Computed Tomography (CT) scans are powerful diagnostic tools that use X-rays to create detailed images of the inside of the body. While they are invaluable for detecting injuries, infections, and diseases, CT scans expose patients to ionizing radiation, which has raised concerns about potential long-term health effects, especially in children. The question of whether CT scan radiation can increase the risk of childhood cancer is complex but increasingly supported by scientific evidence.
Children are more sensitive to radiation than adults because their cells are dividing more rapidly, and their bodies are still developing. This heightened sensitivity means that the ionizing radiation from CT scans can cause damage to DNA, potentially leading to mutations that may initiate cancer. Unlike adults, children also have a longer expected lifespan ahead, providing a larger window of time during which radiation-induced cancers could develop.
Recent large-scale studies involving millions of children have found a clear association between radiation exposure from CT scans and an increased risk of certain cancers, particularly hematologic cancers such as leukemia and lymphoma. These studies tracked children who underwent medical imaging over many years and found that even relatively low doses of radiation—less than 50 milligray (mGy)—were linked to a measurable increase in cancer risk. For example, children who had two or three CT scans showed about a 50% higher risk of developing blood cancers compared to those who had only one scan or none at all.
The risk appears to be dose-dependent, meaning that the more CT scans a child undergoes, the greater the cumulative radiation dose and the higher the risk of cancer. Head CT scans, which deliver higher doses of radiation compared to other types of imaging like chest X-rays, have been particularly associated with increased risks of brain and blood cancers. Children who had one or two head CT scans faced nearly double the risk of hematologic cancers, and this risk increased to about 3.5 times with multiple scans.
It is important to understand that while the relative risk increases, the absolute risk remains small. Childhood cancers are rare, so even a doubling of risk translates to a small number of additional cases. However, because CT scans are commonly used in pediatric medicine, the cumulative impact on public health is significant enough to warrant caution.
Medical professionals emphasize the principle of “as low as reasonably achievable” (ALARA) when it comes to radiation exposure. This means CT scans should only be performed when medically necessary, and the lowest possible radiation dose should be used to achieve diagnostic quality images. Alternative imaging methods that do not use ionizing radiation, such as ultrasound or MRI, are preferred when appropriate.
In summary, CT scan radiation can increase the risk of childhood cancer, particularly blood cancers and brain tumors, with risk rising alongside the number of scans and the radiation dose received. This risk, while small in absolute terms, is significant enough that careful consideration and judicious use of CT imaging in children are essential to minimize unnecessary radiation exposure.