2012 年 47 巻 4 号 p. 270-281
Data are presented on radiation doses to infant, child and adult patients undergoing head, chest and abdominal CT examinations with recent multi-detector row CT scanners (MDCT). Also presented are dose data in CT coronary angiography(CTCA) observed with Toshiba 320MDCT and Siemens 64MDCT. The doses were measured using newborn, 6-year-child and adult anthropomorphic phantoms, in which photodiode dosimeters were implanted at various tissue and organ positions. Measured doses were used to evaluate organ and effective doses. Organ doses in the scan region obtained in head CT were 20-40 mGy for infants and children, and 40-70 mGy for adults. Effective doses in head CT were 2.1-3.3 mSv for infants,and 1.0-2.0 mSv for children and adults. These doses in chest CT were 3-9 mGy and 2-6 mSv for infants, 2-12 mGy and 1-7 mSv for children, and 5-35 mGy and 7-14 mSv for adults. In abdominal CT they were 3-14 mGy and 2-10 mSv for infants, 4-18 mGy and 3-12 mSv for children, and 10-48 mGy and 9-21 mSv for adults. In CTCA radiation doses for helicalscan without using dose modulation were reduced to less than 1/6 and 1/10 by using prospectively gated axial scan of Toshiba320MDCT and “Flash Spiral” scan of Siemens 64MDCT, respectively.
