Answer to Question #5067 Submitted to "Ask the Experts"

Q

When my daughter was three months old she had a hyphema (bleeding in the eye). The emergency room doctor ordered a CT (computerized tomography) of her brain to rule out bleeding in her brain. Later an ophthalmologist said this was unnecessary. She moved during the procedure and it was done twice because the first results were blurry. I have been seeing information on risk of CT in children and wonder what you can tell me.

A

The paper Computed Tomography and Radiation Risks: What Pediatric Health Care Providers Should Know provides a nice overview of pediatric CT, the risks, and methods for minimizing patient radiation exposure. Additionally, I recommend reading the Ask the Experts summary Risk/Benefit of Medical Radiation Exposures for a perspective of radiation risks as they pertain to medical practice.

It is difficult to provide a risk assessment in your particular case because the radiation dose and related risk is very dependent on the machine settings used, e.g., tube current, tube kV, and exposure time. However, there are some generalized estimates of pediatric radiation risk in the literature. In particular, Brenner estimates an increased lifetime cancer mortality risk of 0.04% (1 in 2,500) for a head CT of a young female patient (Brenner 2002). This would be in addition to the normal lifetime cancer mortality risk of approximately 20% (1 in 5). Brenner states, "The individual risks are small, and so the benefit/risk ratio for any individual child would generally be very big."

Brenner's work did highlight the need to develop pediatric-specific imaging protocols, thereby reducing the amount of radiation used to generate clinically useful CT images.

Glenn Sturchio
Certified Health Physicist

Reference
Brenner DJ. Estimating cancer risks from pediatric CT: Going from the qualitative to the quantitative. Pediatric Radiology 32(4):228-231; 2002.