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KMID : 1131320140160020117
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Journal of Korean Society of Computed Tomographic Technology
2014 Volume.16 No. 2 p.117 ~ p.128
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Comparison of Dose Effect and Image Quality by Change in the Scout Test Conditions When applying AEC CT Scan ; 64-section CT scanners of 4 major CT system
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Lee Min-Yung
Han Dong-Kyoon
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Abstract
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Purpose : To know the importance of exam conditions at Scout before the start of exams by doing the measurement and analysis the Noise which is image quality measured quantity at present after measuring each dose of equipment company following the change of exam conditions at Scout scan using AEC phantom and applying AEC mode.
Materials and methods : CT equipments were used Discovery CT 750(General Electric Medical System, Milwaukee, Wisconsin USA) 64 MDCT, Dual Source Somatom Definition Flash (Siemens Healthcare, Forchheim, Germany) and Aquilion 64 (Toshiba Medical System, Japan), Ingenuity 128 (Philips Medical System, USA). And for the evaluation of Scout condition variation, CT-AEC ellipticconical phantom (Kyoto Kagaku Corporation, Japan) was used. Exposure condition was set 120 kVp, 100 mA, 1 second tube rotation time, standard kernel, 5mm slice recon, large SFOV as the basic setting value, and applied the condition value fitted AEC characteristic at each equipment company. To measure and evaluate Noise using ImageJ, which is opened image analysis software, as setting ROI size was average 200 mm2 anddivided center, up, down, left and right on AEC cross-section images after scanning and obtaining as doing the change of Scout kVp, Scout mA, Scout angle, Scout position and etc. at each equipment company using this condition.
Result : 1. When scanning to use high kVpregardless of Scout kVp at GE and Toshiba equipment, to confirm the low dose and low noise of each cross section, to show the same dose and noise distribution at each Scan kVp, but CTDIVOL increased. For Philips equipment, to confirm low mA and noise at each cross section using high kVp, however, CTDIVOL have a consistency because of not effected kVp condition.
2. Both dose and noise differences have no effect forfour different equipments at AEC condition variation by changing Scout mA.
3. For Scout angle change, Toshiba, Siemens equipment is the same without Scout direction, but for GE and Philips, lower dose applied of Scout at frontal projection.
4. When the subject was off the center of gantry isocenter, the results shows that the doses were increased on the top than the center position the gantry isocenter and the dose were decreased and the noises were increased on the bottom than the center position the gantry isocenter.
Conclusion : To better acquire and understand AEC characteristicwhich is to determine patient’s dose in CT exam and should be used in clinical area.
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KEYWORD
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AEC (Auto Exposure Control) mode , Scout
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FullTexts / Linksout information
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Listed journal information
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