Estimated radiation dose according to the craniocaudal angle in cerebral digital subtraction angiography: Patient and phantom study

Routine use of cranial angulation with 15-20 degrees, craniocaudal angled (CC) view, for cerebral digital subtraction angiography (DSA) helps minimize bone subtraction artifacts with less overlapping of the vessels, however, it may increase the radiation dose. We designed the phantom and patient studies to determine the effect of the angulation to the radiation dose and the feasibility of true posteroanterior angled (PA) view, in cerebral DSA.In the phantom study, frontal DSA was simulated with variable angulations. In the patient study with thirty-one subjects, one internal carotid arteriogram was obtained with the CC view and the other, PA view in every patient. The dose-area product (DAP) and reference air-kerma (AK) were measured and compared between the angles. A qualitative analysis was performed to assess the diagnostic performance of the DSA over the angles.The phantom study confirmed that the greater craniocaudal angles caused higher radiation exposure. Especially, the radiation dose (AK) of the CC view was 5.4% higher than that of the PA view. In the patient study, the radiation dose of the PA view was significantly lower compared to the CC view (1.44 vs. 1.63 mGy, AK). In 4 patients, the dose particularly jumped when applying the CC view as the copper filter was automatically removed. The diagnostic ability of the DSA with the PA view tended to be higher without significance.In a daily routine cerebral angiography, a simple modification of the angle may help to minimize the radiation dose.