Significance of an additional unenhanced scan in computed tomography angiography of patients with suspected acute aortic syndrome

Table 2 Radiation exposure as measured by the computed tomography dose-length product

	DLP [mGy*cm]
	Mean	Min	Max
Triphasic CT scan (unenhanced, arterial and venous)	2737.2	1583.0	4476.9
Biphasic CT scan (arterial and venous)	2134.6	766.2	3494.7
Unenhanced acquisition (percentage of a triphasic CT scan)	602.6 (22.0%)

Adding an unenhanced acquisition to a biphasic computed tomography (CT) scan does, as expected, increase radiation exposure, however to a moderate degree. On average the unenhanced acquisition contributes only about 22% to the total radiation dose of a triphasic CT scan. DLP: Dose-length product.