Ultra-Low Dose Cardiac CT Angiography at 80 kV using Second Generation Dual-Source CT: Assessment of Radiation Dose and Image Quality

Objectives: We sought to determine the feasibility of using 80 kV in clinical cardiac CTA, by comparing radiation doses and image quality versus standardized 100 kV protocols. Methods: In this retrospective study, a tube potential of 80 kV was used in 40 consecutive patients (BMI 22.6 ± 2.8). 40 matched patients (BMI 23.1 ± 2.8) were scanned with a tube potential of 100 kV and served as the control group. Qualitative and quantitative image quality parameters were determined in the proximal and distal segments of the coronary arteries. Results: Similar subjective image quality scores were seen between the two protocols. The mean CNR and SNR were at 100 kV vs 80 kV (CNR 19.9 ± 6.0 vs 15.7 ± 5.5; p<0.01 and SNR 17.7 ± 5.5 vs 14.4 ± 4.9). The median radiation dose for the 80 kV protocol was significantly lower compared to the 100 kV protocol (83.0 mGy x cm [58.0- 134.0] vs 193.0 mGy x cm [108.5-225.0]; p<0.01) Conclusion: A tube potential of 80 kV is feasible and results in a radiation dose reduction of 57% compared to 100 kV protocols while preserving subjective image quality.