For almost four decades, computed tomography (CT) has been used to diagnose the presence of cancer by taking cross sectional, three-dimensional images of a particular region of the body where the suspected tumor(s) may reside. CT can also be used to guide biopsies and confirm whether or not cancer is responding to treatment.
However, recent studies have shown that children who receive CT scans have an increased risk for developing cancer in the future. In an article published in JAMA Pediatric, researchers projected that the chances of “radiation-induced cancer” are 4,870 (0.125%) out of 4 million children who have received CT scans. 1
Imaging tests, which are used mainly for diagnostic purposes, send different forms of energy—including x-rays, sound waves, and magnetic fields—throughout the body. Gamma rays, x-rays, and high frequency ultraviolet (UV) rays are examples of ionizing radiation, which can cause DNA mutations and subsequently, cancer. The dose of radiation from one CT scan can be up to three times higher than natural UV light that an individual is exposed to over the course of 1 year (3 mSv compared to 10-20 mSv).4
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Children, in particular, are more susceptible to radiation because of their rapidly growing cells. Even a low level of exposure can put them at risk of developing cancer at a later stage in life. In a recent study by Miglioretti et al, the use of CT was evaluated for children younger than 15 years of age from 1996 to 2010. Data revealed that patients who were female and those who received CT scans at a younger age had a higher risk of developing solid tumors; the trend was similar for those children who received CT scans of the abdomen/pelvis or spine when compared with other areas of the body.
The investigators concluded that reducing the highest quartile of doses to median doses could prevent 43% of these cancers; other studies suggest that one third of these cancers could be prevented if unnecessary scans were not performed.1 By practicing these two methods, the investigators concluded, a total of 62% cancers induced by radiation in children younger than 14 years of age could be prevented.1
In 2008, the United States Food and Drug Administration (FDA) issued a consumer update article focusing on the extra care that is needed for radiological imaging of children.3 Their guidelines indicate that in children, “the lowest radiation dose necessary is used for providing an image from which an accurate diagnosis can be made,” and that whenever possible, other imaging tests such as ultrasound and MRI should be employed for diagnostic purposes.
The FDA also assists Image Gently, a national initiative from the Alliance for Radiation Safety in Pediatric Imaging that helps educate healthcare professionals and parents about special precautions that should be taken for children receiving radiation imaging. Image Gently aims to increase awareness about the risks of CT scans in order to “promote radiation protection in the imaging of children”.
While it is arguable that the benefit of CT scan outweighs any potential cancer risk—particularly because there are many other environmental factors that can contribute to cancer as well—caution should always be taken when performing CT in the pediatric population. Radiation doses must be adjusted for a child, based on their age and size. Despite the recent research, however, CT scan is still a beneficial means of diagnosing cancer, particularly if it means the tumor can be caught early and potentially treated effectively.
References
1. Miglioretti D, Johnson E, et al, “The Use of CT Scan In Pediatric and Associated Radiation Exposure and Estimated Cancer Risk.” JAMA Pediatric, www.jamapeds .com. June 2013.
2. Centers for Disease Control and Prevention. Ionizing Radiation and Diagnostic Examinations. http://www.cdc.gov/nceh/radiation/ionizing.htm. Last accessed, June 17, 2013.
3. U.S. Food and Drug Administration. Radiology and Children: Extra Care Required. http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm048578.htm. Last accessed June 17, 2013.
4. U.S. Food and Drug Administration . reducing radiation from medical X-ray, available at – http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm095505.htm. Accessed on June 21, 2013.
