Comparison of image quality and radiation dose in computed tomography angiography of the peripheral arteries using tube voltage of 80 kV versus 100 kV

Objective: To compare the image quality and dose of radiation in two groups of patients undergoing CT angiography of the lower limbs, one with tube voltage of 80 kV and the other with tube voltage of 100 kV.

Material and methods: We performed CT angiography of the lower limbs in 60 patients with suspected peripheral arterial disease. Patients were randomly assigned to one of two groups; in one group, CT angiography was performed using a tube voltage of 80kV, whereas in the other it was performed using 100 kV. The remaining acquisition parameters were the same in both groups. The images were analyzed by quantifying vascular density (VD) and noise (N) and by calculating the quotients density/noise (QVDN) and contrast/noise (QCN). Two radiologists working independently evaluated the subjective quality of the images. We calculated the estimated effective dose (EED) based on the dose-length product (DLP).

Results: In the group studied at 80 kV, VD was significantly higher (462.5 UH ± 95.6 vs. 372 UH ± 100.9; P<.001), QVDN was significantly higher (241.9 ± 48.1 vs. 194.3 ± 49.6; P<.001), and there were trends toward higher N (21.3 UH ± 13 vs. 16.3 UH ± 3.5; P=.098) and toward higher QCN (21.4 ± 12.1 vs. 22.9 ± 9.1; P=.15). No significant differences were found in the subjective quality of the images. The EED was significantly lower in the group studied at 80 kV (4.73 mSv ± 1.1 vs. 9.6 mSv ± 2.2; P<.001).

Conclusion: Using 80 kV instead of 100 kV for CT angiography of the lower limbs reduces the dose of radiation without affecting the diagnostic efficacy of the study.