ObjectiveTo prospectively assess the value of a test bolus of diluted contrast medium (CM) combined with a personalized contrast protocol in craniocervical CT angiography (cc-CTA) with low radiation and CM doses. MethodsEighty-six consecutive subjects were divided into two groups at random (43 in each one). Group A: 100/Sn140 kVp, filtered back-projection reconstruction, iopromide (370 mgI/ml) 50 ml; Group B: 80/Sn140 kVp, iterative reconstruction, iodixanol (270 mgI/ml). In Group B, the test bolus contained 27 ml of diluted CM, a personalized protocol with low-concentration CM was used for angiography, and the test bolus injection duration in angiography remained the same. Artery values over 200 HU were considered significant. ResultsNo significant difference was found in the sex ratio, age, body weight, or body mass index when comparing the two groups. Image quality for all cases was found to be diagnostic. No significant differences were found in the arterial densities of the ascending aorta or basilar artery between the groups. The values of the common carotid artery, internal carotid artery, and middle cerebral artery in Group B were significantly lower. The effective dose and average iodine uptake were significantly lower in Group B. ConclusionWith double low-dose cc-CTA, test bolus scanning based on diluted CM combined with a personalized contrast protocol can yield diagnostic-quality images and significantly reduce the radiation and CM doses.