Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 69, Issue 9
Displaying 1-6 of 6 articles from this issue
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Opening Article
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  • Investigation of Polymer Gel Dosimetry for Small Circular Irradiated Fields
    Hiraku Kawamura, Kazuya Shinoda, Katsumi Miyamoto, Takeji Sakae, Masah ...
    2013 Volume 69 Issue 9 Pages 933-943
    Published: September 20, 2013
    Released on J-STAGE: September 20, 2013
    DOIhttps://doi.org/10.6009/jjrt.2013_JSRT_69.9.933
    JOURNAL FREE ACCESS
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    Polymer gels can be used as tissue equivalent dosimeters, and polymer gel dosimetry can be employed without perturbation of the radiation field. In this study, polymer gel dosimetry was used for small circular irradiation fields 10–30 mm in diameter using a radiation planning system. The irradiated gels were compared with planned data for a 50% dose width of 6 Gy dose maximum, and for the dose difference between gels and planned data over an 80% dose maximum area. The present study investigated magnetic resonance imaging (MRI) conditions based on an optimal dose-R2 calibration curve. The average difference between the full width half maximum of the 50% dose width between gels and planned data was 11%. The average dose difference over 80% of the dose was 5.6%. Optimal dose-R2 calibration curves were acquired using images with echo times of 30 and 60 ms. For cases of larger thicknesses and an increasing number of averages, the coefficients of variance of the curves were smaller than under other conditions. Compared to other traditional dosimetric tools, polymer gels have the advantage of providing three-dimensional dosimetric data. An arbitrary profile from the gel’s data can be compared with the profile of the planned data. In the future, new gel dosimeters will be needed that demonstrate improved dose evaluation under 1 Gy and stability in high dose areas.
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  • Basic Research for Development of Pinhole Camera Using a Geiger Mueller Counter
    Kazuki Takegami, Hiroaki Hayashi, Ikuma Fukuda, Yuki Konishi, Hiroki H ...
    2013 Volume 69 Issue 9 Pages 944-951
    Published: September 20, 2013
    Released on J-STAGE: September 20, 2013
    DOIhttps://doi.org/10.6009/jjrt.2013_JSRT_69.9.944
    JOURNAL FREE ACCESS
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    To visualize the scattered X-ray distribution in the diagnosis domain, we examined whether a Geiger Mueller (GM) counter could be applied to a pinhole camera as an X-ray detector. The GM counter detects radiation at certain detection points. To obtain two-dimensional images using the GM counter, the detector needs to be moved two-dimensionally. We constructed an apparatus using industrial actuators to move the detector. To investigate the usability of the developed apparatus, the scattered X-rays from the phantom were measured using the GM counter. The images obtained were then compared with those measured using the phosphor plate. Our results demonstrated that the GM counter can detect low count-rate radiation, but further research will be needed to obtain clear two-dimensional images. In this paper, we propose that the GM counter can be used as a complementary detector to a phosphor plate.
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  • Development of an Experimental Apparatus for Energy Calibration of a CdTe Detector by Means of Diagnostic X-ray Equipment
    Ikuma Fukuda, Hiroaki Hayashi, Kazuki Takegami, Yuki Konishi
    2013 Volume 69 Issue 9 Pages 952-959
    Published: September 20, 2013
    Released on J-STAGE: September 20, 2013
    DOIhttps://doi.org/10.6009/jjrt.2013_JSRT_69.9.952
    JOURNAL FREE ACCESS
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    Diagnostic X-ray equipment was used to develop an experimental apparatus for calibrating a CdTe detector. Powder-type samples were irradiated with collimated X-rays. On excitation of the atoms, characteristic X-rays were emitted. We prepared Nb2O5, SnO2, La2O3, Gd2O3, and WO3 metal oxide samples. Experiments using the diagnostic X-ray equipment were carried out to verify the practicality of our apparatus. First, we verified that the collimators involving the apparatus worked well. Second, the X-ray spectra were measured using the prepared samples. Finally, we analyzed the spectra, which indicated that the energy calibration curve had been obtained at an accuracy of ±0.06 keV. The developed apparatus could be used conveniently, suggesting it to be useful for the practical training of beginners and researchers.
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Program of the 41th Autumn Scientific Congress
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