Society News Archive

8 June 2012
Study of CT Scanning of Children Recently Released

We've known for some time that the risk of cancer can be increased by receiving higher radiation doses and that children are an especially important group because they are more sensitive to the effects of radiation than are adults. A new study1, the results of which were published 7 June 2012 in Lancet, confirms this information and shows that the risk of lower radiation doses in children may be greater than previously thought.

Results of the study show, for children under the age of 15, an increase in the risk of brain cancer from head CT scans and in the risk of leukemia from head, abdominal, or pelvic CT scans due to the radiation dose.

What does this mean if your child needs an imaging exam of the head? Should you allow it?

If your child needs an imaging exam (say, for instance, he has fallen from a tree and hit his head on the ground or been in a car accident), the need is justified. This is of primary importance. As a parent or guardian, you must be comfortable that there is a need for the exam and that the exam is necessary for the overall health of the child.

Then the question becomes "What type of imaging exam?" It may not need to be a CT scan. Ask if there are alternative exams that could obtain the needed information (maybe an MRI, which does not use x rays).

If it still comes down to the fact that your child needs a CT scan, if it is justified, it is still safe to do.

Let's look further at the study and its results and what that means to your child.

The published study was very large (about 180,000 patient CT scan records). The authors concluded that the probability of a child being diagnosed with a brain tumor or with leukemia increased by 1 in 10,000 if the child was exposed to about 10 milligray2 of radiation (about the radiation dose received from one or two CT scans of the head) before the age of 10. This means if 10,000 children under the age of 10 underwent one or two CT scans, one of them may be diagnosed with a brain tumor or leukemia. Compare this to the lifetime risk of developing cancer for the general population, which is 1 in 3 (for every three people living, one will develop cancer).

While the increase reported in the study is small and is outweighed by the benefits of CT scanning when the scan is justified, it shows the importance of showing a need for the radiation imaging exam and the need to continually work to keep radiation doses to patients, especially children, as low as possible without affecting the diagnostic integrity of the exam. 

1Pearce MS, Salotti JA, Little MP, McHugh K, Lee C, Kim KP, Howe NL, Ronckers CM, Rajaraman P, Craft AW, Parker L, Berrington deGonzalez A. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet [early online publication]. 7 June 2012. Available at: Accessed 8 June 2012.

2A milligray, or mGy, is a unit of radiation absorbed dose.