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KMID : 1131320140160020033
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Journal of Korean Society of Computed Tomographic Technology
2014 Volume.16 No. 2 p.33 ~ p.42
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Optimization of energy level in abdomal organ with Single-source dual energy CT
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Kim Yung-Kyoon
Kim Wan-Yuk
Kim Kwang-Soo
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Abstract
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Purpose : To find optimal keV using Optimal CNR when using Single source dual energy CT
Subject and Method : Clinical studies were collected the data targeting 132 patients doing abdomen exam by using GE Discovery 750 HD(General Electric medical systems, Milwaukee, USA) CT in 2013 August 1 to December 30. To measure each organ keV using Optimal CNR Tool supported from ADW 4.6(General Electric Healthcare). To have keV after drawing ROI on liver, spleen, pancreas, bile duct, kidney, bladder, fat, muscle and bone (L-spine, Pelvis), and then setting background on water in stomach. Also, to analyze that varying factor following patient’s age, BMI and contrast injection rate speed affect optimal CNR. Scan condition was 120kVp/ 270mAs, Slice thickness and Interval 2.5mm/2.5mm, FOV was 35, pitch was 0.984/1 and Rotation Time 0.7sec, Algorism set soft, and clinic set 70sec scan time after 120cc contrast injection. Statistic was used PASW Statistics 18. Release 18.0.0 and Microsoft Office Excel 2007.
Results : All abdomen organs shows the optimal CNR between 60 and 75keV, over 99.2% was included the range of 65~70keV among the rest. Also, as the comparison the average and the median, the result shows under 66~68keV range. And the mode was between 65 and 69keV. CNR average and standard deviation of each organ were measured liver 8.45±9.93,spleen 8.77±2.96, kidney 13.08±18.06,bile duct 4.16±5.80, pancreas 7.59±8.88,bladder 2.38±2.99,, intra-abdominal fat -5.43±7.48, supra abdominal fat -6.02±8.84, muscle 4.16±5.80, aorta 13.17±16.17,lumbar spine 15.38± 22.43, and pelvis 18.27± 16.84. As doing One-Way ANOBA for evaluating the keV variation following patient’s age, BMI and contrast injection speed, the result shows no significance because intergroup P-value was all higher than 0.05.
Conclusion : When doing abdomen exam using SSDE CT, if using properly to get images applied optimal CNR within the 65~70keV range of each organ, it could be to get the images of optimal CNR. Also, for abdomen routine exam, the optimal CNR is 66~68keV. And, no effects following age, BMI and contrast injection speed.
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KEYWORD
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dual energy CT, optimal CNR, abdominal imaging
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