ABSTRACT:
Background/Objectives: To find optimal keV using Optimal CNR when using Single source dual energy CT Methods/Statistical analysis: Clinical studies were collected the data targeting 132 patients doing abdomen exam by using GE Discovery 750 HDCT. To measure each organ keV using Optimal CNR Tool supported from ADW 4.6. Slice thickness and Interval 2.5mm / 2.5mm, Detector coverage was 40mm, pitch was 0.984:1 and Rotation Time 0.7sec, Algorithm set soft, and clinic set 70sec scan time after 120cc contrast injection. Statistic was used PASW Statistics 18. Findings: 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. Improvements/Applications: When doing abdomen exam using SSDE CT, if using properly to get images applied optimal CNR within the 65~70 keV range. Also, the optimal CNR is 66~68 keV.