Dawood was concerned about the radiation and what it might mean to the girl's development.
Families have reason to be alert to risks associated with diagnostic tests such as CT scans. Kids' changing bodies and brains are especially sensitive to ionizing radiation from X-rays used in the exams. And because children have longer to live than adults, they're more likely to experience delayed effects of radiation exposure, notably a small potential increased risk of cancer.
That's not a cause to shun the tests, medical experts agree. Medical imaging is an extraordinary tool that allows doctors to make diagnoses, select optimal treatments and save lives, they say.
But it does warrant caution, and medical professionals have been adopting measures to reduce children's radiation exposure. These include adjusting CT scanner settings for smaller bodies, imaging only those areas under medical investigation and using other tests, such as ultrasounds and MRIs, whenever possible.
Yet problems remain. Some hospitals and freestanding imaging centers continue to administer adult-size doses of radiation to children, experts report. Facilities also sometimes scan children repeatedly without cause or expose children's breasts, eyes, thyroids and genitals to unnecessary radiation by scanning too broadly or failing to use protective shields.
"We still have a way to go in terms of optimizing these examinations," said Dr. Donald Frush, chief of pediatric radiology at Duke University Hospital, acknowledging the shortcomings in the medical field.
About 7 million CT scans are administered to children every year; the number is expanding nearly 10 percent annually, according to a 2008 review of radiation risks associated with CT scans for kids in Current Opinion in Pediatrics. Almost one-third of the tests are given to children in their first decade of life.
Safa Dawood had complained of feeling "water in her head" for months before her family doctor ordered a CT scan at Children's Memorial, her mother said. The pain was so bad that the gentle girl with soft dark eyes sometimes would lay her head on a table and weep.
The day of the scan, her mother said she was determined to ask Safa's doctor how much radiation Safa received and what effects it might have on her health. To protect the girl's eyes, a radiologic technologist arranged for the scan to be done at an angle that avoided this sensitive area.
Later, Dawood said the test did not identify a specific problem, and Safa's headaches were continuing. The family lives in Hoffman Estates, Illinois.
Experts say that although children's hospitals have focused on minimizing radiation exposure, most kids get scans in adult hospitals or imaging centers that have been slower to improve practices.
"It's common for us to see children who come in from other hospitals having had scans that often weren't necessary," said Dr. James Donaldson, chairman of medical imaging at Children's Memorial.
Often, scans taken at other institutions have to be redone at Children's because kids weren't prepared properly for tests or because the right area wasn't imaged, he said. Many involved high radiation doses that weren't adjusted for a child's size or weight, Donaldson said.
Changing that is the goal of a national campaign called Image Gently that is endorsed by the American College of Radiology, the American Academy of Pediatrics, the Society for Pediatric Radiology and more than a dozen other U.S. medical organizations.
Participants have agreed not to be sidetracked by ongoing controversy over the relationship between CT medical imaging and cancer. Some experts argue that only high doses of ionizing radiation — much higher than those given via CT scanning — are known to be dangerous; others insist that no dose, however low, can be considered safe. The evidence comes from studies on survivors of the atomic bombs in Japan and on workers exposed to radiation.
"While we don't know with absolute certainty that medical radiation causes cancer, we want to act as if it does," said Dr. Marilyn Goske, chair of the Alliance for Radiation Safety in Pediatric Imaging and head of radiology education at Cincinnati Children's Hospital Medical Center.
At Children's Memorial, that means figuring out how little radiation can be used to obtain an image that's useful to physicians. Think of radiation as light: The more used, the more brilliant the image becomes. The trick is to calibrate the radiation so that the exposure is just enough, Donaldson said.