THURSDAY, Jan. 3, 2019 (HealthDay News) — There is considerable international variation in radiation doses for computed tomography (CT) examinations, according to a study published online Jan. 2 in The BMJ.

Rebecca Smith-Bindman, M.D., from the University of California San Francisco, and colleagues conducted a prospective cohort study involving data from more than 2.0 million CT examinations of adults from 151 institutions across seven countries.

The researchers found considerable variation across institutions in the mean effective dose and proportion of high-dose examinations. After adjustment for patient characteristics, there was modest variation (10 to 30 percent) in dose by type of institution and machine characteristics. However, wide variations in doses persisted across countries even after adjustment for patient characteristics, with a fourfold range in mean effective dose for abdomen CT examinations (7.0 to 25.7 mSv) and a 17-fold variation in the proportion of high-dose examinations (4 to 69 percent). Across countries, there was similar variation for chest CT (1.7 to 6.4 mSv; 1 to 26 percent) and combined chest and abdomen CT (10.0 to 37.9 mSv; 2 to 78 percent). Multivariable models revealed that dose variation across countries was mainly due to institutional decisions regarding technical parameters, or how the scanners were used.

“Optimizing doses to a more consistent standard should be possible both within and between countries by modifying the decisions made by radiology teams in developing CT protocols for patients,” the authors write.

Several authors disclosed financial ties to the pharmaceutical and medical device industries.

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