Three-dimensional cardiac rotational angiography: effective radiation dose and image quality implications

Three-dimensional rotational angiography (3DRA) is a promising new online tool for 3D imaging during cardiac ablation procedures. No precise data exist concerning its associated radiation dose. The current study evaluated the effective dose (ED) of cardiac rotational angiography and its relation to patient properties, imaging system input settings, and quality of reconstructed 3D images.

We performed Monte Carlo simulation-based radiation dose calculations in 42 patients referred for ablation of cardiac arrhythmias. Detailed tube setting information from the 3DRA system (Siemens Axiom Artis dBC with Syngo DynaCT Cardiac software) was used to provide an accurate input for dose calculations in all 248 frames used during image acquisition. Our calculations yielded an overall mean ED of 6.6 +/- 1.8 mSv (based on ICRP 103 weighing factors). Manual collimation of the radiation beam can reduce ED by more than 20%. Image quality did not significantly relate to patient body mass index (BMI), dose per frame setting, or dose-area product (DAP), but was rather explained by contrast filling, cardiac motion reduction, and absence of image reconstruction artefacts. In the system evaluated, DAP values are nearly independent from BMI (R(2) = 0.30), due to its technical specifications. Therefore, patient BMI showed an unexpected strong inverse relation to ED.

Three-dimensional rotational angiography can be performed with acceptable patient radiation dose, comparable to cardiac CT. With the 3DRA system studied (Siemens Axiom), slender patients may currently receive unnecessarily high radiation doses when compared with obese patients, so that further dose reduction seems feasible for many patients. Adequate collimation is imperative to limit patient exposure.