RADIOISOTOPES
Online ISSN : 1884-4111
Print ISSN : 0033-8303
ISSN-L : 0033-8303
Current issue
Displaying 1-11 of 11 articles from this issue
Serial Lectures
  • Hajime Seito
    2022 Volume 71 Issue 2 Pages 85-91
    Published: July 15, 2022
    Released on J-STAGE: May 13, 2022
    JOURNAL OPEN ACCESS

    The measurement of absorbed dose is vital technique for the quality assurance in gamma-ray and electron beam irradiation facilities. An exact dose evaluation is essential for optimization of the radiation effect. This report outlines various applications for dose ranges, the kind of dosimeters for the measurement of absorbed dose more than 1 Gy in radiation facilities and the dosimeter’s application. The international trends and the future subjects in high dose measurement are also described in this report.

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  • Toshiyuki Dohino
    2022 Volume 71 Issue 2 Pages 93-99
    Published: July 15, 2022
    Released on J-STAGE: May 13, 2022
    JOURNAL OPEN ACCESS

    Members of the International Plant Protection Convention, including Japan, carry out plant quarantine under international rules in order to protect the agriculture and forestry of their own countries and other countries, and to prevent the invasion and dispersion of quarantine pests that adversely affect them. This paper outlines the mechanism of plant quarantine and the phytosanitary actions in Japan and the method of disinfecting pests adhering to imported and exported agricultural products, that is, the irradiation treatment schedules among the international standards for phytosanitary measures.

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  • Tomoaki Tsutsumi
    2022 Volume 71 Issue 2 Pages 101-107
    Published: July 15, 2022
    Released on J-STAGE: May 13, 2022
    JOURNAL OPEN ACCESS

    In Japan, food irradiation is generally banned under the “Food Sanitation Law.” On the other hand, food irradiation is approved for use in various countries for the purpose of microbial decontamination, phytosanitary treatments, sprouting inhibition etc. Since imported irradiated food violates the law, detection methods for irradiated food have been needed in monitoring inspections for imported food in Japan. This section describes outlines of detection methods introduced in Japan and the monitoring inspections for irradiated food using these detection methods in Japan.

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Articles
  • Michiko Tsuda, Mitsutaka Yamaguchi, Ryota Satori, Wataru Kada, Tomihir ...
    2022 Volume 71 Issue 2 Pages 109-114
    Published: July 15, 2022
    Released on J-STAGE: May 13, 2022
    JOURNAL OPEN ACCESS

    Visualization of beams in particle therapy is useful to eliminate deviations of the irradiation area and to improve treatment outcome. In this study, we propose a beam imaging method using bremsstrahlung as an indicator and imaging plates (IP), which are widely used in the field of radiological diagnosis. We succeeded in obtaining high-resolution beam images through the IPs and indicated that the estimation of the carbon beam range was possible with the accuracy of the standard deviation of 2.5 mm.

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  • Nattawipa Suwannasaeng, Takehiko Kakizaki, Seiichi Wada, Masahiro Nats ...
    2022 Volume 71 Issue 2 Pages 115-126
    Published: July 15, 2022
    Released on J-STAGE: May 13, 2022
    JOURNAL OPEN ACCESS

    External exposure to veterinary staff and pet owners from 18F-fluorodeoxyglucose positron emission tomography (18F-FDG, dose 170±33 MBq/head) in veterinary nuclear medicine was measured by monitoring the surface (SDR) and ambient dose rates (ADR) from animal patients (dogs and cats). The patients’ weights ranged from 4.2 to 32.3 kg (11±9.4 kg). The highest SDR was at the ventral abdomen, and its SDR time course was within the degradation curve with a physical half-life (109.8 min). ADR demonstrated a significant decrease up to approximately 30-to 80-fold by keeping a 100-cm distance from the patient. The estimated occupational radiation dose from the FDG injection before sedation was higher than the dose received from the FDG injection after general anesthesia. All patients showed acceptable SDRs, which was less than 3.8 µSv/h at 24 h post-injection, where cumulative SDR until infinity was less than 1/100 of the limit of the yearly external public exposure (1 mSv/year) which recommended in ICRP publication 103. According to the current legislation in Japan, these results represent an overregulation of detention 24 h after FDG injection in the case of an adequate lower maximum SDR.

