Radiation Dose Estimates From Cardiac Multislice Computed Tomography in Daily Practice

TLDR

Multislice computed tomography angiography is a promising tool for imaging suspected coronary artery disease, but the higher spatial and temporal resolution of 64‑slice CTA compared to 16‑slice CTA is associated with increased radiation dose. This retrospective study compared estimated radiation dose and image quality between 16‑ and 64‑slice CTA in 1,035 patients and examined the impact of different scan protocols. The authors evaluated scanning algorithms with and without ECG‑dependent dose modulation and with reduced tube voltage to assess their effects on dose estimates and image quality. Radiation dose was 6.4 mSv for 16‑slice CTA and 11.0 mSv for 64‑slice CTA, and dose‑saving protocols reduced exposure by 37–40 % with ECG‑modulation alone and 53–64 % when combined with reduced tube voltage, without compromising diagnostic image quality.

Abstract

Multislice computed tomography angiography (CTA) is a promising technology for imaging patients with suspected coronary artery disease. Compared with 16-slice CTA, the improved spatial and temporal resolution of 64-slice CTA (0.6- versus 1.0-mm slice thickness and 330- versus 420-ms gantry rotation time) is associated with an increase in radiation dose. The objective of this retrospective investigation was to compare the estimated dose received during 16- and 64-slice CTA in daily practice and to investigate the impact of different scan protocols on dose and image quality.Radiation dose was estimated for 1035 patients undergoing coronary CTA. Scanning algorithms with and without an ECG-dependent dose modulation and with a reduced tube voltage were investigated on dose estimates and image quality. In the entire patient cohort, radiation dose estimates were 6.4+/-1.9 and 11.0+/-4.1 mSv for 16- and 64-slice CTA, respectively (P<0.01). The reduction in radiation dose estimates ranged between 37% and 40% and between 53% and 64% with the use of ECG-dependent dose modulation and with the combined use of the dose modulation and a reduced tube voltage, respectively. The reduction in dose estimates was not associated with a reduction in diagnostic image quality as assessed by the signal-to-noise ratio and by the frequency of coronary segments with diagnostic image quality.The increase in spatial and temporal resolution with 64-slice CTA is associated with an increased radiation dose for coronary CTA. Dose-saving algorithms are very effective in reducing radiation exposure and should be used whenever possible.