A survey of routine head CT protocols in Australia.

The choice of scanning protocol in CT will affect the dose delivered to the patient. A nationwide survey of CT operators was carried out in Australia in 1994 to determine the variation in routine head CT protocols. Only 29% of respondents used the supraorbitomeatal (SOM) baseline and thus avoided scanning the eyes. At 74% of sites, the routine protocol included scans both before and after injection of contrast. However, the post-contrast protocol differed from that used in the pre-contrast series in a number of cases. Where 5 mm thick slices were used, the mAs was 16% higher than for 10 mm thick slices. Increased awareness of the influence of baseline, slice thickness/spacing and accompanying exposure factors on patient dose may lead to greater standardization of head CT scanning protocols.