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KMID : 0384620080190010049
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Korean Journal of Medical Physics
2008 Volume.19 No. 1 p.49 ~ p.55
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Comparison of Radiation Dose in the Measurement of MDCT Radiation Dose according to Correction of Temperatures and Pressure, and Calibration of Ionization Chamber
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Lee Chang-Lae
Jo Hyu-Min
Kim Hee-Joung
Jung Ji-Young
Jeon Seong-Su
Lee Seung-Jae
Dong Kyung-Rae
Nam So-Ra
Lee Young-Jin
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Abstract
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This study aims to conduct the comparative analysis of the radiation dose according to before and after the calibration of the ionization chamber used for measuring radiation dose in the MDCT, as well as of CTDIω according to temperature and pressure correction factors in the CT room. A comparative analysis was conducted based on the measured MDCT (GE light speed plus 4 slice, USA) data using head and body CT dosimetric phantom, and Model 2026C electrometer (RADICAL 2026C, USA) calibrated on March 21, 2007. As a result, the CTDIω value which reflected calibration factors, as well as correction factors of temperature and pressure, was found to be the range of 0.479~3.162mGy in effective radiation dose than the uncorrected values. Also, under the routine abdomen routine CT image acquisition conditions used in reference hospitals, patient effective dose was measured to indicate the difference of the maximum of 0.7 mSv between before and after the application of such factors. These results imply that the calibration of the ion chamber, and the correction of temperature and pressure of the CT room are crucial in measuring and calculating patient effective dose. Thus, to measure patient radiation dose accurately, the detailed information should be made available regarding not only the temperature and pressure of the CT room, but also the humidity and recombination factor, characteristics of X-ray beam quality, exposure conditions, scan region, and so forth.
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KEYWORD
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MDCT, Ionization chamber CTDIω, Calibration, Correction
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