Shane Foley BSC, Presenter: Nothing to Disclose

Mark F McEntee PhD, Abstract Co-Author: Nothing to Disclose

Louise Ann Rainford PhD, Abstract Co-Author: Nothing to Disclose

Computed Tomography (CT) has undergone rapid technological advances in recent years with repeated increases in the number of detector rows possible. While advances have promised increased efficiencies, “dose creep” remains a concern. This research surveyed CT scanners of varying multidetector row capability across Ireland to establish mean clinical doses delivered for common helical CT examinations.

Thirty one multidetector CT scanners in Ireland from various manufacturers and with either, 4, 6, 16 or 64 slice capabilities were surveyed. Each CT centre was asked to record CT dose data (DLP, CTDIvol, tube voltage and current) prospectively, on 10-20 anonymised adult patients of average size (70 ± 10kg) presenting for three helical CT examinations; thorax, abdomen/pelvis and trunk examinations. Mean results from each site were pooled and resultant data was analysed using SPSS software, including descriptive statistics and ANOVA testing.

Dose data on 1286 patients was collected. The 6-detector CT demonstrated the lowest mean DLP readings for all examinations with a mean of 293, 381 and 563mGycm-1 for CTs of the chest, abdomen/pelvis and trunk exams respectively, in comparison to 296, 559 and 775 for the 4-detector, 355, 524 and 818 for the 16-detector and 386, 639 and 860 for the 64-detector. ANOVA testing showed these differences to be statistically significant (p<0.05) for all abdomen/pelvis and trunk exams and for the 64-detector during chest exams. However a wide variation in scan protocols was observed.

A trend of rising mean DLPs is seen with increasing numbers of multidetector rows, indicating that technological advancements do not always deliver the most dose efficient scanning. Particular attention should be paid to optimisation of CT protocols for wider detector scanners to ensure compliance with the ALARA principle. 

Despite technological advancements, wider detector CT scanners do not automatically deliver the most efficient dose scans for patients.

Foley, S, McEntee, M, Rainford, L, CT Doses across the Generations: A Clinical Comparison.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034572.html