Abstract: Objective：To investigate the image quality and radiation dosage in the 320-slice thoracic and abdominal aorta computed tomography angiography (TAA-CTA) using low tube voltage and low concentration contrast with iterative reconstruction. Methods：Eighty patients requiring TAA-CTA were randomly divided into two groups (40 patients in each group).Patients in group A received CTA scan with 120 kVp and 370 mgI/mL of contrast media.Meanwhile, patients in group B received CTA scan with 80 kVp and 300 mgI/mL of contrast media.SURE Exposure 3D technique and adaptive iterative dose reduction (AIDR) 3D were adopted for both two groups. Image quality, signal-to-noise ratio (SNR), and radiation dose were evaluated on all of the images.Results：There was no significant difference in age, BMI, and five segmental images quality evaluation between the two groups. CT values of five segmental arterial lumina in group B were higher than that in group A, and difference was obviously significant (P<0.05). SNRs of five segmental arterial lumina in group B were also higher than those in group A. Statistical differences were remarkably significant (P<0.05) in SNRs of four segmental arterial lumina excluding that of femoral artery. Valid radiation dosage in group B was 55%, which was lower than that in group A with a significant statistical difference (P<0.05). Valid iodine intake was reduced by 18.92% in group B than that in group A. Conclusions：Low concentration iodinated contrast (300 mgI/mL) and 80 kVp ultra low tube voltage with AIDR 3D iterative reconstruction for patients requiring TAA-CTA could reduce the radiation dosage and iodine intake without weakening image quality.