisotopes.57.313
    JOURNAL FREE ACCESS
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    Measurements of gamma-ray dose rates in air were performed on 12 subway lines in Tokyo from the perspective of health physics, because the subways are commonly used for commuting in the Tokyo metropolitan area. The results showed that the maximum dose rate (36.5nGy/h) was 1.6 times higher than that of the minimum one (23.3nGy/h),and that the dose rate in the subway car was 33% lower than the outside. Also the results strongly suggested that the dose rates depend on the concentration of natural radionuclide around the subway lines and the platform structures rather than the depth.
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Lecture
Radiation Control for Accelerator Facility
Serial Lectures
Fundamentals and Applications of Neutron Imaging
(Applications Part12)
Final
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