RADIOISOTOPES
Online ISSN : 1884-4111
Print ISSN : 0033-8303
ISSN-L : 0033-8303
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Volume 57, Issue 3
Displaying 1-7 of 7 articles from this issue
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Articles
  • Construction of Gamma-ray and Neutron Irradiation Field
    Kazuaki YAJIMA, Hiroshi YASUDA, Toshikazu SUZUKI
    2008 Volume 57 Issue 3 Pages 167-174
    Published: 2008
    Released on J-STAGE: March 31, 2008
    DOIhttps://doi.org/10.3769/radioisotopes.57.167
    JOURNAL FREE ACCESS
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    Gamma-ray and neutron irradiation field was constructed in National Institute of Radiological Sciences, primarily for calibration of survey meters and test of dosimeters that are to be supplied for radiation emergency medicine. This facility has nine irradiation sources:137Cs(7.4MBq, 74MBq, 740MBq, 7.4GBq, 74GBq), 60Co(74MBq), 241Am(3.7GBq), 241Am-Be(185GBq), and a dummy. Experimental investigations about dose rates on the irradiation table, dose rate changes with angle and their dependence on distance have been performed so far. It is found that 1-cm dose equivalent rates at 1m from the sources were in the range from 0.7×10−6 to 6.9×10−3 Sv h−1 in gamma-ray irradiation, and 1.3×10−4 Sv h−1 in neutron irradiation. The distribution of the dose rate from the gamma-ray(neutron) source changed at less than 3%(4%) from isotropic distribution. The dose rate dependence on distance between the gamma-ray source center and the geometrical center of the spherical ionization chamber differed slightly from inverse square law due to gamma-ray scattering by concrete walls and an irradiation table. As a result, it is considered that the constructed irradiation field has satisfying performance for the primary purpose. The future task is to advance the evaluation and maintenance of the irradiation field for more precise experiment.
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  • Variation in the Atmospheric Concentrations of 214Pb with Local Meteorological Conditions at the Observation Site—Observation at Kawasaki, Japan—
    Nanako MATSUZAWA, Yuya KOIKE, Jun SATO
    2008 Volume 57 Issue 3 Pages 175-182
    Published: 2008
    Released on J-STAGE: March 31, 2008
    DOIhttps://doi.org/10.3769/radioisotopes.57.175
    JOURNAL FREE ACCESS
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    Every four hours variations in atmospheric 214Pb concentrations were observed at Kawasaki, Japan. The monthly averaged concentration ranged from 1.3 to 4.1Bq/m3. The variation patterns within 24 hours of the atmospheric concentration of short-lived 214Pb(half-life:26.8 min)is similar to that of 212Pb(half-life:10.6h). The variation in atmospheric concentrations of 214Pb was observed to depend strongly on the local meteorological conditions in a short period. High concentrations of 214Pb tend to appear on the days with westerly wind from inland area, low wind velocity and without precipitation.
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  • Investigations on the Performance of Polymer Gel Dosimeter for Radiation Therapy
    Kiyofumi HANEDA, Hiroki OKUDO, Yusuke TSUNEI, Munenori YOSHIOKA, Shin- ...
    2008 Volume 57 Issue 3 Pages 183-188
    Published: 2008
    Released on J-STAGE: March 31, 2008
    DOIhttps://doi.org/10.3769/radioisotopes.57.183
    JOURNAL FREE ACCESS
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    Gel dosimeters are sensitive chemical dosimeters that aim at measuring the dose in three dimensions(3D). This study aims to evaluate the performance of a commercially available BANG® polymer gel. BANG® gels were irradiated using 6MV photon beams from 0.5Gy to 60Gy. The magnetic resonance(MR)spin-spin relaxation rate(R2=1/T2) of the protons indicates dose response and has a linear relationship to dose. The dose response curve by BANG® gel appeared approximately linear over the 0.5Gy and 20Gy region. The slope of the dose-R2 curve is 0.9s−1Gy−1, and the relative dose distribution can be reproduced with an overall uncertainty of about 2%. R2 was found to increase with increasing time after irradiation. BANG® gels are of comparable quality to MOSFET or PLD in terms of overall dosimetric accuracy and have the advantage of measuring continuous, cumulative 3D dose distributions.
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Review Article
Applications of Stable Isotopes in Life Sciences
Serial Lectures
Fundamentals and Applications of Neutron Imaging
(Fundamentals Part11)
(Applications Part11)
Materials(Data)
Instruments for Radiation Measurement in Life Sciences(5)."Development of Imaging Technology in Life Sciences"
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