| Project/Area Number |
04670661
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Radiation science
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| Research Institution | Yokohama City Univ. |
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Principal Investigator |
MATSUBARA Sho Yokohama City University, Radiology, Professor, 医学部, 教授 (40014120)
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| Co-Investigator(Kenkyū-buntansha) |
KUBOTA Nobuo Yokohama City University, Radiology, Lecturer, 医学部, 講師 (20046139)
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| Project Period (FY) |
1992 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1994: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1993: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1992: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Radiation-induced chromosome aberrations / Cell Killing / High energy electrons / Secondary electrons / Iodine-based contrast medium / Deprh-dose distribution / 放射線誘発染色体異常 / ヨード系造影剤 / 生物学的線量計 / 深部線量分布 |
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| Research Abstract |
Various kinds of electrons including not only high energy electron beams but also secondary electrons of low energy level have very important roles in the field of clinical radiology. The biological effects of these electrons studied by employing chromosome analysis and cell killing showed no significant difference between high energy electron and gamma ray beams. The peak of depth dose distribution of high energy electron beam obtained using chromosome aberration analysis was found to be located in the slightly deeper site compared to that physically determined depth dose destribution. However, addition of iodinated contrast medium at irradiation shifted the peak to the shallower site in slight degree. Further, the energy level of secondary electrons released by X-ray exposure was dependent to its energy level. The energy and number of secondary electrons determined by the energy of exposured X-ray was demonstrated to be enhanced by additon of iodinated contrast medium at irradiation. This enhancement gave rise to increase of chromosome aberration frequencies and cell king. The dose enhancement thus obtained was found partially due to secondary electrons of energy lower than 10 keV which were incapable to penetrate cell nucleus.
Computer simulation revealed that the difference between enhancement of biological effect due to addition of contrast agent and that physically estimated increase of secondary electrons was explained by this microdosimetric phenomenon.
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