Evolution of coronary computed tomography radiation dose reduction at a tertiary referral center

Abstract

Purpose: We aimed to assess the temporal change in radiation doses from coronary computed tomography angiography (CCTA) during a 6-year period. High CCTA radiation doses have been reduced by multiple technologies that, if used appropriately, can decrease exposures significantly.

Methods: A total of 1277 examinations performed from 2005 to 2010 were included. Univariate and multivariable regression analysis of patient- and scan-related variables was performed with estimated radiation dose as the main outcome measure.

Results: Median doses decreased by 74.8% (P<.001), from 13.1 millisieverts (mSv) (interquartile range 9.3-14.7) in period 1 to 3.3 mSv (1.8-6.7) in period 4. Factors associated with greatest dose reductions (P<.001) were all most frequently applied in period 4: axial-sequential acquisition (univariate: -8.0 mSv [-9.7 to -7.9]), high-pitch helical acquisition (univariate: -8.8 mSv [-9.3 to -7.9]), reduced tube voltage (100 vs 120 kV) (univariate: -6.4 mSv [-7.4 to -5.4]), and use of automatic exposure control (univariate: -5.3 mSv [-6.2 to -4.4]).

Conclusions: CCTA radiation doses were reduced 74.8% through increasing use of dose-saving measures and evolving scanner technology.

Figure 1

Study period and context: The timeline plots total quarterly PubMed citations (blue bars) resulting from the search “cardiac CT dose reduction” and notes key developments in the cardiac CT literature during the study period. The locally available equipment during the study period is listed beneath. CT = computed tomography; DSCT = dual-source computed tomography; MDCT = multidetector computed tomography.

Figure 2

Indication-based protocols: The primary decision point revolved around the indication class, which was intended to reflect the pretest probability. Detailed, specific charts were tailored within each class. ECG = electrocardiogram; HR = heart rate; PVC = premature ventricular contraction.

Figure 3

Unadjusted median estimated radiation dose (mSv) versus scanner and protocol type. Progressive decreases in radiation doses were documented with successive scanners and protocols. BMI = body mass index; HRR = heart rate and rhythm; DSCT = dual-source computed tomography; MDCT = multidetector computed tomography.

Figure 4

The proportion of patients who received prospective ECG triggering (including high-pitch helical modes) when actual heart rate and rhythm were compatible according to protocol, (blue bars) and tube potential (kVp) was appropriate to actual patient BMI per department protocol (green bars). The lowest radiation doses coincided with the increased appropriate adjustments. BMI = body mass index; ECG = electrocardiogram; HRR = heart rate and rhythm.

Figure 5

Estimated radiation dose (red line) demonstrates the potential changes in dose to all patients if the same patient characteristics were applied using the multivariate model, adjusted for 64-slice DSCT technology and ideal compliance. DSCT = dual-source computed tomography.