CT scans and cancer risk

Over the years, the diagnostic technique of CT, short for computed tomography imaging, has enabled doctors to detect tumors and save lives. The CT technique uses special x-ray equipment in order to obtain cross-sectional images of the body. The images provide detailed images of organs, bones, and other tissues and enable doctors to view structures not easily visible with traditional X-rays. Unfortunately, this advancement in diagnostic imaging technique comes with a price – exposure to higher X-ray radiation and thereby increased risk for cancer.

Researchers at the University of California San Francisco that newer CT scanners may produce better images but also produce variable levels of radiation that is very much unregulated. Concerns are especially expressed because

The ease and convenience of CT scans make clinicians perform the procedure more frequently than before.

More and more CT scans are performed in healthy people for screening purposes that may not be necessary.

Newer models of scanners are much faster in taking pictures, again often leading the clinicians to take more scans than needed.

According to lead investigator Dr. Rebecca Smith-Bindman, a professor of radiology at UCSF:

“In day-to-day clinical practice, we found significant variation in the radiation doses for the same type of computed tomography procedures within institutions and across institutions. Our results highlight the need for greater standardization because this is a medical safety issue.”

The re4searchers estimated the radiation exposure of patients in connection with the 11 most common types of CT procedures used in US clinical practice and the potential cancer risk associated with each type. Their results revealed:

• 1 in 270 women and 1 in 600 men who underwent a CT coronary angiogram at age 40 years will develop cancer due to the procedure.
• The estimated risk for a routine head CT at the age 40 is 1 in 8,100 for women and 1 in 11,080 for men. The risk doubles in patients having the procedure around the age of 20 years.
• In some patient populations, the risk for cancer of certain CT procedures can be as high as 1 in 80.

To put things into perspective, the researchers compared CT radiation exposure to other imaging procedures. They found that the median effective dose delivered through a single CT scan can be equivalent to doses used in 74 mammograms or 442 chest x-rays

The researchers are calling for more regulation in the use of CT scans in the US. They have identified three key practices necessary to improve the safety of CT procedures and the associated radiation doses:

•Reduction of unnecessary studies and studies thought unlikely to influence clinical decisions.

•Standardization and utilization of low-dose and lower-dose protocols for every CT scanner.

•Standardization of radiation doses across patients and facilities through federal legislation and FDA oversight stipulating how CTs are to be safely performed.

Tagged as: cancer risk, computed tomography, CT scans, radiation, radiation doses

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