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KMID : 0357520170400010013
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Journal of Radiological Science and Technology
2017 Volume.40 No. 1 p.13 ~ p.18
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Estimation of Computed Tomography Dose in Various Phantom Shapes and Compositions
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Lee Chang-Lae
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Abstract
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The purpose of this study was to investigate CTDI (computed tomography dose index at center) for various phantom shapes, sizes, and compositions by using GATE (geant4 application for tomographic emission) simulations. GATE simulations were performed for various phantom shapes (cylinder, elliptical, and hexagonal prism PMMA phantoms) and phantom compositions (water, PMMA, polyethylene, polyoxymethylene) with various diameters (1-50 cm) at various kVp and mAs levels. The CTDI100center values of cylinder, elliptical, and hexagonal prism phantom at 120 kVp, 200 mAs resulted in 11.1, 13.4, and 12.2 mGy, respectively. The volume is the same, but CTDI100center values are different depending on the type of phantom. The water, PMMA, and polyoxymethylene phantom CTDI100center values were relatively low as the material density increased. However, in the case of Polyethylene, the CTDI100center value was higher than that of PMMA at diameters exceeding 15 cm (CTDI100center : 35.0 mGy). And a diameter greater than 30cm (CTDI100center : 17.7 mGy) showed more CTDI100center than Water. We have used limited phantoms to evaluate CT doses. In this study, CTDI100center values were estimated and simulated by GATE simulation according to the material and shape of the phantom. CT dosimetry can be estimated more accurately by using various materials and phantom shapes close to human body.
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KEYWORD
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Computed Tomography , Dose , CTDI , GATE simulation , Phantom
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