| Project/Area Number |
18591363
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Radiation science
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| Research Institution | Oita University of Nursing and Health Sciences |
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Principal Investigator |
KAI Michiaki Oita University of Nursing and Health Sciences, Faculty of Nursing, Professor (10185697)
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| Co-Investigator(Kenkyū-buntansha) |
BAN Nobuhiko Oita University of Nursing and Health Sciences, Faculty of Nursing, Associate Professor (70251220)
AKAHANE Keiichi National Institute of Radiological Sciences, Research Center for Charged Particle Therapy, Principal Researcher (80202521)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,770,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥270,000)
Fiscal Year 2007: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2006: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | CT examination / organ dose / radation-related cancer / risk estimate / medical exposure / 発がんリスク / 臓器線量 / シングルCT / マルチスライスCT / CT / X線 |
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| Research Abstract |
We carried out a nation-wide survey to estimate the yearly frequency of CT examinations. As a result, the frequency of CT examinations was strongly correlated with the number of beds in hospital. When calculation was made using the number of beds in each hospital that has CT equipment, the yearly CT frequency of 2005 in Japan was estimated to be about 27 million. The frequency of pediatric CT examinations under 16 years old can be estimated using the proportion of age-dependent frequency and then resulted in about 78,000. The organ dose from each CT examination must be estimated based on the exposure condition and exposed region. We took calculation-based approach using available programs such as ImPACT and CT-EXPO, because it is impossible to measure the dose from each CT examination in hospital. The calculated data were validated by the measured data and then some organ doses showed 20% higher than measured. There are some controversies about current estimates of radiation-related cancer risk in low dose and dose rates using LNT models. However, the dose from CT examinations is about 10 mGy and it remains unclear whether several ten mGy would give a significant higher excess cancer risk to children exposed on medical purposes. To investigate the health effects of CT uses, we constructed a system of calculating cancer risk related with CT frequency and doses obtained by our results. To establish a follow-up cohort of children exposed to CT, this system would be useful for possible interpretation based on actual data such as doses and CT frequency.
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