Disproportionate CT Scanning Utilisation in Populations most at Risk to Ionising Radiation Burden – Australia's Slice of a Worldwide Trend

Gibson, David

INTRODUCTION: Technological advancements and improved availability has seen CT scanning expand and diversify in utilisation. As a relatively high radiation dose diagnostic imaging technology, the increasing utilisation precipitated concerns in many nations, resulting in establishment Diagnostic Reference Levels and other guidelines. We sought to examine the utilisation CT in Australia and evaluate the risk burden of CT radiation exposure, particularly with relation to at risk groups.

METHODS: A retrospective cohort design using Medicare Benefit Schedule (MBS) records of CT scans in Australia (1/7/2006 to 30/6/2012), population data, and CT dosimetry data. Analysis included aggregate scan numbers, crude rates, Poisson regression models for adjusted relative risk and estimated number of adult incident cancer and related mortality (using Biological Effects of Ionising Radiation VII Phase 2 lifetime attributable risk gender and age specific coefficients).

RESULTS: CT scans numbers and rates increased 136% and 127% respectively from 2006/07 to 2011/12. Only patients aged 0–4 years did not present an increase in CT scanning rates across the study period. The adjusted likelihood of females being scanned was 111% of males. Females were attributed 61% of the mean incident cancers and mean cancer related mortality from 55% of scans performed. Patients 15–44 years were attributed 37% of mean incident cancers and 30% of mean cancer related mortality from 26% of CT scans.

CONCLUSIONS: The increasing CT utilisation in Australia is consistent with comparable nations; however this expansion of utilisation has exposed higher risk groups, producing a disproportionate level of burden for younger adults and females. While a focus on the nature and burden of CT utilisation in youths has emerged, females experience a disproportionate risk and burden from ionising radiation, across all ages, but this is almost completely absent in the scientific literature.