Radiation from CT scans may raise cancer risks

Our Review Summary

There is no doubt that advances in imaging technology have revolutionized how we diagnose and treat disease. The past two decades have seen dramatic increases in the utilization of high tech imaging tests such as magnetic resonance imaging (MRI) and computed tomography (CT). The ever expanding list of indications and uses for these technologies have been a boon for device manufacturers, hospitals and radiologists, however is there a potential for overuse? At what point may the harms of these tests outweigh the benefits? Two new studies published in The Archives of Internal Medicine highlight rather starkly the particular harm of radiation exposure from CT scanning. In one study, the authors predict that between 15,000 and 45,000 future cancers could be caused by ionizing radiation from CT scans.

This story clearly describes the harm of radiation exposure from CT scanning. It could have also mentioned that excessive CT scanning can also lead to unecessary follow-up testing and/or procedures for suspicious findings that turn out to be benign.

The story could have been improved by elaborating on the strength of the evidence to support the findings of the number of deaths attributable to CT scans. The numbers cited in the story come from a risk model that estimates the expected number of deaths based on the amount of radiation exposure in a particular year. These deaths were not directly observed, but were rather predicted. This approach, while valid, has its own limitations and set of caveats that should be mentioned. It could have also discussed costs of CT scanning, which are substantial and increasing.

The story does not quote sources other than the authors of the study. The story should have quoted independent experts who could have provided perspective on the importance of these results.

Finally  the story missed some wonderful opportunities to educate consumers on the problem of radiation exposure. The second article in the journal highlights the dramatic differences in radiation exposure in routine clinical CT scans in four academic hospitals.  The radiation differences noted were significant with up to a 22 fold difference in exposures seen in the same scans.  Radiation exposure from CT scans appears to represent a public health problem, which is particularly important in young and middle aged women.  No attempts were made to point out that in many instances other diagnostic methods are available, including MRI, ultrasound and routine xrays that involve less or no radiation. 

Why This Matters

It matters because, as the story explains, "We’re doing millions of CT scans every year and the numbers are increasing."