Clinical audit of contemporary radiation doses in a university hospital coronary computed tomography angiography practice

Introduction: Coronary computed tomography angiography (CCTA) is increasingly used in clinical practice, but concerns exist regarding the associated ionising radiation. We performed a clinical audit of radiation dose. Methods: Consecutive patients undergoing CCTA (June–September 2017) were prospectively consented. Coronary computed tomography angiography (256-slice GE Revolution) was performed with prospective image acquisition, iterative reconstruction (ASIR-V 50%), electrocardiogram-controlled dose-pulsing, and attenuation-based dose modulation. Demographics, heart rate (HR) and rhythm during the scan, and anteroposterior (AP) chest diameter were analysed in relation to CCTA effective dose (dose-length product [mGy-cm] × 0.014). Results: In total, 326 scans were included (mean patient age 63 ± 12 years; 53% male). Median CTCA effective dose was 1.7 mSv (interquartile range 1.0–2.5 mSv) with 86 (26%), 179 (55%), 48 (15%), and 13 (4%) patients achieving <1 mSv, 1–3 mSv, 3–10 mSv, and >10 mSv, respectively. Compared with patients below the median dose, those above were more likely male ( n = 104/163 [64%] vs n = 68/163 [42%]; p < 0.0001), had a higher body mass index (30.1 ± 5.9 vs 25.4 ± 3.9 kg/m 2 ; p < 0.0001), AP diameter (25.9 ± 3.0 cm vs 23.0 ± 2.4 cm; p < 0.0001), and HR (59.4 ± 9.5 vs 56.1 ± 6.8 bpm; p = 0.0002), and a higher prevalence of atrial fibrillation (AF) ( n = 19/163 [12%] vs n = 1/163 [0.6%]; p < 0.0001). Among patients achieving <1 mSv, 99% were in sinus rhythm, whereas 46% of patients with >10 mSv were in AF. In the <1 mSv group, mean BMI, AP diameter, and HR were 23.9 ± 3.3 kg/m 2 , 22.0 ± 1.9 cm, and 55.2 ± 5.9 bpm versus 33.4 ± 5.6 kg/m 2 , 28.3 ± 2.1 cm, and 59.5 ± 12.3 bpm, respectively, in the >10 mSv group ( Graph 1 ). Conclusion: Coronary computed tomography angiography is performed at low radiation doses in the majority of patients. Body size, HR, and the presence of AF remain important determinants of higher doses in this vendor-specific contemporary audit.