About half of parents of children with head injuries were aware of the potential cancer risks from CT scans, a Canadian study suggests.

Previously, concerns have been raised that parents' desire for a rapid diagnosis could be contributing to increasing use of computerized tomography in children without fully understanding the potential risks. Researchers in Calgary and Toronto surveyed parents to find out how much they knew.

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CT imaging is an important diagnostic tool and its use has increased rapidly. (Cincinnati Children's Hospital/Associated Press)

Of 742 parents at an emergency department, 357 were aware of the potential cancer risk associated with CT, Dr. Kathy Boutis of Hospital for Sick Children in Toronto and her co-authors said in Monday's issue of the journal Pediatrics.

"Our study revealed that approximately 50 per cent of the parents who participated in this survey were aware that ionizing radiation from a CT of the head may potentially increase a child's lifetime malignancy risk," the study's authors concluded.

"Although the provision of risk information reduced parental willingness to proceed with theoretical CT testing, almost all parents were willing to discuss with the doctor the need for CT imaging if it were recommended."

After parents were informed of the potential risks, willingness to proceed with the scan if the doctor recommended it decreased from 90.4 per cent to 69.6 per cent. Less than six per cent would refuse the CT.

Before parents were asked about the impact of knowledge of risks, they were informed: "Although we are not sure, it has been estimated that a head CT scan in a child may carry an increased lifetime cancer risk around one in 10,000. It is very important to remember that the information from a CT scan may help a doctor decide how to best care for a child."

CT scans use high-powered X-rays to create detailed images. 

Most parents thought that the radiation exposure from a head CT were similar to a regular X-ray. In reality, the radiation exposure from a head CT is 60 to 80 times greater than that of a plain X-ray. The discrepancy suggests that parents have a limited understanding of the radiation exposure, the researchers said.

Raise CT conversation with parents

Of the 496 respondents who said they had some previous knowledge about radiation exposure from diagnostic imaging, the sources given were:

  • Health care workers 26.5%.
  • Paper media 21.7%.
  • Radio/television 16.6%.
  • Internet 16%.
  • Communication with a friend/family member 13.1%.
  • Formal education courses 8.2%.

"Clinicians may therefore have a greater responsibility to initiate conversations with families about risks/benefits of CT rather than do so only when prompted by the parent," Boutis' team suggested.

The researchers noted that a 2012 survey of 126 Canadian doctors working in pediatric emergence medicine suggested 69 per cent would discuss potential cancer risk with families "most of the time" when recommending a CT. 

The response rate for the parent survey was 75 per cent. The respondents were English-speaking parents, many of whom had a postsecondary education. Their children had relatively minor head injuries and the findings may not apply to less educated populations or clinical scenarios, the study's authors said.

The study was funded internally at Sick Kids.