3D cerebral angiography: radiation dose comparison with digital subtraction angiography.

Background and Purpose: As the use of 3D rotational angiography (3D RA) for the evaluation of cerebral vasculature becomes more widespread, it is important to evaluate this imaging method's effect on patient radiation dose. The purpose of the study is to measure 3D RA radiation dose as compared with biplanar digital subtraction angiography (DSA).
Methods: The distribution and peak skin dose were measured for 3D RA and biplanar DSA by using an anthropomorphic skull phantom. In addition, the cumulative incident dose, summed over all images in each acquisition, was determined. Measurements were acquired for our facility's standard 3D RA acquisition mode (25 degrees /s rotational speed; 162 total frames) and other available acquisition mode selections.
Results: For 3D RA, the skin dose was found to be distributed across the back and sides of the skull with the peak skin dose located at the center of the back of the skull. The peak skin dose for the standard 3D RA acquisition mode was 15 mGy. For a biplanar DSA run, the peak skin dose was 58 mGy, also located at the back of the skull. The cumulative incident dose for the standard 3D RA acquisition mode was 33 mGy, compared with 53 mGy for biplanar DSA.
Conclusion: The patient radiation dose for 3D RA is significantly lower than for biplanar DSA, by nearly a factor of 4 in peak skin dose and 40% lower in cumulative incident dose.