RADIOISOTOPES
Online ISSN : 1884-4111
Print ISSN : 0033-8303
ISSN-L : 0033-8303
Volume 44 , Issue 9
Showing 1-15 articles out of 15 articles from the selected issue
  • Takuji KOJIMA, Masayuki TSUDA
    1995 Volume 44 Issue 9 Pages 603-607
    Published: September 15, 1995
    Released: September 07, 2010
    JOURNALS FREE ACCESS
    Alanine/electron spin resonance (ESR) dosimetry has excellent characteristics such as wide measurable range, stability after irradiation, and high precision. Different types of dosimeter and easy-handling readout systems have been developed, mainly for dosimetry of process control in radiation processing over high dose range from 100 Gy to 100 kGy. Alanine dosimeter consisted of tissue-equivalent material is expected to be also useful in radiotherapy dosimetry at doses below 100 Gy.
    In this paper, for application of alanine polystyrene (PS) dosimeters to low dose range below 100 Gy, 18 MV X-rays and 6-20 MeV electron beams were used to study on zero-dose response of unirradiated dosimeters, feasibility to subtract zero-dose response from dose response of irradiated ones, dose estimation to normalize dose response to that at 1 kGy, and uncertainty in dose estimation procedure.
    Álanine-PS dosimeters have already enough potential to measure doses higher than 10 Gy within precision of ±3%, although further improvement in sample preparation and ESR signal intensity manipulation procedure are necessary to reduce zero-dose response and to get higher signal/noise ratio.
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  • Naoki SUZUKI, Akimitsu TAKAMORI, Junpei BABA, Junichi MATSUDA, Toshio ...
    1995 Volume 44 Issue 9 Pages 608-615
    Published: September 15, 1995
    Released: September 07, 2010
    JOURNALS FREE ACCESS
    Positron lifetime spectra for general purpose polystyrene (GPPS), polybutadiene rubber (PBR), and their copolymers, styrene-butadiene rubber (SBR) and high impact polystyrene (HIPS) have been measured. A fast-fast coincidence system with BaF2scintillation crystals coupled to photomultiplier tubes (Philips XP2020Q) and constant fraction differential discriminators (OR TEC 583) for selecting the energy of γ-rays was used.
    It has been found that the free volume in the copolymers is smaller than the average over the individual polymers, probably due to the interfacial interaction between the styrene and rubber phases.
    A long-lived component with a mean lifetime of about 123 ns exists in the spectrum for deformed HIPS. These results from the ortho-positronium in the deformation induced crazes. The long lifetime becomes shorter when the sample is placed in oxygen gas atmosphere. This indicates that the ortho-positronium in the crazes undergoes spin-conversion into para positronium on collision with an oxygen molecule. The oxygen pressure in the crazes has been analyzed to be the same as in the external space, showing that the crazes accessible for the positronium, i. e., those existing within about 50μm from the HIPS surface are connected to the external space.
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  • Michihiro NARITA, Tadashi KURIHARA, Takashi SHINDOH, Minoru HONDA, Osa ...
    1995 Volume 44 Issue 9 Pages 616-626
    Published: September 15, 1995
    Released: September 07, 2010
    JOURNALS FREE ACCESS
    To study myocardial norepinephrine (NE) activity in essential hypertension (HT) and especially to clarify the effect of left ventricular (LV) hypertrophy and LV performance reserve upon it, we performed myocardial imaging with 123I-metaiodobenzylguanidine (123I-MIBG) and 201Tl at rest in 23 patients with HT and 10 normal subjects. In addition to ordinary tomograms, we obtained whole body images with 123I-MIBG and 201Tl to calculate the ratio of myocardial accumulation of each radionuclide to total injected dose (%Uptake) . As the index of myocardial 123I-MIBG uptake, we calculated Uptake Ratio (%Uptake of 123I-MIBG in delayed image divided by %Uptake of 201Tl) . Reduction of myocardial 123I-MIBG during 3h (WOR) was also calculated. From the Bull's-eye map, the extent of defect was quantitatively assessed as Defect Score.
    To study the effect of LV hypertrophy upon NE kinetics, patients with HT were divided into 2 groups according to the LV mass (LVM) which was calculated by echocardiography. In Group I (LVM>130g/m2, n=16), Uptake Ratio was lower than that in Group II (LVM<130g/m2, n=7) and WOR was accererated in Group I than in Group II. Uptake Ratio and WOR were identical between Group II and normal subjects. The incidence of 123I-MIBG defect and Defect Score were significantly greater in Groupl (incidence: 94%, Defect Score: 3.0±1.3) than in GroupII (incidence: 43%, Defect Score: 1.1±0.6) . In order to study the effect of LV performance reserve, patients with HT were divided into two groups according to LV ejection fraction (EF) responses to exercise stress (Ex) which were obtained by 99mTc blood pool imaging. In 13 patients LVEF increased by Ex (Group A) and in 7 patients LVEF decreased or did not change by Ex (Group B) . In Group B, Uptake Ratio was significantly smaller than in Group A and normal subject, and WOR was significantly accelerated comparing with those in Group A and normal subjects. The incidence of 123I-MIBG defect and Defect Score were greater in Group B than that in Group A but they were not statistically significant. These two factors (LVM and LVEF response) seemed to influence upon myocardial NE kinetics independently. These results suggested that LVM and LV performance reserve influenced upon myocardial NE kinetics in patients with HT and quantitative analysis of 123I-MIBG imaging may be helpful for assessing the prognosis of HT.
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  • Shigehiko KIMURA
    1995 Volume 44 Issue 9 Pages 627-636
    Published: September 15, 1995
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Sentaro TAKAHASHI, Kenichi IJIRI, Norio KURIHARA
    1995 Volume 44 Issue 9 Pages 637-645
    Published: September 15, 1995
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Isamu HAYATA
    1995 Volume 44 Issue 9 Pages 646-655
    Published: September 15, 1995
    Released: July 21, 2010
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  • Shizuka NAKANO
    1995 Volume 44 Issue 9 Pages 656-676
    Published: September 15, 1995
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Akiyoshi CHAYAHARA, Atsushi KINOMURA, Nobuteru TSUBOUCHI, Yuji HORINO, ...
    1995 Volume 44 Issue 9 Pages 661-666
    Published: September 15, 1995
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • Siro NAGAI
    1995 Volume 44 Issue 9 Pages 667-672
    Published: September 15, 1995
    Released: July 21, 2010
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  • Akihisa YOSHIDA, Takashi HIRAO
    1995 Volume 44 Issue 9 Pages 673-676
    Published: September 15, 1995
    Released: July 21, 2010
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  • [in Japanese]
    1995 Volume 44 Issue 9 Pages 677-678
    Published: September 15, 1995
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • [in Japanese]
    1995 Volume 44 Issue 9 Pages 679-680
    Published: September 15, 1995
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • [in Japanese], [in Japanese]
    1995 Volume 44 Issue 9 Pages 681-682
    Published: September 15, 1995
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • [in Japanese]
    1995 Volume 44 Issue 9 Pages 683-684
    Published: September 15, 1995
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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  • [in Japanese], [in Japanese], [in Japanese]
    1995 Volume 44 Issue 9 Pages 685-686
    Published: September 15, 1995
    Released: July 21, 2010
    JOURNALS FREE ACCESS
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