Radiation Dose from 3D Rotational vs. Conventional 2D Digital Subtraction Angiography in Intracranial Aneurysm Coiling

Purpose: To compare patient effective dose resulting from two alternative imaging protocols for pre-coiling assessment of intracranial aneurysms: a series of 2D Digital Subtraction Angiography (DSA) projections, and a 3D rotational angiography (RA) acquisition. Methods: In a retrospective analysis, we investigated 44 patients who underwent endovascular coiling in our institution. Images were acquired on a biplane Image Intensifier system not equipped with dose-area product (DAP) meter. Conventional 2D DSA images were simulated with an anthropomorphic skull phantom. Entrance skin dose was measured with a 60 cc ion chamber, and the PCXMC Monte Carlo based software was used to calculate patient effective dose. For the RA protocol, a 16 cm computed tomography (CT) dosimetry phantom and a 100 mm pencil ion chamber were employed to measure the CT dose index. Patient effective dose was calculated with the ImPACT calculator. An unpaired two-tailed t-test was used to determine the significance of differences between patient doses in each group. Results: Sixteen patients underwent the 2D DSA protocol with multiple projections; their mean number of cine runs was 5.1; the mean effective dose was 2.11 millisievert (mSv) (range 1.69–3.43 mSv). Twenty eight patients were assessed using the 3D RA protocol with the effective dose of 1.29 mSv. The difference between the means of two dose distributions was statistically significant (p=0.00028). Conclusion: Our study demonstrated that the patient effective dose was significantly lower from the 3D RA protocol than that from the 2D DSA protocol used in the planning of coiling of intracranial aneurysm.