We do x-rays on children when the expected health benefit is greater than the tiny increased risk of eventual cancer. A typical x-ray delivers 0.01 REM. CT scans give us much more information, but they also deliver as much radiation as getting 300 regular x-rays — or 600, if the CT scanner has not been adjusted for children. Children are far more sensitive to the risks of radiation than are adults.
The safety of CT scans was a hot topic at the annual meeting of the American Academy of Pediatrics in October 2002. A few months earlier, the National Cancer Institute had sent out a letter to physicians in an effort to decrease unnecessary CT scans in children. In the previous decade, the number of CT scans in children each year had skyrocketed 700 percent — into the millions. At the AAP meeting, evidence was presented suggesting that among the many children who receive CT’s in the ER after head trauma, only seven percent actually have an injury inside the skull.
How do you know whom to CT? Preliminary evidence suggests that after head trauma the most important kids to scan include those under 2, those in bicycle accidents, those who are dizzy, who have changes in behavior or vision, and those with a skull fracture. How would you know if there had been a subtle skull fracture? People often use the CT to answer this question, but you may be better off to get a regular x-ray first to decide.
I was taught as a resident that skull x-rays were obsolete, that if you were wondering about a fracture you should just get the CT. I now disagree. CT’s are wonderful, lifesaving technology, but as with antibiotics, it is wise to ask if there is a safe way to diagnose the situation without a CT. If a CT is recommended, it is wise to ask that a child-appropriate level of radiation be used, to cut the radiation risk in half.