Implementation of a split-bolus single-pass CT protocol at a UK major trauma centre to reduce excess radiation dose...

To quantify the dose reduction and ensure that the use of a split-bolus protocol provided sufficient vascular enhancement.

Between 1 January 2014 and 31 May 2014, both split bolus and traditional two-phase scans were performed on a single CT scanner (SOMATOM Definition AS+, Siemens Healthcare) using a two-pump injector (Medrad Stellant). Both protocols used Siemens' proprietary tube current and tube voltage modulation techniques (CARE dose and CARE kV). The protocols were compared retrospectively to assess the dose-length product (DLP), aortic radiodensity at the level of the coeliac axis and radiodensity of the portal vein.

There were 151 trauma CT examinations during this period. Seventy-eight used the split-bolus protocol. Seventy-one had traditional two-phase imaging. One patient was excluded as they were under the age of 18 years. The radiodensity measurements for the portal vein were significantly higher (p<0.001) in the split-bolus protocol. The mean aortic enhancement in both protocols exceeded 250 HU, although the traditional two-phase protocol gave greater arterial enhancement (p<0.001) than the split-bolus protocol. The split-bolus protocol had a significantly lower (p<0.001) DLP with 43.5% reduction in the mean DLP compared to the traditional protocol.

Split-bolus CT imaging offers significant dose reduction for this relatively young population while retaining both arterial and venous enhancement.