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Short Review
Materials(Data)
Article
  • Hirofumi Fujii, Kazunobu Ohnuki, Shin’ichiro Takeda, Miho Katsuragawa, ...
    2022 Volume 71 Issue 2 Pages 141-151
    Published: July 15, 2022
    Released on J-STAGE: June 21, 2022
    JOURNAL OPEN ACCESS

    Targeted alpha therapy is attracting significant attention for the treatment of intractable tumors and the development of efficient gamma cameras to evaluate the biodistribution of alpha emitters is expected. 211At, which is a commonly used alpha emitter in Japan, emits characteristic X-rays whose energy is distributed between 77 and 92 keV. We evaluated the biodistribution of this alpha emitter by effectively acquiring these photons. Because the performance of a gamma camera strongly depends on that of collimators, we designed and manufactured high-performance collimators by processing pure tungsten, which can shield radiation more effectively than lead, using state-of-the-art three-dimensional (3D) printing technology. We successfully fabricated a parallel-hole collimator with a honeycomb structure with a hole size of 1.0 mm and septal thickness as thin as 0.07 mm. When a point source of 133Ba that emits photons with the energy of 81 keV, similar to that of characteristic X-rays emitted from 211At, was imaged using this collimator, spatial resolution of this collimator was as short as 5.7 mm and its efficiency was as good as 1.42×10−4; these results are superior to those of commercially available clinical scanners. We also demonstrated that our collimator could successfully depict a shape of the object by imaging a mouse thyroid gland after the injection of the 211At solution. These results suggest that excellent collimators made of pure tungsten could be used to monitor targeted alpha therapy using 211At.

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Technical Report
  • Hirofumi Ichiki, Katsuya Mukae, Shinji Mitsuiki, Toshirou Kawaguchi
    2022 Volume 71 Issue 2 Pages 153-160
    Published: July 15, 2022
    Released on J-STAGE: June 22, 2022
    JOURNAL OPEN ACCESS

    We have conducted a radioactive survey of sake for tritium, which is the isotope of hydrogen with low β-ray energy and is considered difficult to detect and remove. Using a differential-type magnetically levitated electrode ionization chamber (MALIC) developed by Kyushu Sangyo University, we had previously measured gaseous radiation dose (ionization current) for tritium vapor. Based on the result, we analyzed Fukushima specialty sake to determine the radioactive materials and estimated the radioactivity concentration of tritium in sake. As a consequence, our device enabled direct detection at the Japanese drinking water standards level. Besides, we confirmed that the radioactivity concentration of this sake was quite far below the lower limit of the Japan and WHO drinking water standards.

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Short Review
Article
  • Naoki Shinyoshi, Satoshi Seino, Naoto Uegaki, Shun Fujieda, Yuta Uetak ...
    2022 Volume 71 Issue 2 Pages 171-177
    Published: July 15, 2022
    Released on J-STAGE: July 07, 2022
    JOURNAL OPEN ACCESS

    Tin nanoparticles were synthesized by chemical reactions induced by irradiation. γ-ray irradiation of aqueous solution of SnCl2 resulted in the formation of metallic Sn nanoparticles. It was indicated that Sn2+ions are reduced to zero valence by radiochemical species generated by the irradiation. On the other hand, SnO2 nanoparticles were obtained when irradiated in the presence of carbon support. Small metallic Sn nanoparticles were well dispersed on the surface of carbon support which are assumed to be easily oxidized to form SnO2 nanoparticles. It was indicated that nanoparticle synthesis techniques using radiation is applicable to form tin.

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