Radiation Risks and Pediatric Computed Tomography (CT): A Guide for Health Care Providers
The use of pediatric CT, which is a valuable imaging tool, has been increasing rapidly. However, because of the potential for increased radiation exposure to children undergoing these scans, pediatric CT is a public health concern. This page discusses the value of CT and the importance of minimizing the radiation dose, especially in children. It will address the following issues:
- CT as a diagnostic tool
- Unique considerations for radiation exposure in children
- Radiation risks from CT in children
- Immediate strategies to minimize CT radiation exposure to children
CT as a Diagnostic Tool
CT can be a life saving tool for diagnosing illness and injury in children. For an individual child, the risks of CT are small and the individual risk-benefit balance favors the benefit when used appropriately.
Approximately 5 to 9 million CT examinations are performed annually on children in the United States. The use of CT in adults and children has increased about eightfold since 1980, with annual growth estimated at about 10 percent per year. Much of this increase is due to its utility in common diseases, as well as to technical improvements.
Despite the many benefits of CT, a disadvantage is the inevitable radiation exposure. Although CT scans comprise up to about 12 percent of diagnostic radiological procedures in large U.S. hospitals, it is estimated that they account for approximately 49 percent of the U.S. population's collective radiation dose from all medical x-ray examinations. CT is the largest contributor to medical radiation exposure among the U.S. population.
Unique Considerations for Radiation Exposure in Children
Radiation exposure is a concern in both adults and children. However, there are three unique considerations in children.
- Children are considerably more sensitive to radiation than adults, as demonstrated in epidemiologic studies of exposed populations.
- Children have a longer life expectancy than adults, resulting in a larger window of opportunity for expressing radiation damage.
- Children may receive a higher radiation dose than necessary if CT settings are not adjusted for their smaller body size.
As a result, the risk for developing a radiation-related cancer can be several times higher for a young child compared with an adult exposed to an identical CT scan.
In the last decade improvements in CT equipment have allowed for better images at lower doses. The use of appropriate settings has also become much more widespread, resulting in reductions in doses for children. There is no need for higher doses in children, and appropriate settings should always be used.
Regardless of the lower doses, multiple scans to an individual patient present a particular concern. In addition, the use of more than one scan (that is, more than one contrast "phase") during a single examination will further increase the radiation dose. In the vast majority of cases, a single scan should be sufficient during pediatric CT.
Radiation Risks from CT in Children
Major national and international organizations responsible for evaluating radiation risks agree that there probably is no low-dose radiation "threshold" for inducing cancers. In other words, no amount of radiation should be considered absolutely safe.
The first study to assess directly the risk of cancer after CT scans in childhood found a clear dose-response relationship for both leukemia and brain tumors: risk increased with increasing cumulative radiation dose. For a cumulative dose of between 50 and 60 milligray or mGy (mGy is a unit of estimated absorbed dose of ionizing radiation) to the head, the investigators reported a threefold increase in the risk of brain tumors; the same dose to bone marrow (the part of the body responsible for generating blood cells) resulted in a threefold increase in the risk of leukemia. For both findings, the comparison group consisted of individuals who had cumulative doses of less than 5 mGy to the relevant regions of the body.
The number of CT sca