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Objectives To compare image consistency of coronary CT angiography (CCTA) with automatic tube current modulation obtained by automatic tube potential selection and by a body mass index(BMI)-based tube potential selection.Materials and Methods Two hundred and twenty-six consecutive patients underwent CCTA with a first generation dual-source CT.CCTA were taken with automatic tube potential selection in 111 patients (Group A) and with a BMI-based tube potential selection (B1:BMI≤25 Kg/m2 with 100 KV and B2:BMI>25 Kg/m2 with 120 KV) in 115 patients.In all patients, tube current parameters were automatically selected by the vendor.Image noise of descending aorta (DA) at the middle level of left ventricle was measured.Image noise was compared between both groups.Results The mean and inter-individual variance of image noise in DA reduced in group B (mean, 27.4 HU vs 32.1 HU, P=0.002; SD, 5.03 vs 6.83, P<0.001).In group A, image noise of DA showed positive linear correlation to BMI (r=0.585, P<0.001) while no relationship was found in Group B (r=0.061, P=0.519) (Figure A-B).Group A with BMI>25 Kg/m2 had a higher image noise compared with BMI≤25 Kg/m2 (35.4±7.00 HU vs 29.5±5.45 HU, P<0.001) while no difference was found between B2 and B1 (26.58 ±5.31HU vs 28.20±4.68 HU, P=0.08).Conclusions During CCTA, a BMI-based tube potential selection allows better image consistency compared with that by the automatic tube potential selection.