Comparison of image quality and radiation dose of coronary computed tomographic angiography between conventional helical scanning and a strategy incorporating sequential scanning.

Radiation dose from coronary computed tomographic angiography may be decreased using a sequential scanning protocol rather than a conventional helical scanning protocol. We compared radiation dose and image quality from coronary computed tomographic angiography in a single center between an initial period during which helical scanning with electrocardiographically controlled tube current modulation was used for all patients (n = 138) and after adoption of a strategy incorporating sequential scanning whenever appropriate (n = 261). Using the sequential-if-appropriate strategy, sequential scanning was employed in 86.2% of patients. Compared to the helical-only strategy, this strategy was associated with a 65.1% dose decrease (mean dose-length product [DLP] 305.2 vs 875.1 and mean effective dose 14.9 vs 5.2 mSv, respectively), with no significant change in overall image quality, step artifacts, motion artifacts, or perceived image noise. For the 225 patients undergoing sequential scanning, the DLP was 201.9 +/- 90.0 mGy x cm; for patients undergoing helical scanning under either strategy, the DLP was 890.9 +/- 293.3 mGy x cm (p <0.0001), corresponding to mean effective doses of 3.4 and 15.1 mSv, respectively, a 77.5% decrease. Image quality was significantly greater for the sequential studies, reflecting the poorer image quality in patients undergoing helical scanning in the sequential-if-appropriate strategy. In conclusion, a sequential-if-appropriate diagnostic strategy decreases dose markedly compared to a helical-only strategy, with no significant difference in image quality